, Volume 54, Issue 6, pp 1327-1334
Date: 22 Feb 2011

Haemoglobin A1c levels and subsequent cardiovascular disease in persons without diabetes: a meta-analysis of prospective cohorts

Abstract

Aims/hypothesis

The aim of this meta-analysis was to determine the relationship between HbA1c levels and subsequent cardiovascular outcomes in individuals without diabetes.

Methods

We searched Medline, Embase and Scopus from initiation of the study until the end of 2009. One reviewer searched and another verified findings. Data were extracted by one reviewer and verified by another. We accepted prospective studies in any language reporting three or more quartiles for HbA1c levels. Within quartiles, authors must have presented both numbers of patient-years at risk and cardiovascular outcomes. Outcomes per person-time at risk were regressed on average HbA1c values using Poisson regression. We pooled β coefficients using Cochran’s semi-weighted (inverse variance) random-effects model. Study quality was assessed using the Downs–Black scale.

Results

We investigated 16 datasets (nine for total cardiovascular events and seven for death) from five papers with 44,158 patients (44% men) over 404,899 patient-years of follow-up. There were 1,366 cardiovascular deaths (3.1%; 3.37/1,000 person-years) and 2,142 cardiovascular events (4.9%; 5.29/1,000 person-years). The overall meta-analytic β coefficients were 0.720 (95% CI 0.307–1.133) and 0.757 (95% CI 0.382–1.132) for cardiac death and events, respectively. Compared with the baseline value of 0.0427, an HbA1c level of 0.05 was associated with a relative risk for cardiovascular death of 1.13 (95% CI 1.05–1.21), a 0.06 value with 1.34 (95% CI 1.13–1.58), and a 0.07 HbA1c with relative risk 1.58 (95% CI 1.22–2.06). Results for total cardiovascular events were similar. The average study quality was 0.7 (70%).

Conclusions/interpretation

We conclude that HbA1c was significantly associated with cardiovascular events and deaths in persons without diabetes.