MULTICENTER STUDY OF ABBOTT AXSYM(R) DIGOXIN-II ASSAY AND COMPARISON WITH 6 METHODS FOR SUSCEPTIBILITY TO DIGOXIN-LIKE IMMUNOREACTIVE FACTORS

Performance characteristics of the Abbott nonpretreatment AxSYM(R) Dig oxin II assay were evaluated for quantification of digoxin at four ind ependent sites. Correlation of digoxin measurements with the Abbott pr etreatment AxSYM(R), Baxter Stratus(R) II, Abbott TDx/TDxFLx II(R), Ab bott IMx(R), Emit(R) 2000, and Beckman Synchron CX(R) digoxin assays s howed acceptable agreement, as indicated by: slope values >0.84, r >0. 90, y-intercepts for all comparisons at or below the assay detection l imit, and S-y/x ranging between 7.5% and 15.4% of the average digoxin value. Susceptibility to interference from digoxin-like immunoreactive factors (DLIFs) was examined in 233 samples from renal patients, live r disease patients, cord blood, and third-trimester pregnancies; the A xSYM Digoxin II assay demonstrated the least DLIFs interference. DLIF susceptibility for four of the methods was significantly greater (P <0 .05) than in the AxSYM Digoxin II assay; susceptibilities of the Strat us II and Emit 2000 methods were similar to the AxSYM Digoxin II assay .