Mycobacterium tuberculosis infection in a corticosteroid-treated rheumatic disease patient population.

OBJECTIVE: To investigate the incidence and risk factors of Mycobacterium tuberculosis infection in longterm corticosteroid treated rheumatic disease patients.
METHODS: We assessed retrospectively the incidence of active tuberculosis and its risk factors in 269 rheumatic disease patients treated with moderate to high doses of corticosteroid for an evaluation period representing 1,035 corticosteroid years of therapy.
RESULTS: The mean daily dose of steroid was 18.7 mg prednisolone and the mean daily dose during the first year of treatment was 20.4 mg prednisolone. 21 of these patients developed active tuberculosis resulting in an incidence rate of 20/1,000 patient-years. Cumulative and mean daily steroid doses during the follow-up period and during the first year of treatment, and a history of steroid pulse therapy were significantly correlated with the development of tuberculosis. A past history of tuberculosis, initial chest P-A abnormality, the starting dose of steroid, a history of more than 30 mg/day of prednisolone for more than one month, and a history of cytotoxic therapy were not related to the development of tuberculosis.
CONCLUSION: The incidence of active tuberculosis is increased in rheumatic patients on moderate-to-high dose steroid treatment. Its risk factors are the cumulative and mean daily steroid doses during the follow-up period and during the first year of steroid treatment, and a history of steroid pulse therapy.