Incidence Rate of Herpes Zoster Similar in Patients With, Without Ankylosing Spondylitis

Results from a cohort study in Taiwan, published in the International Journal of Rheumatic Diseases, suggest that compared with a healthy control group, patients with ankylosing spondylitis (AS) were not at increased risk for herpes zoster (HZ).

Investigators conducted a retrospective cohort study with data abstracted from the Longitudinal Health Insurance Database 2000 in Taiwan. Patients who were newly diagnosed with AS between 2003 and 2013 were age- and sex-matched at a 1:4 ratio with a healthy control group in which participants had claims data in the same period. Patients with at least 1 inpatient claim or 3 or more outpatient claims for AS were considered to be newly diagnosed with AS. The primary outcome measure was diagnosis of HZ after the AS index date and before the conclusion of follow-up in 2013. Cox proportional hazard models were used to estimate the hazard ratios (HRs) for HZ among patients and the control group.

The final cohort comprised 2819 patients with AS and 11,276 without AS; demographic data were similar across study groups. Compared with the control group, patients with AS were more likely to present with the following comorbidities: chronic urticaria, diabetes mellitus, inflammatory bowel disease, thyroid disorders, hypertension, hyperlipidemia, coronary artery disease, cerebrovascular accident, chronic kidney disease, asthma, chronic obstructive pulmonary disease, esophageal disease, and peptic ulcer.

As per results from the multivariate analysis, patients aged ≥60 years (adjusted HR [aHR], 2.273; 95% CI, 1.314-3.931), patients with comorbid thyroid disorders (aHR, 1.577; 95% CI, 1.008-2.466), and patients with comorbid cancer (aHR, 1.855; 95% CI, 1.248-2.758) had higher HRs for HZ. However, the crude HR for HZ was not significantly elevated among patients with AS (HR, 1.178; 95% CI, 0.953-1.455; P =.1298) compared with the control group (HR, 1.070; 95% CI, 0.835-1.371; P >.05). The HRs remained similar among patients with AS and the control group, even after adjustments for demographic variables, length of hospital stay, and comorbidities at baseline.

No difference in incidence rate of HZ was observed among patients with AS and those without AS in Taiwan. Instead, among patients with AS, older age, thyroid disease, and cancer were major risk factors for incident HZ.

Reference

Wang S, Wei JC-C, Huang J-Y, Perng W-T, Zhang Z. The risk of herpes zoster among patients with ankylosing spondylitis: a population-based cohort study in Taiwan [published online July 23, 2019]. Int J Rheum Dis. doi:10.1111/1756-185X.13650