Efficacy of isoniazid prophylaxis in patients with systemic lupus erythematosus receiving long term steroid treatment

Objective: To study the efficacy of isoniazid prophylaxis (INHP) in patients with systemic lupus erythematosus (SLE) receiving long term glucocorticosteroid treatment. Patients and methods: Treatment with INHP (5 mg/kg/day, max 300 mg/day) together with pyridoxine 10 mg/day for one year was started in all patients with SLE seen between January 1994 and December 1999 and followed up thereafter. Clinical examination and chest radiography were carried out in all patients before the start of INHP treatment. A liver profile was obtained only if liver toxicity was suspected owing to nausea, loss of appetite, and icterus. Only the data of those patients who completed the INHP treatment or who were withdrawn owing to toxicity have been analysed. This was compared with the results of an earlier study of the incidence of tuberculosis (TB) in patients with SLE not receiving INHP. Results: Ninety seven patients were included, of whom 95 completed one year's treatment with INHP. Treatment was discontinued in two owing to toxicity: hepatitis in one and peripheral neuropathy in one, at eight and 10 months, respectively. One patient developed TB within one month of starting INHP. Seventy patients were followed up further for at least one year (mean 26.4 months, range 12-60 months) after completion of the INHP treatment. During this period one patient developed TB after one month. No deaths due to TB or hepatitis occurred. In comparison with earlier series the incidence of TB decreased from 11% to 2%, a reduction of 82%. The cost of treatment for each case of TB prevented in the first year was 5800 rupees. Conclusion: INHP is safe and effective in SLE.