Background HIV infection is a risk factor for development of Herpes Zoster (HZ) and its complications. There is limited evidence on the impact of antiretroviral therapy (ART) on the occurrence of HZ among HIV-infected adults.

Methods Study population was drawn from the KompNet HIV cohort. Inclusion criteria were: age ≥ 18 years, record of HIV diagnosis date (t0), record of CD4 count available ± 6 months from t0. Patients without month of HZ diagnoses were excluded. Study period was 1.1.1985–1.7.2010.

Incidences of all HZ events were estimated assuming Poisson distribution, uni-/multivariate Cox proportional Hazard ratio (HR) regression models were fitted to identify risk factors for a first HZ event. Independent variables were: sex, age at HIV diagnosis, HIV transmission route, ART status, CD4-value before HZ episode, immunosuppressive medication, mode of data documentation (retrospective/prospective).

Results Study population comprised 3,757 subjects (86% male, 66% MSM, 3% IVDU, 92% Caucasian), mean age at HIV diagnosis was 38 years, mean observation time was 5.8 years.

362 HZ events were recorded in 326 patients (8.6%), resulting in an HZ incidence of 16.7/1,000 PY overall and 16.1/1,000 PY for first HZ cases. Main risk factors associated with first HZ event were: no ART compared to an ART containing a non-nucleoside reverse-transcriptase inhibitor (NNRTI vs no ART; HR 0.530, p < 0.001) or a protease inhibitor (PI vs no ART; HR 0.624, p = 0.004), lower CD4-cell count (rise 100 cells/μl, HR 0.918, p = 0.001) and retrospective data documentation (HR 0.582, p < 0.001). No risk factors were: sex, age, HIV transmission route, immunosuppressive medication.

Conclusions According to former studies incidence of HZ in HIV-infected individuals was ∼5 times higher than in the general population. Our study showed ART as important protective associated factor for HZ events. Reasons may be earlier HIV-diagnosis, more recent picturing of ART, and low IVDU proportion in our study.