Adverse drug reaction monitoring--cost and benefit considerations. Part II: cost and preventability of adverse drug reactions leading to hospital admission.

Although adverse drug reactions (ADR) are common, there is little knowledge on their direct, indirect and intangible costs. Our study is focused on the direct costs caused by ADR leading to hospital admission. The objective is to quantify the achievable financial benefits if avoidable ADRs were actually prevented by appropriate measures. A literature search on two subjects was done, first on length of stay (LOS) of hospital admissions due to ADR as a proxy measure for direct costs and second on their preventability. Thirteen studies on the length of stay of hospital admissions due to ADR, published between 1975 and 1996, were identified. The median LOS is 8.7 days (lower quartile=8.0 days; upper quartile=12.3 days). Assuming 4.5 million admissions to departments of internal medicine in Germany with a cost of DM 465 per hospital day and a median proportion of 5.8% of medical hospital admission to be due to ADR this yields direct costs of 1050 million DM per year in Germany. A cost table for other regions is provided. Preventability of ADR was the subject of 14 publications that revealed about 30% of all ADRs to be preventable. With regard to Germany this means that 350 million DM per year could be saved by preventing adverse drug reactions. These conservative estimates-no indirect and intangible costs, no ADRs that occur during hospital stay, no ADRs in outpatient care are included-show a considerable economic burden of ADRs. As about 30% of these ADRs are considered avoidable policy-makers are asked to invest more into ADR monitoring and preventive measures. Their benefit would surmount costs and at the same time increase the quality of care.