Factors related to errors in medication prescribing.

OBJECTIVE To quantify the type and frequency of identifiable factors associated with medication prescribing errors. DESIGN AND SETTING Systematic evaluation of every third prescribing error detected and averted by pharmacists in a 631-bed tertiary care teaching hospital between July 1, 1994, and June 30, 1995. Each error was concurrently evaluated for the potential to result in adverse patient consequences. Each error was retrospectively evaluated by a physician and 2 pharmacists and a factor likely related to the error was identified. PARTICIPANTS All physicians prescribing medications during the study period and all staff pharmacists involved in the routine review of medication orders. MAIN OUTCOME MEASURES Frequency of association of factors likely related to medication errors in general and specific to medication classes and prescribing services (needed for medical, pediatric, obstetric-gynecologic, surgical, or emergency department patients); and potential consequences of errors for negative patient outcomes. RESULTS A total of 2103 errors thought to have potential clinical importance were detected during the 1-year study period. The overall rate of errors was 3.99 errors per 1000 medication orders, and the error rate varied among medication classes and prescribing services. A total of 696 errors met study criteria (ie, errors with the potential for adverse patient effects) and were evaluated for a likely related factor. The most common specific factors associated with errors were decline in renal or hepatic function requiring alteration of drug therapy (97 errors, 13.9%), patient history of allergy to the same medication class (84 errors, 12.1%), using the wrong drug name, dosage form, or abbreviation (total of 79 errors, 11.4%, for both brand name and generic name orders), incorrect dosage calculations (77 errors, 11.1%), and atypical or unusual and critical dosage frequency considerations (75 errors, 10.8%). The most common groups of factors associated with errors were those related to knowledge and the application of knowledge regarding drug therapy (209 errors, 30%); knowledge and use of knowledge regarding patient factors that affect drug therapy (203 errors, 29.2%); use of calculations, decimal points, or unit and rate expression factors (122 errors, 17.5%); and nomenclature factors (incorrect drug name, dosage form, or abbreviation) (93 errors, 13.4%). CONCLUSIONS Several easily identified factors are associated with a large proportion of medication prescribing errors. By improving the focus of organizational, technological, and risk management educational and training efforts using the factors commonly associated with prescribing errors, risk to patients from adverse drug events should be reduced.