Continuous positive airway pressure for sleep apnoea/hypopnoea syndrome: usefulness of a 2 week trial to identify factors associated with long term use.

BACKGROUND The sleep apnoea/hypopnoea syndrome (SAHS) is common and treatment with continuous positive airway pressure (CPAP) is effective. However, not all patients can cope with the demands of using mask positive pressure. Compliance can be improved with an intensive educational programme and patient support, but this is not practical in most centres given the large numbers of patients coming forward for treatment. Several studies have evaluated correlations between various parameters at diagnosis in order to anticipate patients' behaviour and to avoid the social and health implications of undertreated SAHS. We have evaluated the use of additional data derived during a 2 week home CPAP trial to identify factors associated with longer term use of CPAP and compliance. METHODS Following a diagnostic study, 209 patients were offered a CPAP machine for a 2 week home trial. After completing the trial, patients were reassessed and scored their overall satisfaction with CPAP treatment on a five point scale ranging from "much worse" to "much better" and an Epworth score relating to the loan period. Machine run time was recorded from the integral clock. These data were added to those available at diagnosis to construct models indicative of continuing CPAP and average nightly use at 1 year. RESULTS 209 patients were offered the 2 week loan at least a year before June 1999 (90.9% men, mean (SD) age 51.0 (10.6) years, body mass index (BMI) 34.6 (7.7) kg/m(2), Epworth score 15 (IQR 11-18), apnoea/hypopnoea index (AHI) 38.1 (22.9) events/h). 153 patients (73.2%) opted to continue CPAP and 56 declined. One year later data were available for 187 patients; 128 (68.5% on an intention to treat analysis) continued to use the machine with a mean use of 5.0 (2.4) hours/night. A logistic regression model indicated that mean CPAP use during the loan period and the overall satisfaction score accurately defined continuing CPAP and "satisfactory" CPAP use at 1 year. For patients with low machine use and no symptomatic improvement during the loan period, the addition of baseline AHI, baseline Epworth score, and the Epworth score at the end of the loan to the equation identifying factors associated with "satisfactory" CPAP use (mean >2 hours/night) improved the value of the model. CONCLUSION Data derived from a 2 week CPAP trial are useful in identifying patients who will comply with CPAP treatment to 1 year. It can be used to identify patients with significant symptomatic disease who will struggle with CPAP and may benefit from additional education and support. High mean hourly use and a high degree of overall satisfaction during the loan period identified patients likely to use CPAP and be compliant with it at 1 year.