Impact of c. difficile infections on inpatient hospital reimbursement

Background: The CDC (2009) estimates that hospital-acquired Clostridium difficile-associated diarrhea (CDAD) episodes result in $1.6 billion in annual hospital costs. In addition, the number of CDAD discharges has more than doubled in recent years. Recurrent CDAD episodes affect 20–30% of inpatients at an attributable cost of $13,926 per recurrent inpatient episode. The objective of this study was to determine the financial impact of hospital-acquired CAD on inpatient treatment costs and DRG reimbursement. Methods: A retrospective cohort (CDAD group matched with non-CDAD group) analysis was conducted using the 2009 California Office of Statewide Planning and Development Hospital Discharge Public Database, which contains data on approximately four million patients, including diagnosis-related groups (DRGs); International Classification of Diseases, 9th Revision (ICD-9) codes; hospital charges; source of payment; and length of stay (LOS). To understand cost differences between CDAD and non-CDAD cases, a multiple regression model was developed to study the relationship between inpatient CDAD hospital costs and LOS (dependent variables) and a set of independent or explanatory patient and diagnostic variables, including secondary diagnosis of CDAD, age, sex, race, and the top four secondary diagnoses of each DRG (a measure of case-mix complexity). Thirty-three thousand CDAD patient records were identified using ICD-9 code 008.45 (C. difficile). Results: CDAD was found to significantly increase average LOS and average cost for DRGs for which CDAD was listed as a secondary diagnosis (p<0.0001). As examples, chemotherapy DRG 847 (chemotherapy without leukemia) was found to have a non-CDAD LOS of 3.8 vs. 9.7 days for chemotherapy with CDAD; costs were $12,157 vs. $27,370, respectively. Pneumonia (DRG 924) was associated with an LOS of 4.8 days without CDAD vs. 6.7 with CDAD; associated costs were $9,225 vs. $16,979, respectively. Medicare reimbursement rates for DRGs included in the study were significantly lower than unadjusted hospital costs for both primary ($8,847 vs. $14,068 respectively) and secondary CDAD diagnoses ($15,715 vs. $40,724 respectively). Medicare was the primary payment source (64%) for CDAD treatment, followed by private coverage (18%), Medi-Cal (14%) and other (4%). Conclusions: Inpatient treatment costs and LOS associated with CDAD are significantly higher than a matched cohort of non-CDAD patients, resulting in costs exceeding DRG reimbursement.