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Tzu- Chieh Lin 1 Prof. Yea- Huei Kao Yang 1,2

Monitoring Adherence to Treatment for Chronic Diseases ---Using osteoporosis as an example from Taiwan. Tzu- Chieh Lin 1 Prof. Yea- Huei Kao Yang 1,2

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Tzu- Chieh Lin 1 Prof. Yea- Huei Kao Yang 1,2

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  1. Monitoring Adherence to Treatment for Chronic Diseases ---Using osteoporosis as an example from Taiwan Tzu-Chieh Lin1 Prof. Yea-HueiKao Yang1,2 1Institute of Clinical Pharmacy and Pharmaceutical Sciences, 2Health Outcome Research Center, College of Medicine, National Cheng Kung University, Tainan, Taiwan

  2. Conflicts of interest • Our study was supported in part by grants from the MultidisciplinaryCenter of Excellence for Clinical Trial and Research (DOH100-TD-B-111-002) • Department of Health, Executive Yuan, Taiwan and National Science Council, Taiwan (NSC 99-2320-B-006-016-MY3)

  3. Background - 1 • Osteoporosis is characterized by decreased bone mass, deterioration of bone tissue and disruption of bone architecture • ↓ bone strength, ↑fracture risk • Amajor public health burden in developed countries • 10 million people ≥50 years of age have osteoporosis in USA →1.5 million fractures annually • Patients with prior osteoporotic fractures → 2 X higher risk of future fractures • Secondary prevention of osteoporotic fractures → standard practice worldwide

  4. Background - 2 • Bisphosphonates are recommended as the primary pharmacological therapy for secondary prevention of osteoporotic hip fractures • ↓ the risk of hip fractures by 40–50% • Long-term compliance is necessary to ensure optimal therapeutic efficacy • <50% of the patients were compliant during the first year after initiation of treatment • Several studies using claims databases have estimated the impact of compliance on preventing further fracture events • 20–60% reduction in overall fracture risk

  5. Background - 3 • The reimbursement scheme of the Bureau of National Health Insurance in Taiwan • Osteoporosis drugs → patients who have had osteoporotic vertebral or hip fractures • Provides an invaluable opportunity to assess the impact of compliance on outcome in patients who have already had osteoporotic fractures

  6. ClinPharmacolTher 2011 90(1): 109-116

  7. Significance & Objectives • Previous studies focusing on treatment compliance and its impact on fracture risks • Mainly in the developed countries • The objectives of the our study (i) To describe the first-year treatment compliance of patients initiated on alendronate therapy after osteoporotic vertebral or hip fractures (ii) To assess the impact of compliance on the risks of subsequent hip fracture over a longer period

  8. Method – Data source • National Health Insurance Research Database (NHIRD) • Demographic data for enrollees • Information regarding health-care professionals and facilities • Service claims from inpatient, ambulatory care, and contracted pharmacies

  9. Method – Study design and Population • Aretrospective cohort analysis, 2003-2006 • Patients >50 years of age with new osteoporotic vertebral or hip fractures and new to alendronate therapy • The index date → the first day on which patients received an alendronate prescription • The baseline period was defined as the year preceding the index date • To ensure that the index fracture was related to osteoporosis • Patients had at least one osteoporosis-related claim during the baseline period

  10. Method – Study Population • Exclusion criteria • Patients who had experienced any prior osteoporotic vertebral/hip fracture • Patients whose index osteoporotic fracture was associated with car accidents or high-impact trauma • Diagnosis of Paget’s disease or malignant neoplasm • Follow-up period • Compliance with alendronate → The 1st year • Impact of compliance on fracture risk → From the index date to the first date of an incident hip fracture or to the end of the study

  11. Method - Compliance with alendronate treatment • Alendronate is currently the only oral bisphosphonate that approved for insurance reimbursement for osteoporotic fracture • Refill compliance was defined as the medication possession ratio (MPR) for the follow-up period • Dividing the total number of defined daily doses the patient received by the follow-up period • MPR ≥80% as good compliance • Examined the results by adjusting the cutoff point upward and downward

  12. Outcome and Covariates • Incident hip fracture • Retrieved from inpatient claims only • Demographic characteristics (age, gender) • Index osteoporotic fracture, presence of kyphosis, history of any other fracture (radius/ulna, humerus, and other nonvertebral fractures except hip fracture) • Comorbid conditions that could increase fracture risk (Alzhelmer’s disease, asthma, diabetes mellitus, ischemic stroke, history of falls, and rheumatic arthritis) • Comedications(antiepileptics, β-blockers, benzodiazepines, glucocorticoids, hormone replacement therapy, COX-2 agents, selective serotonin reuptake inhibitors, thyroid drugs, and sleep/hypnotic agents).

  13. Statistical analysis • Student’s t-test or χ2→ Primary analysis • Time-to-event analysis → Impact of compliance • Atime-dependent covariate for compliance • Multivariate Cox proportional hazardmodels with time-dependent covariates • Determined whether covariates fitted a proportional hazards assumption • Sensitivity analyses • Different thresholds of good compliance, MPR as a continuous variable • Female patients only, types of index osteoporotic fracture, patients with/without any other fracture 1 year before treatment initiation, stratified patient age groups with 65 years as a cutoff point, and patients not on hormone replacement therapy • Excluding the data for patients who had an incident hip-fracture event within 6 months after treatment initiation

  14. Discussion • This retrospective analysis of Taiwanese patients with osteoporotic vertebral or hip fractures who were new to alendronate found : • Only 38% of patients to be compliant during the first year • Compliant patients had significantly lower hip-fracture risk as compared with noncompliant patients • The results were consistent through various sensitivity analyses

  15. Discussion • It is difficult to make a direct comparison of compliance rates among published studies because of their use of different covariates for adjustment • Age, sex, fracture history, and medications of interest • Several studies have used claims databasesto assess patients’ compliance • MPR: 61-74% in the States, Canada or UK • In our study: 60.2% in Taiwan

  16. Discussion – Impact of compliance

  17. Discussion – Sensitivity analysis • Most studies using MPR ≥80% as the threshold for good compliance • We varied the threshold for good compliance in steps from 70 to 100% • The benefit of compliance was pronounced even when the alendronate treatment was for secondary prevention • Adjusted HR, 0.28; 95% CI 0.18–0.51 • The most pronounced reduction in patients with no history of fracture prior to the index osteoporotic fracture

  18. Discussion - Strength • The first large-scale one in Asia to assess the association between treatment compliance and fracture risk • Demonstrated a pronounced benefit of compliance in preventing secondary hip fracture • The duration of follow-up • Most published compliance studies →1–2 years • Up to 4 years in our study • Included various covariates • Age, comorbidities, and co-medications that were thought to be related to osteoporotic fractures

  19. Discussion - Limitations • The inherent weakness of an observational study and the administrative database →residual confounders • Lack of socioeconomic covariates →confounding by lifestyle • Body mass index, smoking status, and caffeine intake • Misclassification of compliance • Comprehensively captured prescription claims from inpatient, outpatient, and contracted pharmacies • Patients who received HRT may have benefited from its protective effect • Consistent results were found even after excluding data for those kinds of patients

  20. Discussion – Clinical implications • The main policy of Taiwan’s Bureau of National Health Insurance regarding osteoporotic fractures was secondary prevention • Fracture sites other than vertebra/hip (e.g., radius and ulna) ↑ 2 X incident hip-fracture risk • Higher fracture risk in older patients

  21. Summary • The compliance status among Taiwanese osteoporotic patients new to alendronate was suboptimal within the first year after treatment initiation • Compliant patients had a significantly lower incident hip-fracture risk as compared with noncompliant patients • In real-world setting → osteoporosis drugs will not work optimally unless patients actually take them • Every effort should be made to gain greater insight into the factors associated with poor compliance and to initiate interventions to improve patient adherence.

  22. Thanks for your attention! tb897104@mail.ncku.edu.tw

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