Empirically derived classification of coagulation disorders in 224 patients.

Background: It is not known whether the current molecular classification of blood coagulation disorders into severe (0-1%), moderate (1-5%) and mild (5-40% factor activity remaining) corresponds to the actual clinical situation or is in the patients best interest.

Methods: A questionnaire-based study of 244 patients. Principal factor analysis was used to create a set of variables for classification, which was performed using K-means algorithm. The main variables were use of prophylactic treatment during the last five years and during the last 12 months, home treatment, bleeding, surgery, antibody inhibitors, use of cold medication, pain, use of analgesics, functional disability and physical activity level.

Results: The first five variables of the main outcome measures loaded to a factor reflecting bleeding (bleeding factor) and the last four to a pain factor; both factors produced a 3-cluster solution with severe, moderate and mild bleeding or pain. Overlap between the molecular, bleeding and pain classifications was not extensive. Only 16% of 81 patients with severe coagulation factor deficiency had severe musculoskeletal pain and disability. Furthermore, only 28.6% of the patients with severe von Willebrand's disease actually had a severe bleeding disorder.

Conclusions: Molecular classification does not correlate very well with the severity of disease as reflected in bleeding and pain. This is due to better prognosis for patients on modern medical management. Appropriate patient classification is a basis for defining and managing patients' clinical problems.