The development of polypharmacy. A longitudinal study

Background. To date, only a few studies have been carried out on the develo pment and progress of polypharmacy in relation to morbidity in general prac tices in The Netherlands. Objective. The aim of this study was to investigate the relationship betwee n an increase in long-term drug use and the incidence and severity of some chronic diseases, particularly in the elderly. Methods. Data on medication and morbidity of 1544 elderly people were colle cted for the period 1994-1997 from three family practices in the medication and morbidity Registration Network of Groningen (RNG) in the northern part of The Netherlands. Polypharmacy is defined as the long-term simultaneous use of two or more drugs; long-term is defined as >240 days in a year. We l ooked for differences in incidences of some chronic diseases in those subgr oups of the elderly in whom multiple long-term drug use respectively increa sed, stayed constant or did not exist. Polypharmacy at the end of the perio d was predicted using regression analysis. Results. Polypharmacy occurred in 42% of the elderly at the end of 1997, wi th major polypharmacy 1>5 drugs) in only 4%. The average number of drugs us ed long-term increased from 1.3 to 1.8 in 4 years. Predictors for the incre ase of polypharmacy were the number of drugs at the start, age, diabetes, c oronary ischaemic diseases and use of medication without a clear indication (P<0.005). The average number of diseases also increased, especially in th e elderly who showed the greatest increase in long-term drug use; however, there was no significant difference from the groups with a slow or no incre ase in drug use. Discussion. Polypharmacy showed a slow increase over 4 years: almost 20% of the elderly developed polypharmacy, i.e. going from no drugs or one drug t o two or more drugs. Polypharmacy develops mainly in elderly patients who a lready use several drugs, who are known to suffer from cardiovascular disea ses, diabetes or stomach symptoms, those who often take drugs (especially s edatives/hypnotics) without clear indication and those who develop hyperten sion or atrial fibrillation over time.