Frequency, type and clinical importance of medication history errors at admission to hospital: a systematic review.

BACKGROUND: Over a quarter of hospital prescribing errors are attributable to incomplete medication histories being obtained at the time of admission. We undertook a systematic review of studies describing the frequency, type and clinical importance of medication history errors at hospital admission. METHODS: We searched MEDLINE, EMBASE and CINAHL for articles published from 1966 through April 2005 and bibliographies of papers subsequently retrieved from the search. We reviewed all published studies with quantitative results that compared prescription medication histories obtained by physicians at the time of hospital admission with comprehensive medication histories. Three reviewers independently abstracted data on methodologic features and results. RESULTS: We identified 22 studies involving a total of 3755 patients (range 33-1053, median 104). Errors in prescription medication histories occurred in up to 67% of cases: 10%- 61% had at least 1 omission error (deletion of a drug used before admission), and 13%- 22% had at least 1 commission error (addition of a drug not used before admission); 60%- 67% had at least 1 omission or commission error. Only 5 studies (n = 545 patients) explicitly distinguished between unintentional discrepancies and intentional therapeutic changes through discussions with ordering physicians. These studies found that 27%- 54% of patients had at least 1 medication history error and that 19%- 75% of the discrepancies were unintentional. In 6 of the studies (n = 588 patients), the investigators estimated that 11%-59% of the medication history errors were clinically important. INTERPRETATION: Medication history errors at the time of hospital admission are common and potentially clinically important. Improved physician training, accessible community pharmacy databases and closer teamwork between patients, physicians and pharmacists could reduce the frequency of these errors.

Unintended medication discrepancies at the time of hospital admission.

BACKGROUND: Prior studies suggest that unintended medication discrepancies that represent errors are common at the time of hospital admission. These errors are particularly worthy of attention because they are not likely to be detected by computerized physician order entry systems. METHODS: We prospectively studied patients reporting the use of at least 4 regular prescription medications who were admitted to general internal medicine clinical teaching units. The primary outcome was unintended discrepancies (errors) between the physicians' admission medication orders and a comprehensive medication history obtained through interview. We also evaluated the potential seriousness of these discrepancies. All discrepancies were reviewed with the medical team to determine if they were intentional or unintentional. All unintended discrepancies were rated for their potential to cause patient harm. RESULTS: After screening 523 admissions, 151 patients were enrolled based on the inclusion criteria. Eighty-one patients (53.6%; 95% confidence interval, 45.7%-61.6%) had at least 1 unintended discrepancy. The most common error (46.4%) was omission of a regularly used medication. Most (61.4%) of the discrepancies were judged to have no potential to cause serious harm. However, 38.6% of the discrepancies had the potential to cause moderate to severe discomfort or clinical deterioration. CONCLUSIONS: Medication errors at the time of hospital admission are common, and some have the potential to cause harm. Better methods of ensuring an accurate medication history at the time of hospital admission are needed.