This study found substantially higher rates of CDI, representing clusters of disease, in some hospitals. Several features of the hospitals and the neighbourhoods they serve were identified are associated with this clustering. The data reveal a substantial CDI burden at acute care facilities with higher rates of admission from and discharge to LTCFs. New clinical interventions and public policies may be needed to prevent and control CDI clusters in hospitals with a high proportion of patients receiving long-term care. High CDI hospitals had a mean of 34.8 cases of CDI per 1000 discharges, six times greater than the median. This variability in hospital burden of CDI is consistent with our contention that C. difficile
clusters occur throughout the USA.12
A number of studies have reported that outbreaks of disease may lead to significant morbidity and mortality.22–24
We and others maintain that these outbreaks of CDI occur with regular periodicity, are predictable, and may therefore be preventable.
Identifying hospitals with a propensity for CDI clusters may be helpful in efforts to prevent future disease outbreaks. In the past, it has been demonstrated that hospitals with transplant programmes and other complex services have high CDI case burden.12
In this analysis, it was found that hospitals with high rates of admissions from and discharges to LTCFs were at particular risk for CDI clusters. Similarly, in a point prevalence study of Association for Professionals in Infection Control and Epidemiology members, the authors found that 35% of patients with CDI had been admitted to a LTCF within 30 days and that 47% had been hospitalized within 90 days.25
Hospitals with proportionately more admissions from LTCFs have a higher risk of CDI outbreaks. Possible reasons for this association include spread of the pathogen between facilities via symptomatic patients or via asymptomatic carriers, as is known to occur with meticillin-resistant Staphylococcus aureus
Asymptomatic carriage among patients and healthcare workers has been implicated as a source C. difficile
transmission in hospitals and LTCFs.27,28
The differential health status of patients in LTCFs is a possible source of bias in the results of this study, but we adjusted for health status with measures of hospital case-complexity, insurance payer status, age, sex and other covariates. The present study has a number of strengths and limitations that are specific to the use of administrative data. First, because the data are administrative in nature, hospital billers or coders need to base the code for CDI diagnosis on physician report or laboratory assay, raising the potential for miscoding. Also, hospital inpatient discharge files do not provide clinical details commonly found in the medical record, such as laboratory results and treatment details, and we had no information on antibiotic prescription practices in hospitals. More information regarding culture and assay results and treatment patterns would allowed verification of diagnostic codes and examination of other associations. Some patients may have been admitted and discharged more than once with the same infection, but the data available did not allow identification of these. Despite these limitations, the study includes a large representative cohort of hospitalized patients with CDI in 19 states in different geographic regions of the USA.
In conclusion, this study has revealed significant associations between hospitals with high levels of CDI and both admissions from and discharges to LTCFs. Prevention strategies would benefit from better information about transmission patterns both within and between healthcare facilities.