The rapid advancement in molecule technology has led to the discovery of many markers that have potential applications in disease diagnosis and prognosis. In a prospective cohort study, information on a panel of biomarkers as well as the disease status for a patient are routinely collected over time. Such information is useful to predict patients' prognosis and select patients for targeted ther...

OBJECTIVE To apply ROC analysis to select the best threshold scores for the PHQ and SRQ; to compare the sensitivity and specificity of the PHQ and SRQ against a criterion diagnosis of depressive disorder in a community sample in rural Pakistan, and to examine the influence of socio-demographic factors on misclassification. METHODS The study used a two-stage design. Receiver Operating Characte...

The current document describes the methodology adopted for finding the optimal thresholds for ‘cumulative sequence count' and 'overlap percentage' using ROC curves. For each of the four training data sets, i-rDNA program was executed using various pairs of thresholds for cumulative sequence count and overlap percentage. For each pair of thresholds, the True Positive Rate and the False Positive ...

PURPOSE This study evaluated the predictive performance of a combination of self-report questionnaires, salivary hemoglobin levels, and age as a non-invasive screening method for periodontitis. METHODS The periodontitis status of 202 adults was examined using salivary hemoglobin levels, responses to 10 questions on a self-report questionnaire, and the Community Periodontal Index (CPI). The ab...

Test sensitivity and specificity for the FAMACHA(©) clinical test for anaemia due to haemonchosis have previously been shown to be adequate in differentiating between heavily/less heavily infected sheep, but these properties give no objective guidance for setting the optimum threshold at which anthelmintic treatment should occur. The aim of this work was to use Receiver Operating Characteristic...

There are several criteria for determination of the most appropriate cut-off value in a diagnostic test with continuous results. Mostly based on receiver operating characteristic (ROC) analysis, there are various methods to determine the test cut-off value. The most common criteria are the point on ROC curve where the sensitivity and specificity of the test are equal; the point on the curve wit...

OBJECTIVE To determine a high fear cut-off point score for the Dental Fear Survey (DFS) using a single-item self-report questionnaire. METHODS The DFS, a 20-item questionnaire assessing fear of dental treatment, was completed by 1,256 participants with a mean age of 22.3 years (SD = 5.1). Another self-report questionnaire was used to collect data on previous dental experiences. A high fear cu...

BACKGROUND The aim of this study was to propose and validate a new clinical score to predict difficult ventilation through a supraglottic airway device. METHODS The score was proposed from our previously reported derivation data, and we prospectively validated the score in 5532 patients from November 2013 to April 2014. Predictive accuracy of the score was compared by the area under the recei...

BACKGROUND AND RATIONALE Preoperative evaluation is important in the detection of patients at risk for difficult tracheal intubation. Thyromental distance (TMD) is often used for these purposes, but its value as an indicator for difficult intubation is questionable, as it varies with patient size and body proportions. The purpose of the present study was to evaluate and compare the accuracies o...

In the last lecture we saw that the likelihood ratio statistic was optimal for testing between two simple hypotheses. The test simply compares the likelihood ratio to a threshold. The “optimal” threshold is a function of the prior probabilities and the costs assigned to different errors. The choice of costs is subjective and depends on the nature of the problem, but the prior probabilities must...