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Modelling the use of Genexpert and Smear Microscopy on Time to Diagnosis, Treatment Initiation and Treatment Outcomes Among TB Patients at University Teaching Hospitals-Adult Hospital, Chest Clinic, Lusaka Zambia

John Mathias Zulu, MSc1; Sheila Masaku, MSc.1; Moses Mukosha, MSc.1 Chipo Nkwemu, MSc.1 Dr. Gershom Chongwe PhD1,2 Dr. Patrick Kaonga, PhD1; Prof. Patrick Musonda PhD1

1University of Zambia-School of Public Health, 2Tropical Diseases Research Centre

Background: Timely diagnosis and treatment initiation are important determinants of TB prevention and treatment outcomes. The study explored the diagnostic performance of the GeneXpert and Smear Microscopy on time to diagnosis, treatment initiation, and improvement of treatment outcomes.

Methods: A retrospective cohort study which followed up TB patients who used the GeneXpert and smear microscopy at UTH-chest clinic from 2015 january-2019 December. Median time was analyzed at two levels, time to diagnosis and time to treatment initiation. Multivariable Cox proportion models were used to analyze predictors of treatment initiation. While lognormal regression model was used to determine predictors of unfavorable outcomes. A p-value of 0.05 was deemed statistically significant.

Results: A total of 417 TB patients were enrolled in the study, 243 (58.3%) used GeneXpert, and 174(42.7%) used the smear microscopy. Of the total patients, 299(70.5%) were diagnosed in <=5days and 125(30%) in >5 days. Of the total participants, 229(54.0%) were treated in <=14 days and 195(46.0%) > 14days. Further, 156(45.0%) had successful and 191(55.0%) unsuccessful outcomes. Compared to smear, in Xpert arm median days of diagnosis were 1 day [IQR] 1–41) versus 4 days [IQR] 1–15), p<0.0001; Compared to Smear Microscopy, in Xpert arm median days for treatment initiation were 7 days [IQR] 1–31 versus 18 days [IQR] 5–72), p<0.0001. Predictors of delayed treatment initiation were, residence outside district but within catchment area vs within 12 km adjusted [HR] 2.133, 95% CI: 1.375,3.310, P=0.001, GeneXpert vs Smear microscopy: adjusted [HR] 0.777, 95% CI: 0.514–1.052, p<0.135). MDR vs Susceptible: adjusted ([HR] 1.608, 95% CI: 1.094–2.362, p=0.016). diagnosed <=5 days’ vs >5 days: adjusted: [HR] 0.762, 95%CI: 0.561,1.034, p=0.031. Predictors of unfavorable outcomes were method of diagnosis GeneXpert vs Smear microscopy: adjusted [TR] 0.216, 95% CI: 0.139–1.321, p<0.0001). outside district vs within 12km, adjusted [TR] 0.391, 95% CI: 0.149–1.028, p=0.050).xtagstartz/p>