Background: In persons with depression, higher urinary cortisol is associated with lower bone mineral density.
Objective: To examine the relation between urinary free cortisol (UFC) and fractures.
Setting: Community-based samples from Durham, NC, East Boston, MA, and New Haven, CT.
Participants: 684 men and women, aged 70 to 79 at baseline, who were part of the MacArthur Study of Successful Aging.
Design: Cohort study. Participants with previous history of fractures at baseline were excluded.
Measures: The primary exposure variable was overnight (8:00 p.m. to 8:00 a.m.) UFC (microg/g creatinine) at baseline (1988). Outcomes were self-reported hip, arm, spine, wrist, or other fracture during the follow-up period (1988-1995). Covariates were baseline age, gender, race, body mass index, current physical activity, lower extremity strength, depression subscale of the Hopkins Symptom Checklist, and current use of cigarettes and alcohol.
Analysis: Logistic regression was used to predict the occurrence of incident fractures (1988-1995) as a function of quartiles of baseline UFC. Models were adjusted for age, gender, and race and were also multiply adjusted for the remaining covariates listed above. Gender-stratified models and models that excluded corticosteroid users were also run.
Results: In multiply adjusted models, higher baseline levels of UFC were significantly associated with incident fractures. Odds of fracture (95% Confidence Intervals) for increasing quartiles of baseline UFC, multiply adjusted, were: 2.28 (.91, 5.77); 3.40 (1.33, 8.69); 5.38 (1.68, 17.21). Results were not materially influenced by exclusion of persons using corticosteroids.
Conclusions: Higher baseline UFC is an independent predictor of future fracture.