Autor:innen:
M. König (Berlin, DE)
M. Gollasch (DE)
I. Demuth (DE)
E. Steinhagen-Thiessen (DE)
Background. In aging populations with an ever-growing burden of risk factors like obesity, diabetes and hypertension, chronic kidney disease (CKD) is on the rise. Approximately 20% in the age-group of 60-69 years and at least 35% aged 70 years and older were shown to have impaired kidney function. In particular in the elderly, there is controversy as to which formula for the estimation of GFR should be used, especially as recently novel equations for estimating the glomerular filtration rate (eGFR) have emerged, which have not been applied comprehensively to older adults. Moreover, often albuminuria is not provided in the definition of CKD, leading to only vague prevalence estimates. Furthermore, data on CKD awareness in the elderly are sparse.
Objective. To determine the prevalence of CKD among older adults by eGFR and albuminuria, compare the performance of 6 established and novel eGFR formulas, explore risk factors and assess the awareness of CKD in a large cohort of community-dwelling elderly from Germany.
Methods. 1628 subjects from the Berlin Aging Study II (BASE-II) were included in this analysis (mean age 68.7 years; 51.2% female). Extensive cross-sectional data with respect to socio-demographics, lifestyle, medication and diagnoses were inquired during structured interviews and medical examination.
Estimated GFR was calculated using the FAS (Full Age Spectrum), the Lund-Malmö revised (LMr), the MDRD, the BIS1, the Cockcroft-Gault and the CKD-EPI equations. Urinary albumin excretion was expressed as albumin/creatinine ratio (ACR) in mg/g. GFR < 60 ml/min/1.73m2 and/or ACR>30 mg/g were considered as criteria for CKD.
Results. 77.1% of subjects had hypertension, 12.4% had diabetes and 18.3% were obese. Prevalence of CKD strongly depended on the eGFR equations used: 25.4% (FAS), 24.6% (BIS1), 23.1% (Lund-Malmö revised), 19.3% (Cockcroft-Gault), 16.4% (CKD-EPI) and 14.7% (MDRD), respectively. A relevant proportion of all subjects (7.2%) had isolated albuminuria (ACR ≥30 mg/g). Notably, among subjects with CKD, only 3.9% were aware of their condition. Polypharmacy (regular use of 5 or more drugs), age, BMI, coronary artery disease, non-HDL-cholesterol and female sex were identified to be independently associated with CKD in multiple regression analysis. After full adjustment, polypharmacy was associated with a 54% increased risk of CKD.
Conclusions. CKD is common among older adults in Germany, but awareness is low. The FAS equation detects higher rates of CKD than MDRD and CKD-EPI, which are most widely used at present. Also, when CKD is defined based on eGFR and albuminuria, considerably more people are identified than by eGFR alone. Finally, polypharmacy is an underrated risk factor for CKD in the elderly.