Patient- and health care-related factors associated with initiation of potentially inappropriate medication in community-dwelling older persons.

Potentially inappropriate medications (PIMs) in older persons are defined as medications of which the potential harms outweigh their benefits. The purpose of this study was to determine how initiation of PIMs accumulate in community-dwelling persons aged 65-74 and ≥75 years, and which patient- and health care-related factors are associated with PIM initiation over time. Data of this study were gathered from population-based registers by a 10% random sample of persons (n = 28 497) aged ≥65 years with no prior PIMs within a 2-year period preceding the index date (1 January 2002), and the study individuals were followed until 2013. The Finnish Prescription Register was linked using a personal identity code to register on inpatient care and causes of deaths and socio-economic data. In this study, 10 698 (37.5%) persons initiated PIMs during the study period. Female gender was associated with PIM initiation in 65-74-year-olds, but not in ≥75-year-olds. In 65-74-year-olds, the risk of PIM initiation increased with the higher income, whereas in ≥75-year-olds, the association between PIM initiation and the high income was not significant. The prescribing physician explained 9%-16% of the variation in the probability of PIM initiation. In conclusion, there were age-related differences in the factors associated with PIM initiation in relation to gender and socio-economic status. Overall, patient-related factors explained a large proportion of variation of PIM initiation, but there were also differences in PIM prescribing among physicians. However, physician-related variance of PIM initiations decreased during the 12-year follow-up.