Epidemiology and risk factors of postherpetic neuralgia worldwide: protocol for a systematic review and meta-analysis

Postherpetic neuralgia (PHN) is a debilitating complication of herpes zoster (HZ) that significantly impairs quality of life, disrupting sleep, daily activities and work capacity. Globally, PHN represents a major public health challenge, with marked heterogeneity in its epidemiological patterns across different regions and demographic groups. The escalating incidence of both HZ and PHN underscores the urgent need to elucidate modifiable and non-modifiable risk factors, which is critical for implementing targeted prevention strategies and optimising therapeutic interventions. Although previous studies have examined PHN risk factors, there remains a paucity of comprehensive, up-to-date systematic analyses evaluating its global epidemiological trends and associated determinants. This protocol presents the methodology of a planned systematic review to assess an updated global estimate of PHN epidemiology and synthesises critical risk factors associated with PHN prevalence or severity.

This systematic review and meta-analysis will be conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. We will search MEDLINE/PubMed, Embase, Web of Science, CENTRAL, PsycINFO, Google Scholar, CNKI, Wanfang and CBM for English/Chinese studies published from inception through April 2025. Eligible studies will include adults (≥18 years) with HZ or PHN that report PHN prevalence/incidence or relevant risk factors (eg, age, vaccination status, acute pain severity, comorbidities). Two reviewers will independently screen records, extract data (including study characteristics, demographics, risk factors and pain metrics) and assess risk of bias using Joanna Briggs Institute tools and ROBINS-I. Random-effects meta-analyses (R V.4.0) will pool PHN prevalence (logit-transformed Wilson scores) and ORs for risk factors, with subgroup analyses by geography, income level, clinical/demographic factors. Heterogeneity (I²≥50%) will trigger meta-regression or narrative synthesis. Sensitivity analyses will address bias robustness.

Ethics committee approval is not required. The results of the review will be published through an open access journal.

CRD42024510329.