1. Mechanical prophylaxis is a heparin-independent risk for anti–platelet factor 4/heparin antibody formation after orthopedic surgery
by Seiji Bito, Shigeki Miyata, Kiyoshi Migita, Mashio Nakamura, Kazuhito Shinohara, Tomotaro Sato, Takeharu Tonai, Motoyuki Shimizu, Yasuhiro Shibata, Kazuhiko Kishi, Chikara Kubota, Shinnosuke Nakahara, Toshihito Mori, Kazuo Ikeda, Shusuke Ota, Takeshi Minamizaki, Shigeru Yamada, Naofumi Shiota, Masataka Kamei, and Satoru Motokawa
Blood
Volume 127(8):
February 25, 2016
©2016 by American Society of Hematology

2. Study flow diagram.
Study flow diagram. A total of 2069 patients (n = 1244 for TKA and n = 825 for THA) were ultimately eligible, after patients with no postoperative blood samples available or samples taken on or before POD 7 (n = 50 for TKA and n = 43 for THA) were excluded. Approximately half of the patients received postoperative pharmacologic thromboprophylaxis with UFH, LMWH (enoxaparin), fondaparinux, or an antiplatelet drug. The other half received only mechanical thromboprophylaxis, either dynamic (intermittent plantar compression device [foot pump] or IPCD) or static (GCSs), or both. #, Postoperative thromboprophylaxis for each patient was at the treating physician’s discretion, according to his or her usual clinical practice; *, the proportion of patients excluded from the analysis due to postoperative samples being unavailable or taken on or before POD 7 in each treatment group; J-PSVT, Japanese Clinical Study of Prevention and Actual Situation of Venous Thromboembolism After Total Arthroplasty (multicenter, prospective cohort).
Seiji Bito et al. Blood 2016;127:
©2016 by American Society of Hematology

3. Anti-PF4/heparin seroconversion rates and proportion of patients who tested strongly positive.
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.
Seiji Bito et al. Blood 2016;127:
©2016 by American Society of Hematology