Anti-PF4/heparin seroconversion rates and proportion of patients who tested strongly positive. Seroconversion rates and proportion of patients who tested strongly positive (ELISA values ≥1.4 OD units) were calculated for patients receiving UFH, LMWH, fondaparinux, or only mechanical thromboprophylaxis after TKA (A) or THA (B). Each group was divided into 2 subgroups based on the use of DMT (intermittent plantar compression device [foot pump] or IPCD). Data from patients who received antiplatelet therapy as postoperative thromboprophylaxis (n = 45 for TKA and n = 43 for THA) are not shown in these figures. The seroconversion rates and proportion of patients who tested strongly positive with ≥1.4 OD units were compared between the patients treated with or without DMT in each group using the χ² test. When the sample size of a cell in a 2-by-2 table was <10, Fisher’s exact test was used instead. P values were not corrected for multiple hypothesis tests. *, Patients who tested positive before surgery and whose OD values on POD 10 did not meet the definition of seroconversion were excluded from the analysis (n = 12 for TKA and n = 10 for THA). IRQ, interquartile range.