Kidney disease is defined as a glomerular filtration rate (GFR) of less than 60 mL per minute per 1.73 m2. The condition is common in the United States and often progresses to end-stage renal disease (ESRD). Fox and associates investigated risk factors associated with incident kidney disease to help identify modifiable precursors.
Investigators for the Framingham Offspring study enrolled 5,124 men and women who were examined every four years. In the study’s subset, women with a GFR greater than 59.25 mL per minute per 1.73 m2 and men with a GFR greater than 64.35 mL per minute per 1.73 m2 were included. The outcome of interest was the development of a GFR below these cut-points 12 years after baseline. Risk factors such as diabetes, impaired glucose tolerance, elevated blood pressure, abnormal lipid panel, smoking, and increased body mass index (BMI) also were evaluated.
Of 2,585 participants who were available for follow-up (mean follow-up, 18.5 years), the 244 who developed kidney disease were more likely to be older and to have a higher BMI, a higher total cholesterol level, and a higher prevalence of diabetes and hypertension than patients without incident kidney disease. Of note, those who were being treated with angiotensin-converting enzyme inhibitors at baseline had baseline GFR values similar to those in patients who were treated with beta blockers and calcium channel blockers but had higher GFR values, were less likely to smoke, and had lower total cholesterol levels at follow-up.
Among participants whose baseline GFR was less than 90 mL per minute per 1.73 m2, 14 percent developed kidney disease; those whose baseline GFR was less than 90 mL per minute per 1.73 m2 had a threefold increase in the odds of developing kidney disease. Eight percent of participants whose baseline GFR was 90 to 119 mL per minute per 1.73 m2 and 4 percent of those whose baseline GFR was 120 mL per minute per 1.73 m2 or higher developed kidney disease. Baseline predictors of kidney disease included age, systolic blood pressure, hypertension, hypertension treatment, BMI, high-density lipoprotein cholesterol level, smoking, and diabetes. In multivariate analysis, predictors of developing kidney disease included age, diabetes, BMI, and smoking. Long-term, averaged hypertension increased the odds of developing kidney disease by 57 percent.
Established cardiovascular risk factors, as well as a mildly reduced baseline GFR, predicted the development of kidney disease. Diabetes, which is an established risk factor for end-stage renal disease, is also, to a lesser degree, a risk factor for new-onset kidney disease. Although hypertension is a risk factor for kidney disease, previous studies have not shown that rigorous control of blood pressure slows the decline of GFR. The possibility that earlier intervention would make a difference has yet to be clarified.
The authors conclude that established cardiovascular disease risk factors are associated with the development of new-onset kidney disease. Their study differs from previous studies in that it evaluated risk factors for the development of new-onset rather than more advanced kidney disease. Baseline GFR correlates with risk of developing kidney disease. However, it is unclear what kind of early interventions would slow disease progression.