Purpose: To investigate the possibility of improving the results of therapy, we analyzed the association between the performance of directly observed treatment short course (DOTS) and treatment outcomes in patients with tuberculosis.
Methods: Patients with sputum smear-positive pulmonary tuberculosis who were newly registered in Osaka City between 2007 and 2010 were included in the study. The patients' drug-taking was confirmed at least once a week during DOTS.
Results: (1) In total, 2,423 patients were enrolled in the study (676, 563, 631, and 553 in 2007, 2008, 2009, and 2010, respectively). Of these, patients who died, those who were transferred during treatment, and those who remained under treatment at the time of analysis, were excluded. In 2007, 2008, 2009, and 2010, 84.1%, 82.3%, 86.2%, and 92.0% of patients, respectively, underwent DOTS and 91.6%, 91.7%, 92.6%, and 95.1%, respectively, were considered to be cured or to have completed treatment, demonstrating increases in both the parameters. On the other hand, 8.4%, 8.3%, 7.4%, and 4.9% of patients, respectively, were considered to have failed to respond to treatment or defaulted, showing a decreasing trend. (2) We examined the results of treatment of the 2010 cohort of patients with respect to whether a patient was supported by the DOTS service. Four percent of the 377 patients who underwent DOTS failed or defaulted compared with 15.2% of the 33 patients who did not undergo DOTS, which was a significant difference (P<0.01). (3) In total, 131 patients failed to respond to treatment or defaulted between 2007 and 2010, with reasons for such including abandonment of treatment, departure from the hospital, or refusal of treatment in 61 patients (46.6%); premature discontinuation of treatment due to physicians instructions in 33 (25.2%); and side effects in 22 (16.8%). The absence of a DOTS partner was considered a risk factor for discontinuation of treatment in 31 (56.4%) of the 55 patients who failed to respond to treatment or defaulted in 2009 and 2010.
Conclusion: An increase in the coverage of DOTS may be important for improving treatment outcomes. The most common reasons for patients failing to respond to treatment or defaulting were abandonment of treatment, earlier departure from hospital, or refusal of treatment. The absence of a DOTS partner accounted for more than 50% of cases of premature discontinuation of treatment. Thus, it may be mandatory to adequately evaluate the risk of treatment discontinuation in individual patients and to take appropriate action against it.