Herpes zoster increased risk of neuralgic amyotrophy: a retrospective, population-based matched cohort study.

Although neuralgic amyotrophy (NA) has occasionally been reported to be associated with reactivated herpes zoster, their associated risk remains unknown. The aim of this study was to assess the risk of developing NA following preceding herpes zoster. The authors used the National Health Insurance Research Database of Taiwan to select 41,548 patients with newly diagnosed herpes zoster during the period 2000 to 2010 and randomly extracted 166,192 matched control subjects. All participants in the study and control groups were followed for 3 months after the diagnosis to identify those who developed NA. Cox proportional hazards regression analyses were performed to evaluate the subsequent risk of NA. Twenty-one subjects from the group with herpes zoster (0.05%) developed NA over the 3-month period and 46 from the group without herpes zoster (0.03%). The patients with herpes zoster had a higher risk of developing NA (adjusted hazard ratio = 1.408, 95% confidence interval = 1.013-2.319, P = 0.030). In the patients with herpes zoster, female sex, age ≥ 65, hepatitis E virus (HEV), and having had a recent infectious event including pneumonia and influenza were risk factors for developing NA (adjusted HR 2.746, 1.998, 2.735, 2.016, and 1.718, respectively, all P < 0.05). Patients with herpes zoster attack have a higher risk of developing NA over a 3-month period after diagnosis, especially those who are female, age ≥ 65, HEV, or have experienced a recent infectious event or pneumonia and influenza.