Leggiamo un articolo insieme

Il razionale e i metodi

L’obiettivo

I metodi – la fonte dei dati

I metodi – definizione del primary outcome of the study

I metodi – definizione del campione

I metodi – le informazioni raccolte

L’analisi statistica

I risultati

Limitations

I risultati

Le conclusioni

Check-list for a critical review of papers on clinical trials  Design  Is the objective of the trial sufficiently described?  Is there a satisfactory description of diagnostic criteria for entry trial?  Is there a satisfactory description of source of subjects?  Are the treatments well defined?  Is random allocation to treatment used?  Is the method of randomisation described?

Check-list for a critical review of papers on clinical trials  Design  Is there an acceptable delay from allocation to commencement of treatment?  Is there a satisfactory statement of criteria for outcome measures?  Are the outcome measures appropriate?  Is there a power-based assessment of adequacy of sample size?  Is the duration of treatment follow-up stated?

Check-list for a critical review of papers on clinical trials  Conduct of trial  Are the treatment groups comparable in relevant measures ?  Are a high proportion of the subjects followed-up?  Did a high proportion of subjects complete treatment?  Are the drop-outs described?  Are side-effects of treatment reported?

Check-list for a critical review of papers on clinical trials  Analysis and presentation  Is there a statement adequately describing all statistical procedures used?  Are the statistical analyses used appropriately?  Are prognostic factors adequately considered?  Are confidence intervals given for the main results ?  Is the presentation clear and adequate to the objectives ?  Is the conclusion drawn from the statistical analysis justified?

A study bias (interpretation) – Example (1) “A surgical group recently reported that laparoscopic cholecystectomy had significantly lower rates of complications (primary outcome) than the more traditional open cholecystectomy for the management of acute cholecystitis.“ Kiviluoto T, et al. Randomised trial of laparoscopic versus open cholecystectomy for acute and gangrenous cholecystitis. Lancet 1998;351:3215

A study bias (interpretation)- Example (2) The authors failed to discuss the potential bias of their results, namely: The study investigators had completed all the laparoscopic cholecystectomy operations whereas 80% of the open cholecystectomy procedures had been completed by trainees: the positive results observed for laparoscopic cholecystectomy may have been merely a function of surgical experience, thus biasing the results. Evaluation of the results in light of this methodological weakness would have been helpful to readers.