A comparison of cost per case detected of screening strategies for Type 2 diabetes and impaired glucose regulation: Modelling study

Abstract

Background

To determine a cost per case detected for different screening strategies for both Type 2 diabetes alone and in combination with impaired glucose regulation.

Methods

Bayesian framework modelling study using data from the ADDITION-Leicester screening study in UK multi-ethnic primary care setting. There were 5794 people aged 40–75 years (77.4% white European; 22.6% south Asian) without previously known diabetes. We compared 212 screening strategies including blood tests, a computer practice data score and a risk score, as part of a multi-stage process that all used an oral glucose tolerance test as the diagnostic test. Simulation models were created using sensitivity estimates for the expected cost per case.

Results

The estimated costs per case identified for the 18 most sensitive strategies varied from £457 to £1639 (€526–1886, for £1 = €1.15) for diabetes and £148–913 (€170–1050) for both diabetes and impaired glucose regulation. The lowest costing diabetes strategies ranged from £457 to £523 (€526–601) involving a two-stage screening strategy, a non-invasive risk stratifying tool followed by a blood test, producing sensitivities ranging from 67.1 to 82.4%.

Conclusion

Screening a population using a non-invasive risk stratification tool followed by a screening blood test is the most cost-effective method of screening for diabetes and abnormal glucose tolerance.

Introduction

Vascular disease which includes Type 2 diabetes mellitus, cardiovascular disease and chronic kidney disease accounts for 36% of all deaths in developed countries [1]. Type 2 diabetes and its associated long term complications can cost developed nations up to 10% of its financial budget, as well decreasing quality of life and length of life by up to ten years [2]. An estimated 30–50% of people with diabetes are currently undiagnosed [3], and at presentation some 20–30% already has developed complications [4]. Therefore there is emphasis on detecting Type 2 diabetes early in its disease course, especially as the average delay between developing this condition and its eventual diagnosis can be up to seven years [5].

Early detection of diabetes will identify individuals who can be targeted for lifestyle and therapeutic intervention to delay the onset of complications. Furthermore, screening for Type 2 diabetes is feasible and identifies people with a large burden of modifiable cardiovascular risk factors [6]. A strategy of screening for diabetes together with its hyperglycaemic precursor, impaired glucose regulation is suggested to be more cost effective in the long term [7] and is recommended in some national guidelines, as it subsequently facilitates the prevention of diabetes strategies [8], [9], [10]. A recent report suggested the best age to start screening from is 30 years old [11]. However, there is still some debate over the most sensitive and cost-effective method for screening for diabetes.

There are a number of tests available for screening and diagnosing Type 2 diabetes and impaired glucose regulation (also termed prediabetes: impaired fasting glucose and/or impaired glucose tolerance using World Health Organisation, WHO, 1999 diagnostic criteria). These include the oral glucose tolerance test, the fasting plasma glucose test, glycated haemoglobin (HbA1c) and a number of specifically developed risk scores, such as the FINDRISC [12], [13], [14]. These tests can be used individually or in combination as part of a multi-stage strategy. Recently, the WHO recommended HbA1c as a diagnostic tool for Type 2 diabetes but not for impaired glucose regulation [14]. Although there is no consensus on the most accurate screening test for detection of diabetes, the oral glucose tolerance test is often considered the standard diagnostic test for comparison of clinical outcome measures including sensitivity and specificity. However, the oral glucose tolerance test is considered more expensive, inconvenient and cumbersome to both patients and clinical staff in comparison to some of the other available options [15]. Therefore to determine the best screening strategies to implement in clinical practice, other factors including cost-effectiveness, practicality and acceptability to patients should be considered.

This study focuses on the screening options available for Type 2 diabetes alone and in combination with impaired glucose regulation and associated costs. Screening for impaired glucose regulation allows for preventative strategies such as lifestyle or pharmacological interventions to be implemented, which have been shown to be cost-effective in reducing progression rates to diabetes [16]. Our aim is to determine a cost comparison of available and feasible screening strategies to identify the best approaches for identifying people with Type 2 Diabetes and impaired glucose regulation in a community setting.