Factors associated with initiation of bone-health medication among older adults in primary care in Ireland

Background: Adults at high risk of fragility fracture should be offered pharmacological treatment when not contraindicated, however under-treatment is common. Objective: This study aimed to investigate factors associated with bone-health medication initiation in older patients attending primary care. Design: Retrospective cohort study. Setting: 44 general practices in Ireland from 2011-2017. Subjects: Adults aged [≥]65 years who were naive to bone-health medication for 12 months. Methods: Overall fracture-risk (based on QFracture) and individual fracture-risk factors were described for patients initiated and not initiated onto medication and compared using generalised linear model regression with Poisson distribution. Results: Of 36,799 patients (51 % female, mean age 75.4 (SD=8.4)) included, 8% (n=2,992) were observed to initiate on bone-health medication during the study. One fifth of all patients (n=8,193) had osteoporosis or had high fracture-risk but only 21% of them (n=1,687) initiated on medication. Female sex, older age, state-funded health cover and osteoporosis were associated with initiation. Independently of osteoporosis and co-variates, high 5-year QFracture risk for hip (IRR=1.33 (95% CI=1.17-1.50), p<0.01) and all fractures (IRR=1.30 (95% CI=1.17-1.44), p<0.01) were associated with medication initiation. Previous fracture, rheumatoid arthritis, and corticosteroid use were associated with initiation, while liver, kidney, cardiovascular disease, diabetes and oestrogen-only hormone replacement therapy showed an inverse association. Conclusions: Bone-health medication initiation is targeted at patients at higher fracture-risk but much potential under-treatment remains, particularly in those >80 years and with co-morbidities. This may reflect clinical uncertainty in older multimorbid patients, and further research should explore decision-making in preventive bone medication prescribing.