Decisional Thresholds Research Articles

Predictive Performance of Blood S100B in the Management of Patients Over 65 Years Old With Mild Traumatic Brain Injury

We previously assessed the inclusion of S100B blood determination into clinical decision rules for mild traumatic brain injury (mTBI) management in the Emergency Department (ED) of Clermont-Ferrand Hospital. At the 0.10 µg/L threshold, S100B reduced the use of cranial computed tomography (CCT) scan in adults by at least 30% with a ~100% sensitivity. Older patients had higher serum S100B values, resulting in lower specificity (18.7%) and decreased CCT reduction. We conducted this study to confirm the age effect on S100B concentrations, and to propose new decisional thresholds for older patients. A total of 1172 mTBI patients aged 65 and over were included. They were divided into three age-groups: 65-79, 80-89, and ≥ 90 years old. S100B's performance to identify intracranial lesions (sensitivity (SE) and specificity (SP)) was assessed using the routine 0.10 µg/L threshold and also other more efficient thresholds established for each age group. S100B concentration medians were 0.18 µg/L, 0.26 µg/L, and 0.32 µg/L for the 65-79, 80-89, and ≥ 90 years old age-groups, respectively (p < 0.001). The most efficient thresholds were 0.11 µg/L for the 65-79 age-group and 0.15 µg/L for the other groups. At these new thresholds, SP was respectively 28.4%, 34.3%, and 20.5% for each age-group vs. 24.9%, 18.2%, and 10.5% at the 0.10 µg/L threshold. Adjustment of the S100B threshold is necessary in older patients' management. An increased threshold of 0.15 µg/L is particularly interesting for patients ≥ 80 years old, allowing a significant increase of CCT scan reduction (29.3%).

Older adults sacrifice response speed to preserve multisensory integration performance

Aging has been shown to impact multisensory perception, but the underlying computational mechanisms are unclear. For effective interactions with the environment, observers should integrate signals that share a common source, weighted by their reliabilities, and segregate those from separate sources. Observers are thought to accumulate evidence about the world's causal structure over time until a decisional threshold is reached. Combining psychophysics and Bayesian modeling, we investigated how aging affects audiovisual perception of spatial signals. Older and younger adults were comparable in their final localization and common-source judgment responses under both speeded and unspeeded conditions, but were disproportionately slower for audiovisually incongruent trials. Bayesian modeling showed that aging did not affect the ability to arbitrate between integration and segregation under either unspeeded or speeded conditions. However, modeling the within-trial dynamics of evidence accumulation under speeded conditions revealed that older observers accumulate noisier auditory representations for longer, set higher decisional thresholds, and have impaired motor speed. Older observers preserve audiovisual localization performance, despite noisier sensory representations, by sacrificing response speed.

CD180 expression in B-cell lymphomas: A multicenter GEIL study.

CD180, a related member of the Toll-like receptor family, is lost or underexpressed at the plasma membrane in circulating cells of various B-cell lymphomas except marginal zone lymphomas (MZL). In order to confirm its clinical relevance in routine analysis, we evaluated prospectively the expression of CD180 in 236 patients from 5 French University Hospital laboratories on behalf of the GEIL. Highly comparable results were obtained in all centers using the EuroFlow standardization protocol. We observed that CD180 median fluorescence (MdFI) was significantly higher in MZL and hairy cell leukaemia (HCL) compared to all other B-cell proliferations (P < 0.05). CD180 intensity could distinguish lymphomas with numerous villous lymphocytes from other MZL. ROC curve analysis identified a CD180 MdFI threshold for which the diagnosis of MZL could be assessed with 77% sensitivity and 92% specificity. This study showed that CD180 can be considered as a single positive robust marker of MZL and should be therefore included in flow cytometry panels for the diagnosis of mature B-cell neoplasms. Harmonization process is of great interest in order to evaluate new markers in multicentric studies and to set up decisional thresholds. © 2015 International Clinical Cytometry Society.

Spleen Stiffness Measurement By Transient Elastography As a Predictor of Bone Marrow Fibrosis in Primary Myelofibrosis Patients

Introduction: transient elastography (TE) is a standardized, non-invasive tool which predicts severity of chronic liver disease (CLD). Owing to the known relationships between liver fibrosis, portal hypertension and splenomegaly, the measurement of spleen stiffness (SS) has been evaluated as an alternative and/or complementary method to liver stiffness (LS) in order to evaluate liver disease severity. In particular, a significant correlation between SS and portal hypertension has been established with hemodynamic measurements, demonstrating that SS accurately predicts the risk of both esophageal varices and clinical decompensation in patients with viral cirrhosis.Recently, we conducted a study in CLD patients with the aim to assess the diagnostic accuracy of combined LS and SS in the prediction of liver fibrosis and portal hypertension; it also included 64 healthy volunteers and 48 patients with a previous diagnosis of hematological malignancies as control population. Among the few hematological patients enrolled in that study, a significant correlation between SS and bone marrow fibrosis grade (p<0.01) was found and it was more pronounced in the 23 primary myelofibrosis (PMF) patients than in those with other hematological neoplasms.Methods: to validate further these preliminary observations, we enrolled 108 patients with a clinical and histological diagnosis of PMF based on WHO 2008 criteria. All patients concurrently underwent liver and spleen TE, in conjunction with a bone marrow biopsy, ultrasound evaluation of spleen size and chemistries. Once we found normal LS values granted for the absence of liver disease potentially interfering with SS assessments, according to the updated WHO classification, we considered only two main bone marrow fibrosis categories defined as follows: pre-fibrotic/early fibrotic (MF-0/1) and advanced fibrotic stage (MF-2/3).Results: transient elastography of the liver and spleen was successfully performed in 88 PMF patients (81.5%), whereas 20 (18.5%) had indeterminate spleen-TE results; however, this rate of spleen-TE failure is similar to that reported by previous studies in CLD patients (15 to 20% of all cases). The median liver-TE and spleen-TE values were 7.1 kPa (range 3.5-19.6) and 40.1 kPa (range 11.8–75.0), respectively.In a univariate analysis both spleen (p<.0001) and liver stiffness (p=.0074) correlated with the severity of bone marrow fibrosis, whereas age, gender and the PMF prognostic scoring systems IPSS, DIPSS and DIPSS-plus did not. Furthermore, bone marrow fibrosis did not correlate with the presence of JAK2 V617F or CALR mutations, whereas it did with Hb (p=0.0001), LDH (p<.0001) and peripheral blood CD34-positive cells count (p=0.0003).At multivariate analysis, only SS, LDH and CD34-positive cells count maintained a significant correlation with bone marrow fibrosis, with a discriminative ability assessed by the c statistic of 0.904 (95% CI, 0.841-0.967). According to these results, we were able to propose an equation for the estimation of the probability of being MF-2/3, arranged as follows:probability MF-2/3=exp[-4.83+0.0380*SS+0.0039*LDH+0.0148*CD34]/[1+exp(-4.83+0.0380*SS+0.0039*LDH+0.0148*CD34)].The model entails two decisional threshold values that predict the probability of diagnosing PMF severity: the best cut-off for the diagnosis of MF-0/1 was 0.15 (negative predictive value=0.97) and the best cut-off for the diagnosis of MF-2/3 was 0.73 (positive predictive value=0.94), with an accuracy of 97% for the former and 94% for the latter. Figure 1 describes the two decisional thresholds and the distribution of our patients in the MF-0/1 and MF-2/3 categories.Conclusions: to our knowledge, this study represents the first attempt to evaluate the entity of SS in PMF patients as a measure of disease severity. Furthermore, our results allow us to suggest the use of SS as a surrogate marker of bone marrow fibrosis, particularly following the fibrogenetic progression of the disease, especially when it is considered together with such routine chemistries as LDH and CD34-positive cells count, a finding that may limit the need for an invasive and more expensive procedure like bone marrow biopsy in the management of PMF patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

2289 – Integration of emotions towards decision-making: behavioural performances of OCD patients and their MEG correlates compared to healthy controls

Obsessive compulsive disorder is characterised by repetitive behaviour, which is most often repetitive checking. Literature has suggested that these may be due to a lack of cognitive control on automated behavioural patterns. This can be interpreted as a dysfunction of behavioural selection by cortico-basal ganglionic loops. More precisely, we hypothesise that this dysfunction is due to a modification of decisional thresholds. OCD patients show modifications in a circuit involving the frontal cortex and basal ganglia. Therefore, modifications in the decisional threshold and faulty behavioural selection could be due to altered integration of limbic and associative information coded by prefrontal areas. To this aim, we compared behavioural performances of 20 OCD patients and 20 healthy volunteers on a decision-making task. This task included different difficulty levels (associative information), different emotional primes (IAPS) and feedback (limbic information). We hypothesised a lesser variability of the decisional threshold in patients, as well as less interaction between limbic and associative information. These would be linked to modifications in the power spectrum of prefrontal electrophysiological activities.

Saccadometry and LATER model shed light on brain plasticity in aging

As frequency of falls increases in older adults, understanding how motor training programs counteract motor decline is a challenging issue. This study examined ocular saccades to test the effects of fall prevention (FP) on central motor control of older fallers. Saccades were recorded using a saccadometer in twelve participants aged 64–91 years before and after 2.5-month training in FP. We performed LATER analysis enabling us to examine the changes in motor control. FP decreased saccade latency and increased left-right symmetry of motor responses. LATER analysis showed that FP modulated decisional thresholds extending our knowledge of FP influence on motor control.

Sources of non-compliance with clinical practice guidelines in trauma triage: a decision science study

BackgroundUnited States trauma system guidelines specify when to triage patients to specialty centers. Nonetheless, many eligible patients are not transferred as per guidelines. One possible reason is emergency physician decision-making. The objective of the study was to characterize sensory and decisional determinants of emergency physician trauma triage decision-making.MethodsWe conducted a decision science study using a signal detection theory-informed approach to analyze physician responses to a web-based survey of 30 clinical vignettes of trauma cases. We recruited a national convenience sample of emergency medicine physicians who worked at hospitals without level I/II trauma center certification. Using trauma triage guidelines as our reference standard, we estimated physicians’ perceptual sensitivity (ability to discriminate between patients who did and did not meet guidelines for transfer) and decisional threshold (tolerance for false positive or false negative decisions).ResultsWe recruited 280 physicians: 210 logged in to the website (response rate 74%) and 168 (80%) completed the survey. The regression coefficient on American College of Surgeons – Committee on Trauma (ACS-COT) guidelines for transfer (perceptual sensitivity) was 0.77 (p<0.01, 95% CI 0.68 – 0.87) indicating that the probability of transfer weakly increased as the ACS-COT guidelines would recommend transfer. The intercept (decision threshold) was 1.45 (p<0.01, 95% CI 1.27 – 1.63), indicating that participants had a conservative threshold for transfer, erring on the side of not transferring patients. There was significant between-physician variability in perceptual sensitivity and decisional thresholds. No physician demographic characteristics correlated with perceptual sensitivity, but men and physicians working at non-trauma centers without a trauma-center affiliation had higher decisional thresholds.ConclusionsOn a case vignette-based questionnaire, both sensory and decisional elements in emergency physicians’ cognitive processes contributed to the under-triage of trauma patients.

Educational choice in secondary school in Flanders: the relative impact of occupational interests on option choice

The present study aims at unravelling the myriad of student-level (i.e., gender, socioeconomic status [SES], academic self-concept, achievement, ability, and occupational interests) and school-level (i.e., gender composition, maths composition, and SES composition) determinants of option choice in the academic track of secondary school in Flanders. We focused on 2 decisional thresholds in Flemish secondary education, namely, the transition from Grade 8 to Grade 9 (N = 2518) and from Grade 10 to Grade 11 (N = 2871). Data were analyzed through multinomial multilevel analysis. Our results strongly confirm Lent's (2005) jigsaw puzzle metaphor in that different factors go into a complex and dynamic interplay. Especially in the first grades, prior achievement is a major predictor of option choice in secondary education, whereas in the last years occupational interests become increasingly important. From a gender perspective, boys rather choose math/sciences-oriented options than girls. Option choice is mainly determined by student-level rather than school-level predictors.

Decisional procalcitonin thresholds are not adapted toelderly patients admitted to the emergency room

Context: Diagnosis of sepsis in elderly is challenging.Objectives: We investigated whether procalcitonin concentrations in elderly differed from values for the general population.Methods: Procalcitonin measurement was assessed prospectively in 307 apyretic patients ≥75 years visiting the emergency department.Results: Median age was 86 years [IQR81–90] and 222 (72%) were female. Procalcitonin concentration was 0.057 µg/L [0.040–0.092]; 99th percentile was 0.661 µg/L. Patients with procalcitonin concentrations above decisional thresholds had lower glomerular filtration rate and higher C-reactive protein concentrations. Conclusions: Baseline procalcitonin levels are increased in elderly. Elevated values are common and associated to low-grade inflammation and lower eGFR.

Influence of Near Threshold Visual Distractors on Perceptual Detection and Reaching Movements

Providing evidence against a dissociation between conscious vision for perception and unconscious vision for action, recent studies have suggested that perceptual and motor decisions are based on a unique signal but distinct decisional thresholds. The aim of the present study was to provide a direct test of this assumption in a perceptual-motor dual task involving arm movements. In 300 trials, 10 participants performed speeded pointing movements toward a highly visible target located at 10° from the fixation point and ± 45° from the body midline. The target was preceded by one or two close to threshold distractor(s) (80 ms stimulus onset asynchrony) presented ± 30° according to the target location. After each pointing movement, participants judged whether the distractor was present or not on either side of the target. Results showed a robust reaction time facilitation effect and a deviation toward the distractor when the distractor was both present and consciously perceived (Hit). A small reaction time facilitation was also observed when two distractors were physically present but undetected (double-miss)--this facilitation being highly correlated with the physical contrast of the distractors. These results are compatible with the theory proposing that perceptual and motor decisions are based on a common signal but emerge from a contrast dependent fixed threshold for motor responses and a variable context dependent criterion for perceptual responses. This paper thus extends to arm movement control previous findings related to oculomotor control.

Analytical evaluation of NT-proBNP assay on Cardiac Reader

We evaluated a natriuretic peptide NT-proBNP assay on total blood, thanks to unit strips read by an apparatus of delocalized biology, the Cardiac Reader (Roche Diagnostics). Using the principle of immuno-chromatography, (with reading of colour intensity) this test measures concentrations of NT-proBNP from 60 to 3.000 pg/mL. The evaluation of this test shows an excellent repeatability, the absence of hook effect for very high values of NT-proBNP, the absence of BNP recognition and a robustness compared to the interferences classically checked: haemolysis and turbidity. The correlation of this total blood assay with a plasmatic assay by electrochemiluminescence of NT-proBNP is excellent, as well at the analytical level as on the level of the respect of the clinical decisional thresholds classically used. The test's analytical qualities make it an interesting alternative to the assay usually practised on automats in central laboratory. Nevertheless, the provision of this assay in delocalized biology (point of care) must be done according to strict rules of use, to take into account certain analytical constraints guaranteeing results of quality, compared to the therapeutic decisions that can result from.

Reference ranges and diagnostic thresholds of laboratory markers of cardiac damage and dysfunction in a population of apparently healthy black Africans

Due to the increasing migration flows mostly concerning Western countries, the problem of reference ranges and cut-off values is a living matter. In particular, the influence of ethnic origin on traditional and novel biochemical markers of cardiac damage, including cardiac troponin T (cTnT), ischemia modified albumin (IMA) and N-terminal prohormone brain natriuretic peptide (NT-proBNP), has not been investigated, to the best of our knowledge. CTnT, NT-proBNP and IMA were assayed by a Modular System in 34 apparently healthy black Africans originating mainly from Central Africa and in 34 apparently healthy white, non-immigrant Italians, matched for age and sex. All the subjects investigated displayed cTnT values < 0.01 ng/mL. Black Africans displayed significantly increased concentrations of serum IMA (107 vs. 92 kU/L, p < 0.0001), but not of NT-proBNP (4.9 vs. 3.8 pmol/L, p = 0.4), as compared to the white, nonimmigrant Italians. The results of our investigation indicate that the reference ranges and the thresholds values of IMA, but not those of cTnT and NT-proBNP, may be different according to the ethnic origin of the population. Therefore, although the current decisional thresholds of both cTnT and NT-proBNP may be appropriate for diagnosing cardiac damage and dysfunction in the black African population, that of IMA may require a revision toward higher values.

Procalcitonin Level Evaluation in the Diagnostic Work-Up of Severe Infections with Systemic Involvement

Study Objectives: Procalcitonin has been proposed as a reliable serologic tool to be included in the diagnostic protocols of sepsis and related syndromes; it has been also shown to be useful as prognostic factor both for predicting the progression to septic shock and multi-organ failure and for monitoring the response to treatment. This study was aimed at establishing decisional thresholds of procalcitonin levels and assessing their application in the management of patients with suspected sepsis in the emergency department.

Verdict selection processes in insanity cases: Juror construals and the effects of guilty but mentally ill instructions.

Judicial instructions (traditional American Law Institute vs. Guilty But Mentally Ill [GBMI]) were manipulated within an insanity defense vignette portraying a highly psychotic defendant. Construals were highly predictive of verdicts in both instructional conditions. Instead of influencing case construals, the GBMI option seems to operate by increasing respondents' decisional thresholds for insanity and guilty verdicts, creating a “collapsing” effect such that few such verdicts are rendered. Between-instruction comparisons reveal that the construals of respondents who choose insane and guilty verdicts are considerably more homogeneous and extreme under the GBMI conditions. Results suggest that many respondents intend their GMBI verdicts to signify diminished blame and punishment, indicating that such verdicts entail cognitive “compromises” that reflect both the thresholdraising effects and also probable confusion about the jurisprudential meaning of a GBMI verdict.