Preventable and Non-Preventable Risk Factors for Adverse Drug Events Related to Hospital Admission in the Elderly

J. Doucet, A. Jego, D. Noel, C.E. Geffroy, C. Capet, A. Coquard, E. Couffin, A.L. Fauchais, P. Chassagne, D. Mouton-Schleifer and E. Bercoff


Clin Drug Invest. 2002;22(6) 

In This Article

Abstract and Introduction

Objective: To ascertain preventable and non-preventable risk factors for adverse drug events (ADEs) in elderly inpatients at hospital admission.
Patients and Methods: This was a prospective study of 2814 inpatients over 70 years of age who were consecutively admitted from November 1997 to December 1999 to a 60-bed geriatric unit of a French university hospital, and the 500 consecutive ADEs that were present at admission. All drugs administered during the month preceding hospitalisation, signs or symptoms of ADEs, and risk factors related to the drug prescription or patient's diseases were considered: excess drug doses, potential drug-drug interactions (DDIs), interfering chronic disease and acute interfering disease.
Results: 66.7% of the ADEs were associated with cardiovascular, metabolic, renal or neuropsychological symptoms. The drugs involved were mainly cardiovascular (43.7%) and psychotropic (31.2%) drugs. One or more risk factors (mainly DDIs and/or interfering acute diseases) were recorded in 81.2% of ADEs. An interfering acute disorder (usually dehydration) was more frequent in ADEs resulting from drugs or drug combinations administered for 1 month or more (p < 0.05). 41.3% of risk factors were preventable (some DDIs, excess doses, interfering chronic diseases). One risk factor alone or the combination of all risk factors was preventable in 40.2% of ADEs.
Conclusions: This study suggests that many ADEs in the elderly may be decreased by removing all the preventable risk factors before a drug is prescribed (mainly DDIs and excess doses) and by reinforcing drug monitoring when an interfering acute disease occurs.

Drug treatment of the elderly very often presents a dilemma: on the one hand, the elderly are often treated with many drugs because they have several conditions that require treatment; on the other hand, adverse drug events (ADEs) often occur in elderly patients taking one or more drugs and frequently lead to hospitalisation, decreased autonomy and increased mortality.[1,2,3,4,5,6,7,8]

According to some earlier studies, 30 to 55% of ADEs could be prevented if physicians took into account possible risk factors.[4,9,10,11,12,13] Some risk factors are linked to aging and are not possible to assess accurately before prescribing the drug: pharmacological modifications (alteration in liver metabolism, denutrition, modifications of drug-receptors), variations in interindividual metabolism, and alterations in homeostasis. Other risk factors are also present either at the time of the drug prescription or at the time of drug administration. These factors could be partially prevented or taken into account, e.g. physiological alteration of renal function, interfering chronic disease, interfering acute disease, drug-drug interactions (DDIs), inappropriate number or dose of drugs, and poor compliance. To our knowledge, there are no data concerning the respective weight of each preventable risk factor in elderly inpatients with acute disease. Some earlier studies used an overall definition of preventability, but this does not focus on the main preventable factors.[13] In another study, it was demonstrated that DDIs were often involved in ADEs, but only this risk factor was evaluated.[14] Other studies have investigated the preventability of ADEs in nursing homes.[15,16]

The aim of the present prospective study was to ascertain the respective weights of preventable and non-preventable risk factors of ADEs in elderly inpatients on admission to hospital.