163-OR: Sensitivity Analysis of Alternate Definitions of Multiple Islet Autoantibody Positivity

Abstract

The development of multiple islet autoantibodies (IA) predicts progression to type 1 diabetes (T1D), and forms the basis of current staging of T1D. However, age at seroconversion, persistence of IA, and frequency of sampling influence the determination of multiple IA status. Individual IA may appear at different timepoints and fluctuate. This analysis aims to understand how differences in the stringency of multiple IA status definition impact risk estimates of progression to stage 3 T1D. We combined data from three birth-cohort studies (N=18,537): DAISY (U.S.), DiPiS (Sweden) and DIPP (Finland), defining four groups by IA positivity pattern and accounting for variability in persistence and timing in concurrent and sequential patterns of IAA, IA2A, and GADA. Subjects were placed exclusively in their most stringent IA group. Cumulative incidence of progression to T1D was estimated by survival analysis and log-rank test, which showed group differences (p<0.0001). T1D risk 15 years after seroconversion [95% CI] increased according to increasing stringency of the definition: Single IA/Persistent 10% [6%, 14%], multiple IA/Any 17% [3%, 29%], multiple IA/Same Visit 40% [17%, 57%], and multiple IA/Persistent 74% [69%, 77%]. Enhanced understanding of the characteristics of IA patterns can better inform recruitment for intervention studies and improve communication of risk during pre-symptomatic T1D screening. Disclosure B. Liu: None. M. Ghalwash: None. V. Anand: None. E. Koski: None. K. Ng: None. J.L. Dunne: None. M. Lundgren: None. H. Elding Larsson: None. W. Hagopian: Research Support; Self; Novo Nordisk A/S. R. Veijola: None. B.I. Frohnert: None. Funding JDRF