| Summary: | 碩士 === 國立成功大學 === 臨床藥學研究所 === 89 === Abstract
Background In the end of 2000, the population aged 65 or older had approached 8.6% in Taiwan. Owing to physiological changes with aging, the pharmacokinetic disposition and pharmacodynamic effects of drug therapy may be altered. Also, there are considerable drug related problems including drug-drug and/or drug-disease interactions resulted from coadministration of multiple drugs for co-morbidity in elderly patients. Elderly patients are more vulnerable to adverse drug reaction (ADR) than young adults, which may lead to hospitalization. In order to prevent the problem of adverse drug reaction of the elderly, Beers MH developed the potentially inappropriate medication criteria in 1991 and revised in 1997. The criteria were widely applied to evaluate the medication use in older patients to detect the prevalence rate of inappropriate medication use. In Taiwan, there was only prescribing pattern analysis, and study of the appropriateness of medication use in the elderly was still absent. Therefore, it is necessary to investigate the association between the prevalence of inappropriate medication use and the occurrence of adverse drug reactions in elder outpatients.
Objectives 1) To study the incidence of adverse drug reaction; 2) to analyze the associated risk factors of adverse drug reaction; 3) to investigate the prevalence of the inappropriate medication use; 4) to study the associated risk factors of inappropriate medication use; and 5) to compare the difference of the incidence of adverse drug reaction between the groups with or without having inappropriate medications in the elderly outpatients.
Methods This prospective study was conducted in National Chen Kung University Hospital through March to June 2001. The elderly patients were included who came to the clinics of Family and Internal Medicine for the first time and were prescribed medications. The pharmacist collected data by telephone interview with structured questionnaire on the 7th day after medical consultation. This study evaluated the medications prescribed based on Beers revised criteria, and evaluated the probability of adverse drug reaction by Naranjo algorithm. SPSS for Window version 8.0 was used to analyze and describe the data.
Results The 684 interviewed subjects had a mean age of 73.3 5.9 years, 53.8 % were male and 46.2 % were female. They took a mean of 3.0 1.5 items of medications and had 2.2 1.2 illnesses. Among the elderly outpatients, 105 subjects had 198 clinical manifestations of adverse drug reactions possibly caused by medications. It showed the incidence of ADR was 24.8 % (105/424). The most common symptom was drowisness (22, 5.2 %), and the other leading symptoms were weakness (21, 5.0 %), diarrhea (16, 3.8 %), dizziness (14, 3.3 %) and dry mouth (14, 3.3 %). The associated factors with adverse drug reaction were taking more drugs, not taking most prescribed drugs, ever experienced adverse drug reaction, and having inappropriate medications. The prevalence of inappropriate medication use was 11.5 %, and the most common inappropriate medications were chlorzoxazone, zolpidem with more than 5 mg daily, dipyridamole, cyproheptadine and hyoscine N-Butyl bromide. The associated factor of inappropriate medication was demonstrated to be the items of prescribed medications.
Conclusions This study showed that the most inappropriate medications were muscle relaxants, antispasmodics, first generation ahtihistamines with anticholinergic effects, and hypnotics/sedatives with augmented or prolonged effect among the elderly. It is therefore suggested that these drugs should be evaluated carefully before prescribing and the dose be adjusted for elderly patients. The polypharmacy was found to be associated with the incidence of adverse drug reaction and the prevalence of inappropriate medication, which suggested simplify the medication regimen for elderly patients. Besides, to prevent the previous adverse drug reaction, judicious review of the medication history of the elderly patient is necessary. The study also revealed that the elderly with inappropriate medication use had more frequent adverse reaction. Thus, the Beers criteria are highly relevant to the occurrence of adverse drug reaction in elderly patients and can be applied for evaluating the quality of drug therapy in Taiwan. Introducing the Beers criteria to prevent adverse drug reaction in the elderly shall have the clinical significance.
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