A population-based osteoporosis screening program: who does not participate, and what are the consequences?

OBJECTIVES

To describe differences in osteoporosis risk factors and rates of fracture and antiresorptive therapy use in women who did and did not participate in an osteoporosis screening program.

SETTING

Group Health Cooperative, a health maintenance organization in western Washington state.

PARTICIPANTS

A total of 9,268 women (aged 60-80) who were not using any antiresorptive therapy were invited to participate in an osteoporosis screening program. This study compares the 35% who participated with the 65% who did not.

DESIGN

This observational cohort study of women invited to participate in a randomized, controlled trial of an osteoporosis screening program provided all participants with personalized feedback on their risk of osteoporosis. Some participants also received bone density testing. Automated administrative data were used to examine differences between participants and nonparticipants in fracture outcomes and medication initiation before and after invitation.

RESULTS

Baseline fracture rates did not differ between participants and nonparticipants. After age adjustment, nonparticipants had a higher hip fracture rate (14.1 vs 8.3 per 1,000) and a lower rate of initiating any antiresorptive therapy (10.3 vs 17.9 per 100) than participants after an average of 28 to 29 months of follow-up.

CONCLUSION

Participants had reduced hip fracture rates and increased initiation of antiresorptive therapy compared with nonparticipants. It was not possible to determine whether participating in the screening program, unmeasured confounding, or selection bias accounted for differences in hip fracture or therapy initiation rates. These results suggest that women who do not participate in osteoporosis screening should be pursued to identify individuals who could benefit from primary and secondary osteoporosis prevention.