The association between obesity and sleep apnea syndrome (SAS) is well known, as is the fact that TJR patients are often obese. Based on review of 5819 primary TJR patients at our institution, 53% of patients presenting for TJR were obese (mean BMI 31), and of those obese patients 61.3% were female. The potential impact of SAS, diagnosed and undiagnosed, on TJR outcomes has not been well described. In the literature it has been suggested that such patients may be at increased risk of prolonged hospital length of stay (LOS), increased risk of postoperative MI, and risk of postoperative respiratory compromise requiring unplanned transfer to a special care unit (SCU). At our institution, unless deemed required for preoperatively identified co-morbidities, all TJR patients are managed acutely on an orthopaedic ward with no formal step down unit available for enhanced monitoring, even when receiving PCA or epidural for postoperative pain control.

We undertook a prospective non-randomised survey of 1927 primary TJR patients over a fifteen-month period to screen for a preoperative diagnosis of SAS, or symptoms suggestive of SAS using the self-report Epworth Sleep Apnea Questionnaire. In addition, we evaluated impact of SAS on LOS, risk of postoperative MI, risk of postoperative respiratory compromise and unplanned transfer to SCU.

Of our sample, 88/1927 patients (4.6%) had a confirmed preoperative diagnosis of SAS. An additional 74/1927 patients (3.8%) had 3/3 symptoms suggestive of undiagnosed SAS. SAS patients were younger; mean sixty-six years, p=0.005, and predominantly male; 58%, p< 0.0001, as compared to non-SAS patients comprised of 60% females and mean age sixty-nine years. Mean BMI was higher in the SAS group; 32.3 versus 30, p< 0.0001. There was no correlation between SAS and risk of postoperative MI, LOS (mean 5.2 days, both groups), nor unplanned SCU admission.

Despite concerns expressed in the literature, we found that SAS, both diagnosed and suspected, was not associated with prolonged LOS, increased risk of postoperative MI, postoperative respiratory compromise, or unplanned postoperative transfer to a SCU.