Significant clinical impact of a rapid molecular diagnostic test (Genotype MTBDRplus assay) to detect multidrug-resistant tuberculosis

Background: There are limited data on the clinical impact of rapid diagnostic tests to detect multidrug-resistant tuberculosis (MDR-TB). We sought to determine whether the use of a molecular diagnostic test to detect MDR-TB improves clinical outcomes.

Methods: A quasi-experimental study was conducted to analyze the impact of the Genotype MTBDRplus assay on clinical outcomes among patients with culture-confirmed pulmonary MDR-TB. Patients received treatment at the National Center for Tuberculosis and Lung Diseases in Tbilisi, Georgia. Time to MDR-TB treatment initiation, culture conversion, and infection control measures were compared to a time period prior to the implementation of the molecular test.

Results: Of 152 MDR-TB patients, 72 (47%) were from prior to and 80 (53%) following implementation of the MTBDRplus assay ("post-implementation group"). Patients in the post-implementation group initiated a second-line treatment regimen more rapidly than those in the pre-implementation group (18.2 vs 83.9 days, P < .01). Among patients admitted to a "drug-susceptible" tuberculosis ward, those from the post-implementation group spent significantly fewer days on the drug-susceptible ward compared to patients in the pre-implementation group (10.0 vs 58.3 days, P < .01). Among patients with 24 weeks follow-up (n = 119), those in the post-implementation group had a higher rate of culture conversion at 24 weeks (86% vs 63%, P < .01) and a more rapid rate of time to culture conversion (adjusted hazard ratio [aHR] 4.15, 95% confidence interval [CI], 2.5-6.9).

Conclusions: The implementation of a rapid molecular diagnostic test led to significant clinical improvements including reduced time to initiation of MDR-TB treatment, culture conversion, and improved infection control practices.