Suffering Assessment: A Review of Available Instruments for Use in Palliative Care

Introduction

The prevention and relief of suffering are main objectives of palliative care and basic conditions for the quality of life (QOL) of patients and families with life-threatening diseases.^1–4

At the end of life, suffering is widespread, ⁵ leading to significant deterioration in well-being and QOL. ⁶ Suffering is associated with physical, psychological, social, and spiritual factors that interact with each other,^7–11 comprising a unique, complex, and multidimensional experience that needs to be approached in an integrated and individualized fashion.^1,2,11–13 According to Cassell, ¹² suffering is “a specific state of severe distress associated with events that threaten the intactness of person.” More recently, it has been defined as “a multi-dimensional and dynamic experience of severe stress that occurs when there is a significant threat to the whole person and regulatory processes are insufficient, leading to exhaustion.” ¹⁴

A growing interest in the concept of suffering has taken place, in part thanks to the biopsychosocial–spiritual model, ¹⁵ which supports the integration of psychosocial and spiritual aspects into medical practice. Moreover, given that the relief of suffering is central to palliative care, its detection and assessment take the highest priority.^16,17

The detection of suffering presents a challenge, especially at the end of life when pivotal treatment decisions are required.^16–20 Suffering may be related to the severity of disease, and severity of disease can be objectively measured. However, suffering is assessed subjectively.^12,14,21 This subjectivity, when juxtaposed with the objectivity of disease severity itself, makes the choice of intervention strategy especially challenging. Suffering assessment must also factor in the progressive deterioration in the patient's willingness to address complex or excruciating issues, and in his or her energy and personal resources. ¹³

As Bayés^22–24 points out, a suffering assessment instrument should be: able to measure subjective elements over a concrete period of time; understandable and replicable; simple and fast to administer; noninvasive to the patient; and unlikely to suggest new problems. Many available questionnaires may facilitate symptom assessment.^25–28 However, few instruments have been developed to specifically assess suffering, they are not used regularly and none of them constitutes a gold standard. To date, the clinical interview is still considered the best way to assess suffering. ²⁹

The present review aims to (1) identify the suffering assessment instruments available in the palliative care context, (2) describe their main features, and (3) comment on their psychometric properties, in order to facilitate selection according to the specific clinical or research context.

Methods

Two independent researchers conducted an extensive search attempting to identify suffering assessment instruments in palliative care. Published articles in English and Spanish were reviewed up to June 2011 in the MEDLINE, PsycINFO, and SciELO databases, using as search terms: “Suffering” (or “Distress”), “Assessment” (or “Instrument” or “Questionnaire” or “Measurement”) and “Palliative Care” (or “End-of-life” or “Terminally ill”).^30–33 Furthermore, references in the retrieved articles were screened for relevant articles. Initial inclusion of articles was based on the title and abstract.

Articles that (1) specifically assessed the experience of suffering or associated factors in palliative care using a quantitative measure, (2) reported the development of instruments designed to assess suffering, and (3) attempted to validate or examine the psychometric characteristics of current suffering assessment instruments were included. When an instrument was identified, a new search using its specific keywords was carried out, aiming at finding more articles reporting on its psychometric properties.

Since “distress” is sometimes used when referring to the suffering experience, ¹³ we decided to include it to increase search sensitivity. However, articles were only included when the experience of suffering was specifically assessed, acknowledging theoretical differences between the concepts. ³⁴ Also, while recognizing the relevance and frequent use in palliative care of instruments such as the Edmonton Symptom Assessment System (ESAS) ²⁸ and the Distress Thermometer ³⁴ or others designed to assess QOL, we decided not to include them given that they are intended to assess different constructs. A checklist for assessing the psychometric quality and ease of use of the instruments was used (Appendix A). This checklist was developed by Bot et al. ³⁵ and based on Lohr et al. ³⁶ and Bombardier and Tugwell. ³⁷ It has already been used in systematic reviews.^38–40 An adaptation for the present study was done to include not only self-assessment instruments, but also interview-based assessment instruments.

The checklist was used to assess the following properties of each instrument:

1. Validity: the degree to which an instrument measures the construct it is intended to measure, including construct validity, content validity, internal consistency.

All qualities assessed were rated as positive [+], inadequate [ø], or negative [−]. In case information on an element was insufficient or unavailable, no rating was given [ ]. All positive ratings for each instrument were summed to obtain an overall score for each instrument (0=no positive rating, 12=positive rating for all properties). Table 1 shows ratings for each quality and overall score and Appendix A details rating criteria.

Results

Study selection

Initially, 18,113 results were obtained (Fig. 1). Given the breadth of the search terms and the frequency with which palliative care studies refer to suffering, we expected a large number of initial results, even when recommended filters were used. ⁴² We found that many articles use the expression “suffering from” when only referring to a patient's diagnosis. After implementing a search filter eliminating that particular expression, 2240 results were obtained. Then, abstracts that did not fit the inclusion criteria were eliminated. Two hundred three suffering-related abstracts were identified. Afterwards, qualitative and case studies, position papers, and articles in which suffering assessment methods were not specified were excluded, leaving a total of 51 articles (Table 1). The material was then classified according to the assessment instrument mentioned. In the final 22 articles that described the development or assessment of psychometric properties, 10 assessment instruments were identified.

OPEN IN VIEWER

FIG. 1.

Flow chart of selection process of suffering assessment instruments.

Discussion

Since the redefinition of palliative care, ² the relief of suffering has come to the fore. With new, systematic studies of this topic, the field is shifting from “end-of-life care” to “palliation of suffering.”^9,89 There is a growing body of research, and new assessment instruments have been developed throughout the past decade for screening purposes (a brief, rapid and prospective process using standardized tools in order to determine if a referral for further evaluation is necessary ³⁴ ).

According to the results of this review, 10 instruments to assess suffering are now available for both clinical and research purposes.

PRISM and SISC have the strongest psychometric properties among all instruments included in the review. PRISM, a validated tool, enjoys the greatest acceptance and is regularly used in multiple populations,^50–72 aside from being the most conceptually coherent instrument. ⁵⁰ It allows a nondirective approach, provides a quantitative measure and can be used in patients with verbal or written communication difficulties. ⁵¹ However, the assessment of factors related to suffering relies mostly on the clinician's interest and has not been validated at end of life or in traditional palliative care contexts.

The Perception of Time and PRISM use nontraditional approaches to assess suffering. The former uses the perception of time as an indirect measure and is better suited to initiating an informal dialogue, while the latter uses a graphic, indirect approach, allowing assessment of total suffering and quantitative measurement.

The more recently developed scales, SISC, SOS-V, and the Scales of Suffering,^79,80,82 are multidimensional measures that address the various physical, psychological, social,l and spiritual spheres, allowing for quantification of total suffering in all its dimensions.

In the case of the SISC, ⁷⁹ the assessment is conducted through a semistructured interview, which facilitates contact with the patient and delves more deeply into other relevant aspects. Wilson et al.^10,79 used a mixed qualitative and quantitative methodology, yielding richer results.

The length of the instruments under review varies substantially. The SOS-V, SISC, and the Suffering Scales have the most items, while SISC and SOS-V take the longest time to administer. In the case of SOS-V, the length of administration may be inappropriate in the context of unbearable suffering and the patient's wish to hasten death. ⁸⁰ The MSSE,73 the Suffering Scale,81 and SAT ⁵ all have an average length, more comfortable for gravely ill patients. The PRISM, the Single-item Numeric Rating, and the Perception of Time are the shortest. Single-item numeric ratings are practical and used informally in clinical practice. But although they are considered a sensitive metric for subjective constructs, ⁹⁰ they are not precise enough to measure psychometric properties.

PRISM ⁵⁰ and MSSE ⁷³ are the only instruments that allow the assessment of patients with communication difficulties. The MSSE gives an objective measure of a decidedly private and subjective experience, one that does not fit neatly into acknowledged theoretical approaches.^1,11,91

Aside from the PRISM and SISC, the biggest challenge for the assessment of suffering lies in the insufficient data on psychometric properties for most instruments. Accordingly, validation studies of existing instruments will be needed, as well as studies that reflect their coherence with existing theoretical models.

Conclusion

Taking into consideration all features of the assessment instruments under review, the evaluation of suffering can be made easier. A wide and ever expanding range of approaches is now available, which facilitates the selection of the instrument that is best suited to the needs of the specific patient. ⁹² This broad menu of assessments makes it easier to evaluate patients, monitor progress and guide treatment decisions for patients who often face a dismal prognosis. Validated scales not only facilitate the timely screening of suffering in patients and families, but can be used as data points for clinical research in palliative care.