Sleep-Disordered Breathing and Postoperative Outcomes After Elective Surgery: Analysis of the Nationwide Inpatient Sample

Study Questions:

What is the impact of sleep disordered breathing (SDB) on postoperative hospital cost, length of stay, and in-hospital death?

Methods:

Data were obtained from the Nationwide Inpatient Sample, part of databases that form the Healthcare Utilization Project, the largest all-payer database in the United States. It contains information regarding roughly 8 million hospitalizations per year from over 1,000 hospitals in 44 states. ICD-9-CM codes were used to characterize SDB and four surgical procedures. Patients undergoing urgent or emergent surgery were excluded. Regression models were fitted to assess the independent association between SDB and outcomes.

Results:

The cohort included 1,058,710 hospitalized adult patients undergoing elective surgeries between 2004 and 2008. SDB was independently associated with decreased mortality in the orthopedic (odds ratio [OR], 0.65; 95% confidence interval [CI], 0.45-0.95; p = 0.03), abdominal (OR, 0.38; 95% CI, 0.22-0.65; p = 0.001), and cardiovascular surgery groups (OR, 0.54; 95% CI, 0.40-0.73; p < 0.001), but had no impact on mortality in the prostate surgery group. SDB was independently associated with a small, but statistically significant increase in estimated mean length of stay (LOS) by 0.14 days (p < 0.001) and estimated mean total charges by $860 (p < 0.001) in the orthopedic surgery group, but was not associated with increased LOS or total charges in the prostate surgery group. In the abdominal and cardiovascular surgery groups, SDB was associated with a significant decrease in adjusted mean LOS of 1.1 days and 0.35 days, respectively (p < 0.001 for both groups), and adjusted mean total charges of $3,814 and $4,592, respectively (p < 0.001 for both groups). SDB was independently associated with a significantly increased OR for emergent intubation and mechanical ventilation, noninvasive ventilation, and atrial fibrillation in all four surgical categories. Emergent intubation occurred significantly earlier in the postoperative course in patients with SDB. In the subgroup of patients requiring emergent intubation, LOS, total charges, pneumonias, and in-hospital death were significantly higher in those without SDB.

Conclusions:

The authors concluded that despite the increased independent association of SDB with postoperative cardiopulmonary complications, the diagnosis of SDB was not independently associated with an increased rate of in-hospital death, LOS, or total charges in this national cohort of patients undergoing elective surgery.

Perspective:

The prevalence of SDB among this elective surgical population ranged from 3-6%, similar to prior presurgical registry data sets. One novel finding here was that emergent intubation occurs more significantly among patients with SDB than those without SDB. Higher risk for upper airway complication could explain the need for emergent intubation among patients with SDB. Although SDB is independently associated with respiratory complications, it is unclear why SDB is not associated with increased LOS or in-hospital death. The authors speculate this may be explained by the obesity paradox, since patients with SDB are more obese than postoperative patients without SDB. One mechanism considered is ischemic preconditioning among patients with SDB. Further prospective multicenter research on the impact of SDB on postoperative mortality is needed.

Clinical Topics: Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Cardiac Surgery and Heart Failure, Sleep Apnea

Keywords: Odds Ratio, Risk, Postoperative Complications, Pneumonia, Noninvasive Ventilation, Orthopedic Procedures, Inpatients, Sleep Apnea Syndromes, Ischemic Preconditioning, Prevalence, Registries, Intubation, Respiration Disorders, Cardiovascular Diseases, Obesity, Confidence Intervals, Cardiac Surgical Procedures, United States, Prostate


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