High scores on the symptomless multivariable apnea prediction index (sMVAP) showed a strong correlation with increased risk for postsurgery complications, according to a study approved by the University of Pennsylvania, Philadelphia.
This validation helps assert the benefits of using the sMVAP as a tool to screen for obstructive sleep apnea (OSA) before elective inpatient surgeries, a test that is highly underutilized but very important, wrote M. Melanie Lyons, PhD, of the Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, and her colleagues.
“Most patients having elective surgery are not screened for obstructive sleep apnea, even though OSA is a risk factor for postoperative complications,” wrote Dr. Lyons and her colleagues. “We observe that sMVAP correlates with higher risk for OSA, hypertension, and select postoperative complications, particularly in non-bariatric groups without routine preoperative screening for OSA.”
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In a retrospective study of 40,432 patients undergoing elective surgery, high sMVAP scores were strongly correlated with postoperative complications including longer hospital stays (OR = 1.83), stays in the ICU (OR = 1.44), and respiratory complications (OR = 1.85) according to the researchers (Sleep. 2017 Jan 6. doi: 10.1093/sleep/zsw081).
Researchers separated participants into 10 categories according to the type of procedure: bariatric, orthopedic, cardiac, gastrointestinal, genitourinary, neurological, otorhinolaryngology/oral-maxillofacial/ear-nose-throat, pulmonary/thoracic, spine, and vascular.
The sMVAP calculates risk factors for OSA based on gender, age and body mass index, the researchers noted.
Those in the highest sMVAP score quintile were predominantly male (58%), with average age of 61 years, and average BMI of 40.9 kg/m2 (indicating morbid obesity). These patients reported the highest prevalence of having been previously diagnosed with OSA (26%). Comparatively, those patients in the lowest sMVAP quintile reported the lowest prevalence of an OSA diagnosis prior to undergoing their surgeries (9.3%).
Among non–bariatric surgery patients, those undergoing orthopedic procedures showed the highest correlation between complications and sMVAP scores.
The orthopedic surgery category reported a higher percentage of ICU-stay compared with bariatric surgery (14.3% vs 5.4%, P less than .0001), despite 23% of the patients who underwent an orthopedic surgery reporting previous OSA, compared with 50% of those who underwent surgery in the bariatric category.
This difference in previously reported OSA, according to Dr. Lyons and her colleagues, shows another example of the need for sMVAP in non–bariatric surgery preoperative procedure as a way to catch potentially undiagnosed OSA.
“[W]ork by Penn Bariatrics suggests that it is logical that the benefits of rigorous preoperative screening and diagnosis for OSA followed by a tailored team approach toward ensuring compliance toward treatment postoperation ... may be effective in limiting the likelihood of select postoperative complications,” the researchers wrote.
With 9.3% of all patients diagnosed with OSA, and a projected 14%-47% increase in specialty surgeries, there is an urgency in implementation of sMVAP and in conducting further studies, they noted.
This test was limited by the sample population, primarily male commercial truck drivers, the researchers noted. In addition, misclassification of OSA based on weight may have occurred in up to 20% of normal weight patients. Finally, data were collected from one hospital network, so generalizability may be limited.
Dr. M. Melanie Lyons and Dr. Junxin Li, another of the study’s authors, receive grants from the National Institutes of Health. The other authors reported no relevant disclosures.