“Reading and commenting papers” (Scientific English) Alexis Descatha INSERM, UMS UVSQ- Unité de pathologie professionnelle, Garches

Acknowledgments Descatha 2 Harvard School of Public Health Harvard Center for Population and Development Studies, L Berkman, E Sabbath

WHY and HOW Descatha 3 In the context of « Publish or Perish » and potential conflict of interest, be aware of limitations Read and understand original scientific papers (in English) By doing a structured summary (« abstract ») and Answering to questions 8 papers with corrections

Descatha/Davy method for summarizing an original paper Arthur Davy, Alexis Descatha UFR des sciences de la santé, Université de Versailles St Quentin

!Warning! Descatha 5

IMRaD Background (+/-) and objective (aim/goal) Methods population (sample), intervention (if applicable), exposure and outcome variables of interest, and analyses Results Details of sample Answer to the research question (quantitive) and side effects/ tolerance Conclusion = answer to the question PICO 6 Descatha

Descatha/Davy method TIME Reading Quick reading of title, questions, and the paper And the paper, highlighting in yellow the key sentences Drafting Take 3 « word tables» Cut and paste main sentences Writing Shorten the summary! Descatha 7

Advice Tense = past (present form only for evidence that everyone is agreed upon and future for perspectives) Don’t hesitate to use similar sentences, words … The corrector is not a native English speaker (try to do his best) Scoring / rating table +++ You can look for the abstract given by the authors, but … Training is the key ! Descatha 8

Vocabulary DESIGN++++ Observation Epidemiology+++ Cross sectional / case-control / cohort studies (+ review /meta-analysis/ case report…) Experimentation Clinical trials (randomized) Diagnostic studies (ie accuracy) Descatha 9

RCT Question is clear and very precise Method Design Sampling (including randomisation) => Flow chart Outcomes Number of subjects Analyses Results No difference between the two randomized groups Answer to the question Discussion Limitations, « so what » and perspectives Descatha 10

Accuracy in diagnosis Reliable test If repeated, similar results Valid and accurate: No false negative and no false positive => sensitivity/ specificity Practical considerations Screening vs. confirmatory testing Gold standard (but…) All same protocol, blindness Sensitivity, specificity, predictive values, likelihood ratio, ROC curves, AUC-DgOR… Descatha 11

Obervational study Aim and design (cf.) Inclusion criteria Exposure assessment, outcome Risk measurement (ratios and risks) Causality discussion and bias+++++ Descatha 12

Descatha 13 Design Experimentation (+/- randomization) OBSERVATION  Description= Prevalence (Incidence)  « Causation » (association )

Descatha 14 Causative studies Case control Cohort Inclusion of patients AND data Cross sectional Time Inclusion of patients Inclusion data (retrospectively) Inclusion of patients Inclusion data

Descatha 15 Design Experimentation (+/- randomization) OBSERVATION  Description= Prevalence (Incidence)  « Causation » (association )  cross-sectional: prevalence, association OR +/-  Cas control : prevalence, association OR  Cohort : incidence, association RR

Descatha 16 OR RR Disease +Disease -Total Exposedaba+b Not exposedcdc+d Totala+cb+da+b+c+d RR= [a/(a+b]/[c/c+d)], WITH 95% confidence interval OR= a*d/(b*c), with 95% confidence interval P RR (or OR) the CI do not include « 1 »

Statistically significant ? Descatha OR/RR 95%CI CI95% OR/RR 95%CI 1

Bias ? Selection bias Representativness Measurment bias case=case? / exposed = exposed? Confounding other factors not considered, that could explained the observed association Descatha 18

Vocabulary Sampling and intervention Design, observational/ experimental, longitudinal/cross-sectional, prospective/retrospective Participants: settings/Inclusion/ exclusion, case and controls, mono or multicenter (Matched?/paired) Blinding?/ Randomization/ Intention to treat / flow diagram… Measures of the diseases Prevalence/ incidence … Questionnaire, physical examination, laboratory/radiology/pathology findings (data sources) Descatha 19

Vocabulary Analyses Statistical power, number of subject (sample size ) Uni and Multivariate analyses (models) Measures of the effect Association / efficacy or tolerance P<0.05, statistical significance, statistical power Odds ratio, relative risk… Sensitivity, specificity, predictive values, likelihood ratio… Limitation and bias (selection, information, confounding => causation?) Generalizability and perspectives Descatha 20

Now it is your turn! Consort, Stard, Strobe statements Pubmed is helpful Internet +++ (most of the “LCA” books have a glossary, including translation) Descatha 21