PurposeThe purpose of this paper is to introduce and present the first findings of a new English performance indicator in the primary healthcare of adults with Down syndrome. This is a performance target, with associated bonus payment, requiring General Practitioners (GPs) to undertake annually a screening blood test for thyroid hormone deficiency.Design/methodology/approachAnalysis and review of data collected from all GP practices and published by the National Health Service (NHS) Information Centre.FindingsIn total, 82 per cent of those identified as in the target group were screened and 10 per cent were identified as not wanting to be screened or screening inappropriate. The target group numbered just over 60 per cent of the number estimated from epidemiological and other studies. The numbers of cases involved is small (0, 1 or 2 cases in 75 per cent of GP practices), and whilst variation in coverage at local level appears important, numbers are too small for the variations seen in the first year's data to be statistically significant. The scope of the data precludes useful strategic analysis of the value of the intervention.Research limitations/implicationsData from several years need to be taken together. The NHS Information Centre should slightly increase the scope of the data to allow analysis of whether the programme is having useful public health benefits.Originality/valueThe paper examines a new data source and makes points applicable to a wider range of similar datasets in the same programme.