The relationship between hospital volume and mortality following mechanical ventilation in the Intensive Care Unit

A number of recent studies in North America and Europe have investigated the relationship between hospital volume and outcomes following mechanical ventilation in an Intensive Care Unit (ICU). All of these studies have revealed an association between worse outcomes and smaller-volume hospitals. This relationship has not been investigated recently in the UK.

A retrospective cohort study was performed using data from the Birmingham and Black Country Critical Care Network database. Adult patients who received mechanical ventilation for more than 24 hours from the period from April 1, 1996, to March 31, 2006, were included in the study. The odds ratio for death in the ICU was calculated in relation to the hospital's volume of ventilation. Estimates accounted for clustering within hospitals and were adjusted for patient demographics (sex, age), APACHE II score, year of ventilation, length of ICU stay and urgency status.

A total of 17132 adult patient episodes were included in the analysis. The adjusted odds ratio for death in the ICU following mechanical ventilation for more than 24 hours was 1.11 (95% confidence interval: 0.91 to 1.35; P=0.297).

There is no relationship between hospital volume and mortality following mechanical ventilation in the ICU. Further larger prospective studies are needed to confirm this apparent lack of a relationship between hospital volume and mortality following mechanical ventilation in ICUs in a network of hospitals in the UK.