Objective: To determine whether using multiples of the median (MoM) is a useful method of standardization for reporting antiphospholipid antibody results.
Methods: Each antibody was measured by enzyme-linked immunosorbent assay using the Harris calibration set no. 2, with values recorded as phospholipid units and as MoM. The levels of antiphospholipid antibodies were compared in 100 nonpregnant women diagnosed with recurrent pregnancy loss (three or more spontaneous, consecutive losses) and 100 nonpregnant parous women with no history of reproductive problems (controls). Results were analyzed based on phospholipid units for immunoglobulin (Ig) G and IgM and were considered positive if phospholipid units were at least 20 or if MoM was at least 2.5. All lower values were considered negative.
Results: When results were calculated using at least 2.5 MoM as positive, none of the controls had positive levels. Overall, IgG anticardiolipin identified the largest number of women with elevated antiphospholipid antibodies. Immunoglobulin G antiphosphatidyl glycerol was more "selective" when elevated since none of the controls were positive by either analysis; however, only half of the subjects determined to be positive using anticardiolipin were identified.
Conclusion: The MoM method of reporting results may be more useful than phospholipid units for IgG or IgM.