Prevalence, Treatment, and Outcomes Associated With OSA Among Patients Hospitalized With Pneumonia
Does diagnosed obstructive sleep apnea (OSA) increase the risk of complications of pneumonia?
This was a retrospective cohort study of patients hospitalized in the United States between 2007 and 2010, collected in a voluntary database. All patients were discharged with a diagnosis of pneumonia and were treated with antibiotics within 48 hours of admission. Exclusions were patients transferred from an outside institution, length of stay <2 days, cystic fibrosis, or diagnosis-related group codes inconsistent with pneumonia or a modifier indicating that pneumonia was not present on admission. OSA was defined from secondary diagnosis codes. Primary outcomes were defined as serious complications after admission such as: transfer to intensive care unit (ICU) or initiation of mechanical ventilation. Secondary outcomes included: inpatient mortality, length of stay, and cost.
A total of 250,907 patients met study criteria and 15,569 (6.2%) had OSA as a diagnosis. Median age was 71 years and 53% were women. Pneumonia was community acquired in 66% and hospital acquired in 34%. Median length of stay was 5 days, with 7.2% suffering in-hospital death. Despite being younger, patients with OSA were more likely to be diagnosed with obesity, hypertension, heart failure, diabetes, chronic pulmonary disease, and were more likely to be men. Presence or absence of OSA did not change the likelihood of hospital-acquired pneumonia. Patients with OSA were more likely to receive invasive (18.1% vs. 9.3%) and noninvasive (28.8% vs. 6.8%) forms of ventilation upon hospital admission. After multivariable adjustment, OSA was associated with an increased risk of ICU transfer (odds ratio [OR], 1.54; 95% confidence interval [CI], 1.42-1.68) and intubation (OR, 1.68; 95% CI, 1.55-1.81) on or after the third hospital day, longer hospital stays (relative risk [RR], 1.14; 95% CI, 1.13-1.15), and higher costs (RR, 1.22; 95% CI, 1.21-1.23) among survivors, but lower mortality (OR, 0.90; 95% CI, 0.84-0.98).
The authors concluded that OSA is associated with higher rates of mechanical ventilation, increased risk of worsening clinical status, and higher hospital cost, yet a lower risk of inpatient mortality.
This database represents approximately 15% of all US hospital admissions and the study is a cohort of hospitalized adults, not outpatients. Most of these data are intuitive, but the mortality observation is a cause for speculation. Despite a higher rate of complications and comorbidities among those with OSA, there was a lower rate of mortality among those with OSA compared to those without OSA. Given their tendency for hypopnea and apnea, OSA patients would not tolerate desaturations associated with pneumonia. This might be one explanation why OSA patients would be more likely to exhibit respiratory failure earlier in their course, prompting mechanical ventilation. In contrast, those without OSA would likely have more severe complications of pneumonia, such as sepsis, to warrant intubation. An earlier clinical status change resulting in mechanical ventilation among OSA patients might avoid downstream complications, such as death. Last, obesity has been shown in other cohorts to have better outcomes due to earlier medical presentation and increased metabolic reserves. More study is needed to identify which factors are associated or lead to the paradox of OSA associated with higher complications, but lower mortality. Since the true percentage of OSA in this cohort is likely underestimated, the impact of OSA on complications from pneumonia may be overestimated or may simply apply to that group of OSA with severe enough disease to be diagnosed prior to hospital admission.
Keywords: Odds Ratio, Risk, Intensive Care Units, Pneumonia, Hospital Mortality, Sepsis, Diagnosis-Related Groups, Respiration, Artificial, Comorbidity, Respiratory Insufficiency, Cystic Fibrosis, Length of Stay, Survivors, Hospital Costs, Intubation, Heart Failure, Obesity, Confidence Intervals, Hypertension, Sleep Apnea, Obstructive, Diabetes Mellitus
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