Cost effectiveness of 5-alpha reductase inhibitors for the prevention of prostate cancer in multiple patient populations

Predicting utility scores for prostate cancer: mapping the Prostate Cancer Index to the Patient-Oriented Prostate Utility Scale (PORPUS)

BACKGROUND

The Prostate Cancer Index (PCI) is a health profile instrument that measures health-related quality of life with six subscales: urinary, sexual, and bowel function and bother. The Patient-Oriented Prostate Utility Scale (PORPUS-U) measures utility (0=dead and 1=full health). Utility is a preference-based approach to measure health-related quality of life, required for decision analyses and cost-effectiveness analyses. We developed a function to estimate PORPUS-U utilities from PCI scores.

METHODS

The development data set included 676 community-dwelling prostate cancer (PC) survivors who completed the PCI and PORPUS-U by mail. We fit three linear regression models: one used original PORPUS-U scores and two used log-transformed PORPUS-U scores, one with a hierarchy constraint and one without. The model selection was performed using stepwise selection and fivefold cross validation. The validation data included 248 PC outpatients with three assessments on the PCI and PORPUS-U. Scores were retransformed for validation, with Duan's smearing estimator applied to correct potential bias. The predictive ability of the models was assessed with R(2), root mean square error (RMSE) and by comparing predicted and observed utilities.

RESULTS

The best-fitting model used the log-transformed PORPUS-U with no hierarchy constraint. The R(2) was 0.72. The RMSE ranged from 0.040 to 0.061 for the three validation data sets. Differences between predicted and observed utilities ranged from 0.000 to 0.006 but predicted utilities overestimated the lowest 5% of observed PORPUS-U scores and underestimated the highest observed scores.

CONCLUSIONS

Our algorithm can calculate PORPUS-U utility scores from PCI scores, thus supplementing descriptive quality of life measures with utility scores in PC patients. Utilities derived from mapping algorithms are useful for assigning utility to groups of patients but are less accurate at predicting utility of individual patients. We are exploring statistical methods to improve the mapping of utilities from descriptive instruments.

Prostate cancer chemoprevention

Prostate cancer is a leading cause of morbidity and mortality in men and has significant treatment-associated complications. Prostate cancer chemoprevention has the potential to decrease the morbidity and mortality associated with this disease. Chemoprevention research to date has primarily focused on nutrients and 5 alpha-reductase inhibitors (5ARIs). A large randomized trial (SELECT) found no favorable effect of selenium or vitamin E on prostate cancer prevention. Two large randomized placebo controlled trials (the PCPT and REDUCE trials) have been published and have supported the role of 5ARIs in prostate cancer chemoprevention; however, these trials also have prompted concerns regarding the increase in high-grade disease seen with treatment and have not been approved by the US Food and Drug Administration (FDA) for chemoprevention. Conclusive evidence for the chemopreventive benefit of nutrients or vitamins is lacking, whereas the future role of 5ARIs remains to be clarified.

Health care costs for state transition models in prostate cancer

OBJECTIVE

To obtain estimates of direct health care costs for prostate cancer (PC) from diagnosis to death to inform state transition models.

METHODS

A stratified random sample of PC patients residing in 3 geographically diverse regions of Ontario, Canada, and diagnosed in 1993-1994, 1997-1998, and 2001-2002, was selected from the Ontario Cancer Registry. We retrieved patients' pathology reports to identify referring physicians and contacted surviving patients and next of kin of deceased patients for informed consent. We reviewed clinic charts to obtain data required to allocate each patient's observation time to 11 PC-specific health states. We linked these data to health care administrative databases to calculate resource use and costs (Canadian dollars, 2008) per health state. A multivariable mixed-effects model determined predictors of costs.

RESULTS

The final sample numbered 829 patients. In the regression model, total direct costs increased with age, comorbidity, and Gleason score (all P < 0.0001). Radical prostatectomy was the most costly primary treatment health state ($4676 per 100 days). Radical prostatectomy, hormone-refractory metastatic disease ($6398 per 100 days), and final (predeath) ($13,739 per 100 days) health states were significantly more costly (P < 0.05) than nontreated nonmetastatic PC ($3440 per 100 days), whereas the postprostatectomy ($732 per 100 days) and postradiation ($1556 per 100 days) states cost significantly less (P < 0.0001).

CONCLUSIONS

This study used an innovative but labor-intensive approach linking chart and administrative data to estimate health care costs. Researchers should weigh the potential benefits of this method against what is involved in implementation. Modifications in methodology may achieve similar gains with less outlay in individual studies. However, we believe that this is a promising approach for researchers wishing to advance the quality of costing in state transition modeling.

Model-based cost-effectiveness analyses for prostate cancer chemoprevention : a review and summary of challenges

BACKGROUND AND PURPOSE

Decision-analytic modelling is often used to examine the economics associated with using a specific treatment. As a result, it is important to understand structural and methodological approaches used in published decision-analytic models for examining the cost effectiveness of 5α-reductase inhibitors (5ARIs) for prostate cancer (PCa) chemoprevention. This understanding allows us to provide recommendations for using decision modelling in future economic evaluations of chemoprevention for PCa.

METHODS

A review of the published literature was performed using MEDLINE and the Cochrane Library to identify studies involving mathematical decision models that evaluated 5ARIs for PCa chemoprevention. Published articles were reviewed and key modelling components were extracted and summarized. Recommendations for developing future decision models to examine the economic consequences of PCa chemoprevention were presented.

RESULTS

We identified seven published models of PCa chemoprevention. All the models identified used a Markov framework with time horizons ranging from 4 years to lifetime. Due to the wide range of patient risk groups examined, PCa risk data were taken from the Surveillance, Epidemiology, and End Results (SEER) and other databases or estimates published in relevant clinical trials. Treatment effects included change in the incidence of high- and low-grade PCa and impacts on benign prostate hyperplasia. Adverse events were considered to affect compliance, discontinuation and quality of life. Quality-of-life impacts were similar among studies. Examination of modelling parameter sensitivities was comprehensive.

CONCLUSIONS

Published models have examined the cost effectiveness of PCa chemoprevention; however, limitations exist. Decision models should take into account the full PCa clinical pathway when compiling health states. The time horizon should be long enough to consider the full benefit of chemoprevention while allowing actual time receiving the drug to occur from the start of the model until a man's life expectancy is less than 10 years. Baseline PCa risk should be specific to the population of concern. Models should examine the impact on both low- and high-grade tumours and account for the impact of 5ARIs on benign prostatic hyperplasia. Because chemoprevention has an upfront effect, the structure of the model should be constructed so that the downstream effect of avoiding or delaying recurrence can be considered. Adverse events due to chemoprevention should be considered through compliance, discontinuation or quality-of-life impact, and understanding the impact of avoiding PCa and benign prostatic hyperplasia events are important model properties.

Use of number needed to treat in cost-effectiveness analyses

OBJECTIVE

To review the use of number needed to treat (NNT) and/or number needed to harm (NNH) values to determine their relevance in helping clinicians evaluate cost-effectiveness analyses (CEAs).

DATA SOURCES

PubMed and EconLit were searched from 1966 to September 2012.

STUDY SELECTION AND DATA EXTRACTION

Reviews, editorials, non-English-language articles, and articles that did not report NNT/NNH or cost-effectiveness ratios were excluded. CEA studies reporting cost per life-year gained, per quality-adjusted life-year (QALY), or other cost per effectiveness measure were included. Full texts of all included articles were reviewed for study information, including type of journal, impact factor of the journal, focus of study, data source, publication year, how NNT/NNH values were reported, and outcome measures.

DATA SYNTHESIS

A total of 188 studies were initially identified, with 69 meeting our inclusion criteria. Most were published in clinician-practice-focused journals (78.3%) while 5.8% were in policy-focused journals, and 15.9% in health-economics-focused journals. The majority (72.4%) of the articles were published in high-impact journals (impact factor >3.0). Many articles focused on either disease treatment (40.5%) or disease prevention (40.5%). Forty-eight percent reported NNT as a part of the CEA ratio per event. Most (53.6%) articles used data from literature reviews, while 24.6% used data from randomized clinical trials, and 20.3% used data from observational studies. In addition, 10% of the studies implemented modeling to perform CEA.

CONCLUSIONS

CEA studies sometimes include NNT ratios. Although it has several limitations, clinicians often use NNT for decision-making, so including NNT information alongside CEA findings may help clinicians better understand and apply CEA results. Further research is needed to assess how NNT/NNH might meaningfully be incorporated into CEA publications.

Does variation in either age at start of therapy or duration of therapy make chemoprevention with finasteride cost-effective?

BACKGROUND

Incremental cost-effectiveness ratios (ICERs) of finasteride for prostate cancer prevention are consistent with estimates beyond $100 000 per quality-adjusted life-year (QALY). The majority of these analyses are based on chemoprevention starting in men aged 50-55 years. We sought to evaluate the impact of varying both age at commencement of therapy and length of therapy on the cost-effectiveness of finasteride.

METHODS

A probabilistic Markov model was designed to estimate lifetime prostate health-related costs and quality-adjusted survival for men receiving or not receiving chemoprevention with finasteride. ICERs across scenarios varying age at start of therapy and duration of chemoprevention were compared.

RESULTS

The ICER for men starting chemoprevention at age 50 and continuing to age 75 was $88 800 per QALY when assuming finasteride causes a constant risk reduction across all tumor grades (base case 1) and $142 300 per QALY when assuming a differential treatment effect according to Gleason score (base case 2). When starting age is increased, the ICERs trend downward and nadir at 65 years to $64 700 per QALY (base case 1) and $118 600 per QALY (base case 2). Altering duration of therapy had minimal impact. Patient-level experiences with finasteride and BPH significantly influenced the cost-effectiveness of chemoprevention.

CONCLUSIONS

Initiating chemoprevention at ages when prostate cancer incidence is higher improves its cost-effectiveness profile. Only when assuming a constant risk reduction for all tumor grades, did finasteride fall below $100 000 per QALY, but this finding was not upheld when accounting for side effects associated with the drug.

5-α reductase inhibitors and prostate cancer prevention: where do we turn now?

With the lifetime risk of being diagnosed with prostate cancer so great, an effective chemopreventive agent could have a profound impact on the lives of men. Despite decades of searching for such an agent, physicians still do not have an approved drug to offer their patients. In this article, we outline current strategies for preventing prostate cancer in general, with a focus on the 5-α-reductase inhibitors (5-ARIs) finasteride and dutasteride. We discuss the two landmark randomized, controlled trials of finasteride and dutasteride, highlighting the controversies stemming from the results, and address the issue of 5-ARI use, including reasons why providers may be hesitant to use these agents for chemoprevention. We further discuss the recent US Food and Drug Administration ruling against the proposed new indication for dutasteride and the change to the labeling of finasteride, both of which were intended to permit physicians to use the drugs for chemoprevention. Finally, we discuss future directions for 5-ARI research.

Cost effectiveness of chemoprevention for prostate cancer with dutasteride in a high-risk population based on results from the REDUCE clinical trial

BACKGROUND

The REDUCE trial examined whether chemoprevention with the dual 5-alpha reductase inhibitor, dutasteride, reduced risk of prostate cancer (PCa) detection on biopsy.

OBJECTIVE

We examined the cost effectiveness of dutasteride compared with placebo in preventing PCa in men at increased risk as seen in REDUCE, from a US payer perspective.

METHODS

A Markov model was developed to compare costs and outcomes of chemoprevention with dutasteride 0.5 mg/day or placebo with usual care in men aged 50-75 years, with serum prostate-specific antigen (PSA) of 2.5-10 ng/mL (men aged <60 years) or 3.0-10 ng/mL (men aged ≥60 years), and with a single negative prostate biopsy in the prior 6 months. The model simulated the REDUCE cohort annually through different health states over 4-, 10-year and lifetime time horizons. Risks of PCa for men receiving placebo and dutasteride were obtained from REDUCE. Rates of acute urinary retention events and benign prostate hyperplasia-related surgeries also came from REDUCE. Costs and utilities were obtained from published literature. All costs are reported in $US, year 2009 values.

RESULTS

The model indicated that, over 10 years, dutasteride patients would experience fewer PCas (251 vs 312 per 1000 patients) at increased cost ($US15 341 vs $US12 316) than placebo patients. Although life-years were not substantially affected, the model calculated an increase in QALYs of 0.14 for dutasteride patients. Chemoprevention with dutasteride appeared to be cost effective, with an incremental cost per QALY of $US21 781 and cost per PCa avoided of $US50 254. The 4-year and lifetime incremental costs per QALY were $US18 409 and $US22 498, respectively.

CONCLUSIONS

Despite increased cost due to taking a drug for prevention, dutasteride 0.5 mg/day may be cost effective in men at increased risk for PCa.