Prevalence and risk factors of herpes zoster infection in patients with biopsy proven lupus nephritis undergoing immunosuppressive therapies

Objectives To study the prevalence of herpes zoster infection in patients with biopsy-confirmed lupus nephritis undergoing immunosuppressive therapies. Methods Patients who had histologically active lupus nephritis between 2004 and 2018 were retrospectively reviewed. Clinical and laboratory data at baseline and six months post-therapy were collected. The incidence of herpes zoster reactivation within two years of lupus nephritis treatment was calculated. Risk factors for herpes zoster reactivation were studied by logistic regression. Results Patients (N = 251) with 311 episodes of lupus nephritis were studied (92% women; age 34.2 +/- 14.2 years; histological classes III/IV +/- V (69%)). Within two years of therapy, 55 (18%) episodes of lupus nephritis were complicated by herpes zoster infection (incidence 8.84/100 patient-years). Fourteen episodes (25%) of herpes zoster were treated by intravenous anti-viral drugs in hospital but disseminated disease or mortality was not reported. Significant post-herpetic neuralgia developed in 9% of the episodes. Patients with herpes zoster reactivation, compared with those without, were more likely to have first-time renal disease and a shorter systemic lupus erythematosus duration at lupus nephritis than those without. Disease activity, treatment response and other clinical/laboratory parameters were not significantly different between patients with and without herpes zoster reactivation. Herpes zoster-infected patients had been treated with a significantly higher dose of prednisolone as induction therapy. Logistic regression revealed that first-time renal disease, peak daily mycophenolate mofetil dose and cumulative cyclophosphamide dose during induction therapy were significantly associated with herpes zoster reactivation. Conclusions Herpes zoster reactivation is common in lupus nephritis patients but unpredictable from clinical parameters. Although adverse outcomes of herpes zoster infection are uncommon, using the minimally effective doses of mycophenolate mofetil and cyclophosphamide during induction therapy may help reduce the risk of herpes zoster infection.