title: Validation of the haemoglobin colour scale for screening blood donors in Malawi.
abstract: BACKGROUND
  In 2009 Malawi introduced a new protocol to screen potential blood donors for anaemia, using the WHO Haemoglobin Colour Scale (HCS) for initial screening. Published studies of the accuracy of the HCS to screen potential blood donors show varying levels of accuracy and opinion varies whether this is an appropriate screening test. The aim of the study was to assess the validity of the HCS, as a screening test, by comparison to HemoCue in potential blood donors in Malawi.
  
  
  METHODS
  This was a blinded prospective study in potential blood donors aged over 18 years, at Malawi Blood Transfusion Service in Blantyre, Malawi. Capillary blood samples were analysed using the HCS and HemoCue, independent of each other. The sensitivity and specificity of correctly identifying ineligible blood donors (Hb ≤ 12 g/dL) were calculated.
  
  
  RESULTS
  From 242 participants 234 (96.7%) were correctly allocated and 8 (3.3%), were wrongly allocated on the basis of the Haemoglobin Colour Scale (HCS) compared to HemoCue, all were subjects that were wrongly accepted as donors when their haemoglobin results were ≤ 12.0 g/dL. This gave a sensitivity of 100% and specificity of 96.7% to detect donor eligibilty. The negative predictive value of the HCS was 100% but the positive predictive value to identify ineligible donors on the basis of anaemia was only 20%.
  
  
  CONCLUSIONS
  Initial screening with the HCS correctly predicts eligibility for blood donation in the majority of potential blood donors at considerable cost saving compared with use of HemoCue as the first line anaemia screening test, however, by this method a small number of anaemic patients were allowed to donate blood.
authors.affiliation: Malawi Blood Transfusion Service, Blantyre, Malawi.
authors.forename: B
authors.initials: B
authors.lastname: M'baya
authors.affiliation: University of Malawi, College of Medicine, Blantyre, Malawi.
authors.forename: I
authors.initials: I
authors.lastname: Mbingwani
authors.affiliation: University of Malawi, College of Medicine, Blantyre, Malawi.
authors.forename: L
authors.initials: L
authors.lastname: Mgawi
authors.affiliation: University of Malawi, College of Medicine, Blantyre, Malawi.
authors.forename: V
authors.initials: V
authors.lastname: Mkochi
authors.affiliation: Department of International Public Health, Liverpool School of Tropical Medicine.
authors.forename: I
authors.initials: I
authors.lastname: Bates
authors.affiliation: University of Malawi, College of Medicine, Blantyre, Malawi.
authors.forename: S A
authors.initials: SA
authors.lastname: White
authors.affiliation: University of Malawi, College of Medicine, Blantyre, Malawi.
authors.forename: T J
authors.initials: TJ
authors.lastname: Allain
mesh_terms: D000368:Aged; D001782:Blood Donors; D005260:Female; D006452:Hemoglobinometry / Q000379:methods*; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D008295:Malawi; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D006454:Hemoglobins