|
Cost effectiveness of multi-therapy treatment strategies in the prevention of vertebral fractures in postmenopausal women with osteoporosis |
Rosner A J, Grima D T, Torrance G W, Bradley C, Adachi J D, Sebaldt R J, Willison D J |
|
|
Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Ovarian hormone therapy (OHT), bisphosphonate therapy, calcium therapy and no therapy as a treatment strategy for the prevention of vertebral fractures in postmenopausal women with established osteoporosis.
Type of intervention Primary prevention and secondary prevention.
Economic study type Cost-effectiveness analysis and cost-utility analysis.
Study population Women with established osteoporosis and who were at least 8 years postmenopausal.
Setting Community. The economic study was carried out in Canada.
Dates to which data relate Effectiveness data were collected from studies previously published between 1980 and 1996 and from two patient databases published in 1995 and 1996. Resource use and cost data were retrieved from 1992-1996 sources. The price year was 1996.
Source of effectiveness data Effectiveness data were derived from a review of studies and expert opinion.
Modelling A decision tree was used to model costs and outcomes associated with 9 treatment strategies over 3 years.
Outcomes assessed in the review The following outcomes were assessed: vertebral fracture rates (VFR) and relative risk values, adverse event rates, proportion of vertebral fractures that are symptomatic, proportion of patients willing to initiate treatment, and proportion of patients willing to continue treatment for 3 years.
Study designs and other criteria for inclusion in the review The review included studies on the diagnosis and treatment of postmenopausal osteoporosis. No other criterion for inclusion was reported.
Sources searched to identify primary studies A systematic review of studies on Medline and from other databases was conducted. Article bibliographies and related journals were also reviewed. Two patient databases were used as data sources: the Canadian Database of Osteoporosis and Osteopenia Patients (CANDOO) and the General Practice Research Database (GPRD).
Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included 18 primary studies and 2 patient databases were included in the review. The type of studies included was not stated.
Methods of combining primary studies One effectiveness measure (VFR with no therapy) was pooled from published studies using an inverse variance-weighted methodology. Some outcomes were averages of results reported in primary studies, while others were taken from single studies.
Investigation of differences between primary studies Differences between primary studies were treated in a narrative fashion.
Results of the review The number of vertebral fractures per 1,000 patient years for no therapy was 390.3 (95% CI: 531.6 - 286.5). The relative risk of a vertebral fracture compared with no therapy over 3 years was 0.45 for ERT, 0.45 for HRT, 0.37 for alendronate therapy, 0.44 for etidronate therapy, and 0.69 for calcium therapy. The proportion of patients willing to initiate treatment was 36.5% for ERT, 18.1% for HRT, 70.1% for alendronate therapy, 70.1% for etidronate therapy, and 78.3% for calcium therapy. The proportion of patients willing to continue treatment for 3 years was 23.8% for ERT, 21.5% for HRT and 24.0% for alendronate therapy, etidronate therapy and for calcium therapy. The proportion of vertebral fractures that are symptomatic was 50%. The rate of adverse events in year 1 ranged from 33% patients receiving ERT experiencing estrogen symptoms to 0.05% patients receiving calcium therapy developing kidney stones.
Methods used to derive estimates of effectiveness Expert opinion was sought using a modified Delphi process. The panel consisted of 5 physicians (Canadian specialists and GPs) with experience in the use of at least one of the intervention therapies. The authors also made assumptions regarding the duration of treatment effects, which they supported with reference to published studies.
Estimates of effectiveness and key assumptions Doses, formulations and patient distributions for all therapies were based on Delphi panel estimates. The baseline values and ranges of adverse events were also reviewed and adjusted by expert opinion. The authors assumed that no treatment was effective during the first 6 months of use and that the effect of any therapy would last for 6 months after discontinuation.
Measure of benefits used in the economic analysis The measure of benefit used in the cost-effectiveness analysis was the number of vertebral fractures averted. The VFR from the effectiveness analysis was modelled to derive the annual proportion of change in the relative risk of vertebral fracture. Quality-adjusted life years (QALYs) were used in the cost-utility analysis. The Delphi panel (comprising of 5 physicians) estimated the impact of a vertebral fracture on a patient's health status using Health Utilities Index Mark 2. Utility values were estimated for the first 2 weeks following the vertebral fracture and for the 10 subsequent weeks. All outcomes were discounted to present value at a 5% annual rate.
Direct costs The quantity/cost boundary adopted was that of society. Quantities and costs were reported separately. Health care costs included medications, visits to healthcare professionals, diagnostic imaging, laboratory tests and procedures. Non-healthcare costs included the cost of aids and devices, and travel costs. The hospitalisation rate for symptomatic vertebral fractures was derived from the literature review; all remaining resource use was estimated using the Delphi panel. Prices were derived from Canadian charges (Ontario Drug Benefit Formulary, Ontario Schedule of Benefits, Home Care). The price year was 1996. Costs were discounted at an annual rate of 5%.
Statistical analysis of costs Indirect Costs Indirect costs included the cost of carers' time and costs related to patients' lost time from work for osteoporosis therapy. Lost time was valued at the industrial aggregate weekly wage rate; its value was not specified. The Delphi panel estimated the amount of lost time. The quantity/cost boundary adopted was that of society. The price year was 1996. Costs were discounted at an annual rate of 5%.
Sensitivity analysis One-way sensitivity analyses were conducted on the following parameters: VFR (using upper and lower confidence intervals derived from the review), compliance rate, level of resource use costs, proportion of patients seeking treatment for vertebral fractures and discount rate.
Estimated benefits used in the economic analysis Since the type of OHT received was dependent upon previous hysterectomy, results were presented according to the presence or absence of this factor and relate to the 3-year period covered by the model. In those who had not undergone hysterectomy, the number of per-patient vertebral fractures varied between 1.172 for 'no therapy' and 0.948 for the 'alendronate-OHT-calcium-no therapy' strategy. In those who had undergone hysterectomy, the number of per-patient vertebral fractures varied between 1.172 for 'no therapy' and 0.928 for the 'alendronate-OHT-calcium-no therapy' strategy. It was estimated that there would be a gain of 0.066 QALYs per vertebral fracture averted.
Cost results Since the type of OHT received was dependent upon previous hysterectomy, results were presented according to the presence or absence of this factor and relate to the 3-year period covered by the model. In those who had not undergone hysterectomy, the total per-patient cost varied between Can$2,600 for the 'calcium-no therapy' strategy and Can$3,490 for the 'alendronate-OHT-calcium-no therapy' strategy. In those who had undergone hysterectomy, the total per-patient cost varied between Can$2,592 for the 'calcium-no therapy strategy' and Can$3,467 for the 'alendronate-OHT-calcium-no therapy' strategy.
Synthesis of costs and benefits In both patient groups, the strategy 'calcium-no therapy' was less costly and more effective than the strategy 'no therapy'. In those who had not undergone hysterectomy, the incremental cost-effectiveness ratio (ICER) varied between Can$1,376 for the 'OHT-calcium-no therapy' strategy, relative to 'calcium-no therapy' and Can$39,488 for the 'OHT-alendronate-calcium-no therapy' strategy, relative to the strategy 'OHT-etidronate-calcium-no therapy'. In those who had undergone hysterectomy, the ICER varied between Can$166 for the 'OHT-calcium-no therapy' strategy, relative to 'calcium-no therapy' and Can$40,965 for the 'OHT-alendronate-calcium-no therapy' strategy, relative to the strategy 'OHT-etidronate-calcium-no therapy'. In both patient groups, the cost per QALY of strategies involving 'calcium-no therapy' and 'OHT-calcium-no therapy' fell below Can$20,000. The cost per QALY of the 'OHT-etidronate-calcium-no therapy' strategy was within the range of Can$20,000 to Can$100,000. The cost per QALY of the 'OHT-alendronate-calcium-no therapy' strategy was above Can$100,000. The model was found to be 'sensitive' (in terms of a change in strategies that were optimal within the range Can$20,000 to Can$100,000/QALY) to an increase or decrease in the VFR. The model was also found to be sensitive to changes in the compliance rate and to an increase in the cost of treating fractures. However, in most cases there was no change either in which strategies were efficient or in which strategies fell within this cost/QALY range.
Authors' conclusions The results indicated that the treatment strategies 'calcium-no therapy', 'OHT-calcium-no therapy', 'OHT-etidronate-calcium-no therapy', and 'OHT-alendronate-calcium-no therapy' were the efficient options for consideration in the treatment of vertebral osteoporosis.
CRD COMMENTARY - Selection of comparators rationale for the choice of the comparators was clear. You, as a user of this database, should consider whether these health technologies are relevant to your setting.
Validity of estimate of measure of benefit authors considered both effectiveness and utility measures. The type of studies on which the effectiveness measure was based was not stated and the validity of the estimates used in the analysis is therefore uncertain. Some caution needs to be exercised in interpreting the QALY results since utility values were derived from a panel of experts. The model was designed to consider only 3-year therapy effects and, hence, ignored longer-term effects. Not only the quality-of-life impact of vertebral fractures should be considered, but also the impact of hip and wrist fractures, when studying osteoporosis. The results were sensitive to changes in the vertebral fracture rate, on which consensus was difficult to achieve. Willingness to initiate or continue treatment can be increased through patient education, which may influence the cost-utility rankings.
Validity of estimate of costs ect and indirect costs were considered. Charges for physician services and home care visits were used. Charges do not represent true opportunity costs. Caution needs to be exercised in interpreting the cost results since resource use was estimated using a modified Delphi process.
Other issues results presented here are highly dependent on the quality of the effectiveness data used in the model and upon the assumptions made by the authors and by the expert panel regarding both costs and benefits. However, the model was reported in adequate detail to allow the results to be reworked for other settings. Only one other cost-effectiveness study of the prevention of vertebral fractures was identified and this was compared with the authors' approach.
Source of funding Funding from Procter & Gamble Pharmaceuticals Inc.
Bibliographic details Rosner A J, Grima D T, Torrance G W, Bradley C, Adachi J D, Sebaldt R J, Willison D J. Cost effectiveness of multi-therapy treatment strategies in the prevention of vertebral fractures in postmenopausal women with osteoporosis. PharmacoEconomics 1998; 14(5): 559-573 Other publications of related interest 1. Ankjaer-Jensen A, Johnell O. Prevention of osteoporosis: cost-effectiveness of different pharmaceutical treatments. Osteoporosis International 1996;6(4):265-275.
2. Barrett-Connor E. The economic and human costs of osteoporotic fracture. American Journal of Medicine 1995;98(Supplement 2A):S3-S8.
3. Francis R M, Anderson F H, Torgerson D J. A comparison of the effectiveness and cost of treatment for vertebral fractures in women. British Journal of Rheumatology 1995;34(12):1167-1171.
4. Gaspard U. Risks, benefits and costs of hormone replacement therapy in menopause. Revue Medicale de Liege 1998;53(5):298-304.
5. Reid D M, Torgerson D J. Pharmacoeconomic aspects of intermittent cyclical etidronate therapy In the treatment of postmenopausal and corticosteroid-induced osteoporosis. Reviews in Contemporary Pharmacotherapy 1998;9(4):287-292. 6. Whittington R, Faulds D. Hormone replacement therapy. 2. A pharmacoeconomic appraisal of its role in the prevention of postmenopausal osteoporosis and ischaemic heart disease. PharmacoEconomics 1994;5(6):513-554
Indexing Status Subject indexing assigned by NLM MeSH Aged; Alendronate /economics /therapeutic use; Calcium /economics /therapeutic use; Cost-Benefit Analysis; Drug Therapy, Combination; Estradiol /economics /therapeutic use; Estrogen Replacement Therapy /economics; Estrogens /economics /therapeutic use; Etidronic Acid /economics /therapeutic use; Female; Humans; Middle Aged; Osteoporosis, Postmenopausal /complications /economics; Quality-Adjusted Life Years; Retrospective Studies; Sensitivity and Specificity; Spinal Fractures /economics /etiology /prevention & control AccessionNumber 21999008080 Date bibliographic record published 31/01/2000 Date abstract record published 31/01/2000 |
|
|
|