Isoniazid Preventive Therapy

I am responding to the recent article entitled "Isoniazid Preventive Therapy in Areas of High Isoniazid Resistance," by Sterling et al.¹ This decision analysis attempts to evaluate the life expectancies for tuberculin reactors who take isoniazid prophylaxis compared with those who have preventive treatment withheld. Unfortunately, the estimates they used for fatal isoniazid hepatitis were taken from data collected in the 1970s, when patients were not routinely monitored with liver function tests to detect potential drug-induced hepatoxicity.^2-4 After the hepatotoxic effects of isoniazid became known, the American Thoracic Society recommended that prophylaxis be withheld in the presence of acute liver disease and that routine monitoring be performed so that isoniazid treatment could be discontinued before severe side effects occur.⁵I recently reviewed published and unpublished data on chemoprophylaxis performed according to the 1983 guidelines and found two deaths in more than 200 000 patients, for a mortality