Hospital Mechanical Ventilation Volume and Patient Outcomes: Too Much of a Good Thing?

Objectives: Prior studies investigating hospital mechanical ventilation volume-outcome associations have had conflicting findings. Volume-outcome relationships within contemporary mechanical ventilation practices are unclear. We sought to determine associations between hospital mechanical ventilation volume and patient outcomes. Design: Retrospective cohort study. Setting: The California Patient Discharge Database 2016. Patients: Adult nonsurgical patients receiving mechanical ventilation. Interventions: The primary outcome was hospital death with secondary outcomes of tracheostomy and 30-day readmission. We used multivariable generalized estimating equations to determine the association between patient outcomes and hospital mechanical ventilation volume quartile. Measurements and Main Results: We identified 51,689 patients across 274 hospitals who required mechanical ventilation in California in 2016. 38.2% of patients died in the hospital with 4.4% receiving a tracheostomy. Among survivors, 29.5% required readmission within 30 days of discharge. Patients admitted to high versus low volume hospitals had higher odds of death (quartile 4 vs quartile 1 adjusted odds ratio, 1.40; 95% CI, 1.17–1.68) and tracheostomy (quartile 4 vs quartile 1 adjusted odds ratio, 1.58; 95% CI, 1.21–2.06). However, odds of 30-day readmission among survivors was lower at high versus low volume hospitals (quartile 4 vs quartile 1 adjusted odds ratio, 0.77; 95% CI, 0.67–0.89). Higher hospital mechanical ventilation volume was weakly correlated with higher hospital risk-adjusted mortality rates (ρ = 0.16; p = 0.008). These moderately strong observations were supported by multiple sensitivity analyses. Conclusions: Contrary to previous studies, we observed worse patient outcomes at higher mechanical ventilation volume hospitals. In the setting of increasing use of mechanical ventilation and changes in mechanical ventilation practices, multiple mechanisms of worse outcomes including resource strain are possible. Future studies investigating differences in processes of care between high and low volume hospitals are necessary. This work was performed at the National Jewish Health, Denver, CO. Dr. Mehta helped to study design, statistical analysis, data interpretation, and article preparation. Dr. Walkey helped to data interpretation and article preparation. Dr. Curran-Everett helped to statistical analysis and article preparation. Dr. Matlock helped to data interpretation and article preparation. Dr. Douglas helped to study design, data interpretation, and article preparation. Dr. Mehta takes full responsibility for the content of the article, data analysis, and data interpretation. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's website (http://bit.ly/29S62lw). Dr. Mehta is supported, in part, by National Institutes of Health (NIH) K12HL137862. Dr. Walkey is supported by NIH K01HL116768 and R01HL136660. Dr. Curran-Everett is supported by NIH RHL089897B-08. Dr. Matlock is supported by NIH R01HL136403-01. Dr. Douglas is supported by NIH 1R01NR016459-01. Drs. Mehta and Matlock received support for article research from the National Institutes of Health. The remaining authors have disclosed that they do not have any potential conflicts of interest. For information regarding this article, E-mail: mehtaa@njhealth.org Copyright © by 2018 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved.

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