Thrombotic risk in hereditary antithrombin III, protein C, or protein S deficiency. A cooperative, retrospective study. Gesellschaft fur Thrombose- und Hamostaseforschung (GTH) Study Group on Natural Inhibitors.

A cooperative, retrospective study was performed on data from 8 coagulation laboratories and thrombosis units in Austria, Germany, and Switzerland to assess the risk for thrombosis in patients with hereditary antithrombin III (AT-III), protein C (PC), and protein S (PS) deficiencies; to compare the clinical manifestations of these 3 deficiency states; and to estimate the risk for development of thrombosis in high-risk situations. Two hundred thirty patients from 71 families with a documented hereditary deficiency of a natural coagulation inhibitor were included in the study. The patient group comprised 69 patients from 25 families with AT-III deficiency, 86 patients from 27 families with PC deficiency, and 75 patients from 19 families with PS deficiency. Diagnosis of the deficiency state was made at each participating center. Clinical data were documented in a questionnaire that was completed during each patient's visit to the participating center. The questionnaires were sent to the coordinating center (Vienna) and analyzed centrally. The probability of developing thrombosis was 80% to 90% for all deficiency states by 50 to 60 years of age, and this figure did not change considerably after data from the propositi were excluded. AT-III-deficient females developed thrombosis earlier in life compared with PC- and PS-deficient females due to a high thrombotic risk during pregnancy (40% in patients with AT-III deficiency) and oral contraceptive use. The clinical features of thromboembolism were similar in the three deficiency states except for a higher frequency of superficial thrombophlebitis in patients with PC and PS deficiencies. Mesenteric vein thromboses occurred in 4% to 10% of patients and in 2 of 8 patients as a recurrent event. The recurrence rate was 63% (60% of recurrent events occurred spontaneously) and did not differ significantly among the three deficiency states. Before 14 years of age only 1 of 80 surgical procedures and 0 of 21 leg injuries were followed by thrombosis. After 14 years of age thromboembolic events occurred after abdominal surgery or leg injury in one third of patients. Between 40% and 50% of symptomatic patients reported that they felt handicapped by a postthrombotic syndrome. We conclude that diagnosis of a coagulation inhibitor deficiency state should be made before 14 years of age. During childhood thrombosis prophylaxis cannot be regularly recommended but should be instituted after 13 years of age during/after abdominal surgery, including appendectomy, and after leg injury in AT-III-, PC-, and PS-deficient patients. The high recurrence rate (60% spontaneous recurrence) and the relatively high frequency of mesenteric vein thrombosis as a recurrent event favor introduction of long-term oral anticoagulant treatment after the first thrombotic event in patients with a documented hereditary deficiency of AT-III, PC, or PS.