Pre-operative anaemia: prevalence, consequences and approaches to management.

Abstract

Prevalence of pre-operative anaemia A recent study, using public data from 187 countries worldwide and World Health Organization (WHO) definitions of anaemia (Table I), found a significant decrement in the global prevalence of anaemia, which decreased from 40.2% in 1990 to 32.9% in 2010, though the prevalence varied widely across regions1. However, a lower prevalence of mild and moderate anaemia accounted for most of the reduction, while the prevalence of severe anaemia remained largely unchanged1. Previously, the third US National Health and Nutrition Examination Survey (NHANES III, Phases 1&2, 19881994; 26,372 individuals), showed an average prevalence of anaemia of 7% in the 1to 64-year old age group, with the prevalence being slightly higher among females2. In people 65 years old or more, the prevalence of anaemia increased progressively with age (13% in subjects aged 75-84, 23% in those over 85 years) and the condition was more common among males2. However, analysing the distribution of haemoglobin (Hb) levels in men and women aged 65 years and older showed that 32.4% of women and 23.3% of men had Hb levels lower than 13 g/dL, indicating that the higher overall prevalence of anaemia among older men just results from the genderspecific WHO definitions of anaemia2. This progressive increase of anaemia prevalence with age was also noted in a meta-analysis of 34 studies (85,409 elderly individuals); the overall prevalence was 17%, but fell to 6% when considering cases with a Hb of ≤11 g/dL, which indicates that anaemia was mild in the majority of cases3. Do these figures of anaemia prevalence in individuals living in the community apply to hospitalised patients? In a cohort investigation of adult patients (n=232,440) hospitalised for surgical or medical pathologies between January 2009 and August 2011, 19% presented with anaemia upon admission, whereas 60% of those who were not anaemic upon presentation developed hospital-acquired anaemia4. Another retrospective study of patients of any age (n=2,234) hospitalised in the departments of digestive diseases, internal medicine, cardiology or respiratory diseases between September and October 2010 found an anaemia prevalence of 50%5. In cancer patients, the European cancer anaemia survey found a prevalence of anaemia (Hb cut-off 12 g/dL) at recruitment which varied between 25% in patients with head and neck cancer and 53% in those with a haematological cancer5. In addition, among patients receiving treatment, the mean anaemia prevalence was 53%, ranging from 29% for those being treated with radiotherapy to 75% for those given cis-platinum based chemotherapy6. In 18 large observational studies encompassing over 650,000 surgical patients, the mean prevalence of pre-operative anaemia was around 35%, varying between 10.5% and 47.9%7-24. There were