Continuous positive airway pressure (CPAP) adherence rates in each arm before and after crossover
| Order of crossover | Adherence (hours per night) First arm (95% CI) | Adherence (hours per night) Second arm (95% CI) |
|---|---|---|
| Active CPAP then sham CPAP | 5.6 (4.4 to 6.8)* | 3.5 (2.4 to 4.7) |
| Sham CPAP then active CPAP | 3.3 (2.1 to 4.4) | 3.2 (2.0 to 4.3) |
CPAP adherence is higher in the first arm than all other combinations. None of the other three cells are different from one another. This effect drove the difference in adherence seen in the trial overall between active and sham CPAP (1 h 95% CI 0.2 to 1.7, p=0.01) and the overall p value for the interaction between treatment and the order in which it was received was <0.01.
*p<0.01 for comparisons with every other cell.