A Sourcebook for Pain-Related Research

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Although pain is the primary reason most patients will seek the assistance of a physician, the concept of pain as a sensation and as a disease remains confused in the minds of most patients and clinicians. Pain as a distinct disease state, maldynia, has been difficult to define and study. The uniquely subjective nature of pain, the highly variable individual response to pain, and the associated physical and emotional impact of pain on patients' lives creates a formidable challenge for the health care provider. As noted by the authors in Chapter 1, patients with pain have begun to exert greater autonomy in controlling and directing their care, in contrast to other more conventional disease-centered models, reflecting in part the difficulties encountered in measuring such a personal experience. This frequently leaves the health care provider in an uncomfortable and pressured position of trying to balance the risks and benefits of various treatment options without a clear set of objectively measurable parameters to guide therapy. As in other disease models, health care providers continue to seek reliable outcome measures to ensure that optimal care is being provided. Unfortunately, this has led to the propagation of a myriad of pain-related outcome measures, which are often population and diagnosis specific, with individual strengths and weaknesses, depending on the targeted physical, functional, or psychological measure. As a clinician and researcher, it is often difficult to sort out which tools are most appropriate for a given circumstance.

In this text, Wittink and Carr have pulled together a series of excellent monographs written by an accomplished group of authors addressing the evidence, outcomes, and quality-of-life measures that help to guide patient-centered clinical decision making. The text contains 24 chapters dealing with general measures to assess pain, quality of life, and outcomes, as well as specific chapters focusing on individual disease entities. In the more general chapters, there is a broad examination of various assessment tools, comparing and contrasting the relative merits of each in assessing pain intensity and quality of life. A copy of each assessment tool is included in a CD-ROM disc provided with the textbook. There is some repetition in the discussion of these tools in the more specific chapters that focus on headache, acute pain, complex regional pain syndromes, arthritis, palliative care, mental health, and musculoskeletal pain; however, the contextual review provides a relevant perspective. Some of the more technical chapters, dealing with topics such as clinimetric properties and pharmacoeconomics, are unlikely to provide interesting reading for the clinically oriented reader but are useful resources for the clinical scientist seeking a basic foundation identifying the proper measures to include in clinical trials.

The real strength of this text rests in the compilation and comparison of each assessment method. For example, Chapter 5 provides a careful look at pain assessments conducted in clinical trials. Often, researchers may select one or more pain measures to assess an analgesic response. Not all pain intensity measures will work in every population. Although the differences encountered in the pediatric population are widely recognized, the difficulty encountered by the elderly with the visual analog scale are probably not as widely recognized. Choosing the correct measurement tool can reduce patient confusion and improve the validity of the data collected.

Chapter 7 provides an interesting summary dealing with the assessment of treatment-related side effects and numbers needed to harm. Most clinical trials dealing with analgesic medications are powered specifically to address analgesic efficacy, but will seldom show reductions in pain of more than one-third of the baseline pain score. Given such modest results, the relative efficacy of treatment must be viewed carefully with respect to adverse outcomes and side effects. As pointed out in this chapter, most randomized controlled trials have failed to carefully address the adverse events associated with analgesic therapy. Several factors may weigh into this, including the often short duration of many clinical trials, failure to capture adverse events, or failure to report these events. In the face of limited efficacy, the authors point out that a greater emphasis needs to be placed on documenting the magnitude and prevalence of analgesic adverse effects to allow for evidence-based clinical decision making.

The difficulty of combining useful measurements of pain, treatment response, and quality of life is clearly highlighted in Chapter 15, which addresses complex regional pain syndrome (CRPS). Probably no other disease state exhibits so many shades of gray, making assessment and the evaluation of treatment extremely difficult and confusing. The vast number of different treatments, small sample sizes, measurement tools, and scales contributes to confusion and creates difficulty in combining data sets into a workable database to support clinical decision making. Despite considerable progress in evaluating other pain conditions, CRPS continues to be poorly characterized in a consistent fashion. As the authors point out, many of the measurement instruments that have been used were originally developed for other pain populations and may not have sufficient reliability and validity for the CRPS population.

Overall, this textbook will be of considerable value as a reference to anyone interested in conducting or reading pain-related research. As a sourcebook, it achieves the editors' goals of introducing the reader to the concepts that support contemporary research methods to validate or negate treatment options to relieve pain and improve quality of life.