Article type
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Abstract
Background: Bleeding is the main recognised adverse effect of heparins. However, other adverse effects, such as heparin-induced thrombocytopenia (HIT) can also be expected. HIT is an immune reaction, frequent in some clinical scenarios, and associated with paradoxical increase in the risk of thromboembolic complications.
Objectives: To assess the consistency of the assessment of HIT in Cochrane Systematic Reviews (SRs) evaluating heparin interventions for prophylaxis or treatment of thromboembolism.
Methods: The Cochrane Database of Systematic Reviews was searched from inception to March 2015 for SRs including any heparin (unfractionated heparin (UFH), or low molecular weight heparin (LMWH)) for prevention or treatment of thromboembolism. Detailed information obtained from the SRs included: 1) statement of thrombocytopenia or HIT as outcome (primary or secondary); 2) statement of a precise definition for HIT (HIT is defined as a relative reduction in platelet count of about 50% (even if the platelet count at its lowest remains > 150 x 109/L) occurring within five to 14 days after the start of heparin therapy and confirmed by antibody tests); 3) reporting of HIT in the Results section qualitatively or quantitatively.
Results: Fifteen SRs published from 2002 to 2015 were identified. The reviews investigated a wide range of clinical scenarios and most were assessed as up-to-date after 2010 (66.6%). Six reviews (40%) specified thrombocytopenia as a secondary outcome and three (20%) cited HIT as secondary outcome. Only one review provided a clear, though incomplete, definition of HIT. In the Results section, one SR reported no cases of HIT without defining the reaction, one presenting a definition for HIT and reported that participants from the included trials were not investigated for HIT, and another was an empty review.
Conclusions: HIT is a harmful effect of heparins not evaluated in Cochrane Reviews. The assessment of the harm-benefit balance of an intervention cannot be limited to the main recognised adverse effect. Improvements are needed in order to reduce bias in the assessment of HIT, and probably other adverse effects, in Cochrane Reviews.
Objectives: To assess the consistency of the assessment of HIT in Cochrane Systematic Reviews (SRs) evaluating heparin interventions for prophylaxis or treatment of thromboembolism.
Methods: The Cochrane Database of Systematic Reviews was searched from inception to March 2015 for SRs including any heparin (unfractionated heparin (UFH), or low molecular weight heparin (LMWH)) for prevention or treatment of thromboembolism. Detailed information obtained from the SRs included: 1) statement of thrombocytopenia or HIT as outcome (primary or secondary); 2) statement of a precise definition for HIT (HIT is defined as a relative reduction in platelet count of about 50% (even if the platelet count at its lowest remains > 150 x 109/L) occurring within five to 14 days after the start of heparin therapy and confirmed by antibody tests); 3) reporting of HIT in the Results section qualitatively or quantitatively.
Results: Fifteen SRs published from 2002 to 2015 were identified. The reviews investigated a wide range of clinical scenarios and most were assessed as up-to-date after 2010 (66.6%). Six reviews (40%) specified thrombocytopenia as a secondary outcome and three (20%) cited HIT as secondary outcome. Only one review provided a clear, though incomplete, definition of HIT. In the Results section, one SR reported no cases of HIT without defining the reaction, one presenting a definition for HIT and reported that participants from the included trials were not investigated for HIT, and another was an empty review.
Conclusions: HIT is a harmful effect of heparins not evaluated in Cochrane Reviews. The assessment of the harm-benefit balance of an intervention cannot be limited to the main recognised adverse effect. Improvements are needed in order to reduce bias in the assessment of HIT, and probably other adverse effects, in Cochrane Reviews.