Inappropriate prescribing in an elderly population: findings from a South African public sector survey

Prevalence of potentially serious drug-drug interactions among South African elderly private health sector patients using the Mimica Matanović/Vlahović-Palčevski protocol

OBJECTIVES

To determine the prevalence of potentially serious drug-drug interactions (DDIs) and their relationship with gender and age, among elderly in South Africa.

METHODS

A cross-sectional study was conducted using pharmaceutical claims data for 2013, for a total of 103 420 medical scheme beneficiaries' ≥65 years. All medications dispensed within one calendar month where the days' supply of medication dispensed overlapped, were grouped as one prescription. DDIs per prescription were then identified using the Mimica Matanović/Vlahović-Palčevski DDI protocol. Results were interpreted using effect sizes, that is Cramér's V, Cohen's d and Cohen's ƒ² .

KEY FINDINGS

A total of 331 659 DDIs were identified on 235 870 (25.8%, N = 912 713) prescriptions (mean 0.36 (SD 0.7) (95% CI, 0.36 to 0.37)). Women encountered 63.5% of all DDIs. Effect sizes for the association between DDIs and age group (Cramér's V = 0.06), and gender (Cramér's V = 0.05) was negligible. There was no difference between men and women regarding the mean number of DDIs identified per prescription (Cohen's d = 0.10). The number of medicine per prescription (ƒ² = 0.51) was the biggest predictor of the DDIs. The most frequent interacting drug combinations were between central nervous system medicines (30.6%).

CONCLUSION

Our study is the first to report the prevalence of potentially serious DDIs among an elderly population in the South African private health sector utilising the Mimica Matanović/Vlahović-Palčevski DDI protocol. Overall, we identified DDIs in approximately 26% of the prescriptions in our study. Age and gender were not found to be predictors of potentially serious DDIs.

Increasing use of medicines in elderly persons: a five-year follow-up of the Kuopio 75+Study

OBJECTIVE

The aim of this study was to describe the changes in medicine use, polypharmacy and excessive polypharmacy between 1998 and 2003 among a cohort of elderly Finns.

METHODS

For this prospective follow-up study, a random sample of 700 participants aged >or=75 years was drawn from the City of Kuopio, Finland. Of them, 601 participated in the study at baseline in 1998. The changes in medicine use among the survivors (n=339), who were re-examined in 2003, were recorded and are described here. Statistical significance of changes in medicine use was evaluated by Student's paired-samples and independent-samples t-test and Fisher's exact test.

RESULTS

From 1998 to 2003, the mean number of medicines in use per individual increased from 6.3 to 7.5 (p<0.001). The prevalence of polypharmacy (>5 medicines in use) increased from 54% to 67% and excessive polypharmacy (>or=10 medicines in use) from 19% to 28%. The increase was due to increased use of regularly taken medicines, whereas the use of medicines taken as needed decreased during the follow-up in both sexes. At the time of follow-up survey, persons in institutional care used significantly more medicines (10.9) than community-dwelling elderly persons (7.0) (p<0.001). Central nervous system medicines and cardiovascular medicines were the most commonly used medicines in both years.

CONCLUSION

The number of medicines and the prevalence of polypharmacy and excessive polypharmacy increases with advancing age. In order to avoid possible harmful effects and to optimize medication it is necessary to assess the medication regimen at regular intervals.