Evaluation of the accuracy of 99DOTS, a novel cellphone-based strategy for monitoring adherence to tuberculosis medications: Comparison of digital adherence data with urine isoniazid testing.

99DOTS is a cellphone-based strategy for monitoring tuberculosis medication adherence. In a sample of 597 Indian tuberculosis patients, we compared 99DOTS' adherence assessments against results of urine isoniazid tests collected during unannounced home visits. 99DOTS had suboptimal accuracy for measuring adherence, partly due to poor patient engagement with 99DOTS.