Background Anaemia and iron deficiency (ID) are common and associated with adverse outcomes. Guidelines suggest that iron indices should be checked at diagnosis and annually thereafter in patients with heart failure whether or not they are anaemic. Clinical experience suggests this is seldom done. We investigated how often haemoglobin (Hb) and iron indices were checked and in whom in a large cohort of patients with or at increased risk of heart failure. We also investigated the association between anaemia and mortality.
Methods We acquired de-identified data linked to hospital admissions and death from the NHS Greater Glasgow and Clyde (GG&C) Health Board between 2011 and 2015 (population ~1.1 million) for anyone over the age of 50 with a coded diagnosis of coronary or peripheral arterial disease or heart failure or with repeat prescriptions of loop diuretics, renin-angiotensin-aldosterone inhibitors or beta-blockers. Patients were stratified into 5 sex-specific groups according to Hb concentration, from low to high: severe anaemia (<2g/dL below World Health Organisation (WHO) definition (<12g/dL in women and <13g/dL in men)); moderate anaemia (1-2g/dL below WHO); mild anaemia (0-1g/dL below WHO); 0-1g/dL above WHO, and greater than 1g/dL above WHO. The lowest Hb result for each patient was taken. Measurements of ferritin and transferrin saturation (TSAT) within one-year of the documented lowest Hb were identified. Mortality at 3-years stratified according to Hb is also reported.
Results Between 2011 and 2015, 181,368 people (~16% of the GG&C population) had a Hb measurement of whom 19,586 had a diagnosis of heart failure and a further 26,482 were treated with loop diuretics at the time of reference Hb test; 97,811 (54%) had at least one value indicating anaemia, with the lowest value indicating severe anaemia in 50,960 (28%), moderate in 20,704 (11%) or mild in 26,147 (14%). Patients with a lower Hb were more likely to have heart failure and/or receive loop diuretics.
Serum ferritin was measured in 60,075 (33%) patients, including 43,906 who had anaemia (45% of those with anaemia). Patients with more severe anaemia were more likely to have ferritin checked (mild=33%; moderate=44%; severe=51%). In patients with severe anaemia who were tested, serum ferritin was <30ng/mL in 6,617 (25%) and between 30-100ng/mL in 6,675 (25%) compared to, in those with Hb >1g/dL above WHO, 626 (8%) and 3,140 (38%), respectively. TSAT was measured in 19,149 (11%) patients, including 16,732 (86%) with anaemia (17% of those with anaemia; most also had ferritin measured (16,998 (89%)). In patients with severe anaemia who were tested, TSAT was <20% in 8,696 (70%) compared to 282 (25%) in those with Hb >1g/dL above WHO.
Age and sex adjusted three-year mortality rose sharply as anaemia progressed (mild: HR=2.6 (2.5-2.7); p<0.001, moderate: HR=3.8 (3.5-4.0); p<0.001, severe: HR=7.3 (7.0-7.6); p<0.001). People with an Hb >1g/dL above WHO had a mortality of 5% compared to 9% in those with a Hb of 0-1g/dL above WHO (adjusted HR=1.5 (1.5-1.6); p<0.001).
Conclusions A low Hb is common in people with suspected or confirmed heart failure. Mortality is inversely related to Hb with a nadir of risk when values are at least 1g/dL above the WHO definition of anaemia. Many patients with anaemia are not investigated for ID and therefore are less likely to receive appropriate diagnostic investigations and the potential benefits of iron therapy.
Conflict of Interest None
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