Evidence and Hypothesis in Clinical Medical Science by John Alexander Pinkston

Author:John Alexander Pinkston
Language: eng
Format: epub, pdf
ISBN: 9783030442705
Publisher: Springer International Publishing

2.Was allocation adequately concealed?

3.Was knowledge of allocated intervention adequately prevented during the trial from patients, personnel, and outcome assessors (i.e., adequate “blinding”)?

4.Were incomplete outcome data adequately addressed?

5.Are reports of the trial free of suggestion of selective outcome reporting?

6.Was the trial apparently free of other sources of bias (e.g. similarity of patients’ characteristics at baseline)?

An example of one of the analyses that were performed in this review is that of five RCTs involving 1388 patients that compared the combination of chemotherapy alone and chemotherapy plus radiotherapy with the same number of chemotherapy cycles in both arms. The statistic used to report results was the hazard ratio (HR), which was 0.42 for progression free survival (95% C.I. 0.25–0.72; p = 0.001), and 0.48 for overall survival (95% C.I. 0.22–1.06; p = 0.07) for patients receiving radiotherapy plus chemotherapy compared with those receiving chemotherapy alone. The authors considered their evidence to be of moderate quality. They concluded that the addition of radiotherapy to chemotherapy improves progression free survival but probably has little or no effect on overall survival in early stage adult Hodgkin lymphoma. In the weight of evidence account, the weight of evidence for an improvement in progression free survival would be moderately strong, and the weight of evidence for an improvement in overall survival would be weak to none.

It is worthwhile noting here, however, that although meta-analysis as a method of deriving estimates of effect from the aggregation of data from several individual studies is widely used, it has sometimes been considered to be a controversial analytic method. There have, for example, been instances where different meta-analyses of the same evidence have produced different results.1

For etiologic studies where several studies comprise the evidence, an example that illuminates the weight of evidence account is provided by IARC reviews.

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