Drug prescriptions unadapted to the renal function in patients aged 80 years and older

Background: Drug-related problems are common in older people. Often they are related to low estimated glomerular filtration rate (eGFR), which has a high prevalence among older adults. Objectives: The aim of this study was to investigate inappropriate drug prescriptions and dose adaptations in a very old population and their relationship with the eGFR. Methods: Design: A cross-sectional study within a Belgian prospective population-based cohort study (the BELFRAIL study) of 539 participants aged 80 years and older (mean age 85 years). Drug prescriptions at inclusion were reported by the participant's responsible general practitioner. The eGFR was estimated using the MDRD equation. Based on their eGFR, the participants were divided in three groups: >50, 30-50 and <30 ml/min/1.73 m(2), respectively. Drug prescriptions were analysed in different eGFR groups. The prevalence and odds ratios of inappropriate drugs and the unadjusted defined daily doses (DDD) of the participant eGFRs were calculated. Results: Thirty-six (of 111) and eight (of 31) of the participants with an eGFR between 30-50 and <30 ml/min/1.73 m(2), respectively, had at least one inappropriate drug prescribed. No decrease in mean DDD, was observed in any prescribed drug in both lower eGFR groups. Participants with a lower eGFR were at higher risk of receiving gliclazide (OR: 4.51; 95% CI: 1.45-14.02) or unadjusted doses of allopurinol (OR: 3.48; 95% CI: 1.26-9.61). Conclusion: Drug prescriptions inappropriate for patient eGFR are common in subjects aged 80 years and older, despite automatic eGFR reporting.