Influence of race and sex on lipoprotein-associated phospholipase A2 levels: observations from the Dallas Heart Study

Abstract

Aims: Most lipoprotein-associated phospholipase A2 (Lp-PLA2) studies included mainly white men. We sought to determine whether Lp-PLA2 levels differ according to race and sex.

Methods: Lp-PLA2 mass and activity were measured in 3332 subjects age 30-65 participating in the Dallas Heart Study, a multiethnic, population-based, probability sample. Lp-PLA2 levels were compared between different race and sex groups.

Results: Mean age was 45+/-9 years and 44% were men; 30% were white, 17% hispanic, and 53% black. Mean Lp-PLA2 activity and mass were 146+/-40 nmol/min/mL and 191+/-60 ng/mL, respectively. Lp-PLA2 activity was lower in women compared with men (134+/-35 vs. 161+/-40, p=0.001) and was lowest in black (136+/-38), intermediate in hispanic (151+/-36), and highest in white subjects (161+/-39) (trend p=0.0001). In multivariable linear regression models, after adjusting for age, body mass index (BMI), smoking, total, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, triglycerides and high sensitivity C-reactive protein (hsCRP), Lp-PLA2 activity was 19 nmol/min/mL higher in men vs. women (p<0.001); compared with black subjects, adjusted Lp-PLA2 activity was 11 and 20 nmol/min/mL higher in white and hispanic subjects, respectively (both p<0.001). Similar race and sex differences were observed for Lp-PLA2 mass.

Conclusion: Race and sex independently influence Lp-PLA2 activity and mass. Thresholds to define Lp-PLA2 elevation may need to be sex and race specific.

Figure 1

Association between Lp-PLA2 activity and Lp-PLA2 mass in the study population.

Figure 2

Lp-PLA2 activity (Fig. 2a) and mass (Fig. 2b) in 3,332 subjects classified according to race and sex. The upper, middle, and lower line of the shaded box correspond to the 75th percentile, median, and 25th percentile value, respectively. The upper line at the end of the ‘whisker’ coming out of the box on the upper side is the maximum value of either: a) the maximum value in the data set, or b) the largest value in the dataset that is less than the upper quartile value + 1.5 times the interquartile range (IQR). The lower line at the end of the ‘whisker’ coming out of the box on the lower side is the maximum value of either: a) the minimum value in the data set, or b) the smallest value in the dataset that is more than the lower quartile value − 1.5 times the IQR.

Figure 2

Lp-PLA2 activity (Fig. 2a) and mass (Fig. 2b) in 3,332 subjects classified according to race and sex. The upper, middle, and lower line of the shaded box correspond to the 75th percentile, median, and 25th percentile value, respectively. The upper line at the end of the ‘whisker’ coming out of the box on the upper side is the maximum value of either: a) the maximum value in the data set, or b) the largest value in the dataset that is less than the upper quartile value + 1.5 times the interquartile range (IQR). The lower line at the end of the ‘whisker’ coming out of the box on the lower side is the maximum value of either: a) the minimum value in the data set, or b) the smallest value in the dataset that is more than the lower quartile value − 1.5 times the IQR.

Figure 3

Adjusted R² in four multivariable linear regression models with Lp-PLA2 activity as the endpoint: (1) baseline model that includes LDL cholesterol, LDL cholesterol, high sensitivity C-reactive protein, and current smoking; (2) baseline model with sex added; (3) baseline model with race added, and (4) baseline model with sex and race added.