Supplementary Material for: Prevalence of Impaired Kidney Function in the German Elderly: Results from the Berlin Aging Study II (BASE-II)

Background: In aging populations with an ever-growing
burden of risk factors such as obesity, diabetes, and hypertension,
chronic kidney disease (CKD) is on the rise. However, little is known
about its exact prevalence among elderly adults, and often albuminuria
is not included in the definition of CKD. Moreover, novel equations for
the estimated glomerular filtration rate (eGFR) have recently emerged,
which have not been applied comprehensively to older adults. Data on CKD
awareness among the elderly are sparse. Objectives: To
determine the prevalence of CKD among older adults by eGFR and
albumin/creatinine ratio (ACR), compare the performance of 6 established
and novel eGFR formulas, explore risk factors, and determine the
awareness of CKD in a large cohort of community-dwelling elderly from
Germany. Methods: A total of 1,628 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 on
sociodemographics, lifestyle, medication, and diagnoses were inquired
during structured interviews and a medical examination, and blood and
urine parameters were measured. Results: In all, 77.1% of
the subjects had hypertension, 12.4% had diabetes, and 18.3% were obese.
The prevalence of CKD strongly depended on the eGFR equations used:
25.4% (full age spectrum [FAS] equation), 24.6% (Berlin Initiative
Study), 23.1% (Lund-Malmö revised), 19.3% (Cockcroft-Gault), 16.4%
(Chronic Kidney Disease-Epidemiology Collaboration [CKD-EPI]), and 14.7%
(Modification of Diet in Renal Disease [MDRD]). Of the subjects with an
eGFRFAS <60 mL/min/1.73 m2 and/or an ACR
>30 mg/g, only 3.9% were aware of having CKD. Polypharmacy, age, BMI,
coronary artery disease, non-HDL cholesterol, and female sex were
independently associated with CKD. Conclusions: CKD is
prevalent 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 associated with an increased risk for
CKD in the elderly.