Quantifying The Problem The Cost Of Drugrelated Problems

Much of the literature to date describing DRPs and their economic consequences focused on hospitalization secondary to adverse drug effects or medication non-compliance (3). Sullivan et al. (4) surveyed available literature and, using a meta-analytic technique, estimated that non-compliance accounted for 5.3% of hospitalizations; direct medical costs associated with these hospitalizations were estimated to be US $8.5 billion. The authors estimate an additional US $17 to $25 billion in indirect costs related to drug therapy non-compliance. A more recent estimate puts the total costs of non-compliance at greater than US $100 billion (5).

Drug-related problems occurring during hospitalization are also common. Bates et al. (6,7) conducted a six-month prospective cohort study evaluating over 4100 hospital admissions. The authors reported a rate of 6.5 DRPs per 100 admissions, with 28% of the problems preventable. These adverse events extended the length of hospital stay by 2.2 days, and were associated with increased costs of US $2595 per DRP. The authors estimated annual costs attributable to DRPs at US $5.6 million for their institution, of which US $2.8 million was due to preventable events.

In a more recent evaluation (8), Classen et al. performed a matched case-control study with 1580 cases and nearly 21,000 controls. Although the rate of DRPs per 100 admissions was lower than that found by Bates et al. (2.43 versus 6.5), the increase in length of stay and costs per event were similar. Classen reported an increased length of stay of 1.91 days, with increased costs of US $2262. Extrapolating these figures to the US population, DPRs occurring in hospitalized patients would cost US $1.56 billion annually. Using the higher event rate (DPRs in 6.5% of admissions) from the Bates et al. study, US costs increase to US $4.2 billion a year. In addition to these morbidity costs, Classen et al. found that DRPs were associated with an almost two-fold increase in the risk of death (odds ratio 1.88 95% CI, 1.54-2.22; p < 0.001). It is clear from these studies that DRPs in hospitalized patients are associated with prolonged length of stay and increased economic burden.

Studies of emergency departments (EDs) have shown that between 2.9 and 3.9% of ED admissions are directly related to DRPs (9). Dennehy et al. estimated total annual costs of these DRP-related admissions at US$602,597.

Bootman et al. (10) evaluated the occurrence and cost of DRPs in nursing facilities. Decision analysis was used, with event probabilities and DRP management estimated by an expert panel of consultant pharmacists and physicians. The panel estimated that without consultant pharmacist services, approximately 42% of nursing facility residents would have an optimal therapeutic outcome (absence of DRPs). The authors estimated the cost of managing DRPs in this patient population at US $7.6 billion annually. Furthermore, deaths attributable to DRPs were estimated to occur in 3 to 4% of nursing facility patients.

The most comprehensive study to date, conducted by Bootman and Johnson (11,12), suggests that DRPs in the ambulatory setting cost society approximately US $76 billion annually. Using an expert panel, they developed a model of therapeutic outcomes resulting from drug therapy and estimated the magnitude of drug-related mortality and morbidity in the US (excluding hospital DRPs). The largest component of the total cost comprised drug-related hospitalizations (62% of total cost), followed by admissions to long-term care facilities. Based on model estimates, more than 28% of hospitalization admissions result from drug-related morbidity and mortality. Additionally, the panel members estimated that approximately 60% of patients taking prescription medication would have an optimal therapeutic outcome. Recently, the analysis was updated and the estimated cost in 2000 was US$177.4 billion(13). All of these estimates lead to the same conclusion; drug-related morbidity and mortality is a common and costly problem facing society.

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