Abstract:

Objective: To explore the risk factors of delayed sputum smear or culture conversion at the end of 2-month of intensive treatment in cases with drug susceptible tuberculosis (DSPTB) complicated with diabetes mellitus (DM). Methods: A retrospective study was conducted in 70 DSPTB-DM patients in the prospective cohort of “Randomized controlled clinical trial of optimal anti-tuberculosis regimen for drug-sensitive tuberculosis combined with diabetes” in Shenzhen Third People's Hospital from May 2021 to July 2022. According to the study protocol, all study subjects were treated with H-R-Z-E (H: isoniazid; R: rifampicin; Z: pyrazinamide; E: ethambutol) for 2 months intensive treatment, sputum were tested with acid-fast bacilli smear microscopy and tuberculosis mycobacteria culture and divided into sputum negative conversion group and non-negative conversion group at the end of 2 months of intensive treatment. The clinical data of the subjects were collected, including age, sex, body mass index, nutritional screening score (NRS-2002), diagnosis sequence of DM and PTB, sputum acid-fast bacilli smear microscopy results, chest imaging fasting blood glucose and glycated hemoglobin, and peripheral blood laboratory test indicators. The risk factors associated with delayed sputum smear or culture conversion were analyzed using multivariate logistic regression model. Results: Seventy subjects were treated with 2-month intensive treatment. Of them, 20 cases (28.6%; negative conversion group) did not obtained sputum negative conversion and 50 cases (71.4%; non-negative conversion group) obtained sputum negative conversion. At the beginning of anti-tuberculosis treatment, a total of 19 cases were simultaneous diagnosed with DM and PTB, of which 8 cases were in the negative group, accounting for 42.1%; in the negative group, 16.0% (8/50) were diagnosed at the same time, which was lower than that in the non-negative group (55.0%, 11/20), and the difference was statistically significant (χ²=9.104, P=0.003). In the non-negative group, 85.0% (17/20) cases had lung cavities on chest imaging, which was significantly higher than that in the negative group (48.0%, 24/50; χ²=6.607, P=0.010). Multivariate analysis showed that the simultaneous diagnosis of DM and PTB (OR=11.003, 95%CI: 2.548-61.956) and the presence of chest imaging cavities (OR=7.711, 95%CI: 1.837-45.099) were independent risk factors of delayed negative conversion of sputum bacteria in patients with DSPTB-DM during intensive treatment. Conclusion: DSPTB-DM patients have a low rate of sputum negative conversion during the intensification phase of anti-tuberculosis treatment. At the beginning of treatment, it is important to pay attention to the patients with comorbidities between DM and PTB, as well as those with cavities in lung imaging, may experience delayed sputum negative conversion at the end of the intensification phase.

Key words: Tuberculosis, pulmonary, Diabetes mellitus, Comorbidity, Treatment outcome, Factor analysis, statistical