Proteinuria, impaired kidney function, and adverse outcomes in people with coronary disease: analysis of a previously conducted randomised trial

OBJECTIVES: To determine whether data on proteinuria are useful for refining estimates of risk based on kidney function alone, and whether the results of kidney function tests can be a useful adjunct to data on proteinuria. DESIGN: Analysis of data from a randomised trial. Impaired kidney function was defined as low glomerular filtration rate ( or = 1+ protein) on dipstick urinalysis. SETTING: Study of cholesterol and recurrent events: a randomised trial of pravastatin 40 mg daily versus placebo. PARTICIPANTS: 4098 men and women with previous myocardial infarction. MAIN OUTCOME MEASURES: All cause mortality and cardiovascular events. RESULTS: 371 participants died in nearly 60 months of follow-up. Compared with participants without proteinuria or impaired kidney function, patients with both characteristics were at high risk (hazard ratio 2.39, 95% confidence interval 1.72 to 3.30), and those with only proteinuria or only impaired kidney function were at intermediate risk (1.69, 1.32 to 2.16; 1.41, 1.12 to 1.79, respectively) of dying from any cause. The results were similar for cardiovascular outcomes, including new cases of heart failure, stroke, and coronary death or non-fatal myocardial infarction. A graded increase in the risk of all cause mortality was seen for severity of renal impairment and degree of proteinuria by dipstick. CONCLUSIONS: The presence or absence of proteinuria on dipstick urinalysis may be used to refine estimates of risk based on kidney function alone.