Patterns of treatment among a cohort of older low-income adults starting new medications for osteoporosis

Abstract

Summary

Among 125,954 new users of osteoporosis (OP) medications, 77 % of subjects stopped OP medications, and 23 % of subjects added or started a new OP medication during follow-up, with the first addition or start of a new OP medication occurring in a mean of 739 days after original OP treatment.

Introduction

We described patterns and predictors of OP medication use, focusing on treatment changes over time.

Methods

We analyzed health and pharmacy insurance claims for a large cohort of low-income Medicare beneficiaries with a drug benefit for the years 1998–2008. Study subjects had documented Medicare claims and no receipt of OP medications (i.e., bisphosphonate, raloxifene, calcitonin, teriparatide, or hormonal therapy) during a baseline of 180 days. Subjects were then required to start an OP medication. Baseline patient and prescriber characteristics were assessed in multivariable Cox regression models to identify correlates of adding or starting a new OP medication. Fractures, bone mineral density testing, and visits with endocrinologists or rheumatologists occurring after baseline were also examined as correlates.

Results

We included 125,954 new users of OP medications with a mean age of 78 years, 97 % female, and 92 % white. OP medication prescribers included specialists (i.e., endocrinologists or rheumatologists) (6.2 %), orthopedic surgeons (1.0 %), primary care providers (64.9 %), other physicians (3.7 %), and missing (24.1 %). Seventy-seven percent of subjects stopped OP medications, and 23 % of subjects added or started a new OP medication during follow-up, with the first addition or start of a new OP medication occurring in a mean of 739 days after original OP treatment; 4 % added or started a new OP medication more than once. In fully adjusted models, many baseline variables correlated with starting a second OP medication. Post-baseline fractures [hazard ratio (HR) 1.76, 95 % confidence interval (CI) 1.71–1.82] and bone mineral density testing (HR 2.94, 95 % CI 2.86–3.03) were strong predictors.

Conclusion

Approximately one quarter of patients starting an OP medication added or started a new OP medication during follow-up. Long-term sequential treatment strategy trials would inform optimal medication treatment for OP.

Appendices

Appendix 1

List of osteoporosis treatments

Record of at least one pharmacy claim for:

• Oral bisphosphonates: alendronate (10 mg po per day or 70 mg po per week), risedronate (5 mg po per day, 35 mg po per week, or 150 mg po per month), or ibandronate (150 mg po per month).

• Raloxifene (60 mg po per day)

• Calcitonin (200 IU intranasal spray per day)

• Hormone replacement therapy: oral and patches

• IV bisphosphonates: zoledronic acid (measured as an infusion in medical claims J3487 or Q4095)

• Teriparatide (20 μg injectable per day).

Appendix 2

Table 5 Covariate definitions