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Cost effectiveness of pramipexole in Parkinson's disease in the US |
Hoerger T J, Bala M V, Rowland C, Greer M, Chrischilles E A, Holloway R G |
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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 The use of pramipexole in Parkinson's disease in the USA.
Study population Patients with early and advanced PD.
Setting Hospital. The study was carried out in the USA.
Dates to which data relate Effectiveness data were collected from studies published between 1989 and 1997. Resource use and cost data were collected from studies published between 1993 and 1998. The price year was 1997.
Source of effectiveness data Clinical trials, a review of the literature, and consultations with a clinical expert provided effectiveness data.
Modelling A model was used to link Unified Parkinson Disease Rating Scale (UPDRS) Parts II and III scores to costs and quality adjusted life years (QALYs). Medical, ancillary, and community care costs were estimated as a multivariate function of UPDRS scores and other variables using a 3-equation system. Lost productivity costs were also estimated as a function of UPDRS scores.
Outcomes assessed in the review The literature review assessed disease progression parameters based on the change in UPDRS scores for Parts II and III over time, as measured in years since onset of disease.
Study designs and other criteria for inclusion in the review Effectiveness measures for pramipexole were derived from prospective, randomised controlled clinical trials.
Sources searched to identify primary studies The literature review was based on a MEDLINE search on PD epidemiology and drug treatment.
Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Summary statistics from each study.
Number of primary studies included Approximately 10 studies were included.
Methods of combining primary studies Investigation of differences between primary studies Results of the review In the early-stage model, the UPDRS score prior to onset of disease was 3.6. The annual rate of progression for the untreated disease was 8.9. The UPDRS score when disability becomes so severe that levodopa is introduced was 35.0. The one-time drop in UPDRS when levodopa is introduced was -5.5. The annual rate of progression following start of levodopa was 1.4. The UPDRS score when pramipexole is introduced was 27.0. The one-time drop in UPDRS when pramipexole is introduced was -5.5. The annual rate of progression for patients treated with pramipexole was 2.9. The annual rate of progression for patients after levodopa is added to pramipexole was 1.4. In the advanced-stage model, the annual rate of progression for patients treated with levodopa was 1.4. The UPDRS score when pramipexole is added to levodopa treatment was 35.5. The one-time drop in UPDRS when pramipexole is added to levodopa was -5.9. The annual rate of disease progression for patients treated with both levodopa and pramipexole was 1.4.
Measure of benefits used in the economic analysis The loss in quality-adjusted life years (QALYs) was used as the measure of benefits. A multivariate OLS regression equation was used to estimate the EuroQoL Visual Analogue Scale (VAS) score as a function of the combined UPDRS Parts II and III score. QALYs were discounted at an annual rate of 3%. QALY loss was measured relative to a patient with a UPDRS score of 0.
Direct costs Direct costs were discounted at an annual rate of 3%. Quantities and costs were reported separately. Direct costs included three individual types of costs:
(1) medical (including hospitalisation), ancillary and community care costs;
(2) drug costs for patients receiving each treatment regimen;
(3) nursing home costs.
The quantity/cost boundary adopted was that of society. The estimation of quantities and costs was based on actual data. Medical, ancillary and community care costs were derived from a cross-sectional survey of 193 community-based patients with PD from either the Neurology Clinic at the University of Iowa Hospitals and Clinics or the Iowa Methodist Hospital in Des Moines. Drug costs were estimated using average wholesale price information from the 1997 Red Book or from the manufacturers. Nursing home costs were inferred from published data on nursing home use by Parkinson's patients and the general elderly population and were based on 1993 Medicaid average reimbursement to nursing homes. The price year was 1997.
Statistical analysis of costs Indirect Costs Indirect costs were discounted at an annual rate of 3%. Quantities and costs were reported separately. Indirect costs measured lost productivity based on median weekly earnings for full-time and salaried workers. The estimation of quantities and costs was based on actual data. Lost productivity costs were derived from the Bureau of Labour Statistics. The price year was 1997.
Sensitivity analysis Univariate sensitivity analyses were performed by varying model parameters for disease progression, medical costs, and drug costs. Sensitivity analyses also evaluated the use of the dopamine agonists pergolide and bromocriptine as adjuncts to levodopa.
Estimated benefits used in the economic analysis The UPDRS score was significantly related to the VAS score, (p<0.01). For early-stage patients, treatment with pramipexole led to a loss in QALYs of 2.258 compared to 2.553 with no pramipexole. For advanced-stage patients, treatment with pramipexole led to a loss in QALYs of 2.081 compared to 2.414 with no pramipexole.
Cost results The UPDRS score was associated with higher expenditures both for patients with at least one hospital visit and for patients with no hospital visits, (p<0.05). Productivity costs rose as the UPDRS score increased, (p<0.01). For early-stage patients, total direct costs amounted to $67,702 with pramipexole and $57,549 with no pramipexole. Lost productivity costs amounted to $97,391 with pramipexole and $104,937 with no pramipexole. For advanced-stage patients, total direct costs were $66,586 with pramipexole and $56,073 with no pramipexole. Lost productivity costs amounted to $75,887 with pramipexole and $82,300 with no pramipexole.
Synthesis of costs and benefits For early-stage patients, the incremental cost-effectiveness ratio was $8,837/QALY based on total costs and $34,423 based on direct costs. These results were sensitive to changes in pramipexole effectiveness parameters. Pramipexole treatment was both less expensive and more effective than the no-pramipexole treatment regimen with bromocriptine. Pramipexole treatment was slightly less effective and less expensive than the no-pramipexole treatment regimen with pergolide. For advanced stage patients, the incremental cost-effectiveness ratio was $12,294/QALY based on total costs and $31,528/QALY based on direct costs. Pramipexole treatment was both less expensive and more effective than the no-pramipexole treatment regimen with bromocriptine. Pramipexole treatment was both less expensive and less effective than the no-pramipexole treatment regimen with pergolide.
Authors' conclusions Pramipexole is a cost-effective intervention for patients with both early and advanced stage PD, with an incremental cost-effectiveness ratio at least as favourable as the ratios for many commonly accepted therapies.
CRD COMMENTARY - Selection of comparators The rationale for the choice of the comparator was clear. You, as a user of this database, should verify whether these health technologies are relevant to your own setting.
Validity of estimate of measure of benefit A relevant measure of benefits was used. Some researchers have criticised the use of VAS to measure patient health utility because these methods do not satisfy the axioms of expected utility theory. The model was based on a representative patient who experienced the average reduction in UPDRS score during the pramipexole trials. In practice, patients may experience larger or smaller reductions in UPDRS score. Thus, the cost-effectiveness of pramipexole may vary across individual patients. The model did not include complications of drug treatment. Given that the longest clinical trial lasted less than one year, the model had to extrapolate from trial data to longer periods of care. Some of the disease progression parameters were based on uncertain estimates and the results were sensitive to the model's assumptions. The model also assumed that pramipexole had no effect on mortality or nursing home entry.
Validity of estimate of costs Direct costs and lost productivity costs were included. However, the model did not include other indirect costs, such as the opportunity costs of informal care provided to Parkinson's patients by family members and friends. Overall, the explanatory power of the 3 equations in the medical, ancillary, and community cost system was low. The cost estimates used by the authors were lower than published estimates using other data sources. Use of Iowa data on resource use and costs raises the question of whether these data are representative of patients with PS in the USA. The Iowa sample was limited to patients who could be interviewed at an outpatient clinic. As a result, severely disabled PD patients living in the community or nursing homes may be under-represented in the sample.
Other issues No sensitivity analysis was performed on the discount rate. Appropriate comparisons with other relevant studies were made. The generalisability of the results to other settings/countries was discussed. The authors did not present their results selectively. The study considered patients with early- or advanced-stage PD and this was reflected in the authors' conclusions.
Implications of the study Additional data on levodopa and pramipexole progression rates and follow-up data on pramipexole's long term effects should be collected to enhance the model.
Source of funding Support from Pharmacia & Upjohn Inc and Boehringer Ingelheim GmbH.
Bibliographic details Hoerger T J, Bala M V, Rowland C, Greer M, Chrischilles E A, Holloway R G. Cost effectiveness of pramipexole in Parkinson's disease in the US. PharmacoEconomics 1998; 14(5): 541-557 Other publications of related interest Speller J M, Clarke C E Speller J M, Clarke C E. Pramipexole versus bromocriptine for levodopa-induced motor complications in Parkinson's disease (Protocol for a Cochrane Review). In: The Cochrane Library, Issue 1, 2000. Oxford: Update Software.
Indexing Status Subject indexing assigned by NLM MeSH Antiparkinson Agents /economics /therapeutic use; Benzothiazoles; Cost-Benefit Analysis; Humans; Parkinson Disease /drug therapy /economics; Quality-Adjusted Life Years; Sensitivity and Specificity; Thiazoles /economics /therapeutic use; United States AccessionNumber 21999008079 Date bibliographic record published 31/05/2000 Date abstract record published 31/05/2000 |
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