Suboptimal Tests Research Articles

Evaluation of Dyspepsia with Optimal and Suboptimal Gastric Emptying Tests in Patients with Euthyroid Goiter.

The presence of gastroparesis in patients with dyspepsia can be evaluated by gastric emptying scintigraphy. We aimed to evaluate gastroparesis with optimal solid gastric emptying scintigraphy and suboptimal liquid gastric emptying scintigraphy in euthyroid goiter patients with dyspepsia. We included 67 patients diagnosed with euthyroid goiter with dyspepsia complaints. The patients did not use any medication and did not have any other chronic diseases. Solid and liquid gastric emptying scintigraphy was performed on all patients. In our retrospective study; the images were reevaluated. The region of interest was plotted on the area compatible with the stomach and timeactivity curves were obtained. The correlation of solid and liquid gastric emptying test results was evaluated. Twelve (18%) of the patients were male and the mean age of the patients was 64 (49-75). There is a correlation between solid and liquid gastric emptying scintigraphy (p< 0.0005, r: 0.0880). Solid gastric emptying time was prolonged in 27 patients (40%). Liquid gastric emptying was prolonged in 23 patients (34%). Solid gastric emptying was also prolonged in all patients with prolonged liquid gastric emptying. According to the results of the optimal gastric emptying test performed with radio-labeled solid food. The rate of gastroparesis was low in our patient group with dyspepsia complaints. However, there is a correlation between the optimal test and suboptimal gastric emptying test results in our patient group. Liquid gastric emptying scintigraphy may be preferred in specific patient groups in case of suspected gastroparesis because of its easy application and short duration.

Cognitive decline assessment in speakers of understudied languages.

Cognitive decline is a marker for dementia, assessed with neuropsychological tests.There is a lack of culturally valid tests for speakers of understudied languages.For example, suboptimal cognitive tests are used in the Middle East and North Africa region.Linguistic diversity should be considered in the development of cognitive tests.

Unraveling the epidemiology of Mycobacterium bovis using whole-genome sequencing combined with environmental and demographic data.

When studying the dynamics of a pathogen in a host population, one crucial question is whether it transitioned from an epidemic (i.e., the pathogen population and the number of infected hosts are increasing) to an endemic stable state (i.e., the pathogen population reached an equilibrium). For slow-growing and slow-evolving clonal pathogens such as Mycobacterium bovis, the causative agent of bovine (or animal) and zoonotic tuberculosis, it can be challenging to discriminate between these two states. This is a result of the combination of suboptimal detection tests so that the actual extent of the pathogen prevalence is often unknown, as well as of the low genetic diversity, which can hide the temporal signal provided by the accumulation of mutations in the bacterial DNA. In recent years, the increased availability, efficiency, and reliability of genomic reading techniques, such as whole-genome sequencing (WGS), have significantly increased the amount of information we can use to study infectious diseases, and therefore, it has improved the precision of epidemiological inferences for pathogens such as M. bovis. In this study, we use WGS to gain insights into the epidemiology of M. bovis in Cameroon, a developing country where the pathogen has been reported for decades. A total of 91 high-quality sequences were obtained from tissue samples collected in four abattoirs, 64 of which were with complete metadata. We combined these with environmental, demographic, ecological, and cattle movement data to generate inferences using phylodynamic models. Our findings suggest M. bovis in Cameroon is slowly expanding its epidemiological range over time; therefore, endemic stability is unlikely. This suggests that animal movement plays an important role in transmission. The simultaneous prevalence of M. bovis in co-located cattle and humans highlights the risk of such transmission being zoonotic. Therefore, using genomic tools as part of surveillance would vastly improve our understanding of disease ecology and control strategies.

Quickest physical watermarking-based detection of measurement replacement attacks in networked control systems

In this paper, we propose and analyze an attack detection scheme for securing the physical layer of a networked control system (NCS) with a wireless sensor network against attacks where the adversary replaces the true observations with stationary false data. An independent and identically distributed watermarking signal is added to the optimal linear quadratic Gaussian (LQG) control inputs, and a cumulative sum (CUSUM) test is carried out using the joint distribution of the innovation signal and the watermarking signal for quickest attack detection. We derive the expressions of the supremum of the average detection delay (SADD) for a multi-input and multi-output (MIMO) system under the optimal and sub-optimal CUSUM tests. The SADD is asymptotically inversely proportional to the expected Kullback–Leibler divergence (KLD) under certain conditions. The expressions for the MIMO case are simplified for multi-input and single-output systems and explored further to distil design insights. We provide insights into the design of an optimal watermarking signal to maximize KLD for a given fixed increase in LQG control cost when there is no attack. Furthermore, we investigate how the attacker and the control system designer can accomplish their respective objectives by changing the relative power of the attack signal and the watermarking signal. Simulations and numerical studies are carried out to validate the theoretical results.

Optimal tests for continuous-variable quantum teleportation and photodetectors

Quantum teleportation is a primitive in several important applications, including quantum communication, quantum computation, error correction, and quantum networks. In this work, we propose an optimal test for the performance of continuous-variable (CV) quantum teleportation in terms of the energy-constrained channel fidelity between ideal CV teleportation and its experimental implementation. Work prior to ours considered suboptimal tests of the performance of CV teleportation, focusing instead on its performance for particular states, such as ensembles of coherent states, squeezed states, cat states, etc. Here we prove that the optimal state for testing CV teleportation is an entangled superposition of twin Fock states. We establish this result by reducing the problem of estimating the energy-constrained channel fidelity between ideal CV teleportation and its experimental approximation to a quadratic program and solving it. As an additional result, we obtain an analytical solution to the energy-constrained diamond distance between a photodetector and its experimental approximation. These results are relevant for experiments that make use of CV teleportation and photodetectors.

Wald- and Rao-Based Detection for Maritime Radar Targets in Sea Clutter With Lognormal Texture

Non-Gaussian sea clutter causes conventional detectors designed in Gaussian clutter to suffer detection performance degradation, and some nuisance parameters cause the uniformly most powerful test to be unavailable. To improve the detection performance of maritime radar targets, we investigate the design of adaptive detectors in correlated non-Gaussian sea clutter via using suboptimal tests. The non-Gaussian sea clutter is modelled as a product of lognormal-distributed texture and complex Gaussian speckle. Two adaptive radar target detectors are developed by using the suboptimal two-step Wald and Rao tests. Specifically, a non-adaptive detector is derived by the Wald or Rao test when the clutter texture and speckle covariance matrix are assumed to be known in the first step; then the clutter parameters known in the first step are estimated, and the true parameters of the detector obtained in the first step are replaced with the estimated values. Theoretical proof and experimental verification indicate that the two proposed detectors have the constant false alarm property with regard to the clutter speckle covariance matrix and the clutter average power. Numerical results on simulated and measured radar data show that the proposed Rao-based detector outperforms its competitors, and has the stronger robustness to the signal mismatch compared to the proposed Wald-based detector.

Management of COVID patients with convalescent plasma: Do we have the final word?

Immunotherapy with convalescent plasma (CP) has been used in the past in several different infectious diseases and proposed as a potential therapeutic option in patients with COVID-19. However, a clear benefit was never demonstrated and randomized clinical trials (RCTs) conducted in different populations of COVID-19 patients showed contrasting results. In general, current evidences suggest that CP in patients with moderate to severe COVID-19 does not reduce the progression to severe respiratory failure or death within 30 days. However, currently published RCTs have several limitations. The administration of plasma with low titer of neutralizing antibodies (NAbs), the use of suboptimal surrogate serological tests to determine NAbs titer, the delayed administration of CP from the onset of COVID-19 symptoms and the lack of information about antibody titer of recipients before CP infusion, are all limiting factors that may have affected the study results. Thus, a potential benefit of early (within the first 72 h from onset of symptoms), high titer CP in patients with mild COVID-19 (pO2/FiO2>300) cannot be definitively excluded. However, immunotherapy with monoclonal antibodies developed from CP demonstrated efficacy in reducing progression to severe COVID-19 and hospitalization and are today recommended in the early phase of COVID-19.

Оцінка повздовжньої деформації лівого шлуночка і її зміни при інфаркті міокарда та ішемічній хворобі серця з обструктивним ураженням коронарних артерій

The review provides data on a new method of ultrasound diagnostics – speckle tracking echocardiography in the diagnosis of myocardial infarction and coronary heart disease with obstructive coronary artery lesions, the advantages of the global longitudinal strain (GLS) compared to the existing echocardiographic indicators of global systolic and segmental systolic function. The value of measuring GLS in coronary heart disease is the quantitative detection of wall motion abnormalities, when left ventricular ejection fraction is within normal values and visual assessment does not detect violations of regional contractility. In patients with myocardial infarction without ST-segment elevation, GLS measurement may assist in the selection of patients who need urgent reperfusion therapy. In coronary heart disease, GLS can complement the conventional assessment of wall movement; replace the need for additional non-invasive testing for some patients with suboptimal stress tests. The normal limits of the GLS for various manufacturers of ultrasound scanners and technical characteristics for the correct studying of the GLS are described. The value of the GLS gradually decreases in mild, moderate and severe forms of coronary heart disease, and is the lowest in patients with myocardial infarction with ST segment elevation. The possibilities of detecting infarct-related coronary artery using the amplitude of the segmental strain and the «bull’s eye» diagram in isolated lesions of one of the coronary arteries are described. The analysis of the strain curves is carried out, the characteristics of the strain curve in normal conditions and in ischemia are presented. The probable signs of ischemia are the phenomena of early systolic lengthening and postsystolic shortening on the curves of longitudinal deformation. The conditions when the postsystolic contraction on the strain curve is pathological are described. Key words: global longitudinal strain, myocardial infarction, ischemic heart disease, «bull’s eye», early systolic lengthening, postsystolic shortening.

Testing of Poisson mean with under-reported counts

For modelling unbounded count data, Poisson distribution is a natural choice. However, count data arising in various fields of scientific research are often under-reported. In such situations, inference carried out on the basis of Poisson model will result in biased parameter estimates and suboptimal tests. A modified Poisson model is developed to accommodate the possible undercount. For model-identifiability a double sampling scheme of data collection has been adopted. The focus of this paper is to develop asymptotically optimal tests for the Poisson mean in presence of undercount. Simulation study is conducted to compare the performance of the tests with respect to level and power and also to investigate the impact of ignoring undercount on each of the tests. The findings are validated using real life data.

Improving clinical management of COVID-19: the role of prediction models

Improving clinical management of COVID-19: the role of prediction models

The quality of electrodiagnostic tests for carpal tunnel syndrome: Implications for surgery, outcomes, and expenditures.

The quality of electrodiagnostic tests may influence treatment decisions, particularly regarding surgery, affecting health outcomes and health-care expenditures. We evaluated test quality among 338 adults with workers' compensation claims for carpal tunnel syndrome. Using simulations, we examined how it influences the appropriateness of surgery. Using regression, we evaluated associations with symptoms and functional limitations (Boston Carpal Tunnel Questionnaire), overall health (12-item Short Form Health Survey version 2), actual receipt of surgery, and expenditures. In simulations, suboptimal quality tests rendered surgery inappropriate for 99 of 309 patients (+32 percentage points). In regression analyses, patients with the highest quality tests had larger declines in symptoms (-0.50 point; 95% confidence interval [CI], -0.89 to -0.12) and functional impairment (-0.42 point; 95% CI, -0.78 to -0.06) than patients with the lowest quality tests. Test quality was not associated with overall health, actual receipt of surgery, or expenditures. Test quality is pivotal to determining surgical appropriateness and associated with meaningful differences in symptoms and function.

Age-stratified longitudinal study of Alzheimer's and vascular dementia patients.

IntroductionSimilar symptoms, comorbidities and suboptimal diagnostic tests make the distinction between different types of dementia difficult, although this is essential for improved work‐up and treatment optimization.MethodsWe calculated temporal disease trajectories of earlier multi‐morbidities in Alzheimer's disease (AD) dementia and vascular dementia (VaD) patients using the Danish National Patient Registry covering all hospital encounters in Denmark (1994 to 2016). Subsequently, we reduced the comorbidity space dimensionality using a non‐linear technique, uniform manifold approximation and projection.ResultsWe found 49,112 and 24,101 patients that were diagnosed with AD or VaD, respectively. Temporal disease trajectories showed very similar disease patterns before the dementia diagnosis. Stratifying patients by age and reducing the comorbidity space to two dimensions, showed better discrimination between AD and VaD patients in early‐onset dementia.DiscussionSimilar age‐associated comorbidities, the phenomenon of mixed dementia, and misdiagnosis create great challenges in discriminating between classical subtypes of dementia.

Diagnostic tools used in the evaluation of acute febrile illness in South India: a scoping review

BackgroundAcute febrile illness (AFI) is characterized by malaise, myalgia and a raised temperature that is a nonspecific manifestation of infectious diseases in the tropics. The lack of appropriate diagnostics for the evaluation of AFI leads to increased morbidity and mortality in resource-limited settings, specifically low-income countries like India. The review aimed to identify the number, type and quality of diagnostics used for AFI evaluation during passive case detection at health care centres in South India.MethodsA scoping review of peer-reviewed English language original research articles published between 1946-July 2018 from four databases was undertaken to assess the type and number of diagnostics used in AFI evaluation in South India. Results were stratified according to types of pathogen-specific tests used in AFI management.ResultsThe review included a total of 40 studies, all conducted in tertiary care centres (80% in private settings). The studies demonstrated the use of 5–22 tests per patient for the evaluation of AFI. Among 25 studies evaluating possible causes of AFI, 96% tested for malaria followed by 80% for dengue, 72% for scrub typhus, 68% for typhoid and 60% for leptospirosis identifying these as commonly suspected causes of AFI. 54% studies diagnosed malaria with smear microscopy while others diagnosed dengue, scrub typhus, typhoid and leptospirosis using antibody or antigen detection assays. 39% studies used the Weil-Felix test (WFT) for scrub typhus diagnosis and 82% studies used the Widal test for diagnosing typhoid.ConclusionsThe review demonstrated the use of five or more pathogen-specific tests in evaluating AFI as well as described the widespread use of suboptimal tests like the WFT and Widal in fever evaluation. It identified the need for the development of better-quality tests for aetiological diagnosis and improved standardised testing guidelines for AFI.

MA06.03 Poor Pulmonary Function Does Not Define “Medical Inoperability”: Short and Long Term Results of a Matched Lung Cancer Cohort

Patients with suboptimal pulmonary function tests (PFTs) are often denied surgery for NSCLC. However, there is no consensus definition of compromised lung function. This study compared morbidity and survival following surgery in patients with preoperative %predicted FEV1or DLCO ≤50% (Low-Group) versus those with both values >50%(High-Group). A prospectively-maintained database was reviewed for patients undergoing surgery for NSCLC between 1990–2019. Propensity matching (1:2) was performed based on age, gender, histology, pathologic stage, and comorbidity index. Overall survival (OS) was estimated using Kaplan-Meier analysis and multivariable analysis identified predictors of survival. Among 2982 patients with PFT data, 372(12.5%) had FEV1or DLCO ≤50%. We matched 321 patients with FEV1or DLCO ≤50% to 637 patients with both PFTs >50%. No significant differences were observed in perioperative complications (Table) or 30-day mortality between Low and High groups (0.3% vs. 0.6%, p=0.668). The Low group more frequently underwent sublobar resection (41% vs. 22%, p<0.001). Median follow-up was 41 months, and median, 3-, and 5-year OS for the Low and High groups was 118 vs.148 months, 79% vs. 82%, and 70% vs. 74%, respectively (p=0.003). Patients with both FEV1and DLCO ≤50% (n=44) had a median survival of 109 months and 3- and 5-year OS of 77% and 71%. Multivariable analysis identified advanced age (HR=1.03, CI 1.01–1.05), higher clinical stage (HR=1.85, CI 1.22–2.82), and earlier year of surgery (HR=1.06, CI 1.01–1.12) as predictors of poor survival, but not FEV1or DLCO ≤50% (p=0.672). Among the Low group only, advanced age (HR=1.05, CI 1.02–1.07) and sublobar resection (HR=1.60, CI 1.04–2.45) predicted worse OS. Patients with decreased lung function have comparable perioperative outcomes to patients with normal lung function and experience excellent long-term survival. “Medical inoperability” should therefore be determined by surgeons and not by pulmonary function alone.

Vital signs analysis algorithm detects inflammatory response in premature infants with late onset sepsis and necrotizing enterocolitis

BackgroundNonspecific clinical signs and suboptimal diagnostic tests limit accurate identification of late onset sepsis (LOS) and necrotizing enterocolitis (NEC) in premature infants, resulting in significant morbidity and antibiotic overuse. An infant's systemic inflammatory response may be identified earlier than clinical suspicion through analysis of multiple vital signs by a computerized algorithm (RALIS). AimTo evaluate the revised RALIS algorithm for detection of LOS and NEC in preterm infants. MethodsIn this nested case–control study, VS data (heart rate, respiratory rate, temperature, desaturations, bradycardias) were extracted from medical records of infants 23–32 weeks gestation. RALIS generated an output, with score ≥ 5 triggering an alert. Patient episodes were classified based on culture, radiograph, and antibiotic data into categories: LOS, expanded LOS, NEC, and controls. Paired t-tests, linear regression and cross-validation analyses were used to evaluate the relationship between RALIS alert and LOS/NEC. ResultsAmong 155 infants with 161 episodes, there were 41 expanded LOS (+blood, CSF, urine, respiratory culture), 31 LOS (+blood, CSF, urine), 9 NEC, and 93 controls. RALIS alert was 43.1 ± 79 h before culture in LOS (p = .012). There was a significant association between RALIS alert and LOS/NEC (β = 0.72, p < .0001). Sensitivity and specificity for LOS/NEC were 84% and 80%, (PPV = 63%; NPV = 93%). The regression model demonstrated an AUC of 89.9%. ConclusionsFor infants ≤32 weeks, RALIS detects systemic inflammatory responses in LOS and NEC in the first month of life. The algorithm can identify infection earlier than clinical suspicion, even for NEC with negative cultures. RALIS has high NPV to rule-out LOS and NEC, and may, after prospective validation, aid in antibiotic treatment decisions.

Neutrophil-to-lymphocyte ratio and mural nodule height as predictive factors for malignant intraductal papillary mucinous neoplasms

Background: Accurate preoperative prediction for malignant IPMN is still challenging. The aim of this study was to investigate the validity of neutrophil-to-lymphocyte ratio (NLR) and mural nodule height (MNH) for predicting malignant intraductal papillary mucinous neoplasm (IPMN).Methods: The medical records of 60 patients who underwent pancreatectomy for IPMN were retrospectively reviewed.Results: NLR tended to be higher in malignant IPMN (median: 2.23) than in benign IPMN (median: 2.04; p = .14). MNH was significantly greater in malignant IPMN (median: 16 mm) than in benign IPMN (median: 8 mm; p < .01). The optimal cutoff values for the NLR and MNH were 3.60 and 11 mm, respectively. The sensitivity and specificity of NLR ≥3.60 for predicting malignant IPMN were 40% and 93%, and those of MNH ≥11 mm were 73% and 77%, respectively. Univariate analysis revealed that NLR ≥3.60 (p < .01) and MNH ≥11 mm (p < .01) were significant predictive factors. On multivariate analysis, enhanced solid component was identified as an independent factor, but NLR ≥3.60 and MNH ≥11 mm were not.Conclusions: NLR and MNH are suboptimal tests in predicting malignant IPMN; however, they can be useful to assist in clinical decision-making.

Dealing With Longitudinal Data

Dealing With Longitudinal Data

Invariance and Optimality of CFAR Detectors in Binary Composite Hypothesis Tests

We investigate the relationship between constant false alarm rate (CFAR) and invariant tests. We introduce the minimal invariant group (MIG). We show that for a family of distributions, the unknown parameters are eliminated from the distribution of the maximal invariant statistic under the MIG while the maximum information of the observed signal is preserved. We prove that any invariant test with respect to MIG is CFAR and conversely, for any CFAR test an invariant statistic exists with respect to an MIG under some mild conditions. Moreover for a given CFAR test, we propose a systematic method for deriving an enhanced test, i.e., a function of observations exists such that the likelihood ratio (LR) of the maximal invariant of its MIG gives an enhanced test. Furthermore, we introduce the uniformly most powerful-CFAR (UMP-CFAR) test as the optimal CFAR bound among all CFAR tests. We then prove that the UMP-CFAR test for the minimally invariant hypothesis testing problem is given by the LR of the maximal invariant under MIG. For some problems, this test (MP-CFAR) depends on the unknown parameters of the alternative hypothesis, however, provides an upper-performance bound for all suboptimal CFAR tests. We also propose three suboptimal novel CFAR tests among which one is asymptotically optimal.

Optimal invariant detection of a monochromatic plane wave with unknown amplitude, frequency, phase, direction of arrival and noise variance

This study deals with the problem of detecting a monochromatic plane wave with unknown amplitude, phase, temporal frequency and direction of arrival in complex white Gaussian noise with unknown variance. Depending on the natural invariance in scale, temporal modulation and spatial modulation of the problem, the uniformly most powerful invariant (UMPI) test is derived by using the statistical invariance principles. However, the UMPI test does not apply unless the signal-to-noise ratio (SNR) is known. However, it provides us with performance bound to evaluate any invariant test's performance when the SNR is unknown. Typically, the generalised likelihood ratio test (GLRT) and locally most powerful invariant (LMPI) test are derived as realisable suboptimal invariant tests with their performance comparison in different SNR through theoretical analysis. Computer simulation examples corroborate the authors analysis and indicate that the GLRT is close to the UMPI bound especially in the low probability-of-false-alarm (P FA) region of the receiver operating characteristic curve while the performance of the LMPI test is close to that of the UMPI test in the low SNR region.

Factors associated with reduced accuracy in Papanicolaou tests for patients with invasive cervical cancer.

Recent proposals to lengthen the interval in cervical cancer screening highlight the importance of the accurate interpretation of screening tests. Tumor debris present in Papanicolaou (Pap) tests from women with invasive cancer is known to hamper interpretation. The current study evaluated limiting factors in Pap tests from women with invasive cervical cancer. A total of 3003 women with the spectrum of cervical lesions who had ThinPrep (Hologic Inc, Marlborough, Mass) Pap and human papillomavirus (HPV) genotyping tests performed were grouped by their most severe histologic diagnosis. Cytologic and HPV results were analyzed by cross-sectional analysis. The unsatisfactory rate of cytology specimens from patients with cancer (3.1%) was significantly higher than those from patients with cervical intraepithelial neoplasia of type 3 or less (0.8%) (P < .001). The percentage of samples with qualified adequacy was 34.8% in specimens from patients with cancer compared with only 3.6% from specimens from those without cancer (P < .001). The unsatisfactory and qualified adequacy rates were higher in squamous cancers compared with adenocarcinomas. However, adenocarcinomas were identified less frequently than squamous cancers (37.0% vs 61.7%) in the Pap tests. HPV tests were positive in 84.4% of unsatisfactory cases including 8 of 9 cancer cases, although 8.5% of cancers tested negative for HPV. Unsatisfactory and suboptimal ThinPrep Pap tests were increased in cancer cases compared with lesser histologic diagnoses. This was found to be particularly true for squamous cancers. Specimens from adenocarcinomas had fewer adequacy problems but were less frequently recognized as malignant. HPV tests were positive in the majority of unsatisfactory Pap tests in women with carcinoma, suggesting that HPV testing in women aged > 30 years can help to identify high-risk women with unsatisfactory Pap tests.