Unplanned admission after day surgery: a historical cohort study in patients with obstructive sleep apnea

Practice guidelines suggest that patients with obstructive sleep apnea (OSA) should be monitored postoperatively to reduce adverse events. This study evaluated outcomes following ambulatory surgery in patients who had previously undergone polysomnography (PSG), and compared unplanned admissions in patients diagnosed with OSA with those in patients without OSA.

A historical cohort study (July 2003 to March 2009) was conducted using administrative data and supplemented by selective chart review. Patients undergoing ambulatory surgery at the Ottawa Hospital who had a previously documented PSG were identified. The PSG reports were reviewed, and the presence and severity of OSA was determined. Unplanned admissions to hospital within seven days of surgery were identified using administrative data. Using a nested case-control design, three charts were randomly selected for each patient admitted for a focussed health records review. Event rates in patients with OSA and treated with continuous airway pressure were compared with event rates in patients without OSA. An exploratory multivariable analysis was conducted to identify predictors of admission.

There were 77,809 ambulatory surgical procedures in the period studied. A PSG test could be analyzed in 1,547 patients, and OSA was diagnosed in 674 (44%) of those analyzed. The rate of unplanned admission was 7.0% (95% confidence interval [CI] 5.1 to 8.9) in OSA patients compared with 5.6% (95% CI 4.1 to 7.1) in patients without OSA (odds ratio 1.26; 95% CI 0.83 to 1.91; P = 0.246). Median [interquartile range; IQR] hospital length of stay was 7 hr [IQR 5, 8] with OSA and 6 hr [IQR 5, 8] without OSA (P = 0.058). Severity of OSA was not associated with unplanned admission.

We did not identify a clinically important increased rate of unplanned admission associated with a prior diagnosis of OSA.