Prevalence of APC resistance and its relationship to arterial and venous thromboembolism in a general population sample of elderly Swedish men: The Study of Men Born in 1913

BACKGROUND: Most studies of hereditary resistance to activated protein C (APC resistance) as a risk factor for venous thromboembolism are derived from case-control studies of hospitalized patients, whilst the importance of this condition in the general population has been only sparsely investigated. OBJECTIVE: To study the prevalence of APC resistance and its relationship to morbidity and mortality in a general population sample of elderly men. DESIGN: Cross-sectional and prospective follow-up study. SETTING: General community: The Study of Men Born in 1913. SUBJECTS: A random population sample of 404 men, all 75 years of age. MAIN OUTCOME MEASURES: Four hundred and four men participated in a screening examination in 1988. The APC ratio was analysed in 382 of them. All the men were followed up for 5 years. Medical records were reviewed for all the men with a history of deep vein thrombosis, pulmonary embolism, myocardial infarction or stroke. RESULTS: Twenty-five men (6.5%) were found to have APC resistance. The incidence of venous thromboembolism, myocardial infarction or stroke did not differ between men with or without APC resistance, either retrospectively or during follow-up. Only two men experienced a deep vein thrombosis before the age of 80 and there was no case of pulmonary embolism. Mortality during 5 years of follow-up did not differ between men with and without APC resistance. CONCLUSION: The prevalence of APC resistance was 6.5% in this study of Swedish men. Although the size of the population sample is somewhat small, the study shows that, amongst elderly men, the association between APC resistance and venous thromboembolic disease was weak and men with this hereditary condition did not have any increase in morbidity or mortality compared with men without APC resistance.