Factors affecting the uptake of screening: A randomised controlled non-inferiority trial comparing a genotypic and a phenotypic strategy for screening for haemochromatosis

Abstract

Haemochromatosis provides an example where a novel pragmatic genotypic screening strategy may be compared with a phenotypic strategy assessing factors affecting uptake, feasibility and cost. A randomised controlled 'non-inferiority' trial testing the hypothesis that the uptake of testing in the genotypic strategy would not be inferior to the uptake in a phenotypic screening strategy. Three thousand individuals aged 30-70 were randomly selected and randomly allocated (stratified by age and sex) to one of two screening strategies. Phenotypic-transferrin saturation on blood sample taken at GP surgery or genotypic-saliva sample taken at home; followed in screen positive individuals with assessment of iron status and genotyping. The difference in uptake between the two strategies was 3.4% (95% CI=0.5-6.8). Uptake was low (32%) and least in young men from socially deprived areas. Phenotypic screening was least costly. In this study, investigating the uptake of screening for a treatable disease in primary care, the uptake of screening with the genotypic strategy was not inferior to that in the phenotypic strategy. The poor uptake in younger men would further limit the effectiveness of screening for haemochromatosis and may have implications for other screening programmes targeted to this group.