Materials & Methods what to include and where Anthony M. Vintzileos, MD

Materials & Methods (clarity) Results (transparency) One of the Most Important Criteria for Accepting Manuscripts for Publication Is Report likely to be true or correct? Materials & Methods (clarity) Results (transparency)

Materials & Methods Reporting guidelines (depend on study design) CONSORT PRISMA MOOSE STARD STROBE

Vintzileos and Ananth AJOG 2010;202:344.e1-6 Materials & Methods Clarity is essential Define clearly the type of study (prospective, retrospective, case-control etc) Sample size estimation (based on primary outcome) Definition (demographics) of study and control groups (or comparison groups) Clear definitions of exposures, primary and secondary outcomes Inclusion and exclusion criteria Types of measurements used for primary and secondary outcomes Data extraction methodology Clear description of methods, procedures or tests Brief description of methods or procedure (if previously published) IRB approval and type of consent, if applicable Use of Tables or Figures may or may not be necessary Methods of statistical analysis and levels of significance Is there enough detail for the study to be reproduced? Vintzileos and Ananth AJOG 2010;202:344.e1-6

Accuracy of Diagnostic Tests: TIPS Accuracy of Diagnostic Tests: Sensitivity* Specificity* Positive predictive value Negative predictive value * Not influenced by the prevalence of the disease (not always true)

TIPS Sensitivity Specificity Positive predictive value Accuracy of Diagnostic Tests: Sensitivity Specificity Positive predictive value Negative predictive value The main question: Was there any intervention based on abnormal test results which may have altered the outcome of interest?

“Biostatisticians’ Conspiracy” TIPS What Cutoff of a Continuous Variable (Predictor) Should We Use for Prediction? “Biostatisticians’ Conspiracy” 10%? 5%? 1%?

The “Anathema” of Arbitrary Categorization of Continuous Predictors Pitfalls in obstetric practice (aneuploidy screening, maternal age, BMI, CL) Pitfalls in research (loss of statistical power) Vintzileos et al Am J Obstet Gynecol 2014;210:200-3

Consider Using Receiver Operating Characteristic Curve (ROC curve) to Determine Optimal Cutoff The AUC is the measure of accuracy (ideal for comparing diagnostic accuracies of continuous variables) First, determine the outcome of interest Sensitivity (true positive rate) vs. FPR (1-specificity) of various cutoffs Ideal for establishing (before interventional trials) the most optimal cutoff The most optimal cutoff may vary according to the outcome of interest and clinical circumstances AUC AUCs EXAMPLE CL cutoff for preterm labor < 25 mm CL cutoff for labor at term < 15 mm

Materials & Methods Be prepared to give results for all outcome measures described under “Materials & Methods”