Optimal Screening Cut-Off Points for Renal Impairment in Rural Korean Older Adults Taking Medications

Abstract

The purpose of this descriptive, cross-sectional study was to identify the optimal cut-off point of estimated glomerular filtration rate (eGFR) using the area under the receiver operating characteristic curve to screen for renal impairment among rural Korean older adults taking medications (N = 100). Renal function was assessed by eGFR using the Cockcroft-Gault formula. Nearly half of participants took five or more prescription drugs, and 46% took nephrotoxic medications. Participants' optimal eGFR cut-off points in screening for renal impairment with and without polypharmacy were 54.3 mL/min (area under curve [AUC] = 0.824, p < 0.001) and 61.4 mL/min (AUC = 0.768, p < 0.001), respectively. The incidence of renal impairment was 61.2% and 56.9%, respectively, using 54.3 mL/min and 61.4 mL/min as the new optimal cut-offs of eGFR with and without polypharmacy. More than half of the rural older adults require a reduction in medication dosage or a change to non-nephrotoxic medications. These new optimal cut-off points using eGFR according to polypharmacy may be helpful in screening for renal impairment among rural older adults taking medications.