Clinical Trials

Clinical Trials: A Practical Guide ■❚❙❘ratios (0.99 for our row). Detailed reading of the statistical methods section statesthat the authors have adjusted their odds ratios for the stratification variables,namely age group, the side of the body affected by the stroke, time torandomization, and type of stroke – hence the reason for the discrepancy betweenthe two ratios. Ideally, this adjustment should have been noted in a footnote tothe table.The text also explains the reason for the missing numbers against the “globaloutcome” (because it is a composite odds ratio for death or disability), whichmight again have been included in a table footnote. The figure within the tablegives no additional information to the text of the table (representing merely theodds ratios and CIs graphically), but presents it in a more user-friendly way,allowing the reader to quickly appreciate which outcomes are improved by theactive treatment.In this example, there is a slight suggestion that the death rate is increased, sincethe estimated odds ratio is above 1, as well as most of the CI. However, the factthat the CI does encompass the odds ratio of 1 (ie, from 0.98 to 1.53) and theP-value = 0.07 (ie, >0.05) suggests that this is also compatible with no differencein death rates between the treated and control arms. Most other outcomes,including the global outcome, show very little difference between the two arms,with CIs including the odds ratio of 1, and nothing approaching statisticalsignificance. For key outcome results, it is becoming traditional to present thisvery useful combination of both a figure and table.On occasions it is necessary to incorporate subheadings within a table. Table 2shows an example of such a table, based on cost data from a randomized trialfor the evaluation of a new model of routine antenatal care. The costs areappropriately reported separately for each country and also separately, usingsubheadings, for the provider’s costs and the costs borne by the women. As well asgiving descriptive statistics for the costs according to treatment (ie, means andstandard deviations), the table also directly reports a comparison between the twomodels, ie, the authors quote a mean difference with 95% CIs. The use of thissummary measure means that the reader can deduce the mean cost saving thatwould accrue by using the new method on, say, 100 women (by multiplying themean difference in costs by 100), and the level of precision of this estimate,based on differing costs for different women (ie, attributable to sampling variation,as reported in the 95% CI).The cost units are given in the footnotes (since they do not apply to all the datain any one column), as well as detailed information needed to interpret thisinformation fully, namely on how local currencies were converted into US$. Such395