Various factors had been related with sputum conversion in tuberculosis patients, which constituted an essential indicator of the effectiveness of treatment and the infectivity of patients. The study evaluates the factors related with smear sputum conversion in pulmonary tuberculosis. A retrospective cohort study of newly diagnosed pulmonary tuberculosis was performed from January 2013 to September 2016 in Cuban Hospital (Qatar). The data collected includes: demographics, clinical, laboratory test and chest X ray. The Kaplan Meier method was used to calculate the survival time to sputum conversion. The log-rank or Wilcoxon tests and Cox regression was used to identify the variable related with sputum conversion. In 323 patients, the median time of sputum conversion was 23 days, with sputum conversion at 2 months of treatment in 82.1% of patients. In older patients (39-86 years old), the probability of conversion was 31% lower when compared with patients 16-24 years old (RR 0.69, 95% CI, 0.52-0.90). The low figures of serum albumin (0.71, 0.56-0.90) and absolute lymphocyte count (0.64, 0.48-0.85) were associated with a decreased probability of sputum conversion, and the lower probabilities of conversion were found with the increased number of bacilli; among 1501 to 2000 (0.39, 0.23-0.66), and 2001 to 5000 (0.40, 0.28-0.58). The factors associated with delayed smear sputum conversion in tuberculosis patients were identified. Additional studies are required to evaluate the influence of nutritional status on TB diagnosis and the poor glycemic control in conversion times as well as interventions to modify these factors to improve the patient outcomes.
Key words: Infectious tuberculosis, sputum conversion, factors associated, Qatar.
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