Reduction in Clostridium difficile infection rates after mandatory hospital public reporting: findings from a longitudinal cohort study in Canada

Abstract

Background: The role of public reporting in improving hospital quality of care is controversial. Reporting of hospital-acquired infection rates has been introduced in multiple health care systems, but its relationship to infection rates has been understudied. Our objective was to determine whether mandatory public reporting by hospitals is associated with a reduction in hospital rates of Clostridium difficile infection.

Methods and findings: We conducted a longitudinal, population-based cohort study in Ontario (Canada's largest province) between April 1, 2002, and March 31, 2010. We included all patients (>1 y old) admitted to 180 acute care hospitals. Using Poisson regression, we developed a model to predict hospital- and age-specific monthly rates of C. difficile disease per 10,000 patient-days prior to introduction of public reporting on September 1, 2008. We then compared observed monthly rates of C. difficile infection in the post-intervention period with rates predicted by the pre-intervention predictive model. In the pre-intervention period there were 33,634 cases of C. difficile infection during 39,221,113 hospital days, with rates increasing from 7.01 per 10,000 patient-days in 2002 to 10.79 in 2007. In the first calendar year after the introduction of public reporting, there was a decline in observed rates of C. difficile colitis in Ontario to 8.92 cases per 10,000 patient-days, which was significantly lower than the predicted rate of 12.16 (95% CI 11.35-13.04) cases per 10,000 patient-days (p<0.001). Over this period, public reporting was associated with a 26.7% (95% CI 21.4%-31.6%) reduction in C. difficile cases, or a projected 1,970 cases averted per year (95% CI 1,476-2,500). The effect was specific to C. difficile, with rates of community-acquired gastrointestinal infections and urinary tract infections unchanged. A limitation of our study is that this observational study design cannot rule out the influence of unmeasured temporal confounders.

Conclusions: Public reporting of hospital C. difficile rates was associated with a substantial reduction in the population burden of this infection. Future research will be required to discern the direct mechanism by which C. difficile infection rates may have been reduced in response to public reporting. Please see later in the article for the Editors' Summary.

Figure 1. Correlation of aggregate hospital C. difficile cases in administrative datasets and public reporting statistics.

C. difficile cases in the administrative data are plotted against cases from the public reporting database, for the total public reporting period between September 1, 2008, and March 31, 2010. Each bubble represents a distinct institution (n = 165), and bubble sizes reflect hospital sizes (in patient-days). There was an excellent correlation for overall C. difficile cases (A) (weighted Pearson's correlation coefficient 0.92), and hospital-acquired C. difficile cases (B) (weighted Pearson's correlation coefficient 0.91).

Figure 2. Longitudinal trends in C. difficile infection rates and antibiotic prescription rates in Ontario prior to the introduction of mandatory public reporting.

Seasonal variations in overall C. difficile infection rates (black solid line) and post-admission C. difficile infection rates (black dashed line) per 10,000 patient-days appear to follow seasonal changes in the overall monthly population burden of antibiotic prescriptions measured by the number of prescriptions in the Ontario Drug Benefit database (grey dashed line).

Figure 3. Reduced rates of C. difficile infection associated with the introduction of public reporting.

Observed monthly rates of C. difficile infection in Ontario (solid blue line) were generally increasing prior to the introduction of public reporting in September 2008 (identified by black dotted line), and declined after this intervention. Post-intervention rates were significantly lower than rates predicted by a Poisson model (red dashed line) derived from pre-intervention data points and adjusted for age and hospital strata, and overall burden of community antibiotic use (with 0- to 12-mo lags).

Figure 4. Tracer analyses evaluating longitudinal time trends of infections not expected to be impacted by hospital public reporting of C. difficile infection rates.

Neither community-acquired bacterial gastrointestinal infections (A) nor urinary tract infections (B) exhibited a change in incidence concurrent with the introduction of C. difficile infection public reporting in September 2008.