|An economic evaluation of finasteride for treatment of benign prostatic hyperplasia
|Baladi J F, Menon D, Otten N
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.
Using 5 alpha-reductase inhibitor finasteride versus transurethral resection of the prostate (TURP), and watchful waiting (periodic monitoring of a patient by his physician, representing the "do nothing" option) in the treatment of patients (older men) with benign prostatic hyperplasia (BPH).
Economic study type
Cost-effectiveness analysis and cost-utility analysis.
Patients (older men) with benign prostatic hyperplasia (BPH).
Community and hospital. The economic study was carried out in Ontario, Canada.
Dates to which data relate
The effectiveness data came mainly from a 'Statistics Canada, personal communication' which were not reported with dates. Some data concerning adverse effects were obtained from studies published in 1995. Costs were measured in 1994 prices.
Source of effectiveness data
Effectiveness data were derived from a review and synthesis of previously published studies.
A decision tree was used to estimate costs and benefits.
Outcomes assessed in the review
The outcomes assessed in the review were the probability of improvement in health states (symptom severity effects), adverse effect rates of interventions, and utility values for different health states.
Study designs and other criteria for inclusion in the review
Not reported in advance but the primary studies included had randomised and non-randomised designs. No more details were reported.
Sources searched to identify primary studies
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
Methods of combining primary studies
Meta-analysis using the Confidence Profile Method.
Investigation of differences between primary studies
Results of the review
The probability of improvement in health state for the finasteride option (for mild or moderate symptom severity before treatment) was 67%; for TURP (for mild symptom severity before treatment) was 72.3% and for watchful waiting (mild or moderate pre-treatment symptom severity) was 42%. The rates of adverse effects for TURP were as follows: total urinary incontinence, 1%; perioperative death, 1.5%; symptoms of mild prostatism along with either stress incontinence or with impotence, 15.7%.
The utility values for health states were:
mild prostatism, 0.99;
moderate prostatism, 0.90;
severe prostatism, 0.79;
mild prostatism plus stress incontinence (M(IC)), 0.75;
mild prostatism plus impotence (M(IP)), 0.86;
total urinary incontinence following TURP (INCT), 0.70;
and preoperative death (DEA) were 0.00.
Measure of benefits used in the economic analysis
The measure of benefits was incremental patients treated successfully (reducing symptom severity without the occurrence of incontinence) and incremental quality adjusted life years (QALYs) gained. The model used was a decision tree to deal with uncertainty regarding the outcomes. The health states reflected the severity of the condition in a similar fashion to a symptom severity scale such as the American Urological Association symptom index. The valuation tool used was the Health Utilities Index Mark II, a health-related quality of life instrument.
Costs were discounted and quantities were analysed separately, although cost items were not reported separately. The costs measured were operating costs (costs of treatment) and follow up costs. The boundary adopted was that of a healthcare system. The estimation of quantities was based on the model which, in turn, was designed according to guidelines for BHP treatment published by the US Department of Health and Human Services. The estimation of costs (unitary costs) was based on actual data and standard prices. The sources of costs were as follows: Canadian Institute for Health Information (CIHI), the Institute of Clinical Evaluative Sciences in Ontario (ICES), Statistics Canada (governmental office), provincial governments and individual hospitals. 1994 price data were used. The costs associated with the initial evaluation were not included in the cost analysis since they were considered to be common to the alternative treatment strategies.
Sensitivity analysis included the following elements; treatment effectiveness and failure rates (probability of requiring TURP following watchful waiting or finasteride), cost estimates (upper and lower limit values), utility values and the discount rate. Variability and generalisability of data were analysed. One-way simple sensitivity analysis was used.
Estimated benefits used in the economic analysis
Using effectiveness values for treatment options, additional successfully treated patients with finasteride (for mild or moderate symptom severity) was -5.3 % for TURP and 25% for watchful waiting. Using a 5% discount rate, assuming benefits ranging from 1 to 15 years for the intervention and comparator (either TURP or watchful waiting) and using the utility values for mild (0.99) and moderate (0.90) health states, this difference in effectiveness was transformed into incremental quality adjusted life years gained (figures were not reported).
Using a 5% discount rate and assuming a 4 year time horizon of lifetime the incremental costs of finasteride (without including the costs of the initial evaluation which were reported to be common to all the treatment options) were calculated, with respect to TURP and watchful waiting. However the relevant final figures were not reported.
Synthesis of costs and benefits
For the cost-effectiveness outcomes of mild and moderate symptoms, the results were as follows: the incremental cost per additional successfully treated patient over 4 years using finasteride instead of watchful waiting was Can$71,000. Treating patients with moderate symptoms using finasteride rather than TURP leads to savings of Can$32,000 over 4 years.
The cost-utility results were as follows: the incremental cost per QALY gained in using finasteride rather than watchful waiting, for a 4-year time horizon was Can$19,000; the corresponding figure when compared to TURP was not calculated because finasteride was the optimal strategy.
Sensitivity analysis showed that for the first cost-utility result, the most sensitive parameter was the effectiveness of watchful waiting. Sensitivity analysis for the second cost-utility comparison showed that the cut-off value of 13 years of time horizon for finasteride to cease being a cost saving option, can range between 11 to 19 years. The major result concerning severe symptom status was that when finasteride was used for BPH in a time horizon of more than 14 years, it was the dominated strategy. Between 4 and 14 years it was dominated by watchful waiting whereasit was less costly but less effective than TURP starting from Can$20,000 savings per QALY "foregone" and diminishing. It is noteworthy that, in a moderate symptomatic patient sub-population with less than 3 years of lifetime horizon remaining, finasteride appeared to be a dominant strategy, whereas if that horizon expanded to 4 and up to 14 years, TURP would still be dominated whilst the cost utility ratio against watchful waiting would be at least Can$19,000.
This study has shown that finasteride can be of benefit to some patients, but that this benefit comes at a cost. If, for example, all patients with moderate symptoms are given finasteride, then, under the baseline assumptions in the present study model, the incremental cost per 10,000 men aged 60 years and over would be Can$2.7 million for an additional 125 QALYs for the whole cohort.
CRD COMMENTARY - Selection of comparators
The reason for the choice of the comparators is clear.
Validity of estimate of measure of benefit
The internal validity of the benefit results can not be assessed due to lack of information regarding the conduct of the literature review, and methods of quality assessment of the primary studies included in the review.
Validity of estimate of costs
The resource utilisation was reported separately from the costs and adequate details of the methods of cost estimation were given. However, cost items were not reported separately.
In view of the lack of information regarding the literature review, quality assessment of the primary studies included, and statistical analysis of the costs, the results may need to be treated with some caution. The issue of generalisability to other settings or countries was not addressed.
Baladi J F, Menon D, Otten N. An economic evaluation of finasteride for treatment of benign prostatic hyperplasia. PharmacoEconomics 1996; 9(5): 443-454
Subject indexing assigned by NLM
Aged; Canada; Cost-Benefit Analysis; Decision Trees; Enzyme Inhibitors /economics /therapeutic use; Finasteride /economics /therapeutic use; Humans; Male; Middle Aged; Prostatectomy /economics; Prostatic Hyperplasia /economics /therapy; Treatment Outcome
Date bibliographic record published
Date abstract record published