Cumulative incidence of and risk factors for herpes zoster among patients with diabetes mellitus: Results from a 10-year nested case-control study

Background: Diabetes mellitus (DM) is a well-known risk factor for herpes zoster (HZ). Data specific to the incidence of and risk factors for HZ among Thai DM patients are scarce. Methods: This nested case-control study evaluated a 10-year cohort of DM patients (N = 1428) treated at Siriraj Hospital (Bangkok, Thailand). We included 40 cases with ≥1 episode of HZ, and we randomly sampled 175 non-HZ controls. Data were obtained from chart review and the ICD-10 diagnosis code, pharmacy database, and laboratory database. Results: During 2005–2014, the cumulative incidence and incidence rate of HZ among all study patients was 2.80% [95%CI: 2.00–3.79%] and 3.96 [95%CI: 2.90–5.28] per 1000 person-years, respectively. The most common site was trunk (27.5%) followed by zoster ophthalmic (22.5%). Only 1 case required hospitalization. Independent risk factors for HZ included underlying hypertension [aOR: 3.48, 95%CI: 1.28–9.43; p = 0.01], number of hypoglycemic drugs used [aOR: 1.46, 95%CI: 1.03–2.08; p = 0.04], and previous herbal remedy use [aOR: 3.83, 95%CI: 1.06–13.84; p = 0.04]. Higher body mass index was a protective factor against HZ [aOR: 0.89, 95%CI: 0.81–0.98; p = 0.02]. Conclusion: The incidence of HZ among DM patients at our center is comparable to other Asian countries. The identified independent risk factors can be used to discern patients who would benefit most from preventive interventions.