Accuracy and cost-effectiveness of diagnostic testing in patients with abdominal pain in general practice: a decision model based on systematic reviews
12 / 2005 - 12 / 2008
OBJECTIVES: 1) T o summarise evidence on diagnostic accuracy of patient history, physical examination, relevant laboratory tests, and ultrasonography in the classification of patients with non-acute abdominal pain in general practice. 2) To estimate the cost-effectiveness and cost-utility of diagnostic strategies in patients with abdominal pain in general practice using a decision analytical model. The general practitioner (GP) is consulted at least two times each week for abdominal pain. Specific causes are found in approximately 20% of all patients; serious disease (e.g. colorectal cancer) in only 5%. Diagnostic tests are frequently ordered, but are only of value if they add sufficient diagnostic information and influence management decisions by the GP. METHODS: Three sub-studies will be conducted to meet the objectives of the proposed research. First, systematic reviews are carried out or existing reviews are updated to summarise available evidence on the accuracy of diagnostic testing in patients with non-acute abdominal pain. Pooled estimates of diagnostic accuracy will be computed for history taking, physical examination, laboratory tests, and ultrasonography. Regression models are used to address the influence of potential sources of heterogeneity on diagnostic accuracy. Next, a decision analytical model is constructed to simulate all components of the clinical decision-making process. All relevant diagnostic strategies in patients with abdominal pain and all consequences arising from the initial choice of strategy (in terms of quality-adjusted life-years) are mapped out in diagnostic pathways. Missing information will be collected using both quantitative and qualitative methods. Finally, evaluations are carried out to study the cost-effectiveness of commonly used or preferred diagnostic tests in everyday general practice. Diagnostic testing for abdominal pain in everyday practice is assessed using data from the 2nd National Survey and interviews among GPs. The costs and effects of these commonly used or preferred decisions are compared to those of optimal diagnostic strategies obtained from the decision model.