Process Evaluation of a Lifestyle Intervention to Prevent Diabetes and Cardiovascular Diseases in Primary Care

Abstract

Effective, cost-effective, safe, and feasible interventions to improve lifestyle behavior in at-risk populations are needed in primary care. In the Hoorn Prevention Study, the authors implemented a theory-based lifestyle intervention in which trained practice nurses used an innovative combination of motivational interviewing (MI) and problem-solving treatment (PST). This article presents the intervention’s reach, effectiveness in terms of process outcomes, adoption, and implementation. Recruitment strategy and participant flow were documented accurately. The effectiveness in terms of determinants of behavioral change was measured using a validated questionnaire. Questionnaires were also used to assess participant satisfaction and compliance, as well as practice nurses’ confidence in providing the intervention. Counseling sessions were tape recorded to assess MI, PST, and general counseling competence. The findings indicate that the recruitment strategy was adequate and resulted in a reasonably extensive reach of the target population. Practice nurses were competent and confident in their provision of MI and PST, and participant satisfaction was high. Nevertheless, the number of sessions attended was low, and almost no effects were seen on determinants of behavioral change. The authors conclude that implementing this type of intervention in primary care is feasible, but more is needed to effectively facilitate changes in determinants of lifestyle behavior in this population.

Keywords

lifestyle intervention process evaluation diabetes prevention primary care

Background

Lifestyle-dependent risk factors such as being overweight, low levels of physical activity, and an unhealthy diet increase the risk of acquiring chronic diseases such as type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD; Reaven, 1995; Willi, Bodenmann, Ghali, Faris, & Cornuz, 2007; Yusuf et al., 2004). More and more, public health policy makers expect health care providers to identify at-risk groups and to provide effective interventions in an effort to prevent these diseases (Simmons, Unwin, & Griffin, 2010). In the Hoorn Prevention Study, we examined the effectiveness of an innovative lifestyle intervention in at-risk adults compared with the provision of health brochures only. The intervention consisted of a cognitive behavioral program (CBP) based on the theory of planned behavior (TPB) and was carried out by trained practice nurses in 12 general practices. In a maximum of six individual 30-minute counseling sessions, followed by 3-monthly sessions by phone, an innovative combination of motivational interviewing (MI; Miller & Rollnick, 2002) and problem-solving treatment (PST; Mynors-Wallis, 2001) was used. Both MI and PST address various components of the TPB. The aim of the MI was to reinforce the participants’ attitude and the behavioral intention to make a change in one of three lifestyle behaviors of choice (physical activity, diet, or smoking). It also aimed to create a discrepancy between a person’s goal and the actual situation. PST was used to support participants in finding solutions to overcome this discrepancy, to strengthen perceived control, and to provide tools to overcome barriers that hinder lifestyle behavioral changes (Mynors-Wallis, 2001). The intervention incorporated components of previously effective interventions but was tailored to the resources and infrastructure available to national health care services in the Netherlands and was pragmatic in design.

In addition to evaluating the clinical results of an intervention program with regard to its effectiveness, it can be equally valuable to evaluate the program’s translatability, feasibility, and its limitations.

A widely used evaluation framework for the assessment of interventions that includes multiple process indicators and extends beyond assessing effectiveness has been published (Dzewaltowski, Glasgow, Klesges, Estabrooks, & Brock, 2004). The framework includes the following dimensions: (1) the Reach of the program; (2) its Effectiveness; (3) its Adoption by intermediaries and users; (4) its Implementation according to plan; and (5) its Maintenance for a long enough time (RE-AIM; Dzewaltowski et al., 2004). In evaluating these dimensions, not only the strengths of a program but also its limitations can be identified. These limitations can be improved on in future research.

This article describes the evaluation of a primary care–based lifestyle intervention program for adults at risk of diabetes and cardiovascular diseases, based on the RE-AIM framework.

Method

The methods and background theory of the Hoorn Prevention Study have been reported in detail previously (Lakerveld et al., 2008). The Medical Ethics Committee of the VU University Medical Centre in Amsterdam approved the study protocol, and all the participants gave written informed consent.

The RE-AIM Framework

We systematically assessed the dimensions of the RE-AIM framework as described below. Note that some elements of the framework have been modified slightly for the intervention under study.

Reach

The recruitment strategy used for the participants in the Hoorn Prevention Study out of the target population was evaluated. The participant flow was provided, including the reasons for (and percentages of) those who were excluded from the study, those who dropped out during the follow-up, and those who remained.

Effectiveness

The interventions’ effectiveness in terms of affecting determinants of lifestyle behavioral change (according to the TPB) was evaluated. Attitudes, subjective norms, perceived behavioral control, and intentions of lifestyle behavioral change in both groups were measured with the Determinants of Lifestyle Behavior Questionnaire (DLBQ; Lakerveld, Bot, Chinapaw, Knol, et al., 2011). This is a valid instrument for measuring substantial determinants of the intention to change diet, physical activity, and smoking behaviors in adults at high risk of T2DM and CVD. Confirmatory factor analysis supported the theoretical factor structure of the DLBQ (Lakerveld, Bot, Chinapaw, Knol, et al., 2011). Attitudes were measured on a 7-point semantic scale ranging from 1 (e.g., unpleasant) to 7 (e.g., pleasant). All other determinants of behavioral change were measured on a 5-point Likert-type scale ranging from 1 (totally disagree) to 5 (totally agree). Mean scores for behavioral determinants were calculated for each lifestyle behavior. Theoretically, higher scores indicate a stronger intention to change lifestyle behaviors and are, therefore, considered to favor change in behavior. Linear regression was used to analyze differences in behavioral determinants between the intervention and control groups at 6- and 12-month follow-ups (reported as unstandardized B coefficients), with the significance level set at p ≤ .05. Analyses were corrected for baseline values to adjust for regression to the mean tendencies and to take into account the actual changes in behavioral determinants compared with baseline. The analyses were all based on the intention-to-treat principle and were conducted using SPSS 15.0 (SPSS Inc., Chicago, Illinois). The effectiveness of the intervention lifestyle behaviors and risk of T2DM and CVD has been described elsewhere (Lakerveld, Bot, Chinapaw, van Tulder, et al., 2011).

Adoption

Training of practice nurses

The counseling program in the Hoorn Prevention Study was provided by eight practice nurses. Prior to the intervention, all practice nurses received 12 hours of training in MI and 6 hours of training in PST from experienced psychologists who are specialized in providing CBPs and are qualified to teach CBP techniques. A treatment manual was used during the training and counseling. On-the-job coaching was provided halfway through the intervention and consisted of 1-hour individual meetings. In addition, a peer supervision meeting was arranged with all practice nurses to provide ongoing feedback and to increase uniformity of the counseling style.

Attitude toward and confidence in providing the intervention

Practice nurses were asked to give their opinion on five statements regarding the perceived effectiveness of MI and PST and assess their confidence in providing the intervention. Answer categories were 4-point Likert-type scales ranging from 1 (agree) to 4 (disagree). These assessments were administered twice: just after the end of the training and again when the face-to-face counseling sessions were completed (approximately 6 months later).

Participant satisfaction and compliance

Participant satisfaction and compliance were measured at the first follow-up measurement visit (when most face-to face counseling sessions were completed); participants randomized to the intervention group were asked to score their satisfaction with the counseling sessions on a 4-point Likert-type scale (ranging from completely disagree to completely agree). The proportions of participants who (completely) agreed with the various items on satisfaction were calculated. The number of face-to-face counseling sessions attended was recorded by the practice nurses to document participants’ compliance.

Implementation

We assessed the extent to which the various intervention components were delivered as intended. We evaluated MI counseling skills and captured dimensions of therapeutic alliance using the third version of the Motivational Interviewing Treatment Integrity rating scale (MITI; Moyers, Martin, Manuel, Hendrickson, & Miller, 2005), and components of the Motivational Interviewing Skill Code (MISC; Moyers, Martin, Catley, & Ahluwalia, 2003). Both instruments are specifically designed to evaluate MI and have high reliability and validity (Moyers et al., 2003; Moyers et al., 2005). To assess PST skills, we used the modified Problem-Solving Competency Checklist (PSCC) developed by Kendrick et al. (2005). Please refer to Appendixes A and B for more background information on the MITI 3.0, MISC, and PSCC.

The counseling sessions were tape-recorded to allow assessment of the validity of MI and PST provided by the practice nurses. Two tape-recorded sessions of ≥15 minutes from all practice nurses were drawn at random using a computerized randomization program and transcripts were made; all final samples were then independently analyzed by two researchers. Because not all samples contained sessions in which PST was used, 10 extra random sessions have been independently analyzed using the PSCC.

Maintenance

Because the Hoorn Prevention Study set out to evaluate the effects of the intervention given within a predefined time frame (i.e., 2 years), this dimension could not be evaluated.

Results

Reach

Between December 2007 and April 2008, a total of 8,193 men and women aged 30 to 50 years living in several municipalities in a semirural region (West-Friesland) of the Netherlands were invited to participate in a selective screening procedure by mail. The target group was approached after identification of date of birth and absence of diabetes and known CVD from participating general practices (n = 12). The invitation letter included a tape measure with detailed instructions on how to measure the waist circumference. Of the 3,587 respondents (44%), 2,401 responded positively, 921 of whom were eligible with regard to the preset cutoff score of the self-administered waist circumference test (≥101 cm for men and ≥87 cm for women). Of these eligible responders, 772 visited the Diabetes Research Centre for baseline measurements, gave written informed written consent, and participated in the trial. After this research visit, T2DM and CVD risk scores were calculated according to the formulae of the Atherosclerosis Risk in Communities (ARIC) study (Schmidt et al., 2005) and the Systematic Coronary Risk Evaluation (SCORE) project (Conroy et al., 2003). For both scores, age was extrapolated to 60 years for each participant to address the problem of a high relative, but low absolute, risk in younger persons. In doing so, it was possible to flag individuals with a potential high absolute risk at the age of 60 years (Conroy et al., 2003). All respondents with a minimum risk of 10% of developing T2DM and/or CVD, and no known prevalent T2DM or CVD were randomly assigned to either the intervention group or the control group. Before randomization, we excluded 150 people (140 had a risk lower than 10%, and 10 had undiagnosed T2DM). Of the 622 individuals included in the study, 490 (79%) attended the last follow-up at 24 months. Please refer to Figure 1 for the Hoorn Prevention Study’s participant flow and reasons for dropout. A dropout analysis showed no significant differences in baseline values of the outcome measures between participants who completed the study and those who dropped out (data not shown).

Figure 1

Flowchart of the Hoorn Prevention Study

Study population and baseline characteristics

Baseline characteristics of participants of both groups were similar (Table 1). The mean age at baseline was 43.5 years (SD = 5.3), and 363 participants were female (58%).

Table 1

Baseline Characteristics of Randomized Participants in the Hoorn Prevention Study

	Control Group (n = 308)	Intervention Group (n = 314)
Gender: female, n (%)	185 (60.1)	178 (56.7)
Age in years, mean (SD)	43.4 (5.5)	43.6 (5.1)
Educational attainment, n (%)
≤Primary	103 (33.6)	101 (32.5)
Secondary	145 (47.1)	141 (44.9)
College, university	59 (19.2)	69 (22.0)
Family history of diabetes, n (%)	77 (25.0)	94 (29.9)
Anthropometrics, mean (SD)
Body weight, kg	90.7 (15.4)	90.2 (15.5)
Waist circumference, cm	96.7 (9.7)	96.7 (9.8)
Blood pressure
Systolic, mmHg	129.3 (13.3)	128.7 (13.2)
Diastolic, mmHg	73.8 (9.0)	73.0 (9.9)

Effectiveness

Baseline and follow-up values and group differences for all TPB determinants of lifestyle behaviors are shown in Table 2. There were no or very small differences in determinants of lifestyle behavior between groups at both follow-ups. After 6 months, subjective norms with regard to physical activity were significantly lower in the intervention group (B = −0.2; CI = −0.4 to 0.0). This difference did not remain after 12 months. The perceived behavioral control of smoking cessation was significantly higher at 12 months follow-up, in favor of the intervention group (B = 0.3; CI = 0.1 to 0.6).

Table 2

Mean Baseline and Follow-Up Values (SD) and Between-Group Differences Corrected for Baseline (Unstandardized B Coefficient, 95% CI) of Behavioral Determinants

	Control Group (Mean ± SD)				Intervention Group (Mean ± SD)				Group Differences (B, 95% CI)
	Baseline	6 Months	12 Months	24 Months	Baseline	6 Months	12 Months	24 Months	6 Months	12 Months	24 Months
Physical activity
Attitude	5.6 ± 1.0	5.6 ± 1.0	5.6 ± 1.0	5.7 ± 0.9	5.5 ± 1.0	5.5 ± 1.0	5.5 ± 1.0	5.6 ± 0.9	0.1 (−0.1 to 0.2)	0.0 (−0.1 to 0.2)	0.0 (−0.2 to 0.1)
Subjective norms	3.7 ± 1.2	2.3 ± 1.1	2.2 ± 1.1	2.2 ± 1.1	3.7 ± 1.2	2.1 ± 1.1	2.1 ± 1.1	2.2 ± 1.1	−0.2 (−0.4 to 0.0)*	−0.1 (−0.2 to 0.1)	0.0 (−0.2 to 0.2)
PBC	3.1 ± 0.7	3.1 ± 0.7	3.1 ± 0.7	3.1 ± 0.7	3.0 ± 0.7	3.0 ± 0.7	3.0 ± 0.6	3.1 ± 0.7	0.0 (−0.1 to 0.1)	−0.1 (−0.2 to 0.0)	0.0 (−0.1 to 0.1)
Intention	3.2 ± 1.2	3.1 ± 1.2	3.2 ± 1.1	3.0 ± 1.2	3.1 ± 1.3	2.9 ± 1.3	3.0 ± 1.2	3.1 ± 1.2	−0.1 (−0.3 to 0.1)	−0.2 (−0.4 to 0.0)	−0.1 (−0.1 to 0.3)
Dietary behavior
Attitude	5.8 ± 0.9	5.8 ± 0.9	5.9 ± 0.9	5.6 ± 0.9	5.9 ± 0.9	5.8 ± 0.9	5.9 ± 0.9	5.8 ± 0.9	0.0 (−0.1 to 0.1)	0.0 (−0.1 to 0.1)	−0.1 (−0.2 to 0.1)
Subjective norms	2.2 ± 1.1	2.1 ± 1.0	2.0 ± 1.0	2.2 ± 1.1	2.1 ± 1.1	2.0 ± 1.0	2.0 ± 1.0	2.0 ± 1.0	0.0 (−0.1 to 0.2)	0.1 (−0.1 to 0.2)	−0.1 (−0.2 to 0.2)
PBC	3.3 ± 0.8	3.4 ± 0.7	3.4 ± 0.7	3.1 ± 0.7	3.3 ± 0.7	3.4 ± 0.7	3.4 ± 0.7	3.4 ± 0.7	0.0 (−0.1 to 0.1)	0.0 (−0.2 to 0.1)	0.0 (−0.1 to 0.1)
Intention	3.0 ± 1.1	2.9 ± 1.0	2.8 ± 1.0	3.1 ± 1.2	2.7 ± 1.1	2.6 ± 1.0	2.8 ± 1.1	2.7 ± 1.0	−0.1 (−0.3 to 0.0)	0.1 (−0.1 to 0.3)	0.2 (−0.1 to 0.3)
Smoking
Attitude	4.9 ± 1.1	4.7 ± 1.0	4.7 ± 1.0	5.0 ± 0.9	4.8 ± 1.2	4.7 ± 1.0	4.5 ± 1.2	4.7 ± 1.2	0.3 (−0.1 to 0.8)	−0.1 (−0.8 to 0.5)	−0.3 (−0.7 to 0.1)
Subjective norms	3.0 ± 1.2	3.1 ± 1.1	3.0 ± 1.3	3.2 ± 1.0	3.0 ± 1.3	2.8 ± 1.4	2.7 ± 1.2	2.7 ± 1.2	−0.1 (−0.4 to 0.3)	0.1 (−0.4 to 0.5)	−0.3 (−0.7 to 0.2)
PBC	2.8 ± 0.9	2.8 ± 0.8	2.5 ± 0.8	2.9 ± 0.9	2.8 ± 1.1	2.7 ± 1.0	2.9 ± 1.1	2.9 ± 0.9	0.0 (−0.3 to 0.2)	0.3 (0.1 to 0.6)*	−0.2 (−0.5 to 0.1)
Intention	3.4 ± 1.4	3.3 ± 1.3	3.3 ± 1.3	3.3 ± 1.3	3.4 ± 1.3	3.2 ± 1.4	3.2 ± 1.4	3.2 ± 1.4	0.1 (−0.5 to 0.4)	0.1 (−0.4 to 0.6)	−0.1 (−0.7 to 0.4)

NOTE: SD = standard deviation; CI = confidence interval; PBC = perceived behavioral control. Higher scores are in favor of behavioral change. Positive B for between-group differences are in favor of the intervention group.

p < .05.

Adoption

Attitude toward and confidence in providing the intervention

The practice nurses considered MI and PST to be effective methods of supporting participants in a behavioral change process, and most were confident in providing the intervention. After the intervention, their confidence was unchanged or strengthened (Table 3).

Table 3

Mean Scores (SD) of Answers on Statements Regarding Practice Nurses’ Attitudes and Confidence Toward Providing the Intervention

	Before the Start of the Intervention, but After the Training (n = 8)	After the Intervention (n = 8)
I am not (yet) able to guide participants through the counseling sessions	2.8 (1.0)	2.5 (0.9)
I master the counseling skills sufficiently to use them in practice	2.0 (0.0)	1.9 (0.6)
I think MI is a suitable part of the counseling sessions	1.2 (0.4)	1.1 (0.2)
I think PST is a suitable part of the counseling sessions	1.1 (0.2)	1.5 (0.5)
The combination of MI and PST is valuable for supporting lifestyle behavioral change	1.1 (0.4)	1.2 (0.5)

NOTE: MI = motivational interviewing; PST = problem-solving treatment. Scores are means (SD) on Likert-type scale ranging from 1 = agree to 4 = disagree.

Participant satisfaction and compliance

Of the participants who received at least one face-to-face counseling session (n = 207), 78% were content with the sessions. Participants in the intervention group received a median of two (interquartile range = 1-3) of the six scheduled counseling sessions.

Implementation

Competence of practice nurses

Mean scores on the MITI, MISC, and PSCC for both coders are presented in Table 4.

Table 4

Mean Scores (Range) and Intercoder Reliability on the MITI, MISC, and PSCC

	Coder 1	Coder 2	Intercoder Reliability^a
MITI
Reflection question ratio	0.82 (0.35-1.53)	0.82 (0.25-1.78)	NA
% MI adherence^b	94.5 (87-100)	93.2 (82.6-8.9)	NA
Empathy	2.81 (2-3)	2.57 (2-4)	0.43
MI spirit	2.57 (2-3)	3 (2-4)	0.33
Direction	4.13 (2-5)	3.71 (2-4)	0.32
MISC
% Change talk^c	58.2 (10-83)	74.8 (62-82)	NA
PSCC
General therapeutic skills	2.93 (1-4)	3.33 (2-4)	0.31
Problem-solving skills	2.11 (1-4)	2.84 (1-4)	0.51

NOTE: MITI = motivational interviewing treatment integrity; MISC = motivational interviewing skill code; PSCC = Problem-Solving Competency Checklist; NA = not applicable.

Scores are kappas with quadratic weighting between Coder 1 and Coder 2.

(Total amount of utterance − MI nonadherence)/total amount of utterance × 100.

Change talk/(change + sustain talk) × 100.

In at least half of the sessions, global ratings (empathy, MI spirit, and direction) and percentage MI adherence were judged as sufficient by both coders. Almost all scores were 2 or above except for one session on the subscore MI-spirit autonomy. Although the reflection–question ratio was not bad, relatively few sessions (37%) met the preset level of sufficiency for the reflection–question ratio.

The general therapeutic skills and the problem-solving skills of the practice nurses measured with the PSCC were good. The mean scores of Part 2 of the PSCC were above the preset cutoff score, suggesting a satisfactory implementation of PST skills.

Discussion

The Hoorn Prevention Study set out to evaluate the effectiveness of an innovative lifestyle intervention in at-risk adults, compared with the provision of health brochures only. The aim of the current study was to systematically evaluate the program’s reach, effectiveness on intermediate determinants, adoption by the target settings, and its implementation. The findings indicate that the recruitment strategy was adequate and resulted in a reasonably high reach of the target population. Two thirds of the eligible individuals participated in the study. The practice nurses were reasonably competent and confident in providing MI and PST, and participant satisfaction was relatively high. Nevertheless, the number of sessions attended was low, and almost no effects on intermediate determinants of behavioral change were observed.

To select people who are at risk of T2DM and CVD, self-measured waist circumference was used as a first screening step, which proved to be a simple and feasible method. Relatively few participants were lost to follow-up at 6, 12, and 24 months (n = 86, 34, 22, respectively).

Our intervention addressed several components of the TPB and made use of effective components and behavioral change strategies identified in the scientific literature (i.e., MI and PST). Apart from a small increase in perceived control regarding smoking at the second follow-up, participants showed no benefit of the intervention in terms of cognitive behavioral determinants. Thus, in spite of the practice nurse’s actual and perceived competence in providing the intervention, it had a very limited effect on changes in determinants of physical activity, dietary behavior, or smoking behavior in adults at high risk of developing T2DM and/or CVD.

Most participants were content with the face-to-face counseling sessions, but some were not. In particular, at the beginning of the intervention, some practice nurses indicated that various participants expected that they would be told what to do and disliked the directive nature of the counseling. This may have contributed to the rather low attendance rate.

The practice nurses used an innovative combination of MI and PST to prompt the participants to find solutions rather than telling participants how to change behavior and to support them in implementing these solutions in their lives. It has been demonstrated previously that MI and PST were significantly more effective than attention alone (Malouff, Thorsteinsson, & Schutte, 2007; West, DiLillo, Bursac, Gore, & Greene, 2007), and strong evidence exists that supports the efficacy of MI in changing different lifestyle behaviors (Rubak, Sandboek, Lauritzen, & Christensen, 2005). However, the effectiveness of this complex counseling may very well depend on the degree to which they are mastered by the practitioner. With regard to mastery, our assessment using reliable and valid instruments for evaluating the specific counseling skills indicated that the treatment integrity and skills of the nurse practitioners were somewhat low. This study showed that their performance left room for improvement. Improvement of the counseling techniques may require a longer period of training in MI and PST. From a potential implementation standpoint, however, it would not be feasible to provide more training in everyday practice, given the relatively little time for additional education in the practice nurses’ agendas. Furthermore, the daily work of practice nurses requires a different type of professional contact with their patients (e.g., giving advice or explain what needs to be done). Using MI and PST involves a shift in daily practice that may require more time to be implemented fully.

Conclusions

Lifestyle programs to prevent T2DM and CVD have become increasingly popular during the last decade. Our findings indicate that the recruitment strategy was adequate and resulted in a relatively high reach of the target population. Practice nurses were reasonably competent and confident in the provision of MI and PST, and participant satisfaction was high. Nevertheless, the number of sessions attended was low, and no effects on determinants of lifestyle behavioral change were seen. We conclude that implementing this type of intervention in primary care is feasible, but more is needed to effectively facilitate changes in determinants of lifestyle behaviors in adults at risk of T2DM and CVD.

Footnotes

Appendix A

Appendix B

Acknowledgements

The authors thank Laura Doeven and Ellen Schouten for their valuable contributions, and all practice nurses who collaborated with us. This study was funded by the Netherlands Organization for Health Research and Development.

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