Analysis Suggests No Link Between OSA and Postoperative Delirium

May 20, 2020

Contrary to prior literature, a new single-center analysis suggests that obstructive sleep apnea is not associated with delirium in those who were postoperatively admitted to the ICU, though PAP may reduce delirium in this patient population.

Ben Julian Palanca, MD, PhD, MSc

New study findings suggest that there is no association between obstructive sleep apnea (OSA) and delirium in patients who were postoperatively admitted to the intensive care unit (ICU), which can predispose individuals to adverse outcomes, despite prior literature suggesting otherwise.

This analysis, conducted by Ben Julian Palanca, MD, PhD, MSc, department of anesthesiology, Washington University in St Louis, and colleagues, included 7792 patients admitted to the ICU post-surgery, of which 26% (n = 2044) had diagnosed or suspected OSA and 47% (n = 3637) experienced delirium. Ultimately, the proportion of those with incident delirium was lower among those with OSA (44%; n = 897) than those without OSA (48%; n = 2740) for an unadjusted risk difference of −0.04 (99% credible interval [CrI], −0.07 to −0.00).

Additionally, positive airway pressure (PAP) adherence showed a minimal association with delirium (risk difference, −0.00; 99% CrI, −0.09 to 0.09), suggesting that PAP may be an effective intervention to reduce delirium in this patient population.

“Our data strongly contrast with prior work and quantitatively exclude our hypothesis that OSA increases the risk for postoperative delirium by a meaningful amount, [defined as a] <5% absolute difference with a background rate of 47%,” Palanca and colleagues wrote. “If these results are replicated, interventional studies targeting adherence to PAP therapy are therefore unlikely to substantially prevent delirium.”

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When Palanca and colleagues conducted a doubly robust confounder adjustment, it removed the association between OSA and delirium (risk difference, −0.01; 99% CrI, −0.04 to 0.03) and did not impact the association of preoperative PAP adherence (risk difference, −0.00, 99% CrI, −0.07 to 0.07).

Notably, there was no adjusted analysis conducted that generated a point estimate greater than a 0.03 absolute difference in risk, nor excluded 0 from its CrI or CI. Palanca et al. wrote that excluding potential colliders as adjusting variables such as age produced wide CrIs, though other analyses bounded the increase in risk associated with OSA to <5%.

“Selection bias and measurement error limit the validity and generalizability of these observational associations; however, they suggest that interventions targeting sleep apnea and PAP are unlikely to have a meaningful association with postoperative intensive care unit delirium,” Palanca et al. concluded.

The study was retrospective in nature and conducted at a single-center, a US tertiary hospital, with data collected from November 1, 2012, to August 31, 2016. Those included were adults who had undergone a complete preoperative anesthesia assessment, received general anesthesia and at least 1 delirium assessment, were not preoperatively delirious, and had a preoperative ICU stay of <6 days. After April 2014, 92% (n = 42,355) of 45,877 surgical patients responded to a STOP-BANG questionnaire, in which 79% (n = 3701) of the 4666 patients in the analysis who did not have OSA partook. Of the 847 patients who responded to the PAP therapy question, 60% (n = 511) reported routine adherence.

In total, 37% (n = 17,682) of the 48,278 Confusion Assessment Method-ICU assessments were positive, and the aforementioned 47% of patients had delirium at some point in the first 7 days after surgery, with each patient assessed a median of 4 times (IQR, 2—7).

When considering diagnosis and screening in tandem, those with OSA had higher rates of cardiac surgery (48%; n = 970) and greater overall comorbidity (median Charlson Comorbidity Index, 3 [interquartile range (IQR), 2—5]) compared with patients in the ICU without OSA (cardiac surgery: 44%, n = 2522; median Charlson Comorbidity Index, 2 [IQR, 1–4]).

“Validity threats from measurement errors, unmeasured confounding, or differences in postoperative care could mask a true positive association, but a large increase in risk is unlikely,” Palanca and coauthors detailed. “We found a minimal association with preoperative adherence to PAP therapy, with large uncertainty. Our work suggests that additional high-quality data linking these outcomes are needed before interventional trials of PAP therapy and delirium.”

REFERENCE

King CR, Fritz BA, Escallier K, et al. Association Between Preoperative Obstructive Sleep Apnea and Preoperative Positive Airway Pressure With Postoperative Intensive Care Unit Delirium. JAMA Netw Open. 2020;3(4):e203125. doi:10.1001/jamanetworkopen.2020.3125