Predictors of herpes zoster severity and immune responses according to pain trajectories: A community‐based prospective cohort study

The authors aimed to identify determinants of the clinical course of herpes zoster and immunological responses, focusing on pain trajectories. This prospective community‐based cohort study involved the analysis of responses to a valid pain survey provided by 375 patients diagnosed with herpes zoster based on clinical symptoms and virus identification by polymerase chain reaction. The authors analyzed most patients for humoral/cell‐mediated immune response against varicella‐zoster virus at the onset and 3 months post‐onset. Six months post‐initial visit, patients self‐reported pain on a scale of 0 (no pain) to 5 (extremely strong pain) at up to 18 time points. Moreover, the pain trajectories were traced using group‐based trajectory modeling. Subsequently, the authors used analysis of covariance to explore predictors and the humoral/cell‐mediated immune response according to the pain trajectories. In addition, humoral/cell‐mediated immune responses were assessed among each trajectory using paired t tests. Amon the five identified trajectories, two were isolated that particularly developed postherpetic neuralgia, with or without severe acute pain. Cancer therapy and corticosteroid use before herpes zoster onset specifically predicted postherpetic neuralgia without severe acute pain. In contrast, prescription of nonsteroidal anti‐inflammatory drugs was uniquely associated with postherpetic neuralgia accompanied by severe acute pain. The aforementioned trajectories with postherpetic neuralgia showed increased antibodies and decreased cell‐mediated immunity compared with those without postherpetic neuralgia. The authors could successfully distinguish between postherpetic neuralgia trajectories with and without severe acute pain. The identified key predictors and immunological responses against varicella‐herpes zoster contribute further evidence to our understanding of the clinical features of herpes zoster and postherpetic neuralgia.