Development of a Prognosis Nomogram of Treatment Outcomes for MDR-tuberculosis in Guinea (Conakry): A Retrospective Cohort Analysis

Abstract Background: Despite the availability of the drug treatment for tuberculosis (TB) more than 75 years, mortality and drug resistance are increasing. Therefore, little data is available in Guinea. We aimed to develop and validate a prognosis nomogram of MDR-TB treatment outcomes. Methods:A retrospective cohort study was conducted among men and women, aged 18 years or older, with MDR-TB, from three major drug-resistance TB centres in Guinea. We used the logistic regression to analyse treatment outcomes. Prognostic factors with a p value less than 0.05 from a multivariate model were used to build nomogram and assessed their performance based on discriminative c-index, and calibration using the Hosmer-Lemeshow (H-L) test. To derive the optimal cut-off point score, the Youden’s index method was used. Results:Among 232 patients with MDR-TBenrolled and followed between June 07, 2016 and June 22, 2018, 218 were analyzed. All patients were resistant to rifampicin, which diagnosed by the Xpert MTB/RIF. The overall rate of success was 73%.Factors associated with successful treatment in drug-resistant TB patients were higher BMI more than 18.5 kg/m2(p = 0.0253; aOR = 2.94), good adherence to treatment (p = < 0.0001; aOR = 33.92), normal platelets count (p = 0.0053; OR = 1.004), and the absence of clinical symptoms such as chest pain (p = 0.0083; aOR = 3.19) and depression (p = 0.0308; aOR = 8.62). The discrimination (c-index= 0.848 [95% bootstrap CI, 0.780 – 0.916] in the derivation sample and 0.803 after correction for optimism) and calibration (H-LX2= 2.91 [p = 0.94]) were good. The optimal absolute risk threshold was 20%, corresponding to a sensibility of 95% and specificity of 58%. Conclusion:Treatment success outcomes was lower than those recommended by the World Health Organization (75%). We recommend to improve the MDR-TB patient monitoring during treatment, nutritional status, and considering the psychological state. Our prognosis nomogram needs to be validated in an external population before it can be used in clinical practice. Keywords:Nomogram, Multidrug-resistant, Tuberculosis, Guinea.