Predictors of improvements in daytime function outcomes with CPAP therapy

Continuous positive airway pressure (CPAP) therapy improves daytime functio n in the sleep apnea/ hypopnea syndrome (SAHS) but it is unclear which pati ents benefit and what factors predict this Improvement. To test the hypothe sis that brief arousals from sleep predict improvements In daytime function ing with CPAP therapy, we prospectively studied 62 patients with polysomnog raphy-defined SAWS, Each underwent daytime function assessments at baseline and after 6 mo of CPAP therapy to measure objective sleepiness, psychologi cal well-being, quality of life, and cognitive performance. The microarousa l frequency and AHI were poor predictors of improvements in daytime functio n with CPAP. Measures of hypoxemia predicted improvements in the mean sleep latency an the maintenance of wakefulness test, SAWS symptoms, quality of life, and reaction time, but such correlations were weak or moderate only e xplaining between 7% and 22% of variance. Significant relationships were fo und between CDAP use and improvements in self-ratings of daytime function, Results suggest that standard polysomnographic baseline variables are poor predictors of the response to CPAP therapy.