ADVERSE DRUG EVENTS IN HOSPITALIZED-PATIENTS - EXCESS LENGTH OF STAY,EXTRA COSTS, AND ATTRIBUTABLE MORTALITY

Objective.-To determine the excess length of stay, extra costs, and mo rtality attributable to adverse drug events (ADEs) in hospitalized pat ients. Design.-Matched case-control study. Setting.-The LDS Hospital, a tertiary care health care institution. Patients.-All patients admitt ed to LDS Hospital from January 1, 1990, to December 31, 1993, were el igible. Cases were defined as patients with ADEs that occurred during hospitalization; controls were selected according to matching variable s in a stepwise fashion. Methods.-Controls were matched to cases on pr imary discharge diagnosis related group (DRG), age, sex, acuity, and y ear of admission; varying numbers of controls were matched to each cas e. Matching was successful for 71% of the cases, leading to 1580 cases and 20197 controls. Main Outcome Measures.-Crude and attributable mor tality, crude and attributable length of stay, and cost of hospitaliza tion. Results.-ADEs complicated 2.43 per 100 admissions to the LDS Hos pital during the study period. The crude mortality rates for the cases and matched controls were 3.5% and 1.05%, respectively (P<.001). The mean length of hospital stay significantly differed between the cases and matched controls (7.69 vs 4.46 days; P<.001) as did the mean cost of hospitalization ($10 010 vs $5355; P<.001). The extra length of hos pital stay attributable to an ADE was 1.74 days (P<.001). The excess c ost of hospitalization attributable to an ADE was $2013 (P<.001). A li near regression analysis for length of stay and cost controlling for a ll matching variables revealed that the occurrence of an ADE was assoc iated with increased length of stay of 1.91 days and an increased cost of $2262 (P<.001). In a similar logistic regression analysis for mort ality, the increased risk of death among patients experiencing an ADE was 1.88 (95% confidence interval, 1.54-2.22; P<.001). Conclusion.-The attributable lengths of stay and costs of hospitalization for ADEs ar e substantial. An ADE is associated with a significantly prolonged len gth of stay, increased economic burden, and an almost 2-fold increased risk of death.