Simple Tool May Identify Patients at Increased Risk for Adverse Drug Reaction

From Medscape Medical News
Simple Tool May Identify Patients at Increased Risk for Adverse Drug Reaction

Laurie Barclay, MD

July 19, 2010 — A simple tool may identify older patients at increased risk for an adverse drug reaction (ADR), according to the results of a study reported in the July 12 issue of Archives of Internal Medicine.

"Older patients are particularly vulnerable to drug-related illnesses because they are usually on multiple drug regimens, which expose them to the risk of drug interactions, and because age is associated with changes in pharmacokinetics and pharmacodynamics," write Graziano Onder, MD, PhD, from Catholic University of the Sacred Heart in Rome, Italy, and colleagues. "The aim of the present study was to develop and validate a method of identifying elderly patients who are at increased risk for an ...ADR."

To develop the GerontoNet ADR Risk Score, the investigators used data from 5936 patients in the Gruppo Italiano di Farmacoepidemiologia nell'Anziano (Italian Group of Pharmacoepidemiology in the Elderly). Mean age was 78.0 ± 7.2 years. The score was calculated with use of variables associated with ADRs, which were identified by a stepwise logistic regression analysis. In a validation study, the ADR risk score was validated in a sample of older adults admitted to 4 European university hospitals (n = 483; mean age, 80.3 ± 7.6 years).

ADRs occurred in 383 (6.5%) of the 5936 patients in the Gruppo Italiano di Farmacoepidemiologia nell'Anziano sample (derivation cohort). The strongest predictors of ADRs were used to compute the ADR risk score.

These were the number of drugs and history of ADR, followed by heart failure, liver disease, presence of 4 or more comorbid conditions, and kidney failure.

In the derivation cohort, the area under the receiver operator characteristic (ROC) curve, which measures risk score performance at predicting ADRs, was 0.71 (95% confidence interval [CI], 0.68 - 0.73). Of 483 patients in the validation study, 56 (11.6%) had an ADR. In this sample, the area under the ROC curve was 0.70 (95% CI, 0.63 - 0.78).

"This study proposes a practical and simple method of identifying patients who are at an increased risk of an ADR," the study authors write. "This approach may be useful in clinical practice as a tool to identify patients at risk and in research to target a population that can benefit from interventions aimed to reduce drug-related illness."

Limitations of this study include lack of generalizability to younger persons who are living in the community or to those in different countries, and small sample size in the validation study.

In an accompanying invited commentary, Edward L. Schneider, MD, and Vito M. Campese, MD, from University of Southern California, Los Angeles, suggest some practical strategies for reducing ADRs. These include increased use of geriatric expertise, computerized physician entry of prescription orders, and increased communication between physicians and pharmacists.

"We applaud Onder and colleagues for devising a score to assist physicians in preventing ADRs in the older population and encourage other clinician scientists to become engaged in combating this serious menace to the health and well-being of today's and tomorrow's seniors," Drs. Schneider and Campese write.

This study was funded by a grant from the GerontoNet Group, a network of academic departments of geriatric medicine in the European Union, supported by Servier. The study authors have disclosed no relevant financial relationships.

Arch Intern Med. 2010;170:1142-1148, 1148-1149.