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Study Test Battery (Part 4) Measurement properties of the Medical Outcomes Study Sleep Scale in patients with fibromyalgia Objective: Sleep problems are a common symptom of fibromyalgia (FM). The objective of this study was to evaluate the Medical Outcomes Study (MOS) Sleep Scale as a measure of FM-related sleep problems. Methods: Analyses were based on data from the 1056 and 1077 studies, two randomized, double-blind, placebo-controlled trials of pregabalin for adults with FM. MOS Sleep Scale scores of study patients were compared with United States normative scores using a one-sample Z test. Subscale structure of the MOS was evaluated by confirmatory factor analyses, internal consistency was evaluated using Cronbach‟s alpha reliability coefficients. Estimated clinically important differences (CID) in MOS Sleep Disturbance subscale scores were evaluated using mixed-effects models of change in subscale scores as a function of the Patient Global Impression of Change (PGIC). Results: 1056 and 1077 included 748 and 745 patients, respectively. Most patients were female (1056: 94.4%, 1077: 94.5%) and white (1056: 90.2%, 1077: 91.0%). Mean ages were 48.8 years (1056) and 50.1 years (1077). Baseline MOS Sleep Scale scores were statistically (P < 0.001) and substantially poorer than general population values. The MOS subscale structure was confirmed in both studies at each assessment except at baseline in the 1056 study. Cronbach‟s alpha coefficients were acceptable, at least 0.70, for all multi-item scales at baseline and end-of-study assessments in both studies, with the exception of the Sleep Adequacy subscale at baseline. The estimated CID for the MOS Sleep Disturbance subscale was 7.9. Conclusions: The MOS Sleep Scale is an appropriate measure of FM-related sleep problems. These analyses provide the foundation for further use and evaluation of the MOS Sleep Scale in FM patients. Reliability of a 1-week recall period for the Medical Outcomes Study Sleep Scale (MOS-SS) in patients with fibromyalgia Objective: To evaluate the reliability of a one-week versus a four-week recall period of the Medical Outcomes Study Sleep Scale (MOS-SS) in patients with fibromyalgia (FM). Methods: The MOS-SS was administered by mail to patients with a confirmed diagnosis of FM and a current pain rating of > 2 (0–10 point numerical rating scale) recruited through newspapers, support groups, and the Internet. Reliability of MOS-SS subscale domains was evaluated using test-retest methodology separated by a 1–3 day interval for the 4-week recall period and a 7-day interval for the 1-week recall period. Patient Impression of Change was evaluated for sleep, and for patients with no change, the intraclass correlation coefficient (ICC) and the Pearson correlation coefficient was calculated for MOS-SS subscales. Results: Of 129 patients enrolled, 91.3% were female, mean age was 49.4 ± 11.0 years; self-rated FM severity was moderate-to-severe in 88.1% of patients. MOS-SS subscale scores were similar for both recall periods with little variation between test-retest. The 9-item Sleep Problems Index scores ranged from 57.2 ± 14.5 to 61.9 ± 15.8 across all assessments and demonstrated high reliability which was similar for the 1-week (ICC 0.81) and 4-week (ICC 0.89) recall periods. For the other MOS-SS subscales, the 1-week recall period also showed good reliability, which was consistent for the ICC and Pearson correlation coefficients. Conclusion: A 1-week recall period is adequately reliable for use of the MOS-SS in studies evaluating sleep disturbance in patients with FM. The FIQ and the MOS Sleep Scale are contained in Appendix B. |
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