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Screening for type 2 diabetes: literature review and economic modelling

By N. Waugh, G. Scotland, M. Gillet, A. Brennan, E. Goyder, R. Williams and A. John

Abstract

Objectives: To reconsider the aims of screening for\ud undiagnosed diabetes, and whether screening should be\ud for other abnormalities of glucose metabolism such as\ud impaired glucose tolerance (IGT), or the ‘metabolic\ud syndrome’. Also to update the previous review for the\ud National Screening Committee (NSC) on screening for\ud diabetes, including reviewing choice of screening test;\ud to consider what measures would be taken if IGT and\ud impaired fasting glucose (IFG) were identified by\ud screening, and in particular to examine evidence on\ud treatment to prevent progression to diabetes in these\ud groups; to examine the cost-effectiveness of screening;\ud and to consider groups at higher risk at which\ud screening might be targeted.\ud \ud Data sources: Electronic databases were searched up\ud to the end of June 2005.\ud \ud Review methods: Literature searches and review\ud concentrated on evidence published since the last\ud review of screening, both reviews and primary studies.\ud The review of economic studies included only those\ud models that covered screening. The new modelling\ud extended an existing diabetes treatment model by\ud developing a screening module. The NSC has a set of\ud criteria, which it applies to new screening proposals.\ud These criteria cover the condition, the screening test\ud or tests, treatment and the screening programme.\ud Screening for diabetes was considered using these\ud criteria.\ud \ud Results: Detection of lesser degrees of glucose\ud intolerance such as IGT is worthwhile, partly because\ud the risk of cardiovascular disease (CVD) can be\ud reduced by treatment aimed at reducing cholesterol\ud level and blood pressure, and partly because some\ud diabetes can be prevented. Several trials have shown\ud that both lifestyle measures and pharmacological\ud treatment can reduce the proportion of people with\ud IGT who would otherwise develop diabetes. Screening\ud could be two-stage, starting with the selection of\ud people at higher risk. The second-stage choice of test\ud for blood glucose remains a problem, as in the last\ud review for NSC. The best test is the oral glucose\ud tolerance test (OGTT), but it is the most expensive, is\ud inconvenient and has weak reproducibility. Fasting\ud plasma glucose would miss people with IGT. Glycated\ud haemoglobin does not require fasting, and may be the\ud best compromise. It may be that more people would\ud be tested and diagnosed if the more convenient test\ud was used, rather than the OGTT. Five economic\ud studies assessed the costs and short-term outcomes of\ud using different screening tests. None examined the\ud long-term impact of different proportions of false\ud negatives. All considered the costs that would be\ud incurred and the numbers identified by different tests,\ud or different cut-offs. Results differed depending on\ud different assumptions. They did not give a clear guide\ud as to which test would be the best in any UK screening\ud programme, but all recognised that the choice of cutoff\ud would be a compromise between sensitivity and\ud specificity; there is no perfect test. The modelling\ud exercise concluded that screening for diabetes appears\ud to be cost-effective for the 40–70-year age band, more\ud so for the older age bands, but even in the 40–49-year\ud age group, the incremental cost-effectiveness ratio for\ud screening versus no screening is only £10,216 per\ud quality-adjusted life-year. Screening is more costeffective\ud for people in the hypertensive and obese\ud subgroups and the costs of screening are offset in\ud many groups by lower future treatment costs

Publisher: HMSO
Year: 2007
OAI identifier: oai:eprints.whiterose.ac.uk:10716

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