Statement of problem: To develop and evaluate a self-administered health-related quality of life (HRQOL) measure for peripheral neuropathy.
Methods: A field test measure of 162 items was developed that included the RAND-36 Health Survey as a generic core and a neuropathy-targeted supplement whose content was driven by results from three focus groups with 22 adults having peripheral neuropathy. It was administered at baseline and at 3- and 6-month follow-ups to 80 adult clinical trial enrollees with diabetic neuropathy. Item reduction and placement into scales, reliability, construct validity, responsiveness, and HRQOL comparisons to a general U.S. population were conducted.
Results: The final 97-item instrument includes 16 multi-item scales and 6 single items. Internal consistency reliabilities ranged from 0.67 to 0.93 (median = 0.88); intraclass correlation coefficients for those reporting no change in health between baseline and 3 months ranged from 0.42 to 0.84 (median = 0.77). Factor analysis of scales revealed physical and mental health as the two underlying dimensions. Correlations between selected HRQOL scales and sociodemographic variables were modest; there were more noteworthy associations between HRQOL scales and employment, disability days, and neurologic symptom ratings. Associations of HRQOL with neurologic examination (strength and reflexes) and with electrophysiologic findings were nonsignificant (all p > 0.10). Responsiveness of a physical health summary score relative to a criterion of change in subject's ratings of neuropathy symptom severity yielded a moderate effect size (= 0.60) and a Guyatt statistic exceeding 1.0.
Conclusions: Results provide preliminary support for the measure's reliability and validity among adults with diabetic peripheral neuropathy. HRQOL was more strongly associated with symptom ratings than with examination and electrophysiologic test results.