Purpose: Obstructive sleep apnea (OSA) is presumed to be a risk factor for postoperative morbidity and mortality, but the current evidence is incomplete. This retrospective matched cohort study tested the hypothesis that OSA is a risk factor for the development of postoperative complications.
Methods: Hospital ethics approval was obtained for the conduct of this study. The patients who were selected for the study were >18 yr of age, diagnosed preoperatively with OSA, and scheduled to undergo elective surgery. A cohort of surgical patients without OSA was used as a comparator group based on a one-to-one match. Matching criteria included gender, age difference <5 yr, type of surgery, and a <5 yr difference between two surgery dates. Summary data are presented and conditional logistic regression was used to identify risk factors for postoperative complications.
Results: The 240 pairs of study subjects aged 57 +/- 13 yr included 184 (77%) males and 56 (23%) females. The OSA patients had a higher mean body mass index relative to their non-OSA counterparts (35 +/- 9 vs 28 +/- 6 kg . m-2, respectively) and a higher frequency of co-morbidities, including hypertension (48% vs 36%, respectively) and obesity (61% vs 23%, respectively). Also, the incidence of postoperative complications in the OSA patients was significantly greater (44% OSA group vs 28% non-OSA group; P < 0.05). The most commonly observed between-group difference was oxygen desaturation < 90% (17% OSA group vs 8% non-OSA group). The OSA patients who did not use home continuous positive airway pressure (CPAP) devices prior to surgery but required the use of a CPAP device after surgery had the highest rate of complications. Conditional logistic regression was used to diagnose OSA and pre-existing stroke as significant risk factors for developing postoperative complications. The hazard ratio for OSA was 2.0 (1.25-3.19).
Conclusion: Patients with diagnosed OSA have an increased incidence of postoperative complications, the most frequent being oxygen desaturation.