Is a purified protein derivative skin test and subsequent antituberculous chemoprophylaxis really necessary in systemic rheumatic disease patients receiving corticosteroids?

Our objective was to determine whether a purified protein derivative (PPD) skin test and subsequent isoniazid administration to patients with systemic rheumatic disease, who react positively and are about to receive corticosteroids, is necessary. For this purpose, 451 unselected patients with systemic rheumatic diseases, such as rheumatoid arthritis, giant cell arteritis, polymyalgia rheumatica, systemic lupus erythematosus, scleroderma, poly- and dermatomyositis, mixed connective tissue disease, eosinophilic fasciitis, systemic necrotising vasculitis and Behçet's disease, were observed over a 6-year period. All patients had been started on steroids after commencement of the study and had received the drug for at least 1 year by the end of the study. A chest X-ray was performed before entry, every 6 months for the first year and yearly thereafter. A PPD skin test had been performed in 40 patients by other physicians, but it was our policy to omit the test. We divided our patients into age groups by decades. Steroid dosage varied according to diagnosis and severity. An initial chest X-ray revealed old inactive tuberculosis in 65 patients. During the follow-up period, none of the patients exhibited clinical or radiological evidence of reactivations of tuberculosis. However, at least 184 of the patients would have had a positive PPD skin test reaction, if tested. This figure is derived from the results of several studies on Greek army recruits whose current ages correspond to those of our patients. In conclusion, our results suggest that screening with a PPD and isoniazid prophylaxis, with all the potential risks for those who test positive, may not be necessary in patients with systemic rheumatic disease who will receive steroids.