Level and Determinants of Kidney Function in a South Asian Population in Pakistan

Background: People of South Asian origin are at high risk of chronic kidney disease. Some have suggested that the usual level of glomerular filtration rate (GFR) in South Asians may be lower than in populations of European origin. However, measured GFR in a general adult population of South Asian origin has not been studied. Design: Cross-sectional observational study. Setting & Participants: 530 patients 40 years or older randomly selected from communities in Karachi, Pakistan, using multistage cluster sampling. Patients with both diabetes and hypertension were excluded. Predictor: Age, sex, diabetes, and hypertension. Outcome: Measured GFR using urinary clearance of inulin. Results: Mean age of participants was 49.7 +/- 9.5 (standard deviation [SD]) years, 51% were men, 34.9% had hypertension, and 30.5% had diabetes. Mean measured GFR was 94.1 +/- 28.6 mL/min/1.73 m(2). GFR was lower by 0.79 +/- 0.11 mL/min/1.73 m(2) for each 1-year older age. The 5-year age- and sex-specific mean GFR of the study population generally was within 1 SD of the mean of previously reported values for US adults. Factors independently associated with GFR were younger age (beta coefficient, -3.84 [95% CI, -5.46 to -2.21] mL/min/1.73 m(2) per 5 years older), higher serum albumin level (4.58 [95% CI, 0.74-8.42] mL/min/1.73 m(2) per 0.5-g/dL increase), higher fasting plasma glucose level (0.81 [95% CI, 0.44-1.18] mL/min/1.73 m(2) per 10-mg/dL increase), high versus low meat intake (7.81 [95% CI, 1.14-14.48] mL/min/1.73 m(2) for >= 11 vs <= 5 servings/wk), and higher estimated protein intake (1.46 [95% CI, 0.41-2.51] mL/min/1.73 m(2) per 1.0-g/d increase) from urine urea nitrogen. Limitations: Moderate sample size, lack of validation of some items in the dietary assessment for this study population. Conclusions: Mean measured GFR in South Asian adults from the general population in Karachi, Pakistan, is only modestly lower than in European-origin counterparts, with similar age association. This may reflect lower dietary protein intake in South Asians. Am J Kidney Dis. 58(5):764-772. (C) 2011 by the National Kidney Foundation, Inc.