Differences in Estimates of Post-Herpetic Neuralgia Between Medical Chart Review and Self-Report

PURPOSE: Post-herpetic neuralgia (PHN) is a common herpes zoster (HZ) complication, where pain persists 90 days after the initial HZ diagnosis. Evaluating PHN risk is essential for determining the burden on patients and health-care systems, but research shows variable estimates. The extent to which these differences are related to the assessment method has not been examined. The purpose of this study is to compare the proportion of PHN among HZ patients measured by medical chart review and self-report surveys. METHODS: PHN risk was assessed among a sample of Kaiser Permanente Southern California members with HZ. Chart reviews identified lingering pain 90–180 days post-HZ diagnosis and the Zoster Brief Pain Inventory was administered 90 days post-HZ diagnosis by telephone. Frequencies of PHN identified with each approach were cross-tabulated and stratified by sex, age group, and zoster vaccine live vaccination status. RESULTS: Chart review and self-report were largely concordant (n=875, 89.20%); however, chart review yielded lower PHN risk overall and for the stratified subgroups. PHN from self-report was substantially higher (6.30–8.33%) among patients who were male, ≥70 years, or unvaccinated. Among those who typically seek care more often (female, younger, vaccinated), the discrepancy between each method was notably lower (1.60–2.92%). CONCLUSION: Our findings suggest that chart review underestimates cases among those less likely to seek health care, including males, the elderly, and unvaccinated individuals. The agreement between the methods indicates that each can provide a reasonable approximation of PHN, but analyses should carefully control for health-care utilization.