This paper shows that when a classifier is evaluated with nonrandom test data, ROC curves differ from the ROC curves that would be obtained with a random sample. To address this bias, this paper introduces a procedure for plotting ROC curves that are inferred from nonrandom test data. I provide simulations and an example with wine data to illustrate the procedure as well as the magnitude of bia...

Preeclampsia is a pregnancy-specific syndrome that causes substantial maternal and fetal morbidity and mortality. The etiology is incompletely understood, and there is no clinically useful screening test. Current metabolomic technologies have allowed the establishment of metabolic signatures of preeclampsia in early pregnancy. Here, a 2-phase discovery/validation metabolic profiling study was p...

OBJECTIVE To investigate the accuracy of the Brazilian version of the Addenbrooke Cognitive Examination-revised (ACE-R) in the diagnosis of mild Alzheimer disease (AD). BACKGROUND The ACE-R is an accurate and brief cognitive battery for the detection of mild dementia, especially for the discrimination between AD and frontotemporal dementia. METHODS The battery was administered to 31 patient...

Preeclampsia is a pregnancy-specific syndrome that causes substantial maternal and fetal morbidity and mortality. The etiology is incompletely understood, and there is no clinically useful screening test. Current metabolomic technologies have allowed the establishment of metabolic signatures of preeclampsia in early pregnancy. Here, a 2-phase discovery/validation metabolic profiling study was p...

OBJECTIVE To compare progression in short-wavelength automated perimetry (SWAP) and white-on-white (standard) perimetry in eyes with progressive glaucomatous changes of the optic disc detected by serial stereophotographs. METHODS Forty-seven glaucoma patients with at least 2 disc stereophotographs more than 2 years apart, along with standard perimetry and SWAP examinations within 6 months of ...

BACKGROUND Internal medicine fellowship programs have an incentive to select fellows who will ultimately publish. Whether an applicant's publication record predicts long term publishing remains unknown. METHODS Using records of fellowship bound internal medicine residents, we analyzed whether publications at time of fellowship application predict publications more than 3 years (2 years into f...

The predictability of early postoperative ultrasonography (USG) for evaluating the structural integrity of repaired rotator cuffs is still unclear. The aim of this study was to compare the predictability of early USG performed 3 and 6 months postoperatively with magnetic resonance imaging (MRI) performed 1 year after arthroscopic cuff repair for structural failure. Among 213 patients who had ar...

Diagnostic tests are central in the field of modern medicine. One of the main factors for interpreting a diagnostic test is the discriminatory accuracy. For a continuous-scale diagnostic test, the area under the receiver operating characteristic (ROC) curve, AUC, is a useful onenumber summary index for the diagnostic accuracy of the test. When only a particular region of the ROC curve would be ...

BACKGROUND The aim of this study was to explore transient elastography (TE) with quantitative hepatitis B surface antigen (qHBsAg) for detecting advanced hepatic fibrosis. MATERIAL AND METHODS This was a single-center prospective real-life analysis of 111 treatment-naïve chronic hepatitis B (CHB) patients enrolled into the Establishment of Non-invasive Diagnosis Criteria and Model of Hepatitis ...

BACKGROUND Decision curve analysis has been introduced as a method to evaluate prediction models in terms of their clinical consequences if used for a binary classification of subjects into a group who should and into a group who should not be treated. The key concept for this type of evaluation is the "net benefit", a concept borrowed from utility theory. METHODS We recall the foundations of...