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Estimation of GFR in South Asians: a study from the general population in Pakistan.
Am J Kidney Dis. 2014 Jan; 63(1):49-58.AJ

Abstract

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.

STUDY DESIGN

Cross-sectional population-based study.

SETTING & PARTICIPANTS

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

PREDICTORS

eGFR, age, sex, serum creatinine level.

OUTCOMES

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.

LIMITATIONS

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.

Authors+Show Affiliations

Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan.Division of Nephrology, Department of Medicine, Tufts Medical Center, Boston, MA.Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan.Division of Nephrology, Department of Medicine, Tufts Medical Center, Boston, MA.Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan.Clinical Epidemiology, National Heart and Lung Institute, Imperial College London, London, United Kingdom.Service de Néphrologie, Dialyse et Transplantation Rénale, Université de Saint-Etienne, Saint-Etienne, France.Center for Evidence Based Medicine and Department of Biostatistics, Brown University, Providence, RI.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.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

24074822

Citation

Jessani, Saleem, et al. "Estimation of GFR in South Asians: a Study From the General Population in Pakistan." American Journal of Kidney Diseases : the Official Journal of the National Kidney Foundation, vol. 63, no. 1, 2014, pp. 49-58.
Jessani S, Levey AS, Bux R, et al. Estimation of GFR in South Asians: a study from the general population in Pakistan. Am J Kidney Dis. 2014;63(1):49-58.
Jessani, S., Levey, A. S., Bux, R., Inker, L. A., Islam, M., Chaturvedi, N., Mariat, C., Schmid, C. H., & Jafar, T. H. (2014). Estimation of GFR in South Asians: a study from the general population in Pakistan. American Journal of Kidney Diseases : the Official Journal of the National Kidney Foundation, 63(1), 49-58. https://doi.org/10.1053/j.ajkd.2013.07.023
Jessani S, et al. Estimation of GFR in South Asians: a Study From the General Population in Pakistan. Am J Kidney Dis. 2014;63(1):49-58. PubMed PMID: 24074822.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Estimation of GFR in South Asians: a study from the general population in Pakistan. AU - Jessani,Saleem, AU - Levey,Andrew S, AU - Bux,Rasool, AU - Inker,Lesley A, AU - Islam,Muhammad, AU - Chaturvedi,Nish, AU - Mariat,Christophe, AU - Schmid,Christopher H, AU - Jafar,Tazeen H, Y1 - 2013/09/26/ PY - 2013/04/04/received PY - 2013/07/25/accepted PY - 2013/10/1/entrez PY - 2013/10/1/pubmed PY - 2014/4/8/medline KW - CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) Pakistan KW - Glomerular filtration rate (GFR) KW - South Asians KW - estimating equations KW - renal function SP - 49 EP - 58 JF - American journal of kidney diseases : the official journal of the National Kidney Foundation JO - Am J Kidney Dis VL - 63 IS - 1 N2 - 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. STUDY DESIGN: Cross-sectional population-based study. SETTING & PARTICIPANTS: 581 participants 40 years or older were enrolled from 10 randomly selected communities and renal clinics in Karachi. PREDICTORS: eGFR, age, sex, serum creatinine level. OUTCOMES: 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. LIMITATIONS: 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. SN - 1523-6838 UR - https://www.unboundmedicine.com/medline/citation/24074822/Estimation_of_GFR_in_South_Asians:_a_study_from_the_general_population_in_Pakistan_ DB - PRIME DP - Unbound Medicine ER -