Statistical Evaluation of a Biomarker

Department of Emergency Medicine and Surgery, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.
Anesthesiology (Impact Factor: 6.17). 03/2010; 112(4):1023-40. DOI: 10.1097/ALN.0b013e3181d47604
Source: PubMed

ABSTRACT A biomarker may provide a diagnosis, assess disease severity or risk, or guide other clinical interventions such as the use of drugs. Although considerable progress has been made in standardizing the methodology and reporting of randomized trials, less has been accomplished concerning the assessment of biomarkers. Biomarker studies are often presented with poor biostatistics and methodologic flaws that precludes them from providing a reliable and reproducible scientific message. A host of issues are discussed that can improve the statistical evaluation and reporting of biomarker studies. Investigators should be aware of these issues when designing their studies, editors and reviewers when analyzing a manuscript, and readers when interpreting results.

1 Follower
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Pulse pressure variation (PPV) has been shown to predict fluid responsiveness in ventilated intensive care unit (ICU) patients. The present study was aimed at assessing the diagnostic accuracy of PPV for prediction of fluid responsiveness by using the grey zone approach in a large population. The study pooled data of 556 patients from nine French ICUs. Hemodynamic (PPV, central venous pressure (CVP) and cardiac output) and ventilator variables were recorded. Responders were defined as patients increasing their stroke volume more than or equal to 15% after fluid challenge. The receiver operating characteristic (ROC) curve and grey zone were defined for PPV. The grey zone was evaluated according to the risk of fluid infusion in hypoxemic patients. Fluid challenge led to increased stroke volume more than or equal to 15% in 267 patients (48%). The areas under the ROC curve of PPV and CVP were 0.73 (95% confidence interval (CI): 0.68 to 0.77) and 0.64 (95% CI 0.59 to 0.70), respectively (P <0.001). A grey zone of 4 to 17% (62% of patients) was found for PPV. A tidal volume more than or equal to 8 and a driving pressure (plateau pressure - PEEP) more than 20 cmH2O significantly improved the area under the ROC curve for PPV. When taking into account the risk of fluid infusion, the grey zone for PPV was 2 to 13%. In ventilated ICU patients, PPV values between 4 and 17%, encountered in 62% patients exhibiting validity prerequisites, did not predict fluid responsiveness.
    Critical care (London, England) 18(6):587. DOI:10.1186/s13054-014-0587-9
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Near infrared spectroscopy (NIRS) is a non-invasive method for monitoring hemoglobin oxygen saturation within the microvessels. It is therefore also sometimes (erroneously) referred to as a measure of tissue oxygenation. By using self-adhesive optodes on the body surface, measurements can be taken in tissues below the skin up to a depth of 3-4 cm. The near infrared light (unlike visible light) even penetrates bone tissue, allowing measurement of regional cerebral oxygenation (SrcO2). There are numerous devices using NIRS technology available on the market, and the main applications for use include monitoring of SrcO2 during cardiothoracic and vascular (particularly carotid artery) surgery, as well as non-cardiac surgery that is performed in the sitting or so-called beach chair position [1]. Another widespread use is the assessment of SrcO2 in neonates and preterm infants [2]. Furthermore, there have been attempts to use peripheral tissue oxygenation (SptO2) measurements by NIRS for gui ...
    International Journal of Clinical Monitoring and Computing 03/2015; 29(2). DOI:10.1007/s10877-015-9689-4 · 1.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cardiac troponin (cTn) assays have quickly gained in analytical sensitivity to become what are termed 'high-sensitivity cardiac troponin' (hs-cTn) assays, bringing a flurry of dense yet incomplete literature data. The net result is that cTn assays are not yet standardized and there are still no consensus-built data on how to use and interpret cTn assay results. To address these issues, the authors take cues and clues from multiple disciplines to bring responses to frequently asked questions. In brief, the effective use of hs-cTn hinges on knowing: specific assay characteristics, particularly precision at the 99th percentile of a reference population; factors of variation at the 99th percentile value; and the high-individuality of hs-cTn assays, for which the notion of individual kinetics is more informative than straight reference to 'normal' values. The significance of patterns of change between two assay measurements has not yet been documented for every hs-cTn assay. Clinicians need to work hand-in-hand with medical biologists to better understand how to use hs-cTn assays in routine practice. Copyright © 2014 Elsevier Masson SAS. All rights reserved.
    Archives of Cardiovascular Diseases 02/2015; DOI:10.1016/j.acvd.2014.11.001 · 1.66 Impact Factor


Available from
Nov 14, 2014