Prognostic value of anion gap for patients with heart failure: a systematic review and meta-analysis.

Background: Heart failure (HF) is among the cardiovascular diseases with high morbidity and mortality worldwide. Due to the high burden of HF, finding easy-to-use prognostic factors has become important. Studies have investigated the correlation between anion gap (AG) and the HF prognosis. In this systematic review and meta-analysis, we aimed to evaluate the association between AG association with HF prognosis.

Methods: PubMed, Embase, Scopus, and the Web of Science were systematically searched for studies evaluating AG in HF prognosis. Standardized mean difference (SMD) and pooled hazard ratio (HR) in addition to 95% confidence intervals (CIs) were calculated using random-effect meta-analyses to compare survivors vs. non-survivors.

Results: Nine studies were included in this systematic review. In a random-effect meta-analysis comparing AG levels in those who died and survivors, non-survivors had significantly higher levels of AG (SMD 0.57, 95% CI 0.42 to 0.71, P < 0.0001, I = 46.4%). Meta-analysis of HRs for assessment of mortality revealed that high AG levels had significantly higher hazards of mortality, compared with low AG group (HR 1.64, 95% CI 1.35 to 1.99, P < 0.0001). Finally, a study investigated the association between intensive care unit (ICU) length of stay and AG in patients with HF which showed no significant association.

Conclusion: This study found that higher AG levels are associated with higher mortality in patients with HF which could be used in clinical settings and for patient management due to its ease of measurement and calculation. If confirmed in future studies, using this easy-to-measure index in clinical settings could provide useful information for clinicians in determining the risk of HF patients.

Clinical Trial Number: Not applicable.