Risk of venous thromboembolism and arterial events in patients with hypoalbuminemia: a comprehensive meta-analysis of more than 2 million patients

Background: Albumin has antiplatelet and anticoagulant functions. Hypoalbuminemia, as defined by serum values of <3.5 g/dL, is associated with arterial thrombosis; its impact on venous thromboembolism (VTE) is unclear. Objectives: The objective of this meta-analysis is to assess the VTE risk in patients with hypoalbuminemia. Methods: MEDLINE and EMBASE were searched up to January 2024 for observational studies and randomized trials reporting data of interest. Primary outcome was the risk of VTE, while secondary outcomes were myocardial infarction and stroke risk in patients with hypoalbuminemia versus those without hypoalbuminemia. The risk of bias was evaluated using Newcastle-Ottawa scale and Cochrane tool. Risk ratios (RRs) with 95% confidence intervals (CIs) were calculated in a random-effects model. Results: Forty-three studies for a total of 2 531 091 patients (39 738 medical and 2 491353 surgical) were included in primary analysis; 79.1% of the studies used 3.5 g/dL cut-off value for hypoalbuminemia definition. Follow-up duration was 30 days in 60.5% of studies. Patients with hypoalbuminemia had a higher risk of VTE (RR, 1.88; 95% CI, 1.66-2.13). RRs were similar in both medical (RR, 1.87; 95% CI, 1.53-2.27) and surgical patients (RR, 1.87; 95% CI, 1.61-2.16) and in patients with (RR, 1.86; 95% CI, 1.66-2.10) and without cancer (RR, 1.89; 95% CI, 1.47-2.44). Risk of myocardial infarction (RR, 1.88; 95% CI, 1.54-2.31) and stroke (RR, 1.77; 95% CI, 1.26-2.48) was higher in patients with hypoalbuminemia. Conclusion: Hypoalbuminemia is a risk factor for VTE in both medical and surgical patients irrespective of cancer coexistence. Serum albumin analysis may represent a simple and cheap tool to identify patients at VTE risk.