Patients with systemic vasculitis or systemic lupus erythematosus (SLE) who have been exposed to intravenous cyclophosphamide are at a high risk of contracting zoster, according to a recent study published in The Journal of Rheumatology.
The researchers of this retrospective study analyzed the prevalence of zoster in patients with SLE or systemic vasculitis who were treated with cyclophosphamide. Their aim was to determine the potential risk factors and occurrences rate of zoster, and the protective nature of valacyclovir.
The 2 groups consisted of 29 patients with SLE and 81 patients with systemic vasculitis. A combined total of 12 patients had a history of zoster. Both groups had a comparable exposure to cyclophosphamide and follow-up time frames. Patients with SLE had a mean dose of 5227 mg and a mean follow-up of 3.3 ± 1.6 years, and patients with systemic vasculitis had a mean dose of 5748 mg and a mean follow-up of 3.5 ± 1.7 years. Valacyclovir was given to 17.2% of the patients at follow-up, with a mean duration time of 3.6 years, and no adverse effects were found to be associated with the antiviral medication.
A year after cyclophosphamide treatment, the incidence of zoster was 111 per 1000 person-years in the SLE group and 40.5 per 1000 person-years in the systemic vasculitis group. None of the patients treated with valacyclovir developed zoster, even with 2 patients having a history of zoster. The 2 risk factors identified were lymphopenia <500 μl at time of cyclophosphamide treatment (HR, 5.11; 95% CI, 0.94-27.93) and female sex (HR, 4.36; 95% CI, 0.51-37.31).
Some limiting factors of this study include the short follow-up times and a sample size that was too small to compute the relationship between valacyclovir and zoster development. Further research is needed to fully examine the protective benefit of prophylaxis against zoster.
In conclusion, patients with SLE or systemic vasculitis who have been treated with cyclophosphamide have an increased risk of developing zoster compared with the general public, and prophylaxis with valacyclovir might provide protection against the reactivation.
Garnier C, Ribes D, Chauveau D, et al. Zoster after cyclophosphamide for systemic lupus erythematosus or vasculitis: incidence, risk factors, and effect of antiviral prophylaxis. [published online July 15, 2018]. J Rheumatol. doi:10.3899/jrheum.180310