Herpes zoster diagnosis and treatment in relation to incident dementia

Abstract

AbstractBackgroundRecent evidence suggests that some infectious diseases, such as herpes zoster (HZ), are positively associated with cognitive impairment and dementia, while certain anti‐viral medications have been reportedly associated with lower risk. We sought to evaluate associations between HZ diagnosis and treatment with incident dementia in a large, retrospective matched cohort.MethodUsing ICD‐9 and ICD‐10 diagnosis codes in electronic medical records, we identified members of Kaiser Permanente Northwest who were age 50 and older between 2000‐2019 inclusive with a HZ diagnosis during this period. A comparison group without HZ diagnosis was individually matched 3:1 on age at HZ diagnosis date (index date), sex, and membership length prior to index date. We excluded subjects with dementia diagnosed before the index date. Follow‐up time started at the index date and ended on the date of dementia diagnosis (based on ICD‐9 and ICD‐10 codes), membership end date, death, or end of follow‐up, whichever came first. Medication for HZ was identified using the first anti‐viral pharmacy fill within 6 months before or after the index date. We used survival analysis to examine the associations between dementia and HZ diagnosis (yes/no, overall, by sex, age), HZ medication (yes/no), and HZ medication by tertiles of cumulative dose of medication dispensed. We adjusted models for demographic and clinical factors.Result109,830 persons (27,500 with HZ) were included. The mean age was 65.5 years, and 61.5% were female. Over a mean follow‐up of 6.3 years, 11,386 developed dementia. HZ diagnosis, overall or within subgroup, was not associated with higher risk of dementia (Figure). Among persons with HZ, receipt of anti‐viral medication (any vs. none) was not statistically associated with lower dementia risk. None of the hazard ratios for tertiles of cumulative anti‐viral dose was statistically significant, though the one for the highest tertile was suggestive.ConclusionIn our retrospective study of over 27,000 persons with HZ and matched comparison persons without HZ, we found no evidence for an association between HZ diagnosis and dementia. Anti‐viral medications prescribed around the time of the HZ diagnosis were not statistically associated with lower risk of dementia.