New-onset hyperglycemia and acute coronary syndrome: a systematic overview and meta-analysis.

BACKGROUND: Patients without a history of diabetes often develop hyperglycemia during an acute coronary syndrome (ACS). New onset of hyperglycemia (NH) is associated with higher mortality both in the short and long-term. AIM: We performed a systematic review and meta-analysis of observational studies to investigate the association between NH and mortality in patients with ACS. In-hospital, 30-day and long-term mortality were analyzed separately. METHODS: We searched MEDLINE for prospective studies of patients with ACS reporting the association between NH and mortality, using Research Methodology Filters. This was supplemented by hand searching reference lists of retrieved articles. We determined study eligibility and conducted data abstraction independently and disagreements were resolved by consensus. We pooled odds ratios (OR) from individual studies using a random effects model. RESULTS: Our search strategy identified 24 studies. The prevalence of NH varied widely 3\% to 71\% depending on the definition of NH used. NH significantly increased the risk of in-hospital (OR 3.62, 95\% CI: 3.09 - 4.24; p < 0.0001, I2=0.0\%; 15 studies, 10673 patients), 30-day (OR 4.81, 95\% CI: 2.18 - 10.61, p < 0.0001, I2=92.2\%; 4 studies, 101447 patients), and long-term (up to 108 months) mortality (OR 2.02, 95\% CI: 1.62-2.51; p < 0.0001, I2=79.4\%; 12 studies, 102099 patients). CONCLUSIONS: In patients without a prior diagnosis of diabetes who are admitted to hospital for ACS, NH increases the risk of both short and long-term mortality. These data highlight the need for further studies addressing the control of blood glucose levels in patients with ACS. SUMMARY: Patients without history of diabetes may develop new hyperglycemia (NH) on admission to hospital for AMI. We systematically reviewed the prognostic impact of NH on short- and long-term mortality in patients without prior diagnosis of diabetes who attended the hospital for ACS. We identified 24 outcome studies which met a set of pre-specified criteria. Prevalence of NH ranged from 3\% to 71\% according to different thresholds of blood glucose concentrations. NH significantly increased the risk of in-hospital (OR 3.62, 95\% CI: 3.09 - 4.24; p < 0.0001, I2=0.0\%; 15 studies, 10673 patients), 30-day (OR 4.81, 95\% CI: 2.18 - 10.61, p < 0.0001, I2=92.2\%; 4 studies, 101447 patients)), and long-term (up to 108 months) mortality (OR 2.02, 95\% CI: 1.62-2.51; p < 0.0001, I2=79.4\%; 12 studies, 102,099 patients).