Economic evaluation of the impact of medication errors

Purpose: Medication errors (MEs), defined as 'any preventable event that may cause or lead to inappropriate medication use or patient harm,' have recently been highlighted as a top national priority in a report issued by the Institute of Medicine. However, little information is available on ME costs. This study will estimate the cost of MEs reported by clinical pharmacists from an insurer’s perspective.

Methods: Information on over 700 MEs were collected in a previous study, the "Medication Error Detection, Amelioration and Prevention (MEDAP)". Clinical pharmacists in the American College of Clinical Pharmacy (ACCP) Practice-Based Research Network documented MEs observed during a 14-consecutive day period. The rate of MEs, outcomes (number of errors resulting in temporary/ permanent patient harm, prolonged hospitalization, or life-sustaining therapy), and interventions (communication, medication changes, patient monitoring, and treatment referrals) were collected. A decision model was developed to estimate the economic impact of MEs. Event probabilities were derived from MEDAP data, and costs through reviews of the literature, hospital charge data, and Medicare & Medicaid reimbursement. One-way and Monte Carlo sensitivity analyses (SA) were used to explore uncertainty.

Results: In the base-case, the expected cost of managing a ME was $88.57and a mean cost of $13.40 for each patient seen by a clinical pharmacist, regardless of ME occurrence. In the Monte Carlo simulation, the mean cost per patient seen (SD) was $13.51 ($4.58) and $89.35 ($30.17) per patient with a ME. One-way SA revealed that changes in the probability of MEs causing hospitalization and the cost of hospitalization had the greatest variability on the outcome ($7.63 to $23.56 [probability of hospitalization], $4.93 to $20.63 [cost of hospitalization]).

Conclusions: MEs are costly to the healthcare system. Better understanding of their actual costs can be used to justify initiatives to reduce the risk and inefficiency associated with these errors.