Psychometric properties of the MOS (Medical Outcomes Study) Sleep Scale in patients with neuropathic pain.

OBJECTIVE

This study assessed the psychometric properties of the MOS Sleep Scale in neuropathic pain (NeP).

METHODS

Psychometric properties were tested in patients with neuropathic pain enrolled in a prospective study exploring the effectiveness of gabapentin for 3 months. Participants also completed scales for pain intensity, anxiety, depression, disability, and health-related quality of life. Feasibility, reliability, validity and sensitivity to change were measured in this study.

RESULTS

Six-hundred-three patients [58.4+/-14.4 years (65.1% female), mean+/-SD] with pain for 1.2+/-3.3 years were included. The MOS Sleep Scale was acceptable (items with missing data <10% and floor and ceiling effects <50% per item and <15% per domain) and reliable (Cronbach's alpha between 0.64 and 0.87, and test-retest intraclass correlation coefficients between 0.79 and 0.91, p<0.001 for all cases). After adjusting for confounders, the MOS Sleep Scale was able to distinguish between sex, present pain intensity, level of disability and presence of anxiety or depression. Correlations with other scales were moderate; rho-coefficients between -0.21 and 0.57 (p<0.01, all cases). The scale was sensitive to change after treatment with gabapentin; after adjusting, responders (50% reduction in baseline pain) showed a decrease in sleep problems index of -25.6+/-14.3 points vs. -12.1+14.5 points in nonresponders (F=80.5, df=1/398, p<0.0001). Score reduction in summary index and subscales correlated significantly with pain intensity reduction (Pearson r-coefficients between 0.428 and 0.116, p<0.01, all cases).

CONCLUSIONS

The MOS Sleep Scale showed good psychometric properties and was sensitive to changes in patients with NeP of broad aetiology.