Table 1.
Characteristics of studies
| References | Setting (n) | Population (%) | Heparin agent | Median age (years) | No. (%) female | Use of washed platelets? | Prevalence of HIT | Index test
|
Reference standard
|
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| IgG-ELISA [cut-off OD] | Poly-ELISA [cut-off OD] | IgG-ELISA [cut-off OD] | Poly-ELISA [cut-off OD] | ||||||||
| Warkentin 2013 [19] | Canada, Australia, New Zealand (409*) | Mixed medical/surgical from PROTECT trial | UFH or dalteparin | NR | NR | Yes | 0.04 | In-house (McMaster) [> 0.45] | Hologic Gen-Probe [> 0.4] | 4T score ≥ 4 | SRA ≥ 50% release |
| Cuker 2013 [20] | United States (58 samples polyspecific ELISA-positive | CV surgery (28), non-CV surgery (14), medical (15), other (1) | NR | 64† | 28 (48.2%) | No | 0.36 | Hologic Gen-Probe [> 0.4] | Hologic Gen-Probe [> 0.4] | Clinical suspicion of HIT. 4T score assigned retrospectively by chart review. Considered true HIT if 4T score ≥ 4. | SRA ≥ 50% release |
| Galea 2013 [21] | France (200) | Not specified | UFH or LMWH | NR | NR | Yes | 0.11 | Zymutest HIA [> 0.3] | Zymutest HIA [> 0.5] | Clinical suspicion of HIT. 4T score assigned but all clinical probabilities tested. | SRA ≥ 20% release |
| McFarland 2012 [22] | US (116) | CV surgery (41), other surgery (14), 0ther medical (45) | UFH (92), LMWH (15), both (6), NR (3) | 63 | 54 (46.6%) | Yes | 0.22 | In-house ELISA [≥ 0.4] | In-house ELISA [≥ 0.4] | Clinical suspicion of HIT. 4T score assigned retrospectively. | SRA ≥ 75% release and inhibition with high-dose heparin |
| Van Hoecke 2012 [13] | Belgium (87) | CV surgery, hemodialysis, medical (critically ill and treated for thrombosis) | UFH or LMWH | NR | NR | No | 0.09 | Zymutest HIA IgG, calculated cut-off [0.24-0.39] | Zymutest HIA IgGAM, calculated cut-off [0.41-0.46] | Clinical suspicion of HIT; development of thrombocytopenia with exposure to heparin. | Functional flow cytometry (% platelet activation ≥ 2 times control) |
| Morel-Kopp 2010 [23] | Australia (107 samples from 97 individuals) | Medical (51), surgical (56); majority low risk by 4T score (75) | NR | 69† | 39 (40.2%) | Yes | 0.11 | Zymutest IgG [> 0.4] | Zymutest IgGAM [> 0.4] | Clinical suspicion of HIT. 4T score assigned, but all clinical probabilities tested. | SRA ≥ 20% release |
| Pouplard 2010 [24] | France (101) | Medical (32), surgical (42), CV surgical (27) | UFH or LMWH | NR | 44 (43.6%) | Yes | 0.40 | Zymutest HIA IgG, [≥ 0.5] | Zymutest HIA IgGAM, [≥ 0.5] | Clinical suspicion of HIT | SRA ≥ 20% release |
| Bakchoul 2009 [25] | Germany (500) | Mixed medical and surgical | UFH or LMWH | NR | NR | Yes | 0.07 | In-house IgG-ELISA [> 0.40] | Poly-ELISA GTI [> 0.4] | 4T score ≥ 4 | HIPA (loss of turbidity in 30 min in at least two suspensions of 0.2 U mL−1 but not 100 U mL−1) |
| Warkentin‡ 2008 [15] | Canada (405) | Mixed medical, surgical, including ICU and CV surgery | NR | NR | NR | Yes | 0.10 | In-house IgG-ELISA [≥ 0.45] | Poly-ELISA GTI [≥ 0.4] | Clinical suspicion of HIT. 4T score assigned at time of enrollment, but all clinical probabilities tested. | SRA ≥ 50% release |
*
One patient not tested by polyspecific ELISA because of insufficient sample.
†
Mean value.
‡
Six patients underwent IgG-specific but not polyspecific testing because of insufficient sample. HIT, heparin-induced thrombocytopenia; NR, not reported; UFH, unfractionated heparin; OD, optical density; SRA, serotonin-release assay; CV, cardiovascular; LMWH, low-molecular- weight heparin; ICU, intensive care unit.