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An efficient approach for glomerular filtration rate assessment in older adults
Author(s) -
Martus Peter,
Ebert Natalie,
Giet Markus,
Jakob Olga,
Schaeffner Elke S.
Publication year - 2014
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/bcp.12331
Subject(s) - iohexol , renal function , cystatin c , creatinine , medicine , urology , kidney disease , plasma clearance , population , endocrinology , pharmacokinetics , environmental health
Aims Assessment of glomerular filtration rate ( GFR ) is crucial because the GFR value defines the stage of chronic kidney disease and determines the adjustment of drug dosage. The aim was to investigate a new method for the accurate determination of GFR in older adults based on the combination of an exogenous filtration marker, iohexol, and an endogenous marker, serum creatinine or cystatin C . Methods We combined variables for the estimation of GFR with a reduced set of measurements of the marker iohexol. In a population‐based sample of 570 subjects (≥70 years old) from the B erlin I nitiative S tudy ( BIS ), we investigated the following: (i) the BIS 1 and BIS 2 equations based on age, gender and serum creatinine with or without serum cystatin C ; (ii) equations based on one or two iohexol measurements; and (iii) equations based on the combination of variables from BIS 1 or BIS 2 with iohexol measurements. The reference standard was based on eight iohexol measurements. The cut‐off value of 60 ml min −1 (1.73 m) −2 was chosen to assess accuracy. Equations were constructed using a learning sample ( n = 285) and an independent validation sample ( n = 285). Results Misclassification rates were 17.2% ( BIS 1), 11.6% ( BIS 2), 14.7% [iohexol measurement at 240 min (iohexol 240 )], 7.0% (iohexol 240 combined with variables included in BIS 1) and 6.7% (iohexol 240 combined with variables included in BIS 2). Misclassification rates did not decrease significantly after inclusion of two or three iohexol measurements. Conclusions Combined strategies for the determination of GFR lead to a relevant increase of diagnostic validity.