Evaluating the role of primary care physicians in the treatment of latent tuberculosis: a population study.

Setting: Latent tuberculous infection (LTBI) remains a significant source of new active tuberculosis cases. Recent guidelines encourage primary care physicians to prescribe LTBI treatment; however, there have been no investigations into the impact on treatment completion.

Objective: To estimate LTBI treatment initiation and completion rates by primary care physicians.

Design: A historical cohort study was conducted with Quebec residents dispensed isoniazid (INH) between 1 January 1998 and 31 December 2005. Information was obtained from administrative health insurance data. Regression modeling was used to estimate the association of completion rates with prescribing physician specialty, after adjustment for initial health status and other patient characteristics.

Results: A total of 14,753 people were dispensed INH for LTBI treatment. Primary care physicians initiated 3863 (26%) treatments. This proportion decreased from 28.7% in 1998 to 21.1% in 2005. Patients initiated on treatment by primary care physicians were less likely to complete treatment (OR 0.79, 95%CI 0.72-0.86). Only 5977 (40.5%) patients completed treatment; the average treatment duration of the primary care physician group was 11 days less (P < 0.0001).

Conclusion: Primary care physicians initiated a substantial number of LTBI treatments, but less than half of patients completed treatment regardless of the physician specialty. Primary care physicians should be supported to enhance treatment completion.