GSTM1 and anemia: For all identified survey pairs where the non-DHS used HemoCue® Hb 301 and the DHS used HemoCue® Hb 201+, the estimated prevalence of anaemia was lower in the non-DHS survey regardless of type of blood collection (Figure 1, Table S3 in the Online Supplementary Document; median difference of -15.3 pp for NPW (n = 5) and -22.2 pp for PSC (n = 6)).