Higher hospital caseload is associated with better treatment outcomes of patients with pleural infection.

The relationship between hospital caseload or volume and the outcome of various surgical procedures has been well documented. However, such hospital caseload-outcome relationship (HCOR) has been seldom addressed in rare medical conditions, such as pleural infection, which is usually associated with pneumonia and may progress to systemic inflammation and severe sepsis. Pleural infection can be treated with medical or surgical pleural space drainage, but the treatment is still unstandardized. This population-based study, using Taiwan's medical claim data, investigated the HCOR in patients with pleural infection. A total of 24,876 patients with pleural infection (median age of 65 years; men, 76.6%) were identified between 1997 and 2008. Hospital caseload was calculated with the average number of cases per hospital annually. The primary outcome is hospital mortality, and the secondary outcomes include hospital length of stay and charges. The risk of mortality among patients treated in hospitals with the highest caseload quartile (≥ 14 cases per hospital annually) is less than those treated in hospitals with the lowest caseload (1 case per hospital annually) by 27% (adjusted odds ratio = 0.73, 95% confidence interval = 0.55 to 0.96). Such beneficial effect disappeared after adjustment for therapeutic procedures. Hospital caseload explained only a small portion of variation in hospital mortality (-2 log likelihood % = 0.26%). These findings suggest that higher hospital caseload is associated with better outcomes of patients with pleural infection. The difference in therapeutic procedures for pleural infection contributes to the observed effect of hospital caseload on hospital mortality.