[How calcification in the atherosclerotic aorta can be associated with both a lower risk of recurrent stroke in clinical studies and an increased number of strokes in an autopsy study: interpretation based on selection bias]. / Hoe calcificatie in de atherosclerotische aorta kan samengaan zowel met minder recidiefherseninfarcten in klinisch onderzoek als met een toegenomen aantal herseninfarcten in obductieonderzoek: interpretatie op basis van selectiebias.

ABSTRACT

Studies evaluating the role ofcalcification in the relationship between aortic atherosclerosis and stroke have led to contradictory conclusions: clinical studies show that aortic calcification is linked to a reduced risk of recurrence in stroke patients, while an autopsy series found a positive association between aortic calcification and stroke. The controversy can be explained by assuming that the risk associated with aortic atherosclerosis varies among individuals. Low-risk patients would live longer and have more time to develop calcification. Consequently, calcification would be a sign of low risk. This explains the apparent recurrence-reducing effect of calcification in stroke patients. The association between aortic calcification and stroke found in an autopsy series does not contradict this hypothesis but supports it application of Berkson's fallacy shows that calcification is linked to lower mortality.