Impact of the 99DOTS digital adherence technology on tuberculosis treatment outcomes in North India: a pre-post study

99DOTS is a cellphone-based digital adherence technology. The state of Himachal Pradesh, India, made 99DOTS available to all adults being treated for drug-sensitive tuberculosis (TB) in the public sector in May 2018. While 99DOTS has engaged over 500,000 people across India, few studies have evaluated its effectiveness in improving TB treatment outcomes.

We compared treatment outcomes of adults with drug-sensitive TB before and after Himachal Pradesh's 99DOTS launch using data from India's national TB database. The pre-intervention group initiated treatment between February and October 2017 (N = 7722), and the post-intervention group between July 2018 and March 2019 (N = 8322). We analyzed engagement with 99DOTS and used multivariable logistic regression to estimate impact on favorable treatment outcomes (those marked as cured or treatment complete).

In the post-intervention group, 2746 (33.0%) people called 99DOTS at least once. Those who called did so with a wide variation in frequency (< 25% of treatment days: 24.6% of callers; 25-50% of days: 15.1% of callers, 50-75% of days: 15.7% of callers; 75-100% of days: 44.6% of callers). In the pre-intervention group, 7186 (93.1%) had favorable treatment outcomes, compared to 7734 (92.9%) in the post-intervention group. This difference was not statistically significant (OR = 0.981, 95% CI [0.869, 1.108], p = 0.758), including after controlling for individual characteristics (adjusted OR = 0.970, 95% CI [0.854, 1.102]).

We found no statistically significant difference in treatment outcomes before and after a large-scale implementation of 99DOTS. Additional work could help to elucidate factors mediating site-wise variations in uptake of the intervention.