Economic evaluation of therapeutic interventions to prevent Type 2 diabetes in Canada

AIMS

To compare the health and economic outcomes of using acarbose, an intensive lifestyle modification programme, metformin or no intervention to prevent progression to diabetes in Canadian individuals with impaired glucose tolerance (IGT).

METHODS

A model was developed to simulate the course of individuals with IGT under each treatment strategy. Patients remain in the IGT state or transition from IGT to diabetes, to normal glucose tolerance (NGT) or to death. Effectiveness and resource use data were derived from published intervention trials. A comprehensive health-care payer perspective incorporating all major direct costs, reported in 2000 Canadian dollars, was adopted.

RESULTS

Over a decade, 70 of the 1000 untreated patients are expected to die and 542 develop diabetes. Intensive lifestyle modification is estimated to prevent 117 cases of diabetes, while metformin would prevent 52 and acarbose 74 cases. The proportion of those who return to NGT also increases with any treatment. While lifestyle modification is more effective, it can increase overall costs depending on how it is implemented, whereas acarbose and metformin reduce costs by nearly $1000 per patient. Lifestyle modification was cost effective, varying from CAD $10 000/LYG vs. acarbose. Acarbose costs somewhat more than metformin, but is more effective: CAD $1798/LYG.

CONCLUSION

The results of this model suggest that the treatment of IGT in Canada is a cost-effective way to prevent diabetes and may generate savings. While pharmacological treatments tended to be less costly, intensive lifestyle modification, if maintained, led to the greatest health benefits at reasonable incremental costs.

Oxybutynin Extended Release and Tolterodine Immediate Release

OBJECTIVE

To evaluate the cost-effectiveness of a new extended-release (XL) formulation of oxybutynin relative to tolterodine immediate release (IR), currently the most prescribed treatment for overactive bladder in the UK.

METHODS

A state-transition model was developed to compare outcomes over 1 year. Effectiveness and treatment persistence data were derived from the OBJECT (Overactive Bladder: Judging Effective Control and Treatment) study, a 3-month clinical trial comparing oxybutynin XL 10 mg/day with tolterodine IR 4 mg/day. The daily costs of oxybutynin XL and tolterodine IR were pound0.82 and pound1.04, respectively. These data and information from the literature were used to project outcomes beyond the trial time. Severity-specific incontinence cost profiles were developed for the UK (2002 costings).

RESULTS

After 1 year, 3.1 more patients per 100 treated attained complete continence with oxybutynin XL compared with tolterodine IR, and 5.6% more had less than seven incontinent episodes per week. Over 1 year, patients receiving oxybutynin XL had almost 17 additional incontinence-free days and 95 fewer incontinent episodes. Estimated costs were pound86 lower per patient with oxybutynin XL. If drugs are priced equally, savings decrease to pound21 per patient. Oxybutynin XL maintains its advantage over wide ranges of inputs, and outcomes are similar if analyses are limited to 3 months.

CONCLUSION

Base-case analyses suggest that oxybutynin XL provides better effectiveness than tolterodine IR and reduces costs. Results indicate that oxybutynin XL is the dominant therapeutic option under a wide range of alternative inputs and assumptions.

Assessment of health economics in Alzheimer's disease (AHEAD): treatment with galantamine in the UK

OBJECTIVE

To assess the long-term health and economic impact of treating mild to moderate Alzheimer's disease (AD) with galantamine (16 mg or 24 mg per day) compared to no cholinesterase therapy in the UK.

METHODS

The long-term costs and outcomes were assessed using a model developed from longitudinal data on a cohort of AD patients. The model predicts the time until patients require full-time care, defined as the consistent requirement for a significant amount of care and supervision each day. Efficacy data were obtained from three clinical trials comparing galantamine with placebo, forecasts were made for ten years. Costs were determined in 2001 British pounds and discounted at 6% per annum, while outcomes such as time to full-time care were discounted at 1.5%.

RESULTS

Without pharmacological treatment, patients are expected to incur costs of 28,134 British pounds over ten years, 70% of costs accrue from providing full-time care. Galantamine (16 mg per day) is predicted to reduce the duration of the full-time care state by 12%; approximately five patients need to be treated to avoid one year of full-time care. The ten-year incremental costs per month of full-time care avoided average pound 192 British pounds per patient and 8,693 British pounds per QALY. Savings (1380 British pounds) are predicted for patients who continue treatment beyond six months and whose cognitive function is maintained or improved. Comparable results were estimated for the 24 mg dose.

CONCLUSION

In addition to the clinical benefits associated with galantamine treatment, the savings predicted from delaying when full-time care is needed may offset the treatment costs.

Assessment of health economics in Alzheimer's disease (AHEAD): galantamine treatment in Canada

BACKGROUND

Given the high costs of caring for patients with AD in Canada, it is important to evaluate the costs of new therapies that halt or delay the advancement of AD, relative to the savings associated with delaying disease progression.

METHODS

The Assessment of Health Economics in Alzheimer's Disease (AHEAD) model, which uses algorithms to predict the time until patients with AD require full-time care (FTC), was adapted to Canada to compare treatment with galantamine versus no pharmacologic treatment. Data from two clinical trials provided inputs into the algorithms, and forecasts were made for up to 10 years. Drug and health care costs were evaluated according to the stage of disease based on Quebec unit costs along with follow-up data from the Canadian Study of Health and Aging.

RESULTS

Galantamine is predicted to reduce the duration of FTC by almost 10%. Approximately 5.6 patients with mild to moderate disease must be placed on treatment to avoid one year of FTC, resulting in savings averaging $788 CAD ($528 USD) per patient. For patients with moderate disease, 3.9 patients must be placed on treatment to avoid one year of FTC, with savings predicted at $3718 CAD ($2533 USD) per patient.

CONCLUSION

Galantamine cannot only potentially increase the time before patients require FTC, but may also lead to overall savings because treatment costs are offset by reductions in other health care expenditures.

Assessment of health economics in Alzheimer's disease (AHEAD) based on need for full-time care

OBJECTIVE

To develop a framework for estimating the long-term health and economic consequences of AD based on patient characteristics at a given point in time.

METHODS

A pharmacoeconomic model (Assessment of Health Economics in Alzheimer's Disease, AHEAD) was developed based on equations that relate the probability of needing full-time care (FTC) over time to patient characteristics summarized in index scores. These equations were developed from published data on interquartile times until FTC is needed and until death, using nonlinear regressions of the resulting index-specific hazards. These equations were then incorporated into a hidden Markov framework that allows for calculation of expected time to FTC and to death, as well as of the economic consequences of disease progression. There are three major states in the model: not requiring FTC ("pre-FTC"), requiring FTC, and death.

RESULTS

Outcomes for five sample patients are derived to illustrate application of the AHEAD model. The impact of altering disease markers in these patients is also considered.

CONCLUSION

The need for a generally applicable tool to forecast long-term outcomes based on relatively short-term data is becoming increasingly acute with the advent of new therapies for AD. The AHEAD model provides a relatively simple framework for the prediction of time to FTC requirement based on short-term observed data such as those from clinical trials. Although subject to the uncertainties inherent in modeling, the model nevertheless provides a standard estimation technique that may facilitate comparisons between existing and emerging therapies.

Treatment of migraine in Canada with naratriptan: a cost-effectiveness analysis

OBJECTIVE

To evaluate the cost-effectiveness of naratriptan for the treatment of migraine in Canada.

BACKGROUND

The substantial disability brought on by migraine, coupled with the high prevalence of this disorder, leads to substantial costs. Naratriptan is a newly developed triptan shown to be effective in the treatment of migraine.

METHODS

Monte Carlo modeling techniques were used to simulate the experience of Canadian migraineurs over the course of 1 year. Data from a multinational study comparing oral naratriptan 2.5 mg to customary therapies were used in the cost-effectiveness analysis.

RESULTS

Naratriptan leads to an annual reduction in symptom duration of 225 hours compared to customary therapy not including other triptans. Reductions in lost productivity yield savings of Can $390 (1998 Canadian dollars) relative to customary therapy, which exceed the increase in drug costs resulting in overall savings of Can $109 per year.

CONCLUSIONS

The use of naratriptan in the treatment of migraine is an economically attractive option, leading to savings in overall costs. Increases in drug costs seem acceptable in light of reductions in symptom duration.

Diabetes in Canada: direct medical costs of major macrovascular complications

OBJECTIVES

To estimate direct medical costs of managing major macrovascular complications in diabetic patients.

METHODS

Costs were estimated for acute myocardial infarction (AMI) and ischemic stroke by applying unit costs to typical resource use profiles. Data were obtained from many Canadian sources, including the Ontario Case Cost Project, provincial physician and laboratory fee schedules, provincial formularies, government reports, and peer-reviewed literature. For each complication, the event costs per patient are those associated with resource use specific to the acute episode and any subsequent care occurring in the first year. State costs are the annual costs per patient of continued management. All costs are expressed in 1996 Canadian dollars.

RESULTS

Acute hospital care accounts for approximately half of the first year management costs ($15,125) of AMI. Given the greater need for postacute care, acute hospital care has less impact (28%) on event costs for stroke ($31,076). The state costs for AMI and stroke are $1544 and $8141 per patient, respectively.

CONCLUSIONS

Macrovascular complications of diabetes potentially represent a substantial burden to Canada's health care system. As new therapies emerge that may reduce the incidence of some diabetic complications, decision makers will need information to make critical decisions regarding how to spend limited health care dollars. Published literature lacks Canadian-specific cost estimates that may be readily translated into patient-level cost inputs for an economic model. This paper provides two key pieces of the many needed to understand the scope of the economic burden of diabetes and its complications for Canada.

Sumatriptan: economic evidence for its use in the treatment of migraine, the Canadian comparative economic analysis

The objective of this study was to evaluate economic and health effects of sumatriptan relative to customary therapy in Canada. The relationship between treatment and functionality was established based on analysis of existing data from a multinational study. A Monte Carlo model was developed to simulate 1 year for each of customary therapy and six sumatriptan formulations. Costs are expressed in 1998 Canadian dollars. Sumatriptan is expected to reduce the time spent with migraine symptoms and resulting time lost. Under customary therapy, the annual cost of lost time is estimated at pound908 ($1973). With sumatriptan, these costs ranged from pound406 ($882) with subcutaneous sumatriptan to pound577 ($1254) with nasal sumatriptan 10 mg, saving pound331-502 ($719-1091) in the annual cost of time lost. All these benefits are expected to be obtained at an additional drug cost ranging from pound869 ($1889) for subcutaneous sumatriptan to pound278 ($605) for sumatriptan suppository. The cost of sumatriptan treatment is significantly offset by a substantial reduction of costs associated with time lost due to migraine symptoms.

The migraine ACE model: evaluating the impact on time lost and medical resource Use

OBJECTIVE

To describe the Migraine Adaptive Cost-Effectiveness Model in the context of an analysis of a simulated population of Canadian patients with migraine.

BACKGROUND

The high prevalence of migraine and its substantial impact on patients' ability to function normally present a significant economic burden to society. In light of the recent availability of improved pharmaceutical treatments, a model was developed to assess their economic impact.

METHODS

The Migraine Adaptive Cost-Effectiveness Model incorporates the costs of time lost from both work and nonwork activities, as well as medical resource and medication use. Using Monte Carlo techniques, the model simulates the experience of a population of patients with migraine over the course of 1 year. As an example, analyses of a Canadian population were carried out using data from a multinational trial, surveys, national statistics, and the available literature.

RESULTS

Using customary therapy, mean productivity losses (amounting to 84 hours of paid work time, 48 hours of unpaid work time, and 113 hours of leisure time lost) were estimated to cost $1949 (in 1997 Canadian dollars) per patient, with medical expenditures adding an average of $280 to the cost of illness.

CONCLUSIONS

With customary treatment patterns, the costs of migraine associated with reduced functional capacity are substantial. The migraine model represents a flexible tool for the economic evaluation of different migraine treatments in various populations.