Islet autoantibody screening throughout Australia using in-home blood spot sampling: two-year outcomes of Type1Screen.
Objective Type1Screen offers islet autoantibody testing to Australians with a family history of type 1 diabetes (T1D) with the dual aims of preventing diabetic ketoacidosis (DKA) and enabling use of disease-modifying therapy. We describe screening and monitoring outcomes two years after implementing in-home capillary blood spot sampling. Research design and methods Data from 2064 participants who registered between July 2022 and June 2024 were analyzed: 1507 and 557 chose blood spot and venipuncture screening respectively. We compared baseline characteristics and outcomes for 1243 participants (967 blood spot and 276 venipuncture) whose samples were tested by June 2024. Results Unsuccessful sample collections were reported by 1 blood spot and 5 venous participants. The median [Q1, Q3] age of blood spot registrants was lower (12.1 [7.1, 27.1] v 17.2 [9, 38.4] years; p<0.0001) and a higher proportion lived in regional Australia (39% v 29%; p=0.0037). Seventy-two participants (5.9%) had a positive screening test, of whom 5 screened by blood spot and 2 by venipuncture had no autoantibodies on confirmatory testing. Blood spot screening identified the expected 2.1% prevalence of multiple autoantibodies and a 2.5% prevalence of a single autoantibody compared to 1.5% and 4.1%, respectively, for venipuncture screening. Twelve participants developed clinical diabetes. All had screened positive and none had DKA. Conclusions Type1Screen has national reach. In-home blood spot screening is feasible, particularly for younger participants living regionally, and identifies the expected prevalence of preclinical T1D. The lower cost, increased convenience and greater reach of blood spot screening could help meet increasing demand for early T1D diagnosis.