Illustrating Economic Evaluation of Diagnostic Technologies: Comparing Helicobacter pylori Screening Strategies in Prevention of Gastric Cancer in Canada

Objective

The aim of this paper is to present an economic evaluation of diagnostic technologies using Helicobacter pylori screening strategies for the prevention of gastric cancer as an illustration.

Methods

A Markov model was constructed to compare the lifetime cost and effectiveness of 4 potential strategies: no screening, the serology test by enzyme-linked immunosorbent assay (ELISA), the stool antigen test (SAT), and the ¹³C-urea breath test (UBT) for the detection of H. pylori among a hypothetical cohort of 10,000 Canadian men aged 35 years. Special parameter consideration included the sensitivity and specificity of each screening strategy, which determined the model structure and treatment regimen. The primary outcome measured was the incremental cost-effectiveness ratio between the screening strategies and the no-screening strategy. Base-case analysis and probabilistic sensitivity analysis were performed using the point estimates of the parameters and Monte Carlo simulations, respectively.

Results

Compared with the no-screening strategy in the base-case analysis, the incremental cost-effectiveness ratio was $33,000 per quality-adjusted life-year (QALY) for the ELISA, $29,800 per QALY for the SAT, and $50,400 per QALY for the UBT. The probabilistic sensitivity analysis revealed that the no-screening strategy was more cost effective if the willingness to pay (WTP) was <$20,000 per QALY, while the SAT had the highest probability of being cost effective if the WTP was >$30,000 per QALY. Both the ELISA and the UBT were not cost-effective strategies over a wide range of WTP values.

Conclusion

Although the UBT had the highest sensitivity and specificity, either no screening or the SAT could be the most cost-effective strategy depending on the WTP threshold values from an economic perspective. This highlights the importance of economic evaluations of diagnostic technologies.

Introduction

A health technology is any method or intervention used to prevent, diagnose, and treat disease or to improve rehabilitation and long-term care. Health technology assessment (HTA) is a systematic evaluation of the technical performance, safety, clinical efficacy, cost-effectiveness, and social and ethical considerations of the application of a health technology [1]. An economic evaluation is thus an integrated component of any HTA and provides evidence on the cost-effectiveness of new technologies to inform decision making.

Although they share the same underlying principles and methodologies, economic evaluations of diagnostic technologies have unique characteristics compared with evaluations of other types of health technologies (eg, drugs). For example, the performance parameters of diagnostic technologies (ie, sensitivity and specificity) are key factors that are incorporated into evaluations. These parameters determine who will be treated and which treatment options will be selected and consequently model structure, costs, and outcomes of patients. In this paper, we present an example of an economic evaluation illustrating the use of Helicobacter pylori screening strategies for the prevention of gastric cancer in Canada. The methodologies used in this paper can be applied to other diagnostic technologies.

Gastric cancer is the second leading cause of cancer death worldwide [2]. It leads to a substantial increase in health care resource utilization and reduction in the quality of life [3, 4]. Helicobacter pylori was classified as a class I carcinogen by the International Agency for Research on Cancer in 1994 [5], and an H. pylori infection is thus an important risk factor for gastric cancer (distal) [6, 7, 8]. Nearly 50% of the world's population has been estimated to be infected by H. pylori [9]. Although the prevalence of the infection has dropped in developed countries [10], a substantial proportion of the Canadian population is still infected [11]. The early detection and eradication of H. pylori infection may represent a significant opportunity for gastric cancer prevention [12]. Helicobacter pylori can be diagnosed by noninvasive techniques, including the serology test by the enzyme-linked immunosorbent assay (ELISA), the stool antigen test (SAT), and the ¹³C-urea breath test (UBT) [13]. However, the choice among these alternatives varies across countries. European guidelines recommend both the UBT and the SAT for H. pylori diagnosis, while the serology test is to be used only under certain conditions [14, 15]. The Canadian Helicobacter Study Group recommended the UBT as the diagnostic method of first choice, although the serology test is still widely used in Canada [16]. The SAT has not been accepted as an alternative to the UBT in Canada [16]. Currently, there is no economic evidence available to compare these tests for the prevention of gastric cancer in Canada.

The objective of this study was to illustrate economic evaluation of diagnostic technologies by estimating the cost-effectiveness of different H. pylori screening strategies for the prevention of gastric cancer in Canada. It may not reflect the repeat-screening strategy adopted in current clinical practice and the potential for reinfection and reeradication of H. pylori over time.