Relation between volume and outcome for patients with severe sepsis in United Kingdom: retrospective cohort study

OBJECTIVE To evaluate whether a relation exists between volume and outcome for admissions with severe sepsis to adult general critical care units in the United Kingdom. DESIGN Retrospective cohort study using data from a pooled case mix and outcome database. SETTING Adult general critical care units participating in the case mix programme. PARTICIPANTS Consecutive admissions to participating units for the years 2008-09 meeting objective, standardised criteria for severe sepsis. MAIN OUTCOME MEASURES Mortality at ultimate discharge from acute hospital. RESULTS The primary exposure was volume of admissions with severe sepsis per unit per year. A multivariable logistic regression analysis, using generalised estimating equations, was used to assess the association between volume, modelled using fractional polynomials, and ultimate acute hospital mortality while adjusting for potential confounders. No relation was seen between volume and outcome for admissions with severe sepsis to adult, general critical care units in the UK. Subgroup analyses tested for interactions between the effect of volume and acute severity of illness or receipt of mechanical ventilation. No significant interactions were found. CONCLUSIONS This study showed no relation between volume and outcome in admissions with severe sepsis treated in adult general critical care units in the UK.