CoRA-67
Resource:Echinacea for treating the common cold: A randomized…
Resource:Echinacea for treating the common cold: A randomized controlled trial
ncbi.nlm.nih.gov/pmc/articles/PMC3056276/
Please USE the article above to help answer the following questions:
1. Did the study address a clearly focused issue? Yes or No and Why?
-HINT: An issue can be ‘focused’ In terms of the population studied Whether the study tried to detect a beneficial or harmful effect the risk factors studied
2. Did the authors use an appropriate method to answer their question? Yes or No and Why?
-HINT: Consider Is a case control study an appropriate way of answering the question under the circumstances Did it address the study question
3. Were the cases recruited in an acceptable way? Yes or No and why?
-HINT: We are looking for selection bias which might compromise validity of the findings are the cases defined precisely were the cases representative of a defined population (geographically and/or temporally) was there an established reliable system for selecting all the cases are they incident or prevalent is there something special about the cases is the time frame of the study relevant to disease/exposure was there a sufficient number of cases selected was there a power calculation
4. Were the controls selected in an acceptable way? Yes or No and why?
-HINT: We are looking for selection bias which might compromise the generalisability of the findings were the controls representative of the defined population (geographically and/or temporally) was there something special about the controls was the non-response high, could non-respondents be different in any way are they matched, population based or randomly selected was there a sufficient number of controls selected
5. Was the exposure accurately measured to minimise bias? Yes or No and WHY?
– HINT: We are looking for measurement, recall or classification bias was the exposure clearly defined and accurately measured did the authors use subjective or objective measurements do the measures truly reflect what they are supposed to measure (have they been validated) were the measurement methods similar in the cases and controls did the study incorporate blinding where feasible is the temporal relation correct (does the exposure of interest precede the outcome)
6. (a) Aside from the experimental intervention, were the groups treated equally?
-HINT: List the ones you think might be important, that the author may have missed genetic environmental socio-economic
(b) Have the authors taken account of the potential confounding factors in the design and/or in their analysis? Yes or No and WHY?
-HINT: Look for restriction in design, and techniques e.g. modelling, stratified-, regression-, or sensitivity analysis to correct, control or adjust for confounding factors
7. How large was the treatment effect?
-HINT: Consider what are the bottom line results is the analysis appropriate to the design how strong is the association between exposure and outcome (look at the odds ratio) are the results adjusted for confounding, and might confounding still explain the association has adjustment made a big difference to the OR
8. How precise was the estimate of the treatment effect?
-HINT: Consider size of the p-value size of the confidence intervals have the authors considered all the important variables how was the effect of subjects refusing to participate evaluated
9.Do you believe the results? Yes or No and WHY?
-HINT: Consider big effect is hard to ignore! Can it be due to chance, bias, or confounding are the design and methods of this study sufficiently flawed to make the results unreliable consider Bradford Hills criteria (e.g. time sequence, does-response gradient, strength, biological plausibility)
10.Can the results be applied to the local population? Yes or No and WHY?
-HINT: Consider whether the subjects covered in the study could be sufficiently different from your population to cause concern your local setting is likely to differ much from that of the study can you quantify the local benefits and harms
11. Do the results of this study fit with other available evidence? Yes or No and WHY?
-HINT: Consider all the available evidence from RCT’s Systematic Reviews, Cohort Studies, and Case Control Studies as well, for consistency
