Cox model: predictors of 10-year mortality among users of NIV (n=127)
| Variables | Univariate model | Multivariate model | ||
| HR (95% CI) | P value | HR (95% CI) | P value | |
| NIV adherence (% of prescribed duration)* | ||||
| 100–90 | 1† | 1† | ||
| 90–75 | 1.45 (0.63 to 3.35) | 0.15 | 2.81 (1.08 to 7.28) | 0.03 |
| ≥75 | 2.05 (0.90 to 4.68) | 3.26 (1.32 to 8.04) | ||
| Age at DM1 diagnosis | ||||
| <20 | 1† | 1† | ||
| 20–30 | 1.86 (0.65 to 5.30) | 0.05 | 1.64 (0.56 to 4.79) | 0.10 |
| 30–40 | 1.96 (0.57 to 6.70) | 1.39 (0.39 to 4.88) | ||
| >40 | 3.33 (1.38 to 8.05) | 3.13 (1.21 to 8.10) | ||
| Able to walk† | 0.44 (0.18 to 1.07) | 0.07 | 0.44 (0.16 to 1.20) | 0.11 |
| Symptoms of respiratory failure | ||||
| Dyspnoea at rest | 0.40 (0.05 to 2.90) | 0.38 | – | – |
| Exertional dyspnoea | 0.79 (0.40 to 1.58) | 0.72 | – | – |
| Morning headaches | 1.05 (0.52 to 2.12) | 0.45 | – | – |
| Orthopnoea | 2.50 (1.29 to 4.87) | 0.007 | 2.37 (1.17 to 4.80) | 0.02 |
| Sleep disturbances | 1.03 (0.53 to 2.01) | 0.81 | – | – |
| Diurnal sleepiness | 1.30 (0.59 to 2.86) | 0.51 | – | – |
| VC (%) | ||||
| ≥50 | 1† | 0.13 | – | 0.28 |
| 30–50 | 1.70 (0.76 to 3.77) | 0.31 (0.05 to 1.85) | ||
| ≤30 | 3.71 (0.98 to 14.09) | 1.34 (0.52 to 3.50) | ||
| Pacemaker (yes†) | 1.10 (0.21 to 4.38) | 0.89 | – | – |
| PaCO2≥45 mm Hg | 1.26 (0.49 to 3.20) | 0.63 | – | – |
P value significant are bold values.
*NIV adherence was computed as the ratio of NIV duration in hours/day over prescribed NIV duration in hours/day.
†Indicates the reference category.
DM1, myotonic dystrophy type 1; NIV, non-invasive ventilation; VC, vital capacity calculated as the percentage of predicted (≥50, normal; 30–50, restrictive syndrome; ≤30, severe restrictive syndrome).