Anaemia, haemoglobin level and cause-specific mortality in people with and without diabetes

BACKGROUND: Both anaemia and cardiovascular disease (CVD) are common in people with diabetes. While individually both characteristics are known to raise mortality risk, their combined influence has yet to be quantified. In this pooling project, we examined the combined impact of baseline haemoglobin levels and existing CVD on all-cause and CVD mortality in people with diabetes. We draw comparison of these effects with those apparent in diabetes-free individuals. Methods/Principal FINDINGS: A combined analyses of 7 UK population-based cohorts resulted in 26,480 study members. There were 946 participants with physician-diagnosed diabetes, 2227 with anaemia [haemoglobin<13 g/dl (men) or <12 (women)], 2592 with existing CVD (stroke, ischaemic heart disease), and 21,396 with none of the conditions. Across diabetes and anaemia subgroups, and using diabetes-free, non-anaemic participants as the referent group, the adjusted hazard ratios (HR) were 1.46 (95% CI: 1.30-1.63) for anaemia, 1.67 (1.45-1.92) for diabetes, and 2.10 (1.55-2.85) for diabetes and anaemia combined. Across combined diabetes, anaemia and CVD subgroups, and compared with non-anaemic, diabetes-free and CVD-free participants, HR (95% CI) for all-cause mortality were 1.49 (1.32-1.69) anaemia, 1.60 (1.46-1.76) for existing CVD, and 1.66 (1.39-1.97) for diabetes alone. Equivalents were 2.13 (1.48-3.07) for anaemia and diabetes, 2.68 (2.14-3.36) for diabetes and existing CVD, and 3.25 (1.88-5.62) for the three combined. Patterns were similar for CVD mortality. Conclusions/Significance Individually, anaemia and CVD confer similar mortality risks in people with diabetes, and are excessively fatal in combination. Screening for anaemia would identify vulnerable diabetic patients whose outcomes can potentially be improved.