Use of patient-reported sleep measures in clinical trials of pain treatment: a literature review and synthesis of current sleep measures and a conceptual model of sleep disturbance in pain

Abstract

Background: Despite the strong relationship between sleep-related problems and chronic pain, no measures have been developed specifically for the assessment of sleep disorders in patients with chronic pain. In addition, there are no explicit guidelines to suggest which of the existing self-reported measures of sleep disorders best capture the sleep disorders pertinent to patients with chronic pain. Objective: The objective of this paper was to examine the fit between current sleep measures that capture areas of sleep disturbance important to patients with pain and to develop a conceptual model of sleep disturbance in these patients. Methods: A conceptual framework describing the associations between patient-reported experiences of pain and sleep problems was constructed based on a review of the published peer-reviewed literature. The online OVID/MEDLINE and PubMed databases were searched for articles in English published between 1995 and June 2007. Additional relevant material was identified by searching the reference lists of systematic review articles. The literature review and conceptual framework were used to determine the sleep domains that are most relevant to the study of patients with chronic pain. The patient-reported sleep measures most frequently used in pain clinical trials were identified and characterized psychometrically, along with how well they captured the relevant sleep domains. Results: Fourteen pain trials were identified in which sleep instruments were used. A review of the characteristics of the sleep-assessment instruments indicated that both the Medical Outcomes Study (MOS) Sleep Scale and the Pittsburgh Sleep Quality Index (PSQI) are well suited to measuring aspects of sleep that are of particular importance in the study of pain. The PSQI was used more frequently in the identified literature, but the MOS Sleep Scale was also well represented. The MOS Sleep Scale has fewer items than the PSQI, and its scoring system has a better psychometric fit with its conceptual framework. Conclusions: Sleep disturbance was found to be an essential element of the conceptual model for sleep-related problems in patients with pain. Of several sleep-quality instruments that have been used in pain clinical trials, the MOS Sleep Scale was found to be the best option. The PSQI, which was useful in many respects, may have a questionable factor structure. More research is needed comparing the scoring invariance on sleep scales between individuals with sleep disturbance in the general population and patients with pain.