Effects of blood triglycerides on cardiovascular and all-cause mortality: a systematic review and meta-analysis of 61 prospective studies

Abstract

The relationship of triglycerides (TG) to the risk of death remains uncertain. The aim of this study was to determine the associations between blood triglyceride levels and cardiovascular diseases (CVDs) mortality and all-cause mortality. Four databases were searched without language restriction for relevant studies: PubMed, ScienceDirect, EMBASE, and Google Scholar. All prospective cohort studies reporting an association between TG and CVDs or all-cause mortality published before July 2013 were included. Risk ratios (RRs) with 95% confidence intervals (CIs) were extracted and pooled according to TG categories, unit TG, and logarithm of TG using a random-effects model with inverse-variance weighting. We identified 61 eligible studies, containing 17,018 CVDs deaths in 726,030 participants and 58,419 all-cause deaths in 330,566 participants. Twelve and fourteen studies, respectively, reported the effects estimates of CVDs and total mortality by TG categories. Compared to the referent (90-149 mg/dL), the pooled RRs (95% CI) of CVDs mortality for the lowest (< 90 mg/dL), borderline-high (150-199 mg/dL), and high TG (≥ 200 mg/dL) groups were 0.83 (0.75 to 0.93), 1.15 (1.03 to 1.29), and 1.25 (1.05 to 1.50); for total mortality they were 0.94 (0.85 to 1.03), 1.09 (1.02 to 1.17), and 1.20 (1.04 to 1.38), respectively. The risks of CVDs and all-cause deaths were increased by 13% and 12% (p < 0.001) per 1-mmol/L TG increment in twenty-two and twenty-two studies reported RRs per unit TG, respectively. In conclusion, elevated blood TG levels were dose-dependently associated with higher risks of CVDs and all-cause mortality.

Figure 1

Flow diagram of study selection. TG: Triglycerides; CVDs: Cardiovascular diseases

Figure 2

Pooled estimate of RR with 95% CI of all-cause mortality for category analysis. Squares indicate the adjusted relative risk (RR) and horizontal lines indicate the 95% confidence interval (CI). Triglycerides (TG) groups: lowest (<90 mg/dL), intermediate (90–149 mg/dL, the referent), borderline high (150–199 mg/dL), and high (≥ 200 mg/dL).

Figure 3

Pooled estimate of RR with 95% CI of CVDs mortality for categorical analysis. Squares indicate the adjusted relative risk (RR) and horizontal lines indicate the 95% confidence interval (CI). Triglycerides (TG) groups: lowest (<90 mg/dL), intermediate (90–149 mg/dL, the referent), borderline high (150–199 mg/dL), and high (≥ 200 mg/dL). CVDs: cardiovascular diseases.

Figure 4

Pooled estimate of RR with 95% CI of CVDs and all-cause mortality for a 1-mmol/L increase of TG. Squares indicate the adjusted relative risk (RR) and horizontal lines indicate the 95% confidence interval (CI). TG: Triglycerides; CVDs: cardiovascular diseases.

Figure 5

Pooled estimate of RR and 95% CI of CVDs and all-cause mortality for a 1-ln (mmol/L) increase of TG. TG: Triglycerides; CVDs: cardiovascular diseases; CI, confidence interval; RR, relative risk.