Estimation of GFR in South Asians: a study from the general population in Pakistan.
BACKGROUND
South Asians are at high risk for chronic kidney disease. However, unlike those in the United States and United Kingdom, laboratories in South Asian countries do not routinely report estimated glomerular filtration rate (eGFR) when serum creatinine is measured. The objectives of the study were to: (1) evaluate the performance of existing GFR estimating equations in South Asians, and (2) modify the existing equations or develop a new equation for use in this population.


METHODS
Cross-sectional population-based study.


METHODS
581 participants 40 years or older were enrolled from 10 randomly selected communities and renal clinics in Karachi.


METHODS
eGFR, age, sex, serum creatinine level.


RESULTS
Bias (the median difference between measured GFR [mGFR] and eGFR), precision (the IQR of the difference), accuracy (P30; percentage of participants with eGFR within 30% of mGFR), and the root mean squared error reported as cross-validated estimates along with bootstrapped 95% CIs based on 1,000 replications.


RESULTS
The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine equation performed better than the MDRD (Modification of Diet in Renal Disease) Study equation in terms of greater accuracy at P30 (76.1% [95% CI, 72.7%-79.5%] vs 68.0% [95% CI, 64.3%-71.7%]; P < 0.001) and improved precision (IQR, 22.6 [95% CI, 19.9-25.3] vs 28.6 [95% CI, 25.8-31.5] mL/min/1.73 m(2); P < 0.001). However, both equations overestimated mGFR. Applying modification factors for slope and intercept to the CKD-EPI equation to create a CKD-EPI Pakistan equation (such that eGFRCKD-EPI(PK) = 0.686 × eGFRCKD-EPI(1.059)) in order to eliminate bias improved accuracy (P30, 81.6% [95% CI, 78.4%-84.8%]; P < 0.001) comparably to new estimating equations developed using creatinine level and additional variables.


CONCLUSIONS
Lack of external validation data set and few participants with low GFR.


CONCLUSIONS
The CKD-EPI creatinine equation is more accurate and precise than the MDRD Study equation in estimating GFR in a South Asian population in Karachi. The CKD-EPI Pakistan equation further improves the performance of the CKD-EPI equation in South Asians and could be used for eGFR reporting.
Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan.
Saleem
S
Jessani
Division of Nephrology, Department of Medicine, Tufts Medical Center, Boston, MA.
Andrew S
AS
Levey
Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan.
Rasool
R
Bux
Division of Nephrology, Department of Medicine, Tufts Medical Center, Boston, MA.
Lesley A
LA
Inker
Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan.
Muhammad
M
Islam
Clinical Epidemiology, National Heart and Lung Institute, Imperial College London, London, United Kingdom.
Nish
N
Chaturvedi
Service de Néphrologie, Dialyse et Transplantation Rénale, Université de Saint-Etienne, Saint-Etienne, France.
Christophe
C
Mariat
Center for Evidence Based Medicine and Department of Biostatistics, Brown University, Providence, RI.
Christopher H
CH
Schmid
Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan; Division of Nephrology, Department of Medicine, Tufts Medical Center, Boston, MA; Section of Nephrology, Department of Medicine, Aga Khan University, Karachi, Pakistan; Health Services & Systems Research, Duke NUS Graduate Medical School, Singapore. Electronic address: tazeen.jafar@duke-nus.edu.sg.
Tazeen H
TH
Jafar
D000328:Adult; D000367:Age Factors; D003404:Creatinine / Q000097:blood*; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000503:physiopathology; D008297:Male; D010154:Pakistan / Q000453:epidemiology; D011897:Random Allocation; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000208:ethnology / Q000503:physiopathology / Q000517:prevention & control; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors
D003404:Creatinine
CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) Pakistan; Glomerular filtration rate (GFR); South Asians; estimating equations; renal function