A key requirement in the design of diagnostic accuracy studies is that all study participants receive both the test under evaluation and the reference standard test. For a variety of practical and ethical reasons, sometimes only a proportion of patients receive the reference standard, which can bias the accuracy estimates. Numerous methods have been described for correcting this partial verific...

CONTENTS U S E O F GROWTH S T A N D A R D S . . 20 HISTORY . . . 20 D E F I N I T I O N S . . 21 REFERENCE OR S T A N D A R D . . . 21 LOCAL OR I N T E R N A T I O N A L . . . 22 SCALES O F MEASUREMENT . . . 22 Centile . . . 23 Percentage of median . . 23 SD score . . 23 D I S T A N C E A N D VELOCITY S T A N D A R D S . . 26 Weight for height . . . 28 M A R G I N A L A N D C O N D I T I O N A ...

Although information redundancy has been reported as an important problem for clinicians when using electronic health records and clinical reports, measuring redundancy in clinical text has not been extensively investigated. We evaluated several automated techniques to quantify the redundancy in clinical documents using an expert-derived reference standard consisting of outpatient clinical docu...

Background The electrocardiogram (ECG) is often used as initial test to detect or rule out previous myocardial infarction (MI). Although different ECG-criteria with considerable heterogeneity are used for this purpose, their accuracy is not well described. We aimed to determine the diagnostic accuracy of four commonly used ECG-criteria for detecting previous MI: 1) the universal definition of p...

This study aimed to investigate the thyroid peroxidase antibody (TPOAb) positive rate and how TPOAb affects thyroid function between 7 and 12 weeks of gestation. Six hundred and eleven cases of healthy primipara were enrolled in this study between September 2010 and June 2011, and all of them were given a regular prenatal check in Beijing Friendship Hospital. By detecting the levels of thyroid ...

In the early history of photometry, sources such as candles, lamps, or blackbodies were always used as standards to realize, maintain and transfer the photometric base unit. Even after the advent of photodetectors in the early twentieth century, lamps have been traditionally used to maintain and transfer the units of luminous intensity and luminous flux. In this case, a group of primary standar...

BACKGROUND Several studies and systematic reviews have reported results that indicate that sensitivity and specificity may vary with prevalence. STUDY DESIGN AND SETTING We identify and explore mechanisms that may be responsible for sensitivity and specificity varying with prevalence and illustrate them with examples from the literature. RESULTS Clinical and artefactual variability may be r...

which does result in wave speed in m/s. However, the correct equation was used in processing of the data in the article (Fig. 1A). In fact, if we had calculated “pace,” a significant bias would be seen, as shown in Fig. 1B. Weir-McCall rightly draws attention to the difficulty of measuring pulse wave velocity (PWV) in the pulmonary circulation and the relatively wide limits of agreement between...

Often the accuracy of a new diagnostic test must be assessed when a perfect gold standard does not exist. Use of an imperfect reference test biases accuracy estimates of the new test. This paper reviews existing approaches to this problem including discrepant resolution and latent class analysis. Deficiencies with these approaches are identified. A new approach is proposed that combines the res...

A programme for rheumatoid factor (RF) measurement was sponsored by the South East Asian Pacific League against Rheumatism (SEAPAL) and the Clinical Immunology Group (CIG) of the Australian Society for Immunology. Measurements in 29 laboratories in 12 countries showed: a large variety of methods were being used to measure RF, most using semiquantitative agglutination techniques; some laboratori...