A spate of recent research has linked an early sign of kidney disease to higher risks for hypertension and coronary conditions. Now, a new meta-analysis confirms “a strong and continuous association between proteinuria and subsequent risk of coronary heart disease (CHD).” The data are so robust that “proteinuria should be incorporated into the assessment of an individual’s cardiovascular risk,” the Australian researchers urge (PLoS Med. 2008;5:e207).
Meanwhile, a team of French scientists has linked excessive levels of a specific protein to substantially higher risks of developing diabetes in men (J Hypertens. 2008;26:2198-2206). “Measuring urinary albumin excretion (UAE) may provide a simple new test to assess diabetes risk,” they conclude.
The Australians looked at 26 cohort studies involving 169,949 individuals and 7,117 coronary events, 27% of which were fatal. They then analyzed the risk of coronary disease against three factors: proteinuria, microalbuminuria, and macroalbuminuria.
Proteinuria was associated with about a 50% increase in the likelihood of developing CHD (risk ratio [RR] 1.47). Albuminuria appeared to have a dose-dependent relationship. While subjects with microalbuminuria were at about 50% greater risk (RR 1.47), those with macroalbuminuria were more than twice as likely to develop CHD as those without abnormal urinary albumin (RR 2.17).
Using somewhat different criteria, the French researchers also found a dose-dependent relationship — this time between albuminuria and diabetes risk among men. Microalbuminuria was defined as UAE of 20-200 mg/L and macroalbuminuria as UAE >200 mg/L, a level that indicates established kidney disease.
The analysis was based on an ongoing study of risk factors for insulin resistance syndrome. The 3,851 men and women were aged 30-64 years and were not diabetic at baseline. During nine years of follow-up, 171 participants developed the disease.
Among men, that risk rose steadily with UAE, until it more than quadrupled for those with UAE >200 mg/L (RR 4.43) as compared with <9 mg/L. UAE was not a significant risk factor among women, for reasons that are not clear, the researchers report. But in men, it functioned independently of BMI, activity, diet, smoking, family history, and other established variables.
The next step, the researchers suggest, is to determine whether lowering UAE can help reduce diabetes risk.