Table 6. Predictive factors for mortality in patients with pulmonary NTM disease.
| Predictor variables | All-cause death | NTM-related death | ||
|---|---|---|---|---|
| Adjusted HRs (95% CIs) * | p | Adjusted HRs (95% CIs) * | p | |
| Age, years | ||||
| ≥80 | 3.79 (1.82–7.89) | <0.001 | 7.28 (2.91–18.20) | <0.001 |
| ≥70 and <80 | 2.56 (1.27–5.16) | 0.008 | 3.68 (1.46–9.26) | 0.006 |
| <70 | 1 (reference) | – | 1 (reference) | – |
| Male vs. female | 2.20 (1.21–3.99) | 0.010 | 2.40 (1.29–4.45) | 0.006 |
| Serum albumin, g/dl | ||||
| <3.0 | 3.16 (1.34–7.44) | 0.009 | – | – |
| ≥3.0 and <4.0 | 1.29 (0.66–2.51) | 0.46 | – | – |
| ≥4.0 (reference) | 1 (reference) | – | – | – |
| Lymphocyte count, /mm3 | ||||
| <800 | 2.84 (1.41–5.72) | 0.003 | – | – |
| ≥800 and <1000 | 1.50 (0.66–3.41) | 0.33 | – | – |
| ≥1000 (reference) | 1 (reference) | – | – | |
| Causative NTM species | ||||
| M. abscessus complex | – | – | 4.30 (1.46–12.69) | 0.008 |
| M. intracellulare | – | – | 1.36 (0.59–3.13) | 0.48 |
| M. avium | – | – | 1 (reference) | – |
| HRCT pattern of NTM disease | ||||
| Cavitary NB/fibrocavitary form | 2.92 (1.51–5.65) | 0.002 | 4.08 (1.70–9.80) | 0.002 |
| Unclassifiable form | 1.30 (0.44–3.83) | 0.63 | 1.14 (0.31–4.18) | 0.84 |
| Non-cavitary NB form (reference) | 1 (reference) | – | 1 (reference) | – |
*Adjusted HRs (95% CIs) are shown for variables that remained in the final Fine-Gray models.
Fine-Gray competing risks analyses were conducted to evaluate the baseline patient characteristics that predict all-cause mortality and NTM-related mortality over time. All predictor variables with p-values <0.1 in Gray’s test shown in Table 5 were included in Fine-Gray regression analyses. Abnormal HRCT findings were not included in these analyses together with HRCT patterns of pulmonary NTM disease because both predictor variables were highly correlated. A backward stepwise selection with a cut-off significance level of 0.05 was used as the variable selection procedure in each regression analysis.
RA, rheumatoid arthritis; NTM nontuberculous mycobacteria; NB form, nodular/bronchiectatic form; HRs, hazard ratios; CIs, confidence intervals.