COMPARISON OF 3 MEASURES OF QUALITY-OF-LIFE OUTCOME IN THE EVALUATIONOF CONTINUOUS POSITIVE AIRWAYS PRESSURE THERAPY FOR SLEEP-APNEA

Treatment of obstructive sleep apnoea (OSA) with nasal continuous posi tive airway pressure (NCPAP) has become a standard treatment since its introduction in 1981. Following such treatment the apnoeas disappear, sleep duality improves as apparently do daytime symptoms of sleepines s. Sleepiness is an unusual symptom and its impact on conventional ind ices of quality of life has rarely been measured. To allow comparison of NCPAP therapy with treatments for other conditions, measurements of quality of life before and after treatment using standard techniques are required. It is not clear which of the standard measures is most s uited to measuring the health gain from nasal NCPAP, and indeed whethe r the disability of excessive sleepiness is included in all such measu res. This study looks at three well recognized quality of life measure s in OSA, before and after NCPAP therapy; the Short Form 36 (SF-36), F unctional Limitations Profile (FLP), and the EuroQol (EQ-5D). The resu lts were compared with data from normal populations. One hundred and e ight patients with OSA undergoing a therapeutic assessment of NCPAP co mpleted the three quality of life questionnaires before and 5 weeks af ter commencing treatment. Over 90 subjects completed all sections of t he three measures on both occasions. The SF-36 revealed substantial ad verse effects on subjective health of OSA and that NCPAP treatment pro duced dramatic positive effects. For example, the effect sizes (differ ence in score, divided by SD of baseline score) in the Energy/Vitality dimension was 0.98 and for the overall Mental and Physical Component Scores, 0.76 and 0.57, respectively: an effect size over 0.5 is consid ered moderate and over 0.8 as large. The FLP data showed similar pre t reatment decrements in quality of life and substantial improvements fo llowing NCPAP. The changes with treatment in the majority of the dimen sions from both the SF-36 and FLP were statistically significant (P<0. 01). In contrast the EQ-5D did not show significant improvements with therapy, presumably because of its failure to measure the aspects of q uality of life related to severe sleep fragmentation and daytime sleep iness. In conclusion, this study has clearly shown considerable decrem ents in quality of life in patients with OSA, similar to other chronic disabling conditions. Furthermore, NCPAP therapy returns patients to a quality of life similar to the normal population.