Abstract
Correct assessment of the overall treatment effectiveness requires knowledge about therapy compliance and efficacy. This study aimed to determine overall long-term apnoea alleviation after continuous positive airway pressure (CPAP) in a complete sleep laboratory cohort. Out of 209 consecutive CPAP candidates (mean age 57+/-12 yrs, body mass index (BMI) 30.0+/-5.1 kg x m2, respiratory disturbance index (RDI) 32.9+/-29 h), follow-up treatment was performed in 149 of them at 9, 18 and 30 months after CPAP prescription. Compliance with CPAP (machine run time/days CPAP available) was adjusted for the individual subjective sleep-time. Apnoea alleviation was defined as adjusted compliance multiplied by the CPAP effect (RDI with CPAP applied), remaining RDI was calculated. The baseline RDI, age or BMI in 75 patients, who did not tolerate nasal continuous positive airway pressure (nCPAP), did not differ from those accepting CPAP (acceptors, n=74). In acceptors at 9 months follow-up RDI with CPAP applied was 1.4+/-2.6 (CPAP effect, n=66), mean CPAP use was 3.6+/-2.5 x 24 h(-1) (n=68), mean apnoea alleviation was 52.4+/-32.0% (range 1-100%, n=47), the average remaining whole-night RDI was 17.8+/-26. At 9, 18 and 30 months (n=47), the mean daily CPAP use increased from 3.6+/-2.5 h to 4.1+/-2.5 h and 4.4+/-2.4 h (p<0.01). Effectiveness of continuous positive airway pressure is potentially high but acceptance was low. When accounting for sleep-time, its actual effect and use, only 50% adjusted continuous positive airway pressure effectiveness was observed.
