Predictors of spontaneous sputum conversion in the untreated stationary group of 93 patients
| Univariate analysis | Multivariate analysis | |||
| HR (95% CI) | p-value | HR (95% CI) | p-value | |
| Age years | 0.969 (0.945–0.994) | 0.015 | 0.973 (0.948–0.999) | 0.043 |
| Male | 1.087 (0.612–1.929) | 0.776 | 0.885 (0.484–1.621) | 0.693 |
| BMI kg·m−2 | 1.108 (1.018–1.205) | 0.017 | 1.101 (1.007–1.205) | 0.035 |
| Nonsmoker | 0.961 (0.542–1.704) | 0.892 | ||
| Presence of comorbidity# | 1.309 (0.730–2.345) | 0.366 | ||
| Positive sputum AFB smear | 0.536 (0.259–1.110) | 0.093 | 0.377 (0.156–0.912) | 0.030 |
| Causative organism | 0.817 | |||
| Mycobacterium avium | 1 | |||
| Mycobacterium intracellulare | 0.932 (0.514–1.691) | |||
| Radiological type: nodular bronchiectatic | 1.246 (0.634–2.450) | 0.524 | ||
| Involved lobes | 1.012 (0.770–1.329) | 0.934 | ||
| FVC % pred <80% | 1.165 (0.655–2.072) | 0.604 | ||
| Transient anti-TB medication (≥1 month)¶ | 2.091 (0.974–4.490) | 0.059 | 3.769 (1.505–9.435) | 0.005 |
HR: hazard ratio; BMI: body mass index; AFB: acid-fast bacilli; FVC: forced vital capacity; TB: tuberculosis. #: bronchiectasis was not included in the comorbidities because nodular bronchiectatic type significantly overlapped with the presence of bronchiectasis; ¶: a few patients were transiently administered anti-TB medication before isolation of nontuberculous mycobacteria due to radiological findings indistinguishable from those of pulmonary TB or positive sputum AFB smear at the onset of disease; this was regarded as a potential confounder and input into multivariate analysis to determine predictors of spontaneous sputum conversion. p<0.05 was considered significant.