[Prescription to elderly patients: reducing underuse and adverse drug reactions and improving adherence]

Many elderly people take multiple medications, usually for multiple health disorders. This "polymedication" increases the risk of iatrogenic disorders, may affect adherence to treatment, and represents an economic burden for society. It is therefore essential to optimize drug prescription to the elderly. The general practitioner is most involved in treating the elderly, who tend not to consult specialists as frequently as younger adults do. Most elderly subjects with comorbidities and polymedication are excluded from clinical trials, and geriatrics is not considered a priority during medical training. Three suboptimal prescription modalities have been described in the elderly population : "overuse", "misuse", and "underuse". Adverse drug reactions are frequent in the elderly and have a major economic cost. They are behind about 10 % of hospital admissions over the age of 65, and 20 % over 80. Yet most advers drug reactions are preventable. The public health consequences of non adherence to drug therapy are poorly documented. Elderly people may have several risk factors for non adherence, and a combination of measures may be necessary to improve the situation.