BURDEN OF COMMUNITY-ACQUIRED CLOSTRIDIUM DIFFICILE INFECTION IN ONTARIO, CANADA: A POPULATION-BASED STUDY
To assess attributable health and cost outcomes associated with community-acquired Clostridium difficile infection (CDI).
We conducted a population-based matched cohort study. Between 01/01/2003 and 31/12/2010, we identified incident cases of community-acquired CDI (infected patients) defined as patients with the ICD-10-CA code A04.7 present during: an emergency department (ED) visit (principal/non-principal diagnosis, index date: ED registration date); a non-elective hospital admission (principal/non-principal diagnosis) with length of stay ≤2 days (index date: hospital admission date); or a non-elective hospital admission (principal diagnosis) with CDI symptoms (e.g., diarrhea) documented during a physician or ED visit within two weeks prior to the hospital admission date (index date: physician visit or ED registration date). We followed infected patients until 31/12/2011. Infected patients were matched 1:1 without replacement to uninfected subjects in the general population using propensity score and hard matching on a set of baseline characteristics. Health outcomes included colectomy within 1-year post index date and all-cause mortality. Cost outcomes (from the healthcare payer perspective in 2012 Canadian dollars) included phase-specific costs, up-to-1-year costs unadjusted for survival, and up-to-3-year costs adjusted for survival.
We identified 7,903 patients infected with community-acquired CDI. The crude mean annual incidence was 7.8 per 100,000. The mean age was 63.5 years (standard deviation=22.0) and 63% were female. The relative risk for undergoing a colectomy within 1-year post index date was 5.53 (95% confidence interval [CI], 3.30-9.27) and the relative risk for mortality within 1-year post index date was 1.58 (95%CI, 1.44-1.75). Infected patients had 1.3- to 5.3-fold higher mean costs versus uninfected subjects. The mean attributable cost (adjusted for survival) of an incident community-acquired CDI patient was $8,881 (95%CI: $7,951-$9,904) in the first year, $2,663 in the second year, and $2,480 in the third year. Mean attributable costs were generally higher among those diagnosed in 2010 (possibly due to a virulent strain), males, those aged ≥65 years, and those who died within 1-year after the index date.
Community-acquired CDI is associated with a substantial health and economic burden. CDI leads to a greater risk for colectomy and all-cause mortality, and higher short- and long-term healthcare costs. This is the first study to evaluate the costs of community-acquired CDI using a large population-based sample and to evaluate long-term costs of community-acquired CDI.