2006 A prospective study on the determinants of CPAP compliance in patients with obstructive sleep apnoea syndrome
Dr. Michael Chio-ho Chan, Department of Medicine and Therapeutics, Prince of Wales Hospital
Study Objectives
To determine short-term and long-term compliance rates to continuous positive airway pressure (CPAP) therapy in patients with obstructive sleep apnoea and predictors for long-term CPAP compliance.
Design
To determine CPAP compliance and predictors for long-term CPAP compliance at 1 year after commencement of treatment.
Setting
A University Hospital.
Patients
One hundred and thirty one patients newly diagnosed with an apnoea-hypopnoea index (AHI) >= 10/hr on polysomnography.
Interventions
A CPAP device equipped with a time counter was used. Within the first year, patients were followed up at 4 weeks, 12 weeks, 26 weeks and 52 weeks.
Measurements
We evaluated the following factors for any correlation with objective CPAP compliance (machine run time [hours per day]) at 1 month, 3 months, 6 months and 1 year: demographic data, common OSA symptoms, baseline AHI, minimum arterial oxygen saturation (SaO2), mean SaO2, arousal index (AI), Epworth sleepiness scale (ESS), education level, CPAP levels, satisfaction with CPAP at the night of CPAP titration, side effects, and machine price.
Results
There were 109 males and 22 females , with a mean (± SD) age of 51.4 ± 9.4 yrs; body mass index 28.5 ± 3.9 kg/m2; AI, 28.4 ± 15.2/h; AHI, 40.4 ± 20.1/h; minimum SaO2 of 77.4 ± 10.2 %; mean CPAP pressure (95 %), 10.6+/-2.1 cmH20. Objective CPAP usage was 4.7 ± 2.0 h/d, 4.2 +/- 2.4 h/d, 4.3 +/- 2.3 h/d and 3.5 ± 2.4 h/d at 1, 3, 6 and 12 months, while 66.7% and 37.4% of our patients were using CPAP objectively for ≥4 h/d at 1 month and 1 year respectively. Following univariate analysis of variance, high baseline AHI (p = 0.003), obstructive apnea index (p=0.007), subjective compliance at 1st month (p <0.001) and objective compliance at 1st month (p <0.001) were associated with higher objective CPAP compliance at 12 months. Moreover, an equation involving the AHI and objective compliance at 1st month was developed for predicting the 12 months objective compliance with a correlation coefficient (r = 0.711).
Conclusion
CPAP usage and compliance were initially high in this patient population but decreased with time. A high baseline AHI, obstructive apnoea index, subjective /objective compliance at 1st month were the significant independent positive predictors of better CPAP compliance at 1 year.
