Under-recognition and undertreatment of obesity hypoventilation syndrome (ohs) after hospital discharge: a persistent challenge

Abstract Introduction Hospitalization for acute-on-chronic hypercapnic respiratory failure (ACHRF) in OHS is associated with increased short-term mortality. The 2019 American Thoracic Society’s guidelines recommend that hospitalized OHS patients be discharged on nocturnal noninvasive ventilation (NIV). However, this was graded as a weak recommendation given that the data was retrospective and derived from European/Australian studies limiting generalizability to other healthcare systems. We aimed to assess post-discharge therapeutic plans for hospitalized patients with ACHRF and suspected OHS in an urban, tertiary care center in Chicago serving a large minority population. Methods We retrospectively queried the electronic health record of University of Chicago from 2008 to 2020 for hospitalized adults with BMI ≥35 kg/m2 admitted from the emergency department, requiring NIV/mechanical ventilation with evidence of respiratory acidosis on first blood gas (pH < 7.35 with PaCO2 ≥ 45 mmHg or PvCO2 ≥ 50mmHg). Subjects were excluded for obstruction on spirometry, greater than 20-pack year smoking history, CT evidence of parenchymal lung disease, acute neurologic process, significant left-sided heart failure and neuromuscular disease. Results Of the 797 obese patients requiring NIV/mechanical ventilation, we excluded 672 for lack of acute hypercapnia or low suspicion for OHS. The remaining 125 patients were predominantly Black (n = 116, 93%) and female (n = 94, 75%), mean age of 53±13.9 years, mean BMI of 50.8±12.8 kg/m2, mean first pH of 7.22±0.097, PaCO2 79.9±24.5 mmHg (n = 31) and PvCO2 74.7± 20.2mmHg (n = 94). On admission, 84 patients (67%) did not carry a diagnosis of OHS and 66 patients (53%) were PAP-naïve. 54% were discharged on PAP (43% CPAP, 43% Bilevel, and 14% other). Patients discharged on PAP were more obese (p = 0.001) and more hypercapnic (p = 0.002). Post-discharge polysomnography/sleep clinic referral was planned for 40% of patients. The 1-year mortality rate was 8% with no association recognized between 1-year mortality and PAP on discharge. Conclusion In our cohort, the proportion of patients discharged on nocturnal NIV was low. In contrast to the guideline recommendation, we did not find an association between being discharged on PAP therapy and mortality. Larger studies in more diverse populations are needed. Support (if any)