Background/Purpose:

To assess the incidence of Herpes Zoster (HZ) in patients with psoriatic arthritis (PsA) and its relation to treatment regimen:Traditional disease-modifying anti-rheumatic drugs (c-DMARDs) versus anti-TNF α agents.

Methods:

A retrospective cohort study of patients with PsA insured by Clalit Health Services between 2006 and 2012 was conducted. The incidence of HZ events was calculated among four groups of patients with PsA: no DMARDS treatment (Group A); treatment with c-DMARDS (Group B); treatment only with anti-TNF α agents, including infliximab, adalimumab or enbrel (Group C); treatment with  an anti-TNF α agent (infliximab, adalimumab or enbrel) in combination with c-DMARDS (Group D). For each group, incidence rates of HZ events were calculated as well as hazard ratios (HR) adjusted for age, sex, steroid use, comorbidities index, current and previous treatment regimens. Crude incidence rates were calculated as the number of HZ infections per 1000 follow-up patient-years (under specific treatment). Survival analysis methods (Cox regression Andersen-Gill models) were applied to identify risk factors for HZ and to estimate the contribution of anti-TNF α treatment and time-independent and time-dependent covariates at the first development of HZ reactivation.

Results:

The study population consisted of 3158 patients, with a mean age of 52.31±14.74 years; 1479 (46.8%) were male. During the accumulated study period of 15763 years, 156 HZ events occurred. The incidence rate (95% Confidence Interval (95%CI)) of HZ events per 1000 treatment years among Groups A-D were 8.59 (6.72-10.97), 10.28 (8.05-13.14), 9.45 (5.53-16.11), 18.42 (11.53-29.30), respectively. In a multivariate analysis, only age (HR=1.016, 95% CI 1.003-1.03, P=0.015), treatment with steroids (HR=1.079, 95% CI 1.027-1.133, p=0.003) and a combination of anti-TNF α agents and c-DMARDS (HR =2.29, 95%CI=1.204-4.358, p=0.012) were statistically significantly associated with the time until the first HZ event. Treatment with c-DMARDS, anti-TNF α agents alone, previous treatment with biological agents, sex and the Charlson Comorbidity Index Score did not statistically significantly influence the time to the first HZ event.

Conclusion:

In the study population the incidence rate of an HZ event is 9.9 per 1000 treatment years. The risk of a first HZ event increased statistically significantly with patient age, treatment with steroids, and a combination of an anti-TNF α agent and c-DMARDS, but not with c-DMARDS or anti-TNF α therapy administrated separately.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/incidence-of-herpes-zoster-in-patients-with-psoriatic-arthritis/