Open Access Original investigation

Joint relationship between renal function and proteinuria on mortality of patients with type 2 diabetes: The Taichung Diabetes Study

Cheng-Chieh Lin123, Ching-Chu Chen4, Pei-Tseng Kung5, Chia-Ing Li23, Sing-Yu Yang6, Chiu-Shong Liu123, Wen-Yuan Lin12, Cheng-Chun Lee27, Tsai-Chung Li56* and Sharon LR Kardia89

Author Affiliations

1 Department of Family Medicine, China Medical University Hospital, Taichung, Taiwan

2 School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan

3 Department of Medical Research, China Medical University Hospital, Taichung, Taiwan

4 Division of Endocrinology and Metabolism, Department of Medicine, China Medical University Hospital, Taichung, Taiwan

5 Department of Healthcare Administration, College of Health Science, Asia University, Taichung, Taiwan

6 Graduate Institute of Biostatistics, College of Public Health, China Medical University, 91 Hsueh-Shih Road, Taichung 40421, Taiwan

7 Department of Neurology, China Medical University Hospital, Taichung, Taiwan

8 Graduate Institute of Clinical Medical Science, College of Medicine, China Medical University, Taichung, Taiwan

9 Department of Epidemiology, University of Michigan, Ann Arbor, MI, USA

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Cardiovascular Diabetology 2012, 11:131  doi:10.1186/1475-2840-11-131

Published: 19 October 2012

Abstract

Background

Estimated glomerular filtration rate (eGFR) is a powerful predictor of mortality in diabetic patients with limited proteinuria data. In this study, we tested whether concomitant proteinuria increases the risk of mortality among patients with type 2 diabetes.

Methods

Participants included 6523 patients > 30 years with type 2 diabetes who were enrolled in a management program of a medical center before 2007. Renal function was assessed by eGFR according to the Modification of Diet in Renal Disease Study equation for Chinese. Proteinuria was assessed by urine dipstick.

Results

A total of 573 patients (8.8%) died over a median follow-up time of 4.91 years (ranging from 0.01 year to 6.42 years). The adjusted expanded cardiovascular disease (CVD)-related mortality rates among patients with proteinuria were more than three folds higher for those with an eGFR of 60 mL/min/1.73 m2 or less compared with those with an eGFR of 90 mL/min/1.73 m2 or greater [hazard ratio, HR, 3.15 (95% confidence interval, CI, 2.0–5.1)]. The magnitude of adjusted HR was smaller in patients without proteinuria [1.98 (95% CI, 1.1–3.7)]. An eGFR of 60 mL/min/1.73 m2 to 89 mL/min/1.73 m2 significantly affected all-cause mortality and mortality from expanded CVD-related causes only in patients with proteinuria. Similarly, proteinuria affected all outcomes only in patients with an eGFR of <60 mL/min/1.73 m2.

Conclusion

The risks of all-cause mortality, as well as expanded and non-expanded mortality from CVD-related causes associated with proteinuria or an eGFR of 90 mL/min/1.73 m2 or greater are independently increased. Therefore, the use of proteinuria measurements with eGFR increases the precision of risk stratification for mortality.

Keywords:
Renal function; Mortality; Type 2 diabetes