High serum phosphate is an established risk factor for cardiovascular events in patients with chronic kidney disease, and many studies show that high phosphate is a cardiovascular risk factor in the general population
Researchers in the United Kingdom (UK) investigated whether serum phosphate levels are predictive of primary cardiac events in a large UK primary care patient population.
The cohort study evaluated records from 121,605 patients from 135 primary care medical practices.
All patients were between the ages of 18 and 90 years old, had at least one serum phosphate measurement on record, and had no history of cardiovascular events at time zero.
Time zero refers to the date of the first serum phosphate measurement. The primary outcome was a cardiac event (myocardial infarction, acute coronary syndrome, or revascularisation procedure) after time zero and within the 9-year study duration.
Results showed an increased risk of cardiac events at 5 years in patients with both low serum phosphate (75% increased risk; OR = 1.75; 95% CI, 1.36-2.23; p<.001), high serum phosphate (74% increased risk; OR=1.74; 95% CI, 1.06-2.07; p=.02), and high-normal serum phosphate of 1.26-1.50 mmol/L (OR=1.50; 95% CI, 1.29-1.74; p<.001).
Similar results were observed at the 9 year review.
Whereas high serum phosphate has been known to increase cardiovascular risk, novel findings of this study are that low serum phosphate, in addition to high-normal serum phosphate, increases risk.
These results pertain to the general population, suggesting that phosphate levels should be evaluated within a narrower reference range in the primary care setting.
The majority of dietary phosphate is derived from phosphorus in dairy and meat, although certain grains, legumes, potatoes and nuts are also high in phosphorus.