Home Mechanical Ventilation and Risk of Hospitalization in Obesity Hypoventilation Syndrome: The Population-Based DISCOVERY Study

<b>Rationale:</b> Patients with obesity hypoventilation syndrome (OHS) have high risk of hospitalization, which might be decreased by home mechanical ventilation (HMV). <b>Objectives:</b> To evaluate annualized hospitalization rate (AHR) and changes in AHR in patients with OHS starting HMV and explore if there were any differences in AHR by starting HMV acutely or electively. <b>Methods:</b> This was a population-based longitudinal study of patients with OHS starting HMV in the Swedish DISCOVERY (Swedish Population-based Course of Disease in Patients Reported to the Swedish CPAP Oxygen and Ventilatory Registry) cohort between 1996 and 2018, cross-linked with the National Patient Registry for national data on hospital admissions. AHR was calculated for each patient for 3 years before (Years -3, -2, and -1) and 3 years after (Years 1, 2, and 3) the year of starting HMV (Year 0; start date ± 6 mo). Differences in AHR were analyzed using Wilcoxon signed-rank test (between years) and Mann-Whitney <i>U</i> test (between acute/elective). The proportion of patients hospitalized in each year was analyzed, and a comparison between years was done with McNemar's test. Factors associated with change in AHR were identified using multivariate linear regression models. <b>Results:</b> In total, 2,445 patients were included: 47% females, mean age 62.3 ± 12.2 years, and 1,418 (58%) started HMV electively. Overall, AHR decreased, with 0.88 (95% confidence interval, 0.74-1.02) hospitalizations/yr after start of HMV, and starting treatment acutely was associated with a greater decrease in AHR. There was no statistically significant difference in AHR in Year 1 between acute and elective start (<i>P</i> = 0.199). The year after the start of HMV, the proportion of patients hospitalized decreased from 84% to 54% (<i>P</i> < 0.05). <b>Conclusions:</b> Initiation of HMV was associated with reduced hospitalization rate in patients with OHS, irrespective of acute or elective start. The majority of patients with OHS are hospitalized in the year of HMV initiation.