Andrew D. Oxman

Laboratory diagnosis of iron-deficiency anemia: an overview.

BACKGROUND AND METHODS To determine the diagnostic values of laboratory tests used in the diagnosis of iron-deficiency anemia, the authors conducted a systematic overview of the relevant literature. Computerized searches of the MEDLINE database yielded 1,179 potentially relevant citations. Fifty-five studies included the results of laboratory tests and histologic examination of the bone marrow for at least 50% of an identifiable patient group. In these 55 studies, quality was assessed and descriptive information concerning the study populations, the tests conducted, and the results was extracted, all in duplicate. RESULTS Serum ferritin radioimmunoassay was by far the most powerful test, with an area under the receiver operating characteristic curve of 0.95. Test properties differed for populations of patients with inflammatory, liver, or neoplastic disease and patients without these conditions. Likelihood ratio lines, which allow precise interpretation of results across the entire range of ferritin concentration values, were constructed for the individual populations. CONCLUSION Serum ferritin radioimmunoassay is an extremely powerful test for the diagnosis of iron-deficiency anemia and, appropriately interpreted, can be applied to the complete range of patients.

Agreement among reviewers of review articles.

OBJECTIVE To assess the consistency of an index of the scientific quality of research overviews. DESIGN Agreement was measured among nine judges, each of whom assessed the scientific quality of 36 published review articles. ITEM SELECTION: An iterative process was used to select ten criteria relative to five key tasks entailed in conducting a research overview. SAMPLE The review articles were drawn from three sampling frames: articles highly rated by criteria external to the study; meta-analyses; and a broad spectrum of medical journals. JUDGES: Three categories of judges were used: research assistants; clinicians with research training; and experts in research methodology; with three judges in each category. RESULTS The level of agreement within the three groups of judges was similar for their overall assessment of scientific quality and for six of the nine other items. With four exceptions, agreement among judges within each group and across groups, as measured by the intraclass correlation coefficient (ICC), was greater than 0.5, and 60% (24/40) of the ICCs were greater than 0.7. CONCLUSIONS It was possible to achieve reasonable to excellent agreement for all of the items in the index, including the overall assessment of scientific quality. The implications of these results for practising clinicians and the peer review system are discussed.

Laboratory diagnosis of iron-deficiency anemia

Background and methods:To determine the diagnostic values of laboratory tests used in the diagnosis of iron-deficiency anemia, the authors conducted a systematic over-view of the relevant literature. Computerized searches of the MEDLINE database yielded 1,179 potentially relevant citations. Fifty-five studies included the results of laboratory tests and histologic examination of the bone marrow for at least 50% of an identifiable patient group. In these 55 studies, quality was assessed and descriptive information concerning the study populations, the tests conducted, and the results was extracted, all in duplicate.Results:Serum ferritin radioimmunoassay was by far the most powerful test, with an area under the receiver operating characteristic curve of 0.95. Test properties differed for populations of patients with inflammatory, liver, or neoplastic disease and patients without these conditions. Likelihood ratio lines, which allow precise interpretation of results across the entire range of ferritin concentration values, were constructed for the individual populations.Conclusion:Serum ferritin radioimmunoassay is an extremely powerful test for the diagnosis of iron-deficiency anemia and, appropriately interpreted, can be applied to the complete range of patients.

Effectiveness of steroid therapy in acute exacerbations of asthma: A meta-analysis

The objective of this study was to determine the effect of steroid therapy on pulmonary function, admission rates, and relapse rates in patients presenting with acute exacerbations of asthma. Computerized MEDLINE and SCIENCE CITATION searches were combined with review of reference lists from book chapters and articles to identify published randomized trials on steroid interventions. Over 700 articles were reviewed by two independent reviewers who identified 30 relevant randomized controlled trials for analysis. Study validity was independently assessed by two reviewers and information regarding populations, interventions, and outcomes was abstracted. Binary outcomes were combined and reported as odds ratios (OR), using the Mantel-Haenszel method. Individual and pooled effect sizes (ES) were determined for pulmonary function data. The authors found that the use of steroids early in the treatment of asthmatic exacerbations reduces admissions in adults (common OR 0.47; 95% confidence interval (CI) 0.27, 0.79) and children (OR 0.06-0.42). They found steroids effective in preventing relapse in the outpatient treatment of asthmatic exacerbations (OR 0.15; CI 0.05, 0.44). Oral and intravenous steroids appear to have equivalent effects on pulmonary function in acute exacerbations (ES -0.07; CI -0.39, 0.25). The authors conclude that overall, steroid therapy provides important benefits to patients presenting to emergency departments with acute exacerbations of asthma. Further research into dosage, alternative routes of administration, and alternative outcome measures is needed.

To what extent do congestive heart failure patients in sinus rhythm benefit from digoxin therapy? A systematic overview and meta-analysis

PURPOSE To reappraise the effectiveness of digoxin for the treatment of congestive heart failure (CHF) in patients with sinus rhythm in light of data from recently published randomized controlled trials and to quantitatively assess its usefulness. STUDY IDENTIFICATION Computerized searches of the MEDLINE database were performed, and the reference list of each retrieved article was reviewed. STUDY SELECTION Review of more than 360 citations and the reference lists of 19 review articles and 61 potentially relevant articles revealed seven double-blind randomized controlled trials that were included in this overview. DATA EXTRACTION Study quality was assessed and descriptive information concerning the study populations, the specific interventions, and clinically relevant outcome measurements was extracted. RESULTS OF DATA SYNTHESIS The common odds ratio for CHF deterioration while receiving digoxin versus placebo was 0.28, with a 95% confidence interval of 0.16 to 0.49. Predictors of digoxin benefit included presence of a third heart sound and the severity and duration of CHF. CONCLUSION Data from seven trials of high methodologic quality suggest that, on average, one out of nine patients with CHF and sinus rhythm derive a clinically important benefit from digoxin (with a 95% confidence interval of 1/33 to 1/5).

An index of scientific quality for health reports in the lay press

Although the quality of health reporting has been criticized for being unscientific, evaluations of health care reporting have been limited by the lack of a reliable and credible measure of scientific quality. We developed an index of scientific quality (ISQ) for health-related news reports and tested its reliability and sensibility. Items were generated from a survey of the literature and experts in research methodology. Items that were unclear, confusing or discriminated poorly between articles of high and low scientific quality were revised or deleted in an iterative process wherein potential criteria were independently applied to samples of 5 to 15 articles by 6 raters. To test the reliability of the final criteria 60 articles were drawn from three sampling frames: newspapers, magazines, and professional journals. Articles were intentionally selected to obtain a wide range of quality and topics. Two categories of raters were used: research assistants and physicians with research training. All 6 raters assessed all 60 articles. The sensibility of the index was tested by a questionnaire with 13 items related to face validity and content validity as well as other aspects of sensibility. The questionnaire was completed by 20 researchers and 13 health and science writers. The final ISQ includes 7 items that address the extent to which a report allows readers to draw conclusions about the applicability, validity and practical importance of the information that is reported. Chance corrected agreement (kappa) among all 6 raters for overall scientific quality was 0.62 (SE 0.02). The index was found to be sensible with only one major problem, the need for judgment in making ratings. While some degree of subjectivity appears to be inevitable in rating the scientific quality of health reports, the ISQ is acceptable reliable and credible and should be useful for evaluating and improving the scientific quality of health reporting.

An assessment of the sensibility of a quality-of-life instrument.

The objective of this study was to assess the sensibility of an asthma quality-of-life questionnaire (AQLQ); therefore, a structured survey of asthma patients seen in Hamilton, Ontario, emergency departments and physicians involved in asthma management was performed. Twenty-five consecutive patients who had completed the AQLQ questionnaire twice during a 7- to 10-day pilot study assessed sensibility using a 12-item questionnaire. The same number of practicing physicians from four centers in Ontario were sent the asthma AQLQ questionnaire and were asked to complete a 13-item sensibility form. All patients who were approached successfully completed the sensibility assessment; 80% (20 of 25) of the practicing physicians completed the assessment. Mean response scores were more than 5 of a possible 7 points in all questions for both groups. Patients had more mean responses greater than 6 (7 of 12) than did physicians (2 of 13). The AQLQ seems acceptable and sensible to both patients and physicians. A formal assessment of the sensibility of an outcome measurement can provide valuable information regarding its use. Both research and clinical outcomes should be subjected to this form of evaluation.