Drug-Related Hospital Admissions of Family Medicine Patients: The High Cost of Non-Adherence

Presenter: Tom Lynch, Pharm.D.

Institution: Eastern Virginia Medical School and Virginia Commonwealth University, School of Pharmacy

Co-Author: Tom Grant, M.D.

Introduction: Most published studies of drug-related hospital admissions focus on adverse drug reactions as a cause and rely on data collected retrospectively. Adverse drug reactions in the community are just one of nine drug-related problems that can result in a hospital admission. Retrospective data collection may underestimate the true prevalence of drug-related events because relevant information may be missing. Also, many studies were published more than a decade ago and may not reflect the current climate of escalating drug usage and costs.

Methods: Clinical pharmacists associated with a family medicine residency program, as part of their normal routine, concurrently monitored the progress of all adult patients admitted to the family medicine inpatient service at a large tertiary care teaching hospital. Data collected included all factors that directly caused admission to the hospital. Drug-related problems that can potentially cause an admission include untreated indication, drug used without indication, improper drug selection, subtherapeutic dosage, failure to receive drug, unintentional overdosage, intentional overdosage, adverse drug reaction, and drug interaction. A modified Naranjo score was used to determine the probability of a drug-related event directly causing admission.

Results: Of 68 adult, family medicine patients admitted over a period of 40 consecutive days, 24 (35%) were admitted primarily because of a drug-related event. Admissions due to adverse drug reactions made up 10% (7 patients) of the total, a figure that compares favorably with other prospective studies. Four of these admissions (57%) were considered preventable. The majority of drug-related admissions (22% of all admissions) were due to a failure to receive prescribed drugs prior to admission. We determined three potential reasons for this problem: non-adherence due to behavioral factors (9/15 patients or 60%), non-adherence due to cost factors (5/15 patients or 33%), and problems with the drug distribution system (1/15 patients or 7%). All of the admissions secondary to non-adherence (100%) were considered preventable. Of the 24 patients admitted secondary to drug-related causes, 21% had no outpatient medication coverage versus only 2% of the 44 patients admitted secondary to other causes. The average length of stay of patients admitted due to drug-related events was 6.5 days versus 4.5 days for all other patients.

Discussion: Although only a preliminary, observational study in one hospital, these results suggest that current drug-related hospital admissions may be higher than previously reported, with a majority of events secondary to non-adherence to prescribed medications in the community. Possible explanations for this will be discussed as well as a proposed medication management intervention strategy involving both hospital and outpatient physicians and clinical pharmacists to identify and counsel patients at high risk for non-adhernece in order to prevent drug-related events and hospital readmissions.