Investigation of gender heterogeneity in the associations of serum phosphorus with incident coronary artery disease and all-cause mortality

Abstract

Serum phosphorus levels in the general population have been reported to be associated with cardiovascular morbidity and mortality and increased carotid intima-media thickness. The authors examined gender heterogeneity in the association of phosphorus with all-cause mortality and incident coronary artery disease using data from the Atherosclerosis Risk in Communities Study (1987-2001). Baseline phosphorus levels were higher in women and were associated differently among men and women with traditional atherosclerosis risk factors such as age, low density lipoprotein cholesterol, diabetes mellitus, and hypertension. In a multivariable-adjusted model, men in the highest quintile of serum phosphorus level (>3.8 mg/dL) had an increased mortality rate (hazard ratio = 1.45, 95% confidence interval: 1.12, 1.88), while women did not (hazard ratio = 1.18, 95% confidence interval: 0.89, 1.57). The multivariable likelihood ratio test of effect modification by gender was significant at alpha = 0.1 (P = 0.085) for all-cause mortality. Although the associations of phosphorus with coronary artery disease also appeared to differ substantially by gender, the multivariable test for effect modification suggested that the difference was consistent with random variation (P = 0.195). These results suggest the need for further investigation into gender differences in the contribution of mineral metabolism to cardiovascular disease in the general population.

Figure 1.

Distribution of serum phosphorus levels among men (top; mean = 3.25 mg/dL; standard deviation, 0.45) and women (bottom; mean = 3.56 mg/dL; standard deviation, 0.46), Atherosclerosis Risk in Communities Study, 1987–2001. T test for gender difference: P < 0.0001.

Figure 2.

Cumulative incidence of coronary artery disease according to quintile of serum phosphorus level among men (top; for comparison of outcomes in various phosphorus quintiles, P = 0.005) and women (bottom; P = 0.37), Atherosclerosis Risk in Communities Study, 1987–2001.

Figure 3.

Age-adjusted all-cause mortality according to quintile of serum phosphorus level among men (top; for comparison of outcomes in various phosphorus quintiles, P < 0.0001) and women (bottom; P = 0.16), Atherosclerosis Risk in Communities Study, 1987–2001.