Study population Hypothetical patients with suspected internal derangement of the shoulder.

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1 Internal derangements of the shoulder: decision tree and cost-effectiveness analysis of conventional arthrography, conventional MRI, and MR arthrography Oh C H, Schweitzer M E, Spettell C M Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Strategies to diagnose internal derangement of the shoulder. Type of intervention Diagnosis. Economic study type Cost-effectiveness analysis. Study population Hypothetical patients with suspected internal derangement of the shoulder. Setting Outpatient hospital setting. The study was carried out in the USA. Dates to which data relate Effectiveness and resource use data were collected from studies published between 1989 and Cost data were collected from a 1996 source. The price year was Source of effectiveness data Effectiveness data were derived from a literature review and expert opinion. Modelling A decision analytic model was used to determine the cost-utility of the three diagnostic strategies. Outcomes assessed in the review The review assessed the following outcomes: prevalence of RCTs and tears, and the sensitivity and specificity of the diagnostic tests. Study designs and other criteria for inclusion in the review English language medical publications from 1985 to 1997 were searched for papers reporting on the diagnosis and treatment of rotator cuff tears and labral tears. Page: 1 / 5

2 Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Individual data. Number of primary studies included At least 26 studies were included in the review. Methods of combining primary studies Meta-analysis: data estimates were pooled and a weighted average was used. Investigation of differences between primary studies Results of the review Prevalence results were as follows: full-thickness RCTs, 0.1; partial-thickness RCTs, 0.1; labral tears, 0.1; absence of tears in patients who present with internal derangement, 0.7. The sensitivity of single-contrast arthrography for detecting full-thickness RCTs was 99% and specificity was 94%. The sensitivity of single-contrast arthrography for detecting partial-thickness RCTs was 0.4. The sensitivity of doublecontrast arthrography for detecting partial-thickness RCTs was Methods used to derive estimates of effectiveness Estimates of effectiveness were also based on expert opinion. Estimates of effectiveness and key assumptions The true positive rate for detecting labral tears using single- or double-contrast arthrography was 0.1. Any true negative or positive diagnosis of full-thickness RCT, partial-thickness RCT, or labral tear was given a utility value of 1. The false positive diagnosis of any tear had a utility of -1. A false negative diagnosis of full-thickness RCT or labral tear had a utility value of -1. Any false negative diagnosis of partial-thickness RCT had a utility value of Measure of benefits used in the economic analysis Utility values, based on the authors' assumptions reported above, were used to represent the effectiveness of each strategy. Page: 2 / 5

3 Direct costs Direct costs were not discounted given the short time frame of the study (less than 1 year). Quantities and costs were reported separately. Direct costs measured the costs of the alternative imaging strategies and surgical interventions. The quantity/cost boundary adopted was that of the hospital. The estimation of quantities and costs was based on actual data. Charges were taken from the 1997 Medicare Part B Fee Schedule for Pennsylvania, Metropolitan DC, New Jersey and Delaware providers. The price year was Statistical analysis of costs Not reported. Indirect Costs Not included. Currency US dollars ($). Sensitivity analysis Sensitivity analyses were conducted on the sensitivity of single-contrast arthrography for detecting partial-thickness RCTs and labral tears, the sensitivity of double-contrast arthrography for detecting partial-thickness RCTs and labral tears, and the prevalence of each disease state in the population. Estimated benefits used in the economic analysis The effectiveness of double-contrast arthrography was , of conventional MRI was , and of MR arthrography was Cost results Average costs for double-contrast arthrography were $1,090, for conventional MRI were $2,033, and for MR arthrography were $2,339. Synthesis of costs and benefits The marginal cost-effectiveness of conventional MRI and MR arthrography over double-contrast arthrography was $89,895 and $21,029. These results were sensitive to the prevalence of each disease state in the population. Authors' conclusions Arthrography performed with admixed diluted gadolinium, which if negative is immediately followed by MRI, had the highest cost-effectiveness. Conventional arthrography was less expensive, but had severely limited effectiveness. CRD COMMENTARY - Selection of comparators A justification was given for the comparators used, namely diagnostic methods currently under debate. You, as a user of this database, should decide if these health technologies are relevant to your own setting. Validity of estimate of measure of benefit The authors adopted a systematic approach to classifying relevant data for their model. The methods and conduct of the review were satisfactorily reported. The effectiveness estimates were combined using reliable approaches such as metaanalysis and data pooling. Effectiveness estimates were derived credibly from the primary studies. The utility scores Page: 3 / 5

4 adopted for each outcome (true/false results) have reasonable coherence but assigning values in this manner is subjective and predicates the outcome. Validity of estimate of costs All categories of costs relevant to the perspective adopted were included. Inpatient hospital costs were not included. Costs such as productivity costs and rehabilitation costs were not considered. Quantities and costs were reported separately. Limitations include the fact that no sensitivity analysis was conducted on quantities or costs and that charges were used to proxy prices. The price year was, however, reported. Other issues The authors did make appropriate comparisons of their findings with those from other studies and the issue of generalisability to other settings was addressed. The authors do not appear to have presented their results selectively. The study examined patients with suspected internal derangement of the shoulder and this was reflected in the authors' conclusions. The proposed hypothetical protocol would pose problems in terms of practical implementation and would differ from typical practice, making it more difficult for clinicians to accept. Medicare charges may not adequately reflect the costs of physician time. The majority of primary studies used patient populations that were not fully representative of the spectrum of patients on whom these tests might be used. Little evidence was available on the accuracy of single- and double-contrast conventional arthrography. Implications of the study The use of conventional arthrography performed with admixed diluted gadolinium, which if negative, is followed by MRI, is both more expensive and more effective than conventional MRI. The added costs are reduced as the prevalence of labral tears increase in the population. Source of funding Supported by the RSNA Research and Education Fund. Bibliographic details Oh C H, Schweitzer M E, Spettell C M. Internal derangements of the shoulder: decision tree and cost-effectiveness analysis of conventional arthrography, conventional MRI, and MR arthrography. Skeletal Radiology 1999; 28(12): PubMedID Indexing Status Subject indexing assigned by NLM MeSH Algorithms; Arthrography /economics; Contrast Media; Cost-Benefit Analysis; Decision Support Techniques; Gadolinium; Humans; Magnetic Resonance Imaging /economics /methods; Rotator Cuff /injuries; Sensitivity and Specificity; Shoulder Joint /pathology /radiography; Wounds and Injuries /diagnosis /economics /radiography AccessionNumber Date bibliographic record published 31/10/2000 Date abstract record published Page: 4 / 5

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