HTML
-
The participants were categorized into four groups according to Lp(a) quartiles. Clinical and biochemical characteristics of the study population are shown in Table 1. Overall, 3, 876 (37.5%) of the participants were diagnosed with MetS. Levels of TC, HDL-C, and LDL-C increased with Lp(a) quartiles, while levels of BMI, WC, 2-h PG, TG, TG/HDL-C, and proportions of diabetes and liver steatosis decreased with Lp(a) quartiles (Ps < 0.0001). However, there was no significant difference among the four groups for physical activity, family history of CVD, use of lipid-lowering medications, antihypertensive medications, and antidiabetic medications.
Characteristics Lp(a) Level Quartiles P for Trend Quartile 1
(n = 2, 506)Quartile 2
(n = 2, 747)Quartile 3
(n = 2, 598)Quartile 4
(n = 2, 485)Lp(a), mg/mL, median (range) 5 (≤ 8) 13 (9-18) 25 (19-29) 35 (≥ 30) Age, y 57.6 ± 9.6 58.5 ± 9.6 59.1 ± 9.8 59.0 ± 9.8 < 0.0001 Male, n (%) 1, 097 (43.8) 1, 061 (38.6) 952 (36.6) 834 (33.6) < 0.0001 BMI, kg/m2 25.6 ± 3.3 25.1 ± 3.3 25.0 ± 3.3 24.9 ± 3.2 < 0.0001 WC, cm 84.2 ± 9.2 82.8 ± 8.9 82.3 ± 9.1 81.5 ± 8.8 < 0.0001 Current smoker, n (%) 597 (23.8) 560 (20.4) 498 (19.2) 435 (17.5) < 0.0001 Current drinker, n (%) 325 (13.3) 268 (10.1) 242 (9.6) 203 (8.5) < 0.0001 Physical activity (moderate to vigorous), n (%) 361 (14.4) 380 (13.8) 376 (14.5) 383 (15.4) 0.24 Education status (high school or above), n (%) 594 (23.8) 603 (22.1) 528 (20.5) 493 (19.9) 0.0004 Family history of CVD 313 (24.7) 342 (26.9) 311 (24.5) 304 (23.9) 0.67 SBP, mmHg 142.1 ± 20.4 141.1 ± 19.8 140.2 ± 19.8 141.2 ± 20.3 0.01 DBP, mmHg 83.5 ± 10.4 82.5 ± 10.4 82.3 ± 10.1 82.7 ± 10.4 < 0.0001 FPG, mmol/L 5.68 ± 1.67 5.54 ± 1.53 5.48 ± 1.42 5.49 ± 1.36 < 0.0001 2-h PG, mmol/L 8.69 ± 4.61 8.25 ± 4.31 8.11 ± 4.15 7.99 ± 4.10 < 0.0001 TG, mmol/L 1.57 (1.05-2.39) 1.41 (0.98-1.95) 1.30 (0.95-1.79) 1.30 (0.95-1.79) < 0.0001 TC, mmol/L 5.14 ± 1.06 5.25 ± 0.94 5.37 ± 0.99 5.62 ± 1.01 < 0.0001 HDL-C, mmol/L 1.27 ± 0.33 1.31 ± 0.31 1.35 ± 0.31 1.38 ± 0.31 < 0.0001 LDL-C, mmol/L 2.92 ± 0.82 3.14 ± 0.81 3.25 ± 0.84 3.46 ± 0.90 < 0.0001 TG/HDL-C 1.30 (0.77-2.23) 1.11 (0.69-1.72) 0.98 (0.65-1.51) 0.96 (0.64-1.45) < 0.0001 Hypertension 1, 574 (62.8) 1, 667 (60.7) 1, 539 (59.2) 1, 479 (59.5) 0.009 Diabetes 546 (21.8) 500 (18.2) 446 (17.2) 398 (16.0) < 0.0001 Liver steatosis 250 (10.0) 230 (8.4) 191 (7.4) 173 (7.0) < 0.0001 Lipid-lowing medications 6 (0.24) 10 (0.36) 7 (0.27) 7 (0.28) 0.96 Antihypertensive medications 771 (30.8) 799 (29.1) 750 (28.9) 727 (29.3) 0.25 Antidiabetic medications 192 (7.7) 203 (7.4) 156 (6.0) 172 (6.9) 0.11 Note. Data are mean ± standard deviation (SD) or median (interquartile) for the continuous variables, or percentages for categorical variables. Medications include lipid-lowering medications, antihypertensive medications, and antidiabetic medications. Abbreviations: Lp(a), lipoprotein (a); BMI, body mass index; WC, waist circumference; CVD, cardiovascular disease; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, fasting plasma glucose; 2-h PG, 2-h post-load plasma glucose; TG, triglycerides; TC, total cholesterol; HDL-C, high-density lipoprotein-cholesterol; LDL-C, low-density lipoprotein-cholesterol. Table 1. Baseline Characteristics of the Study Population by Lp(a) Level Quartiles
The prevalence of MetS significantly decreased with the increment of Lp(a) level (46.9%, 38.2%, 34.1%, and 30.9%, for the lowest to the highest quartile group, respectively, P for trend < 0.0001). The multivariate-adjusted OR (95% CI) was estimated to evaluate the association of Lp(a) levels with prevalent MetS (Table 2). In the age- and sex-adjusted model, the highest quartile of Lp(a) level was associated with a lower risk of MetS, when compared with the lowest quartile (OR 0.51, 95% CI 0.45-0.57). Further adjustments for BMI, smoking status, drinking status, education, and physical activity didn't significantly change the risk estimate (OR 0.48, 95% CI 0.42-0.55). Although further adjustment for LDL-C significantly attenuated the association of Lp(a) levels with prevalent MetS, the risk estimate remained significant (OR 0.45, 95% CI 0.39-0.51). The tests for the trend in the multivariable analyses were all significant (Ps for trend < 0.0001).
Items Lp(a) Level Quartiles P for Trend Quartile 1 Quartile 2 Quartile 3 Quartile 4 Cases/n 1, 174/2, 506 1, 049/2, 747 885/2, 598 768/2, 485 Prevalence, % 46.9 38.2 34.1 30.9 < 0.0001 Model 1 1.00 0.70 (0.63-0.78)* 0.59 (0.52-0.66)* 0.51 (0.45-0.57)* < 0.0001 Model 2 1.00 0.70 (0.62-0.80)* 0.56 (0.49-0.64)* 0.48 (0.42-0.55)* < 0.0001 Model 3 1.00 0.68 (0.60-0.77)* 0.54 (0.47-0.61)* 0.45 (0.39-0.51)* < 0.0001 Note. Model 1: adjusted for age and sex; Model 2: further adjusted for BMI, smoking status, drinking status, education, and physical activity; Model 3: further adjusted for LDL-C. *P < 0.05. MetS, metabolic syndrome; Lp(a), lipoprotein (a); BMI, body mass index; LDL-C, low-density lipoprotein-cholesterol. Table 2. Odds Ratios (ORs) and 95% Confidence Intervals (CIs) for Risk of Prevalent MetS by Lp(a) Level Quartiles
The associations between Lp(a) levels and the components of MetS are shown in Table 3. Prevalence of central obesity, high triglycerides, and low HDL cholesterol significantly decreased with the increment of Lp(a) levels (Ps for trend < 0.0001). Compared with individuals in the lowest quartile, those in the highest quartile of Lp(a) level had a decreased risk of central obesity, high fasting glucose, high triglycerides, and low HDL cholesterol, but not high blood pressure. The multivariate-adjusted ORs (95% CIs) for central obesity, high fasting glucose, high triglycerides, and low HDL cholesterol were 0.63 (0.53-0.75), 0.70 (0.60-0.81), 0.43 (0.38-0.49), and 0.66 (0.58-0.75), respectively (Ps for trend < 0.0001). The number of the components of MetS also decreased along with serum Lp(a) level quartiles in participants that had three or more components (Figure 1, P < 0.0001).
Items Lp(a) Level Quartiles P for Trend Quartile 1 Quartile 2 Quartile 3 Quartile 4 Central obesity Cases, n (%) 1, 275 (50.9) 1, 265 (46.1) 1, 174 (45.2) 1, 072 (43.1) < 0.0001 OR (95% CI) 1.00 0.78 (0.67-0.92)* 0.79 (0.67-0.94)* 0.63 (0.53-0.75)* < 0.0001 High blood pressure Cases, n (%) 1, 896 (75.7) 2, 051 (74.7) 1, 885 (72.6) 1, 860 (74.9) 0.23 OR (95% CI) 1.00 0.92 (0.80-1.06) 0.80 (0.69-0.92)* 0.91 (0.78-1.05) 0.06 High triglycerides Cases, n (%) 1, 128 (45.0) 954 (34.7) 759 (29.2) 708 (28.5) < 0.0001 OR (95% CI) 1.00 0.63 (0.56-0.71)* 0.46 (0.41-0.52)* 0.43 (0.38-0.49)* < 0.0001 High fasting glucose Cases, n (%) 566 (22.6) 506 (18.4) 456 (17.6) 439 (17.7) < 0.0001 OR (95% CI) 1.00 0.76 (0.66-0.88)* 0.71 (0.61-0.82)* 0.70 (0.60-0.81)* < 0.0001 Low HDL cholesterol Cases, n (%) 1, 041 (41.5) 1, 009 (36.7) 821 (31.6) 733 (29.5) < 0.0001 OR (95% CI) 1.00 0.87 (0.77-0.98)* 0.69 (0.61-0.78)* 0.66 (0.58-0.75)* < 0.0001 Note. The Model was adjusted for age, sex, BMI, smoking status, drinking status, education, physical activity, and LDL-C. *P < 0.05. MetS, metabolic syndrome; Lp(a), lipoprotein (a); HDL, high-density lipoprotein; LDL-C, low-density lipoprotein-cholesterol. Table 3. Odds Ratios (ORs) and 95% Confidence Intervals (CIs) of Each Component of MetS According to Lp(a) Level Quartiles
Figure 1. Number of components of MetS according to serum Lp(a) level quartiles. Median (interquartile range) Lp(a) levels for the quartiles are as follows (mg/mL): Quartile 1, 5 (4-7); Quartile 2, 13 (10-15); Quartile 3, 25 (22-27); Quartile 4, 35 (30-45). MetS, metabolic syndrome; Lp(a), lipoprotein (a).
We further investigated the association of Lp (a) levels with MetS in subgroups according to strata variables (Figure 2). A higher prevalence of MetS was found in participants of ≥ 60 years of age, female, BMI ≥ 24 kg/m2, non-smokers, non-drinkers, with diabetes, hypertension or dyslipidemia, compared with their counterparts. Notably, increased levels of Lp(a) was associated with decreased risk of MetS in all the subgroups.
Figure 2. Multivariate-adjusted odds ratio (OR) and 95% confidence interval (CI) for risk of MetS among subgroups. The Model was adjusted for age, sex, BMI, smoking status, drinking status, education, physical activity, and LDL-C. †The Model was adjusted for age, sex, BMI, smoking status, drinking status, education, and physical activity. MetS, metabolic syndrome; BMI, body mass index; LDL-C, low-density lipoprotein-cholesterol.