Abstract and Introduction
Abstract
This study evaluated hospital demographics, staffing, pharmacy variables, health care outcomes measures (severity of illness-adjusted mortality rates, drug costs, total cost of care, and length of stay) and medication errors. A database was constructed from the 1992 American Hospital Association's Abridged Guide to the Health Care Field, the 1992 National Clinical Pharmacy Services database, and 1992 mortality data from the Health Care Financing Administration. Simple statistical tests and a severity of illness-adjusted multiple regression analysis were employed. The study population consisted of 1116 hospitals that reported information on medication errors and 913 hospitals that reported information on medication errors that adversely affected patient care outcomes. We evaluated factors associated with the 430,586 medication errors and 17,338 medication errors that adversely affected patient care outcomes. Medication errors occurred in 5.07% of the patients admitted each year to these hospitals. Each hospital experienced a medication error every 22.7 hours (every 19.73 admissions). Medication errors that adversely affected patient care outcomes occurred in 0.25% of all patients admitted to these hospitals/year. Each hospital experienced a medication error that adversely affected patient care outcomes every 19.23 days (or every 401 admissions). The following factors were associated with increased medication errors/occupied bed/year: lack of pharmacy teaching affiliation (slope = 0.8875, p=0.0416), centralized pharmacists (slope = 1.0942, p=0.0001), number of registered nurses/occupied bed (slope = 1.624, p=0.032), number of registered pharmacists/occupied bed (slope = 25.0573, p=0.0001), hospital mortality rate (slope = 2.8017, p=0.0192), and total cost of care/occupied bed/year (slope = 0.01432, p=0.0091). Factors associated with decreased medication errors were location in the Mid-Atlantic census region (slope = -1.5182, p=0.03), affiliation with a pharmacy teaching program (slope = -1.0252, p=0.0349), decentralized pharmacists (slope = -0.9843, p=0.0037), and number of medical residents/occupied bed (slope = -1.478, p=0.0014). There was a 45% decrease in medication errors (1.81-fold decrease) in hospitals that had decentralized pharmacists, compared with hospitals that had centralized pharmacists. In addition, there was a 94% decrease in medication errors that adversely affected patient care outcomes (16.88-fold decrease) in hospitals that had decentralized pharmacists compared with hospitals that had only centralized pharmacists. Based on previous field studies and our findings in 1116 hospitals, it appears that one of the most effective ways to prevent or reduce medication errors is to decentralize pharmacists to patient care areas. The results of this study should help hospitals reduce the number of medication errors that occur each year.
Introduction
The Institute of Medicine's 1999 report suggested that medical errors accounted for 44,000-98,000 deaths each year. These deaths exceed the eighth leading cause of death in the United States. It is estimated that the total cost of medical errors is $17 billion-$29 billion annually. Although the percentage of drug-related medical errors in ambulatory settings is unknown, drugs are the most common cause of medical errors in hospitals, affecting 3.7% of patients. Clearly, medication errors are a significant component of medical errors in U.S. hospitals.
Hospital medication errors occur in 3-6.9% of inpatients. The error rate for inpatient medication orders was reported to be 0.03-16.9%. One analysis determined that 11% of medication errors in hospitals were pharmacy dispensing errors related to the wrong drug or strength. Whereas medication-related errors occur frequently in hospitals, many of these errors apparently do not result in patient harm. In a 1999 report on hospital medication errors compiled by the United States Pharmacopeia, only 3% of 6224 medication errors caused patient harm. Although the frequency of medication errors has been documented, there has been little study of the factors associated with the root causes of these errors.
Unfortunately, nearly all studies of medication errors involved a small number of sites (hospitals or pharmacies) or a limited number of patients. Little is known about what factors might be associated with medication errors in a large population of hospitals. More studies assessing the risk of medication errors are needed to determine the best methods for reducing these errors. This study employed a population-based approach to assess factors associated with the reporting of medication errors in U.S. hospitals.
We tested the associations and correlations between hospital demographics, staffing, and pharmacy variables with the number of medication errors reported in U.S. hospitals. In addition, we determined the correlation between the number of medication errors and four major health care outcome measures: severity of illness-adjusted mortality rates, drug costs, total cost of care, and length of stay. This is the first study to evaluate factors associated with medication errors in a large number of hospitals.