Predictive Factors for Poor Outcome in Danaparoid-Treated HIT-Patients: A French Multicentre Case-Control Study.

Objective: to identify predictive factors of complications and mortality in danaparoid-treated HIT-patients.

Patients and Methods: case-control study involving HIT-patients defined by a relative decrease in platelet count of over 40% with or without thrombosis at presentation and positive laboratory testing (functional assay +/− ELISA). A patient presenting a complication 48 hours after heparin replacement with danaparoid (thrombosis, DIC, amputation, haemorrhage, death) was considered as a case.

Results: 49 cases and 65 controls were included (mean age 67±14 y; 51% women), from cardiovascular (53%) or orthopaedic (5%) surgery, intensive care (6%) or medicine (8%) units. Mean duration to complication was 7 days (D): death (n=26); thromboses (n=23); DIC (n=6); amputations (n=4); and haemorrhages (n=8).

In univaried analysis, compared to controls, cases presented:

• an earlier HIT (7.9±3.5 versus 10.1±7.1 D; p=0.03)

• a lower platelet nadir (53±37 versus 70±37 G/L ; p=0.01),

• a more frequent thrombosis at HIT diagnosis (59% versus 32%, p=0.004),

• a later heparin withdrawal after HIT diagnosis (2.8 versus 1.3 d; p=0.01),

• a delayed heparin replacement (3.7 versus 1.9 d ; (p=0.001),

• an inadequate dosage of replacement therapy (44% versus 19% ; p=0.004).

In multivaried analysis, predictive factors leading for poor outcome were:

1. an initial thrombosis at HIT diagnosis (OR=3.2 [1.3–8]),

2. a delay greater than 48 h for replacement therapy with danaparoid (OR=6.6 [2.5–17.3]),

3. insufficient doses of danaparoid (OR=4.3 [1.5–12]).

Conclusion: this study confirms the mandatory need for a prompt replacement therapy and strict adherence to recommended doses for HIT-patients.