Background and purpose: The prospective link between osteoporosis and future risk of stroke requires evidence from large-scale population-based long-term studies.
Methods: Calcaneum broadband ultrasound attenuation was measured in the Norfolk cohort of the European Prospective Investigation into Cancer-Norfolk between 1997 and 2000. Incident strokes were ascertained by hospital record linkage and death certificates in March 2009 and December 2011, respectively. A search of MEDLINE and EMBASE was performed to evaluate the relationship between bone mineral density and incident stroke. After data extraction of relevant studies, pooled risk of stroke was estimated using meta-analysis.
Results: In 14 290 participants (mean follow-up of 9.3 years; total person-years 132 574), there were 599 incident strokes. Participants in the lowest 10% of the calcaneum broadband ultrasound attenuation distribution had an increased stroke risk (hazard ratio 1.41; 95% confidence intervals, 1.02-1.94) compared with those in the top 30% of the distribution after adjustments. A decrease of ~1 standard deviation in broadband ultrasound attenuation (20 db/MHz) was associated with a 17% increase in relative risk of stroke (95% confidence intervals, 5%-30%). Meta-analysis of 4 studies (25 760 participants, 1237 cases of stroke) found that for every decrease in 1 standard deviation in bone mineral density, there was an increased risk of incident stroke among women (pooled relative risk 1.22; 95% confidence intervals, 1.09-1.37; I2=0%, 3 studies) but not in men (pooled relative risk 1.05; 95% confidence intervals, 0.94-1.17; I(2)=0%, 2 studies).
Conclusions: Bone mineral density predicts total stroke risk. The evidence is stronger in women with regard to the continuous relationship.
Keywords: bone density; epidemiology; osteoporosis; risk factors; stroke.