Cost-effectiveness of interventions to prevent and control diabetes mellitus: a systematic review

Methodological quality of the review: Medium confidence

Author: Li R, Zhang P, Barker LE, Chowdhury FM, Zhang X.

Region: United States of America (USA), Australia, Japan, Canada, Europe (including France, Germany, Switzerland, United Kingdom (UK), Sweden, Austria, Spain).

Sector: Diabetes mellitus

Sub-sector: Cost-effectiveness, prevention, control, complications, interventions

Equity focus: None specified

Review type: Systematic review

Quantitative synthesis method: Narrative analysis

Qualitative synthesis methods: Not applicable

Background

Many interventions can reduce the harm of diabetes. However, health care resources are limited, and therefore interventions for diabetes prevention and control should be prioritized. Cost-effectiveness analysis is a useful tool for the purpose of this review.

Research objectives

‘To synthesize the cost-effectiveness (CE) of interventions to prevent and control diabetes, its complications, and comorbidities.’  

Main findings

A total of 56 studies were included in the review. Only one study was conducted in a developing country (Thailand), the remaining studies were conducted in developed countries: USA, Australia, Japan, Canada, European countries including France, Germany, Switzerland, UK, Sweden, Austria and Spain.

The interventions evaluated in these CE studies covered a wide range: lifestyle and medication therapy to prevent type 2 diabetes among high-risk individuals (eight studies); screening for undiagnosed type 2 diabetes or gestational diabetes mellitus (GDM) (three studies); intensive glycemic control (12 studies); self -monitoring of blood glucose (one study); intensive hypertension control (four studies); statin therapy for cholesterol control (five studies); smoking cessation (one study); diabetic health education programme (two studies); diabetes disease management programme (two studies); screening to prevent diabetic retinopathy (five studies); optimal foot care to prevent foot ulcer and amputation (two studies); ACE inhibitor (ACEI) or angiotensin receptor blocker (ARB) therapy to prevent diabetic end-stage renal diseases (ESRD) (15 studies); comprehensive interventions using a combination of several of the above secondary prevention interventions (two studies); and interventions treating diabetic retinopathy and foot ulcers (two studies). The methodology of the studies included in the review were not reported.

Authors reported the following as ‘cost saving’ (defined as an intervention that generates a better health outcome and costs less than the comparison intervention):

1. ACE inhibitor (ACEI) therapy for intensive hypertension control compared with standard hypertension control;
2. ACEI or angiotensin receptor blocker (ARB) therapy to prevent end-stage renal disease (ESRD) compared with no ACEI or ARB treatment;
3. Early irbesartan therapy (at the microalbuminuria stage) to prevent ESRD compared with later treatment (at the macroalbuminuria stage);
4. comprehensive foot care to prevent ulcers compared with usual care;
5. multi-component interventions for diabetic risk factor control and early detection of complications compared with conventional insulin therapy for persons with type 1 diabetes; and
6. multi-component interventions for diabetic risk factor control and early detection of complications compared with standard glycemic control for persons with type 2 diabetes.

The following were reported as very cost-effective (defined as 0 < ICER ≤ $25,000 per Quality Adjusted Life Year (QALY) or Life Year Gained (LYG)):

1. Intensive lifestyle interventions to prevent type 2 diabetes among persons with impaired glucose tolerance compared with standard lifestyle recommendations;
2. Universal opportunistic screening for undiagnosed type 2 diabetes in African Americans between 45 and 54 years old;
3. Intensive glycemic control as implemented in the UK Prospective Diabetes Study in persons with newly diagnosed type 2 diabetes compared with conventional glycemic control;
4. Statin therapy for secondary prevention of cardiovascular disease compared with no statin therapy;
5. Counselling and treatment for smoking cessation compared with no counselling and treatment;
6. Annual screening for diabetic retinopathy and ensuing treatment in persons with type 1 diabetes compared with no screening;
7. Annual screening for diabetic retinopathy and ensuing treatment in persons with type 2 diabetes compared with no screening;
8. Immediate vitrectomy to treat diabetic retinopathy compared with deferred vitrectomy.

Authors noted that many interventions intended to prevent/control diabetes were cost saving or very cost-effective and supported by strong evidence. Policy makers should consider giving these interventions a higher priority. More studies were needed to evaluate the CE of interventions that fell in the ‘supportive’ evidence category of this review. For studies with weaker efficacy data, further efficacy trials were needed. There were 38 interventions recommended by the ADA but they had not been evaluated for their CE or the studies did not meet the inclusion criteria for this review, therefore studies that were excluded in this review should be assessed.  More studies were needed that evaluate CE in real-world settings and to evaluate the CE of public policy changes.

Methodology

Authors included studies which reported: (1) original CE analysis; (2) intervention directed toward patients with type 1, type 2, or gestational diabetes mellitus and recommended in the 2008 ADA standards for medical care; (3) outcomes were measured as LYG or QALYs; and (4) publication written in English conducted between January 1985 and May 2008. Only studies assessed as ‘good’ or ‘excellent’, according to a 13-item quality-assessment tool, were included.

Authors searched MEDLINE, EMBASE, CINAHL, PsycINFO, Social Abstracts, Web of Science and Cochrane databases. Authors created a search strategy involving medical subject headings indicating diabetes (for example, “type 1 diabetes”, “type 2 diabetes”), costs (for example, “costs or expenditure”), effectiveness (for example, “benefit” or “life years”) and CE analysis (combining words for costs and key words for effectiveness).  Reference lists of all included studies were screened and also Diabetes Care was manually reviewed for additional citations.

Authors reported the study results in two ways: summarizing the key features and results for each included study; and synthesizing the CE of the interventions based on the classifications criteria. Interventions were classified as cost saving, very cost-effective, cost-effective or not cost-effective.

Applicability/external validity

The authors did not discuss the applicability/external validity of the results. Nevertheless, authors acknowledged that conclusions of this review are based on information up to May 2008.  Since then, more studies have been published which could change the conclusions of this review.

Geographic focus

This review focus on a variety of countries, although out of 56 studies, only one was conducted in a developing country. Authors did not discuss or describe the applicability of the results in low- and middle- income countries.

Quality assessment

Authors conducted a thorough literature search of the literature to ensure that all relevant studies were included in the review, despite limiting the search to articles written in English only. It was not possible to conclude if selection bias was avoided within the review and if authors used appropriate criteria to assess the quality of the studies included due to the lack of details. Also, it was not possible to determine the reliability of the reported results as authors did not state if data extraction was conducted by two reviewers. Nevertheless, authors acknowledged the limitations of this study and state that this review’s conclusion should be used with caution.

Therefore, a medium confidence was awarded to this review in the methods used to analyse the findings relative to the primary question addressed in the review.