A review of employment outcome measures in vocational research involving adults with neurodevelopmental disabilities

Abstract

BACKGROUND:

Adults with neurodevelopmental disability (NDD) have poor employment outcomes when compared to their peers without disabilities. Examining employment outcomes beyond common dichotomous descriptive metrics (i.e., employed versus unemployed) depends on the use of standard measures and structured procedures.

OBJECTIVE:

This review of vocational research literature focused on identifying measures of employment outcomes for adults with NDD.

METHODS:

Searches were conducted across five databases - ERIC, MEDLINE, CINAHL, HaPI, and PsycINFO. Screening was conducted in duplicate, with all disagreements adjudicated by the senior researcher.

RESULTS:

A total of 45 articles met inclusion criteria, and data extraction revealed that 64 different employment measures were used in these vocational research studies.

CONCLUSIONS:

This work summarizes the employment measures for people with NDD utilized in the literature. Descriptions of these measures were provided and coding by person and environment themes, which is a useful resource for planning future vocational research for people with NDD.

Keywords

Adults neurodevelopmental disabilities employment outcome measures review

1 Introduction

1.1 Global issue of neurodevelopmental disabilities and employment

In the industrialized world, approximately one in six children have neurodevelopmental disabilities (NDD), such as, cerebral palsy, autism, attention deficit hyperactivity disorder, and developmental delay (Dietrich et al., 2005). With an increase in the lifespan of children with NDD, recent reports, including the World Health Organization (WHO), have emphasized the importance of a lifespan approach to care and community integration, including employment (WHO, 2013). Data from the WHO from across 51 countries provides clear evidence of lower employment rates for persons with disabilities (52.8% males, 19.6% females) than for their peers without disabilities (64.9% males, 29.9% females) (WHO, 2011). For persons of working age with disabilities, data from the developed world show rates are as low as 50 to 70%, at least twice the rate of persons without disabilities (International Disability Rights Monitor, 2004; WHO, 2011). In developing countries, these rates are much worse since the focus of employment for people with NDDs was largely unaddressed (Durkin, 1991), and recent estimates of unemployment may be as high as 80 to 90% (Zarocostas, 2005).

In 2006, the United Nations (UN) adopted the Convention on the Rights of Persons with Disabilities (CRPD), which specifies the right to equal participation in work and employment. This document calls for access to vocational guidance, placement and training programmes, as well as ensuring opportunities for job placement, accommodations and supports (CRPD, article 27, items a-k) (UN, 2006). To address the issues related to employment for people with NDD, it is important to collect valid, reliable and relevant data that can be uniform around the world (WHO, 2013). The WHO Global Disability Action Plan (2014–2021) calls for member states to collect data that is relevant and internationally comparable to support research on disability and related services (WHO, 2015). A fundamental step in this global action plan involves identifying and developing sound measures, including standardized instruments and procedures, especially in the area of employment.

1.2 Vocational rehabilitation services and research tools

Over the last 20 years, there have been initiatives around the world aimed at providing vocational rehabilitation to persons with disabilities (Chan et al., 1997; UN, 2006; WHO, 2011; WHO, 2013). Specific examples from North and South America, Europe, Asia and Africa have demonstrated how employment agencies have responded to the needs of job seekers with disabilities by expanding their activities for improving employment opportunities (WHO, 2011). Vocational rehabilitation (VR) training programmes are ultimately designed with the goal of enabling better rates of participation in the labour market. The foundation of VR services involves information gathering about the client’s interests and abilities, in order to establish a good job matching and facilitate an on-site training plan (Hall et al., 2014).

Related work opportunities have historically been available through sheltered workshop environments, supported community settings, or competitive placements within the broader community (Jiranek & Kirby, 1990; Kober & Eggleton, 2005; Cimera et al., 2012). Disability researchers have traditionally examined the success of VR programs through descriptive employment status metrics. In many studies, the most commonly explored metrics include job status (i.e., employed or not) and wages (i.e., hourly rate) (Cimera et al., 2010, 2011). These are important metrics contributing to the global picture of employment for persons with disability; however, to better measure the sensitivity of factors that impact on employment, both “personal” and “environmental” factors for work functioning must be considered (WHO, 2011b; WHO, 2011). When planning future interventions and studies, researchers should think beyond monitoring typical employment outcomes of job rate and compensation. While these data are essential for informing disability policy, they are not sufficient to informing new directions of practice towards meeting local needs.

VR professionals and researchers have a wide array of employment outcome instruments from which to choose because of the different sectors involved, such as health, education and social services. These sectors often operate independently, and to date there is no centralized list of employment outcome measures utilized across sectors. Knowing what other instruments are available in the literature is useful because this saves work and the necessity of constructing new measures (Norman & Streiner, 2008). Furthermore, understanding the properties of existing employment outcome measures across NDD can provide insights on the common and distinct constructs measured for different groups and in different contexts. These insights can be helpful with identifying common tools to be used for better surveillance and service development, as well as inform specific diagnostic groups within NDD about different constructs that can better inform employment outcome evaluation. To identify the employment outcomes across sectors in the field of VR, a review was conducted to survey the standard scales and systematic procedures used for employment outcomes measured in neurodevelopmental disability research.

2 Methods

The objective of this study is to identify the peer review literature for employment outcome instruments used by VR disability researchers for adults with NDD. Inclusion criteria consisted of studies involving adults who had to have exposure to VR services or employment experience, and were evaluated beyond traditional employment outcomes (i.e., job status and wages) with assessment tools or systematic procedures. The research question is the following: for adults with NDDs, what employment outcome measures are utilized in the peer reviewed literature?

2.1 Search strategy

The search strategy involved three domains: population (i.e., people with neurodevelopmental disabilities), exposure (i.e., employment/vocational programs), and outcome (i.e., employment-related evaluation). To be representative of individuals across all disabilities, population terms were derived from NDD understood as disabilities acquired or manifest during youth, as defined by the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) and supplemented with information from the ICF-10 (APA, 2013). There were no limits for date of publication; however, non-English studies were excluded. The final list of search terms covered individualized terms for each database for population (40), exposure (58) and outcomes (16).

One reviewer (HV) conducted the searches in five international databases – Education Resources Information Center (ERIC), MEDLINE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Health and Psychosocial Instruments (HaPI), and PsycINFO – for all publications up to March 2015.

2.2 Eligibility criteria and screening

Prior to screening, eligibility criteria were developed as in Table 1. Using these predetermined criteria, two reviewers (HV and RP) conducted independent screening in two stages. First, after duplicate removal, title and abstract screening was conducted for all records. Second, with the refined number of selected articles, full texts were screened and presented for data extraction using the same pre-determined eligibility criteria as outlined in Table 1. At the end of each screening stage- title and abstract, and full text screening- reviewers submitted unresolved disagreements for adjudication by the senior investigator (BDR).

Table 1
Eligibility and screening criteria for journal article selection process

Reasons for inclusion

•Study target populations are adults with neurodevelopmental disability (NDD) diagnosis

•NDD was acquired/manifest during youth (i.e., from 0 to 22 years)

•Adults are employed, previously employed, or involved in vocational training program

•Employment outcomes are evaluated with measurement tools or standardized procedures

•Record must available in English translation

•Record must be a journal article

Reasons for exclusion

•Study target populations are family/caregivers/support providers/therapists of persons with NDD

•Study target populations are employers/coworkers assessed primarily for knowledge of NDD

•NDDs are characterized/evaluated as a psychiatric/mental health issues

•NDDs are only assessed for stigma/stress/loneliness/disclosure

•NDDs are characterized/evaluated only as barriers to employment

•Non-employment outcomes are the primary focus for measurement (quality of life, recreation & exercise)

•Employment outcomes are based on descriptive status alone (employed or un-employed)

•Employment outcomes are based primarily on cost benefit analyses (especially of a program)

•Employment outcomes are based primarily on ergonomic work aids/issues

•Employment predictors studies

•Transition age youth studies

•Review of previous studies

Reasons for inclusion
•Study target populations are adults with neurodevelopmental disability (NDD) diagnosis
•NDD was acquired/manifest during youth (i.e., from 0 to 22 years)
•Adults are employed, previously employed, or involved in vocational training program
•Employment outcomes are evaluated with measurement tools or standardized procedures
•Record must available in English translation
•Record must be a journal article
Reasons for exclusion
•Study target populations are family/caregivers/support providers/therapists of persons with NDD
•Study target populations are employers/coworkers assessed primarily for knowledge of NDD
•NDDs are characterized/evaluated as a psychiatric/mental health issues
•NDDs are only assessed for stigma/stress/loneliness/disclosure
•NDDs are characterized/evaluated only as barriers to employment
•Non-employment outcomes are the primary focus for measurement (quality of life, recreation & exercise)
•Employment outcomes are based on descriptive status alone (employed or un-employed)
•Employment outcomes are based primarily on cost benefit analyses (especially of a program)
•Employment outcomes are based primarily on ergonomic work aids/issues
•Employment predictors studies
•Transition age youth studies
•Review of previous studies

2.3 Data extraction

In Fig. 1, an outline of the stages of our search, screening, and selection process are presented. For all journal articles in the included article pool, and using a standardized form, one reviewer (HV) extracted all data according to the following criteria: authors, year of publication, country where research was conducted, target population characteristics (i.e., age, gender, type of NDD diagnosis, and employment or VR exposure), and study characteristics (i.e., research study type, comparison groups included, and rater/assessor groups included).

Fig.1

PRISMA flow diagram of journal article selection process. Source: Adapted from PRISMA (Moher et al., 2009) flow diagram.

Both reviewers (HV and RP) conducted data extraction for the measures and procedures utilized to collect employment outcomes. For those measures that were not fully described within the selected journal article, the original source document was searched for a detailed description and a copy of the tool, if publically available on the world-wide-web.

In Table 2, a list of included articles is provided with extracted data on target populations, as well as the employment measures. For each measure, a brief description about major domains and items are provided. One reviewer (HV) scanned tool domains and individual items from each measure to code into work themes describing the essence of work being measured. The wording utilized for each theme was derived based measurement constructs described by the domains and items of each measure. Validity of the coding themes was confirmed through ongoing consultations between this reviewer and with the senior investigator (BDR). Common terminology was utilized where possible to improve the comparability of measures.

Table 2

Included journal articles and data extraction of employment outcome measures (with brief description, as well as person and environment themes)

[Ref]	Author (Year), Country	NDD	Administration Mode	Name of Measure (Author & Year of measure, if different from study article)	Brief Description of Measure (General characteristics, Domains, & Individual Items when available)	Person & Environment Themes
[1]	Bullis & Foss (1986), USA	MR	Self-report or Verbally administered	Test of Interpersonal Competence for Employment (TICE)	Test of social skills & interpersonal competence within the areas of relationships with supervisors & coworkers. 2 domains: 1) Supervisor related areas, 3) Coworker related areas. 6 subdomains: 1) Handling criticism & correction, 2) Requesting assistance, 3) Following instructions, 4) Cooperative work behavior, 5) Handling teasing & provocation, 6) Resolving personal concerns.	Work Readiness, Work Skills, Social Integration, Work Culture
[2]	Burnham & Housley (1992), USA	MR, LD	Self-report or Verbally administered	Successful Employment Survey (SES) Form-A & Form-B	2 parts: A) Employer/Service provider ratings, B) VR student employee ratings. 14 items: 1) Pride in work, 2) Amount of money made, 3) Good attendance at work, 4) Dependable transportation, 5) Talks easily with supervisors, 6) Talks easily with co-workers, 7) Encouragement from family, 8) Entry level job skills, 9) Employee likes work, 10) Works well with others, 11) Desire to work, 12) Job security, 13) Accepts praise & criticism, 14) Dresses appropriately.	Employment Success, Work Skills, Work Personality
[3]	Chen et al. (2012), Taiwan	ID	Self-completed	Service Quality & Corporate Social Responsibility (CSR) Survey	Consumer reported survey from the perspective of customers of a sheltered employment bakery (adopted from DINESERV^*).	Service Quality
					4 major parts: 1) Service quality, 2) Corporate social responsibility, 3) Post-purchase Intention, 4) Customer satisfaction.
					^*DINESERV (Stevens et al 1995) measure of perceived service quality of restaurant customers.
					5 dimensions: 1) Tangibles, 2) Reliability, 3) Responsiveness, 4) Assurance, 5) Empathy.
[4]	Cimera et al. (2010), USA	ID/MR	Database survey	RSA 911 database of closed cases	4 areas: 1) Rates of employment, 2) Wages earned, 3) Hours worked, 4) Cost efficiency.	Employment Status (rate)
[5]	Cimera & Burgess (2011), USA	ASD	Database survey	RSA 911 database of closed cases	5 areas: 1) Successfully (competitively) employed, 2) Hours/wk, 3) Wages/month, 4) Monthly net benefit, 5) Benefit cost ratio.	Competitive Employment Status
[6]	Cimera et al. (2012), USA	ASD	Database survey	RSA 911 database of sheltered & non-sheltered employees	4 areas: 1) Rate of employment, 2) Hours of work, 3) Earnings, 4) Cost to serve.	Employment Status (rate)
[7]a	Cobigo et al. (2009), Canada	ID	Rater-reported	Quebec Adaptive Behavior Scale (QABS) (Maurice, Morin, Tasse’, Garcin, & Vaillant 1997)	French instrument assesses adaptive behaviours with a global score of general adaptive skills & 7 partial scores. 2 of 7 partial score areas: 1) Communication, 2) Vocational skills.	Work Skills
[7]b			Direct observation	Work Task Preference (WTP) Assessment	WTP assessment procedure via observations of behaviours.	Work Preference
					5 areas of observation: 1) Choice, 2) Refusal, 3) Positive emotional behaviours, 4) Disruptive (off-task) behaviours, 5) Length of time spent on task.
[7]c			Rater-administered	Inventaire visual des interets professionnel (IVIP) (Dupont, Gingras, & Tetreau 2000)	An instrument for assessing vocational interests using 80 pictures of work areas. (alternative to WTP)	Work Preference
[7]d			Rater-administered	Multiple stimuli without replacement method (MSWO) (Hagopian, Long, & Rush 2004)	An easy & quick assessment procedure, consisting of the simultaneous presentation of all possible work task pairs as opposed to the pair presentation. (alternative to WTP)	Work Preference
[8]a	Dipeolu (2007), USA	LD	Self-report or Verbally administered	Career Thoughts Inventory (CTI) (Sampson et al 1996)	An inventory for assessing work/career readiness and thoughts. 3 areas: 1) Decision-making confusion, 2) Commitment anxiety, 3) External conflict.	Work Readiness
[8]b			Self-report or Verbally administered	Career Maturity Inventory-Revised (CMI-R) (Crites & Savikas 1995)	An inventory of work/career maturity of beliefs. 3 scales: 1) Attitude, 2) Competence, 3) Career maturity total.	Work Readiness, Work Motivation
[8]c			Self-report or Verbally administered	My Vocational Situation (MVS) (Holland et al 1980)	An instrument to measure work/career interests, goals, personality, and talent. 3 scales: 1) Vocational identity, 2) Occupational information, 3) Barriers to occupation.	Work Readiness, Work Motivation
[9]a	Farris & Stancliffe (2001), Australia	ID	Job-coach administered interview & observations	Co-Worker Involvement Instrument (CWII) (Rusch et al 1989)	Areas of worker interaction rated by model program directors or supported employment services. 9 areas: 1) Physical integration, 2) Social integration, 3) Training, 4) Associating (frequency), 5) Associating (appropriateness), 6) Befriending, 7) Advocating, 8) Evaluating, 9) Giving information.	Social Integration, Workplace Support
[9]b			Self-report	Values Questionnaire (York 1991)	6-item assessment of values about people with a disability in the workplace.	Coworker Involvement
[9]c			Self-report	Co-worker Survey	7 areas: 1) Job satisfaction before training, 2) Satisfaction after becoming a co-worker trainer, 3) Recognition received from management, 4) Support provided by open employment agency, 5) Co-worker training course, 6) Supported employee’s work, 7) Supported employee fit into the workplace.	Job Satisfaction, Job Supports
[9]d			Database survey	Supported Employee Outcomes data retrieval from NIMS data or agency records	Supported employee outcomes retrieved from NIMS database or agency records. 3 areas: 1) Employment hours, 2) Wages, 5) Job tenure.	Employment Status (tenure added)
[10, 11]	Fillary & Pernice (2005, 2006) New Zealand	ID	Semi-structured interview & observations	Workplace Culture Survey (WCS) (Hagner 2000)	Workplace culture strength score derived from part A, & social inclusion level score derived from part B. 2 parts: A) Employer part; B) Supported employees & TD co-workers part. 5 areas of assessment: 1) Orientation & review, 2) Workplace policies, 3) Job design, 4) Workplace customs & practices, 5) Workplace social opportunities.	Workplace Culture, Social Inclusion
[12, 13]	Gal et al. (2013; 2015), Israel	HFASD	Interview-administered	Autism Work Skills Questionnaire (AWSQ)	A self-report vocational profile assessment developed to produce a good person-job match. 6 Domains: 1) Work habits, 2) Working style, 3) Independence in work & studying, 4) Sensory responses & needs, 5) Routine daily activities, 6) Interpersonal skills.	Job Skills, Work Personality
[14]a	Gaylord-Ross et al. (1995), USA	MR & DB	Direct observations	On-site interaction Observations	Social interaction with & social acceptance by non-disabled co-workers. 3 interactions features: 1) Exchange type, 2) Number, 3) Duration.	Social Integration
[14]b			Self-report	Social Validity Questionnaire (SVQ) (Park et al 1991)	10-item social validation questionnaire completed by employment specialist & non-disabled coworkers.	Social Interaction, Social Acceptance
[15]a	Hall et al. (2014), USA	ID	Self-report or Verbally administered	Web-based Job Preference Assessment (JPA)	Web-based assessment completed by students.	Job Preference
[15]b			Job coach administered	Web-based Job Matching Assessment (JMA)	Web-based assessment completed by job coaches.	Job Matches
[15]c			Researcher designed VR procedure	Job Sites/Conditions developed by Researcher	Job sites or conditions matched to performance & satisfaction, supplemented with work sessions & job tasks teaching. 2 job sites/conditions: 1) High preference & match, 2) Low preference & match.	Work Skills, Job Performance, Job Satisfaction
[15]d			Direct observations	On-site Observation conducted by Researcher & Job Coaches	4 observation areas: 1) Productivity, 2) Accuracy of job tasks, 3) Choice/satisfaction, 4) Independent observer’s judgement.	Work Skills, Job Satisfaction
[16]a	Howlin et al. (2005), UK	AS, HFASD	Database survey	NAS Prospectus Database (8-year follow-up)	4 observation areas: 1) Number of jobs obtained, 2) Hours worked, 3) Contract duration, 4) Type of enterprise.	Employment Status
16]b			Self-report	Satisfaction report	Satisfaction rated with statement such as “I feel much more confident than before and better able to cope with my present job”.	Job satisfaction
[16]c			Rater-reported	Social integration report	2 perspectives: Social integration rates with statements from employees, & compared to managers.	Social integration
[17]	Jiranek & Kirby (1990), Australia	ID	Interview-administered	In-depth Study Questionnaire of Job Satisfaction & Well-being	In-depth study questionnaire of job satisfaction and well-being (with sections informed by various standard measures). 5 sections: 1) Competency test, 2) Social & leisure activities, 3) Psychological scales (negative mood, self-esteem, locus of control, depressive affect)‘, 4) Job satisfaction“, 5) Personal & employment details (time in competitive employment).	Work Satisfaction, Perceptions of Control, Employment Status
[18]a	Kober & Eggleton (2005), Australia	ID	Interview-administered	Quality of Life Questionnaire (QOL.Q) (Schalock & Keiterh 1993)	40 items assessing 4 factors of personal levels affecting work ability. 4 subdomains: 1) Satisfaction, 2) Competence/Productivity, 3) Empowerment/Independence, 4) Social belonging/Community integration.	Work Satisfaction, Social Integration
[18]b			Interview-administered	Functional Assessment Inventory (FAI) for 2 factors (Crewe & Athelstan 1984)	30 items assessing capabilities & deficiencies related to work ability. 2 areas: 1) Work capabilities, 2) Deficiencies.	Work Skills
[19]	Li & Tsang (2002), Hong Kong	MR	Direct observations	Becker Work Adjustment ProfileChinese Version (BWAP) (Becker 1989)	A rater-completed profile of observed work behaviour and competency. 6 Domains: 1) Work attitudes & performance skills, 2) Cognitive skills, 3) Work related social behaviors, 4) General social behaviors, 5) Hygiene & clothing.	Work Skills, Job Performance, Work Readiness, Social Integration
[20]	Malgady & Barcher (1982), USA	MR	Rater-administered	Vocational Adaptation Rating Scales (VARS)	Assessment measure of maladaptive social behavior related to vocational success. 6 scales: 1) Verbal manners, 2) Communication skills, 3) Attendance & punctuality, 4) Interpersonal behavior, 5) Respect for property, rules, regulations, 6) Grooming & hygiene. Concurrent validity testing conducted with 2 measures: ^San Francisco Vocational Competency Scale (SFVCS) (Levine & Elzey 1968) ^AAMD Adaptive Behaviour Scale Vocational Activity Scale (Nihira et al 1974)	Work Personality, Work Adaptation
[21, 22, 24]	Mank et al. (1997, 1997b, 1998, 2000), USA	MR	Rater-administered	In-depth Survey of Natural Supports & Job Typicalness	62 items across 3 areas: 1) Demographics, 2) Disability, 3) Employment features (including worksite interactions). 5 job typicalness areas: 1) Job Acquisition & Hiring, 2) Compensation {work schedule, wages, weekly hours}, 3) Work Roles, 4) Orientation & Training, 5) Social/Integration Aspects.	Job Typicalness, Natural Supports, Employment Status, Social Integration
[25]a	Martorell et al. (2008), Spain	ID	Interview-administered	World Health Organization Disability Assessment Schedule- Second Version (WHO-DAS II) (WHO 2000)	6 domains of function: 1) Cognition - understanding & communicating, 2) Mobility- moving & getting around, 3) Self-care- hygiene, dressing, eating & staying alone, 4) Getting along- interacting with other people, 5) Life activities- domestic responsibilities, leisure, work & school, 6) Participation- joining in community activities.	Job Personality (Functioning)
[25]b			Interview-administered	Arc’s Self-Determination Scale (ARC’s) (Wehmeyer 1995)	4 subdomains: 1) Autonomy, 2) Self-regulation, 3) Psychological Empowerment, 4) Selfrealization. 1 total score: 1) Self-Determination.	Work Readiness
[25]c			Interview-administered	Psychiatric Assessment Schedule for Adults with Developmental Disability (PAS-ADD 10) (Costello et al 1997)	A semi-structured clinical interview using a computer algorithm to produce diagnoses and other diagnostic information based on ICD 10 criteria.	Job Personality
[25]d			Interview-administered	Inventory for Client and Agency Planning (ICAP) for behavioural problems (Bruininks et al 1986)	Behavioural problems general index: a tool designed for assessment of adaptive & maladaptive information to determine the type & amount of social assistance that people may need.	Job Personality
[25]e			Interview-administered	Personal factors & work outcomes Survey	Personal variables: 1) Demographics, 2) Residence type, 3) Pension benefits. 2 employment types: 1) Sheltered workshop, 2) Sheltered employment programme.	Employment Status
[26]a	Morgan (2011), USA	ID	Self-reported	Self-Directed Search (SDS) Form E (Holland 1994)	A non-net based questionnaire, with Form E especially developed for individuals with grade 4–6 reading levels, qualified as a job matching assessment for relationship between skills & preferred job requirements. 3 assessment areas: 1) Job preferences, 2) Skill levels, 3) Job requirements.	Job Preference, Job Skills
[26]b			Interview-Administered	Job Match Pattern (JMP) Instrument (Swenson 2005)	A non-net based instrument to assess the extent to which cognitive abilities, interest, & personality traits match particular job requirements. 4 assessment areas: 1) Cognitive abilities, 2) Interests, 3) Personality traits, 4) Job requirements.	Job Preference, Job Skills
[26]c			Rater-reported (teachers/job coaches)	Yes Job Search website (www.yesjobsearch)	A job matching website, informed by the O^*NET database of importance ratings for specific occupations. 3 importance rating areas: 1) Knowledge, 2) Skills, 3) Abilities.	Job Preference, Job Skills
[27]	Novak & Rogan (2010), USA	MR, ASD, EBO, CP, Other	Rater-reported	Employment Specialist Survey (ESS)	Social integration outcomes informed by Intergroup Contract Model & by Workplace Contact Model. 12 variables: 1) Opportunity to interact, 2) Equal status, 3) Outcome dependency, 4) Authority support, 5) Vocational competence, 6) Social competence, 7) Workplace culture, 8) Coworker interventions, 9) Social participation, 10) Coworker attitudes, 12) Employees’ feeling of social support. 5 Employment outcomes: 1) Type of work, 2) Hours worked, 3) Job tenure, 4) Wages, 5) On site job support.	Social Integration, Workplace Culture, Job Supports
[28] a	O’Sullivan & Strauser (2015), USA	LD, Physical, Psych	Self-report	Developmental work personality scale (DWPS) (Strauser & Keim 2002)	A 26-item screening instrument for adults to assess childhood experiences believed to contribute to work personality. 5 areas: 1) Role Model, 2) Social Skills, 3) Work Tasks, 4) Developmental work personality, 5) Adult work behaviours	Work Personality, Interpersonal skills
[28]b			Self-report	Work Personality Profile-Self-Report (WPP-SR) (Bolton 1992)	A 58-item Instrument assessing skill levels in dealing with the work environment, frequently used in rehab settings to assess typical job maintenance behaviours. 5 scales: 1) Task orientation, 2) Social skills, 3) Work motivation, 4) Work conformance, 5) Personal presentation.	Work Motivation, Work Personality, Interpersonal skills
[28]c			Self-report	Revised NEO Personality Inventory (NEO-FFI) (Costa al 1992)	Assessment measure for personality traits in 5 areas, with 2 subscales particularly related to positive expression of work behaviours (but final 3 unrelated). 2 (of 5) domains: 1) Agreeableness, 2) Conscientiousness.	Work Personality
[29]a	Painter et al. (2008), USA	ADHD	Self-report	Minnesota Satisfaction Questionnaire (MSQ) (Weiss et al 1967)	A measure of 20 items related to vocational needs and values satisfied within a vocational setting. 3 scales: 1) Intrinsic satisfaction, 2) Extrinsic satisfaction), 3) General satisfaction.	Job Satisfaction
[29]b			Self-report	Career Thoughts Inventory (CTI) (Sampson et al 1996)	An inventory for assessing work/career readiness and thoughts. 3 areas: 1) Decision-making confusion, 2) Commitment anxiety, 3) External conflict.	Work Readiness
[30]	Parent et al. (1996), USA	CP, Physical, MR, TBI, Mental	Interview-administered	Consumer Satisfaction Survey (CSS)	An assessment interview for levels of satisfaction with supported employment services. 8 categories: 1) Consumer & job demographics, 2) Pay & benefits, 3) Supervision, 4) Relationship & teamwork, 5) Job conditions, 6) Job satisfaction, 7) Job coach satisfaction, 8) Service satisfaction. 3 scales: 1) Job satisfaction, 2) Service satisfaction, 3) Choice making in the workplace.	Employment Status, Work Supports, Job Satisfaction
[31, 32]a	Parr et al. (2013), USA	ASD	Interview-administered	List of exemplar behaviours of supervisor leadership behavior (adapted from Yukl 2010, & from Rafferty & Griffin 2004)	Participants rated frequency of supervisors’ behaviours from list of exemplar behaviours. 3 leadership styles: 1) Transformational, 2) Two-factor Model, 3) Authentic.	Leadership Preference, Workplace Culture
[31, 32]b	Parr & Hunter (2014), USA		Interview-administered	Michigan Organizational Assessment Questionnaire (MOAQ) (Cammann et al 1979)	Job satisfaction was measured using 3 items for the MOAQ. Intentions to turnover were measured using 3 items from the MOAQ.	Job Satisfaction, Turnover Intentions
[31, 32]c			Interview-administered	Allen and Meyer’s Affective Commitment Scale (Allen & Meyer 1990)	Organizational commitment was assessed using 8 items from the ACS. 3 commitment scales: 1) Affective commitment to the organization, 2) Continuance, 3) Normative.	Organizational Commitment
[31, 32]d			Interview-administered	Utrecht Work Engagement Scale (UWES) (Schaufeli et al 2006)	Work engagement was assessed using 6 items from the shortened form of the UWES. 3 scales: 1) Vigor, 2) Dedication, 3) Absorption.	Work Engagement
[31, 32]e			Interview-administered	Self report of performance perceptions	Performance rated by “my supervisor would probably rate my overall performance as...”	Job Performance, Job Skills
[33]	Paul (1992), USA	MR	Rater-assessment	Pennsylvania Bi-Manual Worksample (PBWS) Assessment (Roberts 1969)	Battery of work skills performance tests requiring assembly & disassembly of nut & bolt units. 5 areas: 1) Finger dexterity of both hands, 2) Gross movements of both arms, 3) Eye-hand coordination, 4) Bimanual coordination, 5) Ability to use both hands in cooperation.	Work Skills, Work Performance
[34]	Rose et al. (2010), UK	ID, ASD, LD, MR MH, Other	Interview-administered	Work Readiness Scale (WRS)	A 13-item self-report scale via interview, adapted from the Readiness to Change Questionnaire, incorporating 3 stages from the transtheoretical model of intention to change. 3 scales: 1) Pre-contemplation items, 2) Contemplation items, 3) Action items.	Work Readiness, Work Motivation
[35]	Ross et al. (2013), USA	ID & ASD	Database Survey	2011 Annual Survey of TIL Alumni	7 Sections: 1) Demographics, 2) Employment Status & Income, 3) Job Coaches, Benefits, & Satisfaction, 4) Independent Living & Place of Residence, 5) Housing Support & Independent Living Assistance, 6) Transportation, 7) Banking, Shopping, & Meal Preparation.	Employment Status (benefits & support), Job Satisfaction
[36]a	Ruggeri-Stevens & Goodwin (2007), UK	LD	Interview-administered	Questionnaire A- survey On Learning Disability & Supported Employment	2 sections: 1) Job requirements met, 2) Job adjustments made.	Work Adaptation
[36]b			Interview-administered	In-depth interview (to inform ILP)	6 sections: 1) Work awareness, 2) Motivation, 3) Self awareness, 4) Risks, 5) Travel, 6) Other.	Work Motivation, Work Personality
[36]c			Interview-administered	Individual Learning Plan (ILP) progress record	Structured plan informed by questionnaire & interview findings.	VR Plan
[37]	Rusch et al. (1995), USA	MR	Rater-reported	Co-Worker Involvement Index (CWII) (McNair & Rusch 1992)	Areas of worker interaction rated by model program directors or supported employment services. 9 areas: 1) Physical integration, 2) Social integration, 3) Training, 4) Associating (frequency), 5) Associating (appropriateness), 6) Befriending, 7) Advocating, 8) Evaluating, 9) Giving information.	Social Integration, Workplace Support
[38]	Song & Song (1971), USA	MR	Rater-reported	Vocational Adjustment Rating Scale (VARS)	Measure of 52 items to assess how well an individual performs & behaves in work settings. 5 domains: 1) Work ability, 2) Work habits, 3) Withdrawn behavior, 4) Aggressive behavior, 5) Bizarre behaviour.	Work Skills, Work Personality
[39]	Taylor & Selzer (2012), USA	ASD	Rater-reported	Vocational Index (VI) of experience for Adults with ASD	Index of 11 categories for activities based on 9 levels of independence (settings & hours/week), ranged from most to least independent.	Employment Status, Vocational Experience
[40]	Tse (1994), Hong Kong	ID	Rater-reported	Questionnaire of employer expectations & employee performance ratings	25 work aspects/items: 1) Work Safety, 2) Reliability, 3) Motivation, 4) Bearing Responsibilities, 5) Honesty, 6) Willingness to work hard, 7) Speed, 8) Work without supervision, 9) Job stability, 10) Productivity, 11) Desire to get ahead, 12) Attendance, 13) Being Punctual, 14) Getting on well with coworkers, 15) Ability to learn, 16) Loyalty, 17) Leadership, 18) Capable of doing jobs, 19) Good physique, 20) Ability to handle money, 21) Experiences, 22) Personality, 23) Transportation to work, 24) Education, 25) Appearance. 5 other items: 1) Demographics, 2) Education, 3) Training, 4) Position, 5) Wages.	Work Skills, Work Motivation, Work Personality
[41]a	Van Bourgondien et al. (2003), USA	ASD & MR	Rater-reported	Environmental Rating Scale (ERS)	32-items across 5 subscale areas: 1) Communication, 2) Structure, 3) Socialization, 4) Developmental Assessment & planning, 5) Behaviour management.	Workplace Culture Work Skills
[41]b			Rater-reported	Adolescent & Adult Psychoeducational Profile (AAPEP) (Mesibov et al 1988)	6 functional areas: 1) Vocational skills, 2) Independent functioning, 3) Leisure skills, 4) Vocational behaviour, 5) Functional communication, 6) Interpersonal behaviour. Complemented by two additional measures: ^Vineland Adaptive Behavior Scales-Expanded Form (VABS) (Sparrow et al 1984) ^Autism Behavior Inventory (ABI) (van Bourgondien & Mesibov 1989)
[42]	Wehman et al. (2014), USA	ASD, ID, SLI, Other	Rater-administered	Supports Intensity Scale (SIS) (Thompson et al 2004)	Standardized measure of adaptive behaviour and support needs index (SNI). 6 subscales: 1) Home living, 2) Community living, 3) Lifelong learning, 4) Employment, 5) Health & safety, 6) Social.	Work Skills, Workplace Supports
[43]	Wehmeyer (1994), USA & Canada	MR	Self-report or Verbally administered	Adult version of the Nowicki- Strickland Internal-External (ANS- IE) Scale for locus of control (Nowicki & Strickland 1973)	Self-report survey about locus of control perceptions. 2 areas: 1) Internal locus of control, 2) External local of control.	Perceptions of Control
[44]a	West & Patton (2014), USA	Rhett, ID, CP	Rater-reported	Motivation Assessment Scale (MAS) (Duran & Crimmins 1988)	A 16-item questionnaire to help identify challenging behaviours (supplemented this measure with file reviews & at home observations). 4 functional assessment subscales: 1) Attention, 2) Escape, 3) Sensory, 4) Tangible.	Work Personality
[44]b			Interview-administered	Inventory for Client and Agency Planning (ICAP) for behavioural problems (Bruininks et al 1986)	Behavioural problems general index: a tool designed for assessment of adaptive & maladaptive information to determine the type & amount of social assistance that people may need. ^*Supported with Positive Behaviour Support (PBS) Procedures (Reid et al 1998) & Community job selection	Work Personality
[44]c			Direct observations	PBS Task Analyzed Job Performance	Job/task performance assessment, via frequency of independent correct responses in routine tasks.	Work Skills, Work Preference
[45]	White (1983), USA	MR	Self-reported or Rater-reported	Work Performance Evaluation Form (WPEF)	Measure of 26 items to evaluate job skills & interpersonal relationships in the job environment (completed by managers, supervisors, coworkers, employees). 4 areas: 1) Job skills & work quality, 2) Level of responsibility, 3) Relationship to supervisors & coworkers, 4) Ability to manage time.	Work Skills, Work Personality, Social Integration

Within the first column, the square brackets contain the reference number for each included journal article and the subsequent lower case lettering is used when more than one measure is identified in a single article.

3 Results

3.1 Literature search and selection process

The study selection process is represented by the PRISMA flow diagram in Fig. 1 (based on Moher et al., 2009). Through electronic searches of the final five databases resulted in a total of 2,151 records reviewed – ERIC (n = 790 records), MEDLINE (n = 665), CINAHL (n = 430), HaPI (n = 222), and PsycINFO (n = 44). After title and abstract screening against the predetermined eligibility criteria, and removing duplicate records, 167 articles underwent full-text review. In this process, only 17% of the identified papers underwent adjudication. In total, 45 journal articles met the inclusion criteria.

3.2 Included articles and population characteristics

Global study distribution

Table 2 provides descriptive information extracted from each of the 45 included articles. Articles were published within a 45-year span, from 1971 through to 2015. Rather than a global perspective, we have no papers retrieved from outside of developed countries. Of the 45 articles, 29 involved target populations recruited from within the USA (e.g., Bullis & Foss, 1986; Burnham & Housley, 1992; and Wehman et al., 2014). The remaining studies were conducted across the UK (n = 3 articles) (Howlin et al., 2005; Rose et al., 2010; Ruggeri-Stevens & Goodwin, 2007) [16, 34, 36], Australia (n = 3) [9,17,18], New Zealand (n = 2) (Fillary & Pernice, 2005, 2006), Hong Kong (n = 2) (Li & Tang, 2002; Tse, 1994), Israel (n = 2) (Gal et al., 2013; Gal et al., 2015), Spain (n = 1) (Martorell et al., 2008), Taiwan (n = 1) (Chen et al., 2012), and Canada (n = 1) (Cobigo et al., 2009). One study recruited participants from across the USA and Canada (Wehmeyer, 1994).

Population representation

The majority of studies included target populations of adults with intellectual disability (ID) (n = 16 articles) (e.g., Chen et al., 2012; Cimera et al., 2010, 2011; West & Patton, 2014), or mental retardation (MR) (n = 15 articles) (e.g., Bullis & Foss, 1986; Burham & Housley, 1992; Gaylord-Ross et al., 1995). The next largest target population included adults with autism spectrum disorder (ASD) (n = 14 articles) (e.g., Howlin et al., 2005; Parr & Hunter 2014; Taylor & Selzer, 2012). Persons with learning disabilities (LD) were included in five articles (e.g., Dipleolu, 2007; Rose et al., 2010; Rugerri-Stevens & Goodwin, 2007), persons with cerebral palsy (CP) in three articles (Novak & Rogan, 2010; Parent et al., 2013; West & Patton, 2014), and persons with attention deficit hyperactivity disorder (ADHD) in only one article (Painter et al., 2008).

Across the lifespan

At least five studies included a small sample of adolescents in their study populations: with a few participants as young as 13 years of age for one study (Malgady & Barcher, 1982), but with a minimum age of 17 years for the other four studies (Bullis & Foss, 1986; Farris & Stancliffe, 2001; Novak & Rogan, 2010; Rose et al., 2010). The highest age range for included participants was at the upper range of 69 years in only one study (O’Sullivan & Strauser, 2015).

3.3 Types of measures identified

As indicated in Fig. 1, 64 measures were identified across the 45 articles. In Table 2, we list each article with the target population according to NDDs, as well as all extracted tools along with a brief description. Of these measures, 22 are interview-administered questionnaires/scales, 19 are self-report surveys/measures (several of which can be administered verbally, if needed), 11 are rater-reported assessments, six are direct observation tests, five are rater-administered assessments, and four are longitudinal national database surveys.

There was little overlap in the use of similar employment instruments across the included studies. The following assessments were used in two studies with independent samples: the combined use of the Career Thoughts Inventory, the Mature Career Beliefs Inventory, and My Vocational Situation instrument were reported in two studies (Dipeolu, 2007; Painter et al., 2008); the Co-Worker Involvement Index (Rusch et al., 1995; Farris & Stanacliffe, 2011); the Nowiki-Strickland Locus of Control Scale (Jiranek & Kirby, 1990; Wehmeyer, 1994); and versions of the Inventory for Client and Agency Planning (ICAP) (Martonell et al., 2008; West & Patton, 2014).

3.4 Person and environment themes

As described in Table 2, there was a wide range of measurement constructs represented by the identified measures that could be demarcated as person (i.e., characteristics of the employee) and environment themes (i.e., physical, social institutional or cultural aspects of the workplace) (WHO-ICF, 2011). Person-focused themes included, work readiness, personality, motivation, adaptation, skills, performance, engagement, preferences, and satisfaction. Examples of environment-focused themes included, organizational commitment, social inclusion, social integration, workplace support, workplace culture, social acceptance and coworker involvement.

4 Discussion

This review sought only those studies that used standardized measures and clearly described procedures for examining employment outcomes beyond common metrics of job status (i.e., employed or unemployed) and compensation (i.e., wages and hours). While such outcomes are important to monitor, they are common in the research literature. For this review, the full array of instruments assessing employment outcomes in VR training and research amounted to 64 employment outcome measures. From this review, vocational researchers working with adults across various NDDs (including ID, MR, LD, ASD, CP, and ADHD) have developed and/or utilized measures that evaluate a variety of employment outcomes. There was little-to-no overlap in use of these instruments across the included studies. In this review we found an over representation of certain NDDs over others. The largest target population included persons with ID, and this was followed by persons with ASD. It is unclear if these differences are related to diagnostic prevalence, client services availability, publication bias, or even stakeholder group advocacy, but these differences are worthy of further investigation (Bishop, 2010).

The compiled list of outcome measures provided in this paper could be used as a starting point or repository of measures to trial in future studies. The measures identified represented various constructs that could be relevant to be tested across different disability groups, and age cohorts. How these tools are used (i.e., job matching, evaluating outcomes, or predicting employment success) and in what combination will be important to examine in future work. Future reporting on outcome measures could also be improved by researchers to better describe the work context or industry where the measures are best suited, which could complement the population profile.

The WHO has identified the critical importance of both “individual” and “environmental” factors for functioning in the ICF model (WHO, 2011b) and in the report on disability (WHO, 2011). By examining measures specifically for person (i.e., employee) and environment (i.e., workplace) constructs, the identification of measures for each construct highlight the diversity of employment outcomes researchers can assess beyond typical metrics. A variety of person and environment themes covered by the measures identified in the pool of included articles. The six most common person themes include job motivation, preference, personality, readiness, skills, and satisfaction. The three recurrent themes for environment measures include workplace culture, social integration, and supports. These are overlapping themes, and most measures cover more than a single theme.

Fewer studies were focused on the environment, especially in relation to the population of people with ASD. A recent systematic review by Ellenkamp et al. (2016) highlighted the importance of several work-environment related factors for people with Intellectual Disabilities. This could be further explored in ASD to determine the other work environment factors that could be relevant to this population. Using this repository of measures to test new constructs in ASD would be a good starting point.

This work represents the first time that employment outcome measures are reviewed from the literature across NDDs. It is important to look at measures across NDDs, because of the common employment challenges that exist in this population across various diagnoses. Rigorous methods were utilized in this review, such as throughout the selection process of relevant studies with two reviewers. Stratifying identified measures that were person versus environment focused was another strength of this paper in describing unique properties of the measures that are important for future researchers to consider.

This review had a few limitations, such as the inclusion of adolescents within some of the study samples, when the search criterion specified adult-focused population. However, given that the majority of participants were 17 or older across studies, the inclusion of a few adolescents that were mixed with an adult population within the employment study did not warrant the removal of these studies from our final pool. A second limitation was the lack of a quality assessment of studies that were included in this review. Although this would have enhanced the descriptive content included in the study table, the objective of this review was to identify all outcome measures utilized within the literature and be rather conservative about how employment outcomes are evaluated in the NDD literature. A third limitation was the challenge in identifying measures and their constructs within the identified papers in this review. Due to the lack of standard reporting methods, the identification of the measures and consistent themes was difficult to do objectively, thus relying on ongoing discussions within our investigative team to reach consensus.

5 Conclusion

With the growing number of people with NDDs living well into adulthood, we must target our efforts to mitigating the barriers to fair participation in work and employment (WHO, 2011). Through this review, a list was compiled of the wide array of employment outcome instruments available for research involving persons with disabilities. Many of these person- and environment-focused tools should prove useful in both job matching and training practices, as well as in follow-up evaluation and monitoring efforts to encourage best outcomes. When designing future studies, disability researchers should plan to report systematically about their study participant characteristic and clearly identify the standardized measures or structured procedures used for assessing employment outcomes. Evidence informed data are essential to inform good clinical practices and policies, and VR professionals are poised to play an important role in enabling good vocational outcomes. This repository can serve as a good starting point for researchers to utilize similar tools for better surveillance, as well as sharing outcomes of employment initiatives to begin to identify best practices to best increase the employability of people with disabilities.

Conflict of interest

The authors have no conflict of interest to report.

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