Risk factors for herpes zoster infection among Filipinos with systemic lupus erythematosus

Aim To identify clinical risk factors associated with herpes zoster (HZ) infections in systemic lupus erythematosus (SLE). Methods A case-control study of HZ infection was performed in SLE patients seen at the University of Santo Tomas Lupus Clinics from 2009-2014. Cases were matched 1:2 to SLE controls without HZ infection for age, sex, and disease duration. Clinical characteristics, SLE disease activity, and immunosuppressive use were compared. Results Sixty-five SLE patients (61, 93.8% female) who developed HZ were matched with 130 SLE patients without HZ. Mean age was 36.75 years (+/- 1.35; P = 1.00) for the case group; mean SLE disease duration at first HZ infection was 6.1 years (+/- 3.3; P = .919). Four patients had more than 1 episode of HZ. There was localized HZ in 63/65 (97%), and 2 (3%) disseminated HZ infections. The case group received higher doses of prednisone 64/65 (P = .012), mean prednisone dose 18.62 mg/d (+/- 1.48, P < .001) and more were exposed to cyclophosphamide (Cyc) (19/65; P < .001) compared to the control group's mean prednisone dose of 11.73 mg/d (+/- 1.16); there was Cyc use in 7/130 patients. Cyc in addition to mycophenolate mofetil (MMF) use among lupus nephritis patients conferred the highest risk for HZ infection occurrence. Hydroxychloroquine (HCQ) use reduced the risk for HZ by 87% (adjusted odds ratio 0.13, P = .003). Conclusion Immunosuppressives and corticosteroid use are risk factors associated with the development of HZ in SLE. The risk for HZ increases among patients given intravenous Cyc and MMF for lupus nephritis. SLE disease activity did not show a direct association with HZ occurrence. HCQ use appeared to have a protective role against HZ infection.