The guideline group was selected to be representative of UK-based medical experts. The writing group met and communicated by email. The guideline was reviewed by a
multidisciplinary sounding board, selected non-UK experts in thrombosis and thrombophilia, the British Committee for Standards in Haematology (BCSH) and the British Society for Haematology) (BSH and comments incorporated where
appropriate. Criteria used to quote levels and grades of evidence are according to the GRADE system (Guyatt et al, 2006). As this guideline relates specifically to laboratory tests, reference is made to grading quality of evidence and strength of recommendations for diagnostic tests and strategies recognising that tests are only of value if they result in improved outcomes for patients (Schunemann et al, 2008). Strong
recommendations (grade 1, ‘recommended’) are made when there is confidence that the benefits either do or do not outweigh the harm and burden and costs of treatment. Where the magnitude of benefit or not is less certain, a weaker grade 2
recommendation (‘suggested’) is made. Grade 1 recommendations can be applied uniformly to most patients whereas grade 2 recommendations require judicious application. The quality of evidence is graded as A (high quality randomised
clinical trials), moderate (B) or low (C) (Guyatt et al, 2006; www.bcshguidelines.com).
The target audience for this guideline is healthcare professionals involved in the management of patients and families with venous thrombosis or pregnancy morbidity.
First published online 28 January 2010
British Journal of Haematology, 149, 209–220 doi:10.1111/j.1365-2141.2009.08022.x