Beyond the Abstract - Cost-effectiveness analysis of antimuscarinics in the treatment of patients with overactive bladder in Spain: A decision-tree model, by Salvador Arlandis-Guzman, et al

BERKELEY, CA (UroToday.com) - The objective of this analysis was to assess the 1-year economic value of OAB treatment with fesoterodine relative to extended release (ER) tolterodine and solifenacin, from the societal perspective.

A cost-effectiveness analysis (CEA) was performed in this study through a decision-tree model. Cost-effectiveness is typically expressed as an incremental cost-effectiveness ratio (ICER) between the difference in costs and the difference in benefits of two interventions. The decision-tree model was developed to simulate the typical clinical treatment pathway of an individual initiating OAB therapy with fesoterodine 4mg/day, ER tolterodine 4mg/day, or solifenacin 5mg/day. This economic model was based on data from two 12-week, randomized clinical trials and the published literature. At weeks 4, 12, 24, and 52 patients were classified as responders (those who are restored continence or less than one urge urinary incontinence episode/24 hrs.) or non-responders. At four weeks after treatment initiation, treatment responders are assumed to continue their initial therapy. Non-responders are assumed to titrate to the higher dose of fesoterodine or solifenacin. Responders to treatment at week 12 are assumed to remain responders for the duration of the model unless they discontinue for non-efficacy reasons.

The model is populated with data from more than 1,000 patients with OAB and incontinence enrolled in two 12-week, randomized, placebo controlled, double blind, international clinical trials.[1,2]

The cost (€,2010) of each treatment arm is the sum of purchased medical and non-medical resources used and non-purchased resources (lost productivity of the patient or unpaid family member/caregiver support). Both direct and indirect costs related to OAB were considered in the base case analysis following a societal perspective. Additionally, the Spanish National Healthcare system perspective was obtained and presented separately as a sensitivity analysis.[3] Direct medical costs included were antimuscarinic drugs, physician visits, laboratory tests, incontinence pads, and costs of OAB- or incontinence-related comorbidities (fractures, skin infections, urinary tract infections, depression, and nursing home admissions associated with incontinence), and the cost of treating constipation adverse events. The probability of OAB-related comorbidities depended on patients’ responder and treatment status. The utility decrements for fracture, depression, and nursing home are also considered in the analysis.

We assumed those incontinent patients who are employed work 21% fewer hours than those without incontinence to capture the monetary value of productivity loss. Spanish employment and wage data were entered into the model to estimate the decreased productivity due to incontinence.

Effectiveness of medical interventions was expressed in term of Quality-Adjusted-Life-Years (QALY) gain. Changes in HRQL were assessed from the King’s Health Questionnaire,[4] which was transformed into preference-based utility values for responders and non-responders.[5] Utility for patients not on therapy was assumed equal to the baseline value. The QALY gains were calculated based on patients’ treatment status. The difference between week 52 utilities and baseline utilities for responders and non-responders were the effect measure in the cost-effectiveness ratio.

For each intervention, the model calculates the expected total one-year direct and indirect costs. The model also determines the expected proportion of patients on each treatment having restoration of continence at the end of 1 year and the QALYs gained for each intervention. These outputs are combined to create the ICER.

Several univariate sensitivity analyses of fesoterodine versus tolterodine ER or solifenacin were performed in order to find if the results were robust to changes in main assumptions of the analysis.

At week 12, the proportion of continent patients on each treatment at the end of the model period (responders) was higher for fesoterodine and solifenacin than for tolterodine. By week 52, the projected proportions of patients remaining on therapy was again higher in the fesoterodine arm. The projected QALY gain over the 52-week simulation period showed greater gain for fesoterodine in comparison with the other two drugs evaluated, while the overall treatment costs were similar among the three drugs. These results are related to the lower total treatment costs of fesoterodine in 52 weeks due to the proportion of responder patients continuing therapy throughout the 52-week period. Therefore, treatment with fesoterodine resulted in lower overall costs and greater QALY gain than treatment with either tolterodine or solifenacin.

Sensitivity analysis showed that, for the majority of plausible scenarios, results obtained were robust to changes performed showing similar cost but higher effectiveness for fesoterodine over the other compared antimuscarinics (cost-saving ICERs). If the total duration of treatment was approximately 3 months, fesoterodine would be a cost-effective option, with an ICER of €574 and €14,568 compared to tolterodine and solifenacin, respectively when the NHS perspective is analyzed. When societal perspective is considered, fesoterodine would not be cost-effective relative to solifenacin for treatment duration of 12 weeks or less. However, ICERs of fesoterodine over tolterodine and solifenacin were, respectively, of €39,447 and €17,814 per QALY gained, which are still in the range of acceptable cost-effectiveness in Spain.

Fesoterodine acquisition cost is outweighed by the lower costs related to both direct and indirect resources used considered. We tried to make this analysis as robust as possible, including the relevant comparators (the ones that represent 96% of the Spanish year 2010 OAB treatment market), the adequate efficacy data, and costs. The model is considered to be comprehensive by including several aspects of OAB affecting the overall economic burden of disease.

A possible limitation is that our analysis was not able to incorporate the so-called out-of-pocket expenses and that the model was designed as deterministic. Then only point estimates are shown, not allowing for statistical comparison between drugs in both cost and effectiveness. However, these results are encouraging for development of more sophisticated economic models.

Results of this economic analysis, supported by sensitivity analyses and despite the limitations mentioned, suggest that fesoterodine is a cost-effective alternative to tolterodine and solifenacin for the treatment of patients with OAB in Spain. Fesoterodine provides additional health benefits while maintaining a similar level of costs making them a cost-effective treatment strategy from a societal perspective and from the NHS as well.

 

 

 

References

  1. Chapple C, van Kerrebroeck P, Tubaro A, Haag-Molkenteller C, Forst H-T, Massow U, Wang J, Brodsky M: Clinical efficacy, safety, and tolerability of once-daily fesoterodine in subjects with overactive bladder. Eur Urol 2007, 52:1204-1212.
  2. Nitti VW, Dmochowski R, Sand PK, Forst HT, Haag-Molkenteller C, Massow U, Wang J, Brodsky M, Bavendam T: Efficacy, safety, and tolerability of fesoterodine in subjects with overactive bladder. J Urol 2007, 178:2488-2494.
  3. Bastida JL, Oliva J, Antoñanzas F, García-Altés A, Gisbert R, Mar J, Puig-Junoy J: A proposed guideline for economic evaluation of health technologies. Gac Sanit 2010, 24:154-170.
  4. Kelleher CJ, Cardozo LD, Khullar V, Salvatore S: A new questionnaire to assess the quality of life of urinary incontinent women. Br J Obstet Gynaecol 1997, 104:1374-1379.
  5. Brazier J, Czoski-Murray C, Roberts J, Brown M, Symonds T, Kelleher C: Estimation of a preference-based index from a condition-specific measure: the King's Health Questionnaire. Med Decis Making 2008,28:113-126.

 

Written by:
Salvador Arlandis-Guzman,a Carlos Errando-Smet,b Jeffrey Trocio,c Daniel Arumi,d and Javier Rejase as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.

  1. Department of Urology, Hospital Universitario La Fe, Valencia, Spain;
  2. Female and Functional Urology Department. Fundacion Puigvert, Barcelona, Spain;
  3. Pfizer Inc., New York, NY, USA;
  4. Pfizer Inc Europe, Alcobendas, Madrid, Spain;
  5. Health Economics and Outcomes Research Department, Pfizer España, Alcobendas (Madrid), Spain.

 

Cost-effectiveness analysis of antimuscarinics in the treatment of patients with overactive bladder in Spain: A decision-tree model - Abstract

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