Medical diagnostic accuracy measures: an innovative approach based on the area under predictive values curves

Positive and negative estimates are commonly used by clinicians to evaluate the likelihood of a disease stage being present based on test results. The predicted values are dependent on the prevalence of the underlying illness. However, for certain diseases or clinical conditions, the prevalence is unknown or different from one region to another or from one population to another, leading to an erroneous diagnosis. This article introduces innovative post-test diagnostic precision measures for continuous tests or biomarkers based on the combined areas under the predictive value curves for all possible prevalence values. The proposed measures do not vary as a function of the prevalence of the disease. They can be used to compare different diagnostic tests and/or biomarkers' abilities for rule-in, rule-out, and overall accuracy based on the combined areas under the predictive value curves. The relationship of the proposed measures to other diagnostic accuracy measures is discussed. We illustrate the proposed measures numerically and use a real data example on breast cancer.

Quantification of Metamorphopsia in Resolved Idiopathic Central Serous Chorioretinopathy: An Analysis Using M-CHARTS, Amsler Grid, and Optical Coherence Tomography

Purpose

To quantify metamorphopsia in patients with resolved idiopathic Central Serous Chorioretinopathy (CSCR) using M-CHARTS and compare the results with the traditional Amsler grid and optical coherence tomography (OCT).

Patients and Methods

For the purpose of this study, all consecutive cases of patients with resolved CSCR were evaluated for metamorphopsia (using the standard Amsler grid and M-CHARTS) and spectral domain OCT. The OCT images were analyzed for the following five parameters: central macular thickness, pigment epithelial detachment, retinal pigment epithelial bumps, discontinuation in the inner segment/outer segment junction or the external limiting membrane, fibrinous exudates in the subretinal space, and hyperreflective dots in the intraretinal and/or subretinal layer. Binary logistic regression was used to find the association between metamorphopsia and foveal morphology. Cohen's Kappa was used to determine the agreement between the M-CHARTS and Amsler grid for diagnosing metamorphopsia. The sensitivity, specificity, and accuracy in the diagnosis of metamorphopsia were calculated against the Amsler grid.

Results

Of 41 eyes, Amsler Grid detected metamorphopsia in 39.02%, and M-CHARTS detected metamorphopsia in 53.66%. The agreement rate of detection between the two tests was moderate (Kappa=0.52). M-CHARTS had a sensitivity of 87.50%, a specificity of 68.00%, a positive predictive value of 63.64%; and a negative predictive value of 89.47% for the diagnosis of metamorphopsia compared to the Amsler grid. The presence of PED in OCT was significantly associated with metamorphopsia.

Conclusion

M-CHARTS can be a useful ancillary test to detect and quantify metamorphopsia even after fluid resolution in CSCR. Structural changes in macular morphology as observed with OCT can predict the likelihood of metamorphopsia.

Post-test diagnostic accuracy measures under tree ordering of disease classes

The medical field commonly employs post-test measures such as predictive values and likelihood ratios to assess diagnostic accuracy. Predictive values, including positive and negative values (PPV and NPV), indicate the probability that individuals have a target health condition based on test results. On the other hand, likelihood ratios, including positive and negative ratios (LR+ and LR- respectively), compare the probability of a particular test result between the diseased and non-diseased groups. While predictive values are useful in evaluating diagnostic test accuracy in populations with varying disease prevalence, likelihood ratios provide a direct link between pre-test and post-test probabilities in specific patients. In this study, we introduce and analyze a new approach called generalized predictive values and likelihood ratios, using a tree ordering of disease classes. We evaluate the effectiveness of these methods through simulation studies and illustrate their use with real data on lung cancer.

The Effects of Human Papillomavirus Status and Treatment on the Positive Predictive Value of Post-radiotherapy 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in Advanced Head and Neck Squamous Cell Carcinoma

AIMS

The high negative predictive value of post-chemoradiation (CRT) positron emission tomography-computed tomography (PET-CT) is well established in head and neck squamous cell cancers (HNSCC). The positive predictive value (PPV) remains under scrutiny, with increasing evidence that it is affected by several factors. The aim of this study was to assess the PPV of post-treatment PET-CT for residual nodal disease when stratified by treatment modality and tumour human papillomavirus (HPV) status.

MATERIALS AND METHODS

This was a retrospective cohort study in a tertiary oncology centre carried out between January 2013 and December 2019. Patients were radically treated with radiotherapy only/CRT for node-positive HNSCC. PET-CT nodal responses were categorised as complete, equivocal (EQR) or incomplete (ICR), and outcomes extracted from electronic records.

RESULTS

In total, 480 patients were evaluated, all had a minimum potential follow-up of 2 years, with a median of 39.2 months. The PPV of 12-week PET-CT was significantly different between HPV-positive (22.5%) and HPV-unrelated (52.7%) disease, P < 0.001. It was also significantly different between the CRT (24.8%) and radiotherapy-only (51.1%) groups, P = 0.001. The PPV of an EQR was significantly less than an ICR, irrespective of HPV status and primary treatment modality. In HPV-positive disease, the PPV of an EQR was 9.0% for the CRT group compared with 21.4% for radiotherapy only, P = 0.278. The PPV in those who achieved an ICR was 34.2% in the CRT group, significantly lower than 70.0% in the radiotherapy-only group, P = 0.03.

CONCLUSION

The PPV of 12-week PET-CT is significantly lower for HPV-positive compared with HPV-unrelated HNSCC. It is poorer in patients with HPV-positive disease treated with CRT compared with radiotherapy alone.

Enhancing Cervical Cancer Prevention in South African Women: Primary HPV mRNA Screening with Different Genotype Combinations

BACKGROUND

Cervical cancer prevention in regions with limited access to screening and HPV vaccination necessitates innovative approaches. This study explored the potential of a test-and-treat strategy using mRNA HPV tests to impact cervical cancer prevention in a high-prevalence HIV population.

METHODS

A cervical screening study was conducted at three South African hospitals involving 710 under-screened, non-pregnant women (25 to 65 years) without known cervical diseases. Cytology, HPV testing, colposcopy, and biopsies were performed concurrently. Histopathologists determined final histological diagnoses based on biopsy and LLETZ histology. mRNA-HPV-genotyping for 3 (16, 18, 45) to 8 (16, 18, 31, 33, 35, 45, 52, 58) high-risk types was performed on leftover liquid-based cytology material. The preventive potential of the test-and-treat approach was estimated based on published data, reporting the causative HPV types in cervical cancer tissue from South African women. Treatment was provided as needed.

RESULTS

The HPV positivity rate more than doubled from 3-type (15.2%; 95% CI: 12.6-17.8) to 8-type mRNA (31.5%; 95% CI: 28.8-34.9) combinations, significantly higher among HIV-positive women. CIN3+ prevalence among HIV-positive women (26.4%) was double that of HIV-negative women (12.9%) (p < 0.01). The 6-type combination showed the best balance of sensitivity, specificity and treatment group size, and effectiveness to prevent cervical cancer. A 4-type combination (16, 18, 35, 45) could potentially prevent 77.6% (95% CI: 71.2-84.0) of cervical cancer burden by treating 20% and detecting 41.1% of CIN3 cases in the study group. Similarly, a 6-type combination (16, 18, 31, 33, 35, 45), treating 25% and including 62% of CIN3 cases, might prevent 85% of cervical cancer cases (95% CI: 79.6-90.6) among HIV-positive and negative women.

CONCLUSION

Employing mRNA HPV tests within a test-and-treat approach holds huge promise for targeted cervical cancer prevention in under-screened populations. Testing for mRNA of the 6 highest-risk HPV types in this population and treating them all is projected to effectively prevent progression from CIN3 to invasive cervical cancer while reducing overtreatment in resource-constrained settings.

Performance of Methicillin-Resistant Staphylococcus aureus Polymerase Chain Reaction Nasal Screening for Ruling Out MRSA Pneumonia in Hospitalized, Immunocompromised Patients

Background: Recent literature demonstrates support for using methicillin-resistant Staphylococcus aureus (MRSA) nasal swab polymerase chain reaction (NaPCR) screening as an antimicrobial stewardship tool aiding early de-escalation of anti-MRSA antimicrobials. However, immunocompromised patients have been underrepresented in previous studies despite increased risk of morbidity and mortality from multidrug-resistant organisms (MDRO). Objective: The purpose of this study was to determine the negative predictive value (NPV) of the MRSA NaPCR in hospitalized, immunocompromised adult patients with suspected pneumonia. Methods: A single-center, retrospective, observational review was conducted of hospitalized, immunocompromised adult patients that had an MRSA NaPCR obtained between March 1, 2020 and January 10, 2021. For inclusion, bacterial cultures must have been collected within 2 weeks after MRSA NaPCR. The primary outcome was the NPV of MRSA NaPCR in hospitalized, immunocompromised patients with suspected pneumonia. Secondary outcomes include NPV in other infections. Results: Between March 1, 2020 and January 10, 2021, 59 patients with 78 unique cultures, including 28 respiratory cultures, were included in the study. The NPV of the MRSA NaPCR for pneumonia was 91.7%. The NPV for bloodstream infections was 100% and for urinary tract infections was 100%, but interpretation of these results should be cautioned due to the small sample sizes. Conclusion: The NPV of MRSA NaPCR in pneumonia remains high in this study. The MRSA NaPCR has utility as a de-escalation tool in hospitalized, immunocompromised adult patients, but larger studies are warranted to evaluate all immunocompromised patient populations.

Whole-Genome Sequencing to Predict Mycobacterium tuberculosis Drug Resistance: A Retrospective Observational Study in Eastern China

Pulmonary tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (MTB). Whole-genome sequencing (WGS) holds great promise as an advanced technology for accurately predicting anti-TB drug resistance. The development of a reliable method for detecting drug resistance is crucial in order to standardize anti-TB treatments, enhance patient prognosis, and effectively reduce the risk of transmission. In this study, our primary objective was to explore and determine the potential of WGS for assessing drug resistance based on genetic variants recommended by the World Health Organization (WHO). A total of 1105 MTB strains were selected from samples collected from 2014-2018 in Zhejiang Province, China. Phenotypic drug sensitivity tests (DST) of the anti-TB drugs were conducted for isoniazid (INH), rifampicin (RFP), streptomycin, ethambutol, fluoroquinolones (levofloxacin and moxifloxacin), amikacin, kanamycin, and capreomycin, and the drug-resistance rates were calculated. The clean WGS data of the 1105 strains were acquired and analyzed. The predictive performance of WGS was evaluated by the comparison between genotypic and phenotypic DST results. For all anti-TB drugs, WGS achieved good specificity values (>90%). The sensitivity values for INH and RFP were 91.78% and 82.26%, respectively; however, they were ≤60% for other drugs. The positive predictive values for anti-TB drugs were >80%, except for ethambutol and moxifloxacin, and the negative predictive values were >90% for all drugs. In light of the findings from our study, we draw the conclusion that WGS is a valuable tool for identifying genome-wide variants. Leveraging the genetic variants recommended by the WHO, WGS proves to be effective in detecting resistance to RFP and INH, enabling the identification of multi-drug resistant TB patients. However, it is evident that the genetic variants recommended for predicting resistance to other anti-TB drugs require further optimization and improvement.

The Ability of Emergency Medical Service Staff to Predict Emergency Department Disposition: A Prospective Study

Purpose

Paramedics' decision to notify receiving hospitals and transport patients to an appropriate healthcare facility is based on the Prediction of Intensive Care Unit (ICU) and Hospital Admissions guide. This study aimed to assess the paramedics' gestalt on both ward and ICU admission.

Patients and Methods

A prospective study was conducted at King Abdulaziz Medical City between September 2021 and March 2022. Paramedics were asked several questions related to the prediction of the patient's hospital outcome, including emergency department (ED) discharge or hospital admission (ICU or ward). Additional data, such as the time of the ambulance's arrival and the staff years of experience, were collected. The categorical characteristics are presented by frequency and percentage for each category.

Results

This study included 251 paramedics and 251 patients. The average age of the patients was 62 years. Of the patients, 32 (12.7%) were trauma, and 219 (87.3%) were non-trauma patients. Two-thirds of the patients (n=171, 68.1%) were predicted to be admitted to the hospital, and 80 (31.8%) of the EMS staff indicated that the patient do not need a hospital or an ambulance. The sensitivity, specificity, PPV, and NPV of the emergency medical service (EMS) staffs' gestalt for patient admission to the hospital were, respectively (77%), (33%), (16%), and (90%). Further analysis was reported to defend the EMS staffs' gestalt based on the level of EMS staff and the nature of the emergency (medical vs trauma), are reported.

Conclusion

Our study reports a low level of accurately predicting patient admission to the hospital, including the ICU. The results of this study have important implications for enhancing the accuracy of EMS staff predictive ability and ensuring that patients receive appropriate care promptly.

A systematic review and meta-analysis of miRNAs for the detection of cervical cancer

Aim: This study aimed to critically appraise the evidence of the diagnostic effectiveness of miRNAs for the detection of cervical cancer. Methods & materials: A systematic review and meta-analysis was performed, searching PubMed, EMBASE and Web of Science. An umbrella meta-analysis of meta-analyses of individual biomarkers was performed. A Grading of Recommendations, Assessment, Development and Evaluations (GRADE) assessment of evidence was also performed. Results: A total of 52 miRNAs were included. Umbrella meta-analysis revealed significant heterogeneity in terms of sensitivity, specificity, receiver operating characteristic (ROC), positive predictive value and/or negative predictive value. Umbrella effects were 0.76 (95% CI: 0.73-0.78), 0.78 (95% CI: 0.75-0.81), 0.77 (95% CI: 0.75-0.80), 0.75 (95% CI: 0.71-0.79) and 0.76 (95% CI: 0.74-0.79), respectively. Conclusion: Moderate quality evidence suggested miR199a-5p, miR21-5p and miR-141a had excellent diagnostic performance.

Principled leveraging of external data in the evaluation of diagnostic devices via the propensity score-integrated composite likelihood approach

In the area of diagnostics, it is common practice to leverage external data to augment a traditional study of diagnostic accuracy consisting of prospectively enrolled subjects to potentially reduce the time and/or cost needed for the performance evaluation of an investigational diagnostic device. However, the statistical methods currently being used for such leveraging may not clearly separate study design and outcome data analysis, and they may not adequately address possible bias due to differences in clinically relevant characteristics between the subjects constituting the traditional study and those constituting the external data. This paper is intended to draw attention in the field of diagnostics to the recently developed propensity score-integrated composite likelihood approach, which originally focused on therapeutic medical products. This approach applies the outcome-free principle to separate study design and outcome data analysis and can mitigate bias due to imbalance in covariates, thereby increasing the interpretability of study results. While this approach was conceived as a statistical tool for the design and analysis of clinical studies for therapeutic medical products, here, we will show how it can also be applied to the evaluation of sensitivity and specificity of an investigational diagnostic device leveraging external data. We consider two common scenarios for the design of a traditional diagnostic device study consisting of prospectively enrolled subjects, which is to be augmented by external data. The reader will be taken through the process of implementing this approach step-by-step following the outcome-free principle that preserves study integrity.

Diagnostic Accuracy of Cell Block and Immunohistochemistry in Effusion Cytology

Introduction Although the cytology of effusion fluids is considered a routine laboratory test, it has recently emerged as an essential tool in determining the primary site of origin of carcinoma of unknown primary. The sensitivity for diagnosing malignancy has enhanced with the inclusion of cytospin, cell block (CB), and immunohistochemistry (IHC) to effusion fluid cytology due to the improvement in morphological preservation and good cellular yield. The purpose of this study was to assess the diagnostic yield, sensitivity, specificity, positive predictive value, and negative predictive value of IHC and CB in effusion cytology. Methodology An institution-based cross-sectional study was conducted over a period of six months on 150 cases of effusion fluids submitted for diagnostic purposes. After the preparation of cytospin, the residual amount of centrifuged deposit was mixed with CytoLyt solution, thrombin, and plasma, and CBs were prepared. IHC was applied to the CB. Calretinin was used for mesothelial cells, and BerEP4, TTF-1, ER, WT-1, and CD-X2 were used for the confirmation and origin of malignant cells. Results The mean age of the patients was 51.75 ± 16.63 years. The male-to-female ratio was 1:1.24. Out of 150 cases, 78 were pleural effusions, 68 were peritoneal effusions, and four were pericardial effusions. Out of 150 cases, based on cytological examination alone, 66 (44%) were classified as benign, 27 (18%) as malignant, and 57 (38%) were suspicious for malignancy. When cytology was combined with CB and IHC, the diagnostic yield was increased to benign 95 (63.33%), malignant 48 (32%), and suspicious for malignancy 7 (4.67%). The most common cause of malignant pleural effusion was breast carcinoma in females and lung carcinoma in males. The most common primary tumor in malignant peritoneal effusion was ovarian carcinoma in females and colonic adenocarcinoma in males. The sensitivity and specificity of combined cytology with cell block and IHC were 92.31% and 98.95%, respectively. This combination produced significantly better results (p-value = 0.001) for detecting malignancy and reduced suspicious cases from 38% to 4%. Conclusion CB, in combination with IHC, increases the diagnostic yield and aids in detecting malignancy at an unknown primary site in effusion fluids. Both of these techniques can thus enhance the sensitivity and specificity of the diagnosis of effusion cytology. Hence, CB and IHC have advanced utility over cytological smears in effusion fluid cytological diagnosis.

Accuracy of COVID-19-Like Illness Diagnoses in Electronic Health Record Data: Retrospective Cohort Study

BACKGROUND

Electronic health record (EHR) data provide a unique opportunity to study the epidemiology of COVID-19, clinical outcomes of the infection, comparative effectiveness of therapies, and vaccine effectiveness but require a well-defined computable phenotype of COVID-19-like illness (CLI).

OBJECTIVE

The objective of this study was to evaluate the performance of pathogen-specific and other acute respiratory illness (ARI) International Statistical Classification of Diseases-9 and -10 codes in identifying COVID-19 cases in emergency department (ED) or urgent care (UC) and inpatient settings.

METHODS

We conducted a retrospective observational cohort study using EHR, claims, and laboratory information system data of ED or UC and inpatient encounters from 4 health systems in the United States. Patients who were aged ≥18 years, had an ED or UC or inpatient encounter for an ARI, and underwent a SARS-CoV-2 polymerase chain reaction test between March 1, 2020, and March 31, 2021, were included. We evaluated various CLI definitions using combinations of International Statistical Classification of Diseases-10 codes as follows: COVID-19-specific codes; CLI definition used in VISION network studies; ARI signs, symptoms, and diagnosis codes only; signs and symptoms of ARI only; and random forest model definitions. We evaluated the sensitivity, specificity, positive predictive value, and negative predictive value of each CLI definition using a positive SARS-CoV-2 polymerase chain reaction test as the reference standard. We evaluated the performance of each CLI definition for distinct hospitalization and ED or UC cohorts.

RESULTS

Among 90,952 hospitalizations and 137,067 ED or UC visits, 5627 (6.19%) and 9866 (7.20%) were positive for SARS-CoV-2, respectively. COVID-19-specific codes had high sensitivity (91.6%) and specificity (99.6%) in identifying patients with SARS-CoV-2 positivity among hospitalized patients. The VISION CLI definition maintained high sensitivity (95.8%) but lowered specificity (45.5%). By contrast, signs and symptoms of ARI had low sensitivity and positive predictive value (28.9% and 11.8%, respectively) but higher specificity and negative predictive value (85.3% and 94.7%, respectively). ARI diagnoses, signs, and symptoms alone had low predictive performance. All CLI definitions had lower sensitivity for ED or UC encounters. Random forest approaches identified distinct CLI definitions with high performance for hospital encounters and moderate performance for ED or UC encounters.

CONCLUSIONS

COVID-19-specific codes have high sensitivity and specificity in identifying adults with positive SARS-CoV-2 test results. Separate combinations of COVID-19-specific codes and ARI codes enhance the utility of CLI definitions in studies using EHR data in hospital and ED or UC settings.

Diagnostic Value of Oral Provocation Tests in Drug Hypersensitivity Reactions Induced by Nonsteroidal Anti-Inflammatory Drugs and Paracetamol

Oral drug provocation tests (DPT) are the basic diagnostic tool for the detection of hypersensitivity to non-opioid analgesics and for selecting a safe alternative for a patient. They are of great practical importance due to their common use, but the data on the follow-up of patients after negative DPT are still very scarce. We examined the further fate of 164 such adult patients after negative NSAID or paracetamol tests and analyzed which excipients in the studied drugs they could be exposed to after the diagnostic workup. A structured medical interview was performed 32.9 months (mean) after the provocation tests. Of the 164 patients, 131 (79.9%) retook the tested drug and 12 developed another hypersensitivity reaction, giving the estimated negative predictive value of 90.8%. These reactions were induced by acetylsalicylic acid, paracetamol, meloxicam, and diclofenac, and were clinically similar to the initial ones (most commonly urticaria and angioedema). There are 93 generics of these drugs on the local market, containing a total of 33 excipients for which hypersensitivity reactions have been reported. All available generics contain such excipients. Thirty-one patients (20.1%) did not take the previously tested drug again, most often because it was not needed or because they were afraid of another reaction. DPT with analgesics has a high diagnostic performance. A minority of patients had relapsed after reexposure. One of the underestimated reasons for this may be drug excipients provoking a reaction, so it is advisable to use exactly the same medical product that has been negatively tested. Many patients avoid reexposure to a given drug, despite negative tests, therefore very reliable patient education in connection with DPT is highly needed.

Accuracy of the International Classification of Diseases, 9th Revision for Identifying Infantile Eye Disease

PURPOSE

To determine the predictive value of International Classification of Diseases, 9th Revision (ICD-9) codes for identifying infantile eye diagnoses.

METHODS

Population-based retrospective cohort study of all residents of Olmsted County, Minnesota diagnosed at ≤1 year of age with an ocular disorder. The medical records of all infants diagnosed with any ocular disorder from January 1, 2005, through December 31, 2014, were identified. To assess ICD-9 code accuracy, the medical records of all diagnoses with ≥20 cases were individually reviewed and compared to their corresponding ICD-9 codes. Main outcome measures included positive predictive value (PPV), negative predictive value (NPV), sensitivity, and specificity of ICD-9 codes.

RESULTS

In a cohort of 5,109 infants with ≥1 eye-related ICD-9 code, 10 ocular diagnoses met study criteria. The most frequent diagnoses were conjunctivitis (N = 1,695) and congenital nasolacrimal duct obstruction (N = 1,250), while the least common was physiologic anisocoria (N = 23). The PPVs ranged from 8.3% to 88.0%, NPVs from 96.3% to 100%, sensitivity from 3.0% to 98.7%, and specificity from 72.6% to 99.9%. ICD-9 codes were most accurate at identifying physiologic anisocoria (PPV: 88.0%) and least accurate at identifying preseptal cellulitis (PPV: 8.3%). In eye specialists versus non-eye specialists, there was a significant difference in PPV of ICD-9 codes for conjunctivitis (26.8% vs. 63.9%, p < .001), pseudostrabismus (85.9% vs. 25.0%, p < .001), and physiologic anisocoria (95.5% vs. 33.3%, p = .002).

CONCLUSION

The predictive value of ICD-9 codes for capturing infantile ocular diagnoses varied widely in this cohort. These findings emphasize the limitations of database research methodologies that solely utilize claims data to identify pediatric eye diseases.Abbreviations/Acronyms PPV: positive predictive value; NPV: negative predictive value; CNLDO: congenital nasolacrimal duct obstruction.

Characteristics of lymph node stations/basins metastasis and construction and validation of a preoperative combination prediction model that accurately excludes lymph node metastasis in early gastric cancer

OBJECTIVE

To explore the candidate indications for function-preserving curative gastrectomy and sentinel lymph node navigation surgery in early gastric cancer (EGC).

METHODS

The clinicopathological data of 561 patients with EGC who underwent radical gastrectomy for gastric cancer at Peking University Cancer Hospital from November 2010 to November 2020 with postoperative pathological stage pT1 and complete examination data, were collected. Pearson's Chi-square test was used and binary logistic regression was employed for univariate and multivariate analyses. Combined analysis of multiple risk and protective factors for lymph node metastasis (LNM) of EGC was performed. A negative predictive value (NPV) combination model was built and validated.

RESULTS

LNM occurred in 85 of 561 patients with EGC, and the LNM rate was 15.15%. NPV for LNM reached 100% based on three characteristics, including ulcer-free, moderately well differentiation and patient <65 years old or tumor located at the proximal 1/3 of the stomach. Regarding lymphatic basin metastasis, multivariate analysis showed that the metastatic proportion of the left gastric artery lymphatic basin was significantly higher in male patients compared with female patients (65.96% vs. 38.89%, P<0.05). The proportion of right gastroepiploic artery lymphatic basin metastasis in patients with a maximum tumor diameter >2 cm was significantly greater than that noted in patients with a maximum tumor diameter ≤2 cm (60.78% vs. 28.13%, P<0.05).

CONCLUSIONS

Characteristics of lymph node stations/basins metastasis will facilitate precise lymph node resection. The NPV for LNM reaches 100% based on the following two conditions: young and middle-aged EGC patients, well-differentiated tumors, and without ulcers; or well-differentiated tumors, without ulcers, and tumors located in the proximal stomach. These findings can be used as the recommended indications for function-preserving curative gastrectomy and sentinel lymph node navigation surgery.

Likelihood Ratios: An Important Concept for Palliative Physicians to Understand

Palliative care has several tools and questionnaires which are commonly used for patient-related outcomes and prognosis. As an example, the Surprise Question (I would or would not be surprised that this person would have died in a year) has been used as a screen for palliative care referral but also used as a prognostic tool. Diagnostic tests, prognostic tools, and tools for gauging outcomes have certain sensitivity and specificity in predicting a diagnosis or outcome. Clinicians often use positive and negative predictive values in judging the merits of a diagnostic tool or questionnaire. However positive and negative predictive values are highly dependent on the prevalence of disease or outcome in a population and thus are not portable across studies. Likelihood ratios are both portable across populations but also provide the strength of the diagnostic or predictive measure of a test or questionnaire. In this article, we review the value and limitations of likelihood ratios and illustrate the value of using likelihood ratios using 3 studies centered on the Surprise Question published in 2022.

The Clinical Value of Methicillin-Resistant Staphylococcus aureus Nasal Screening in the Management of Diabetic Foot Infections

Nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) remains an important risk factor for diabetic foot infections (DFIs). We explored herein the clinical value of MRSA-nasal screening in the management of DFIs. In this retrospective case-control study, patients admitted with a DFI between 1/1/2014-6/30/2020 were studied and divided into cases (positive MRSA-nasal screening) and controls (negative MRSA-nasal). We included 171 patients (22 cases and 149 controls). MRSA nasal screening had a negative predictive value (NPV) of 86%. Compared to controls, cases were treated with intravenous vancomycin for a longer duration: (median [IQR], 5[3,11] vs 2[2,6]) days, P = .037). In multivariate analysis, a negative MRSA nasal screening was associated with a 74% decreased risk of AKI (OR = 0.26, 95% CI = 0.07-0.89). MRSA nasal screening in patients admitted with DFI has a high NPV. Obtained early, it can shorten the duration of intravenous vancomycin, consequently preventing AKI.

Making Sense of Sensitivity: Using Candy and Anthropometric Data to Visually and Manipulatively Illustrate Sensitivity, Positive Predictive Value, and Related Terms

The classic concepts of sensitivity and specificity are commonly taught by definition only, often with discipline-specific jargon and without any tangible relation to their use in the real world. Yet, the COVID pandemic and the spotlight on diagnostic screening tests have brought a need for science and health care students, health professionals, and the general public to have improved understanding of sensitivity and specificity and how they connect to further interpretive values. These understandings are critical for correct communications and explanations to those outside the sciences. Using simple candies or marbles as visuals, in conjunction with real-world scenarios, this activity was designed to help frame these concepts for students. Additionally, this activity provides practice with basic calculations and interpretations to reinforce how data can be used in determining testing values, surrogate testing, data cutoffs, and accuracy predictions. The activity is flexible and can easily be done in 1 to 2 h in a classroom setting, as a laboratory exercise, or as an outreach or online activity.

Performance of Hepatitis C Virus (HCV) Core Antigen Assay in the Diagnosis of Recently Acquired HCV Infection among High-Risk Populations

How the hepatitis C virus (HCV) core antigen (HCVcAg) assay performs in detecting recently acquired HCV infection among people living with HIV (PLWH) and HIV-negative men who have sex with men (MSM) is rarely assessed in the Asia-Pacific region. High-risk participants, including PLWH with sexually transmitted infections (STIs), HCV clearance by antivirals or spontaneously, or elevated aminotransferases, HIV-negative MSM with STIs or on HIV preexposure prophylaxis, and low-risk PLWH were enrolled. Blood samples were subjected to 3-stage pooled-plasma HCV RNA testing every 3 to 6 months until detection of HCV viremia or completion of the 1-year follow-up. The samples at enrollment and all of the archived samples preceding the detection of HCV RNA during follow-up were tested for HCVcAg. During June 2019 and February 2021, 1,639 blood samples from 744 high-risk and 727 low-risk PLWH and 86 HIV-negative participants were tested for both HCV RNA and HCVcAg. Of 62 samples positive for HCV RNA, 54 (87.1%) were positive for HCVcAg. Of 1,577 samples negative for HCV RNA, 1,568 (99.4%) were negative for HCVcAg. The mean HCV RNA load of the 8 individual samples positive for HCV RNA but negative for HCVcAg was 3.2 (range, 2.5 to 3.9) log10 IU/mL, and that of the remaining 54 samples with concordant results was 6.2 (range, 1.3 to 8.5) log10 IU/mL. The positive predictive value (PPV) and negative predictive value (NPV) of HCVcAg were 85.7% and 99.5%, respectively. In at-risk populations, HCVcAg has a high specificity and NPV but lower sensitivity and PPV, particularly in individuals with low HCV RNA loads. IMPORTANCE The HCV core antigen assay has a high specificity of 99.4% and negative predictive value of 99.5% but a lower sensitivity of 87.1% and positive predictive value of 85.7% in the diagnosis of recently acquired HCV infection in high-risk populations. Our findings are informative for many countries confronted with limited resources to timely identify acute HCV infections and provide effective direct-acting antivirals to halt onward transmission.

Recognizing the Emergent and Submerged Iceberg of the Celiac Disease: ITAMA Project-Global Strategy Protocol

Coeliac disease (CD) is frequently underdiagnosed with a consequent heavy burden in terms of morbidity and health care costs. Diagnosis of CD is based on the evaluation of symptoms and anti-transglutaminase antibodies IgA (TGA-IgA) levels, with values above a tenfold increase being the basis of the biopsy-free diagnostic approach suggested by present guidelines. This study showcased the largest screening project for CD carried out to date in school children (n=20,000) aimed at assessing the diagnostic accuracy of minimally invasive finger prick point-of-care tests (POCT) which, combined with conventional celiac serology and the aid of an artificial intelligence-based system, may eliminate the need for intestinal biopsy. Moreover, this study delves deeper into the "coeliac iceberg" in an attempt to identify people with disorders who may benefit from a gluten-free diet, even in the absence of gastrointestinal symptoms, abnormal serology and histology. This was achieved by looking for TGA-IgA mucosal deposits in duodenal biopsy. This large European multidisciplinary health project paves the way to an improved quality of life for patients by reducing the costs for diagnosis due to delayed findings of CD and to offer business opportunities in terms of diagnostic tools and support.

Real Time Polymerase Chain Reaction for the Diagnosis of SARS-CoV-2 Infection: A Retrospective Cohort Study

Background: Real time reverse transcription polymerase chain reaction (real time RT-PCR) testing is the gold standard for the diagnosis of SARS-CoV-2 infections. However, to expand the testing capacity, new SARS-CoV-2 rapid antigen tests (Ag-RDTs) have been implemented. Ag-RDTs are more rapid, but less reliable in terms of sensitivity, and real-life data on their performance in comparison with the real time RT-PCR test are lacking. Methods: We aimed at assessing the diagnostic performance of the third-generation antigenic swab LumiraDx™ compared with real time RT-PCR in a retrospective cohort study at the Infectious Diseases Unit of Padua. All of the patients who were consecutively tested for SARS-CoV-2 in our centre (by both real time RT-PCR and Ag-RTD LumiraDxTM) from 19 January to 30 May 2021, were included. Cycle-threshold (Ct) values of positive real time RT-PCR were recorded as well as the number of days from symptoms’ onset to testing. Results: Among the 282 patients included, 80.9% (N = 228) tested positive to real time RT-PCR, and among these, 174 tested positive also to LumiraDx™. Compared with real time RT-PCR, which is considered as the gold standard for the assessment of the presence/absence of SARS-CoV-2 infection, LumiraDx™ showed an overall sensitivity of 76.3% and specificity of 94.4%. Sensitivity increased to 91% when testing was performed <10 days from symptoms’ onset, and to 95% when considering Ct < 25. Multivariable binomial logistic regression showed that false negative LumiraDx™ results were significantly associated with high Ct values, and with further testing from symptoms’ onset. Conclusions: The results of our study suggested that the LumiraDx™ SARS-CoV-2 antigen assay may be appropriate for the detection of SARS-CoV-2 infection, especially in its early phase when the test largely meets the performance requirements of the European Centre for Disease Prevention and Control (ECDC).

Critical Care Randomized Trials Demonstrate Power Failure: A Low Positive Predictive Value of Findings in the Critical Care Research Field

BACKGROUND

We aimed to determine the post-hoc power of randomized controlled trials (RCTs) in critical care, and describe the implications for long-term positive (PPV) and negative predictive value (NPV) of statistically significant and non-significant findings respectively in the research field.

METHODS

We reviewed three cohorts of RCTs. "Adult-RCTs" were 216 multicenter RCTs with a mortality outcome from a published systematic review. "Pediatric-RCTs" were 120 RCTs with a mortality outcome, obtained by search of picutrials.net. "Consecutive-RCTs" were 90 recent RCTs obtained by screening publications in 6 journals. Post-hoc power for each study was calculated at α 0.05 and 0.005, for measures of small, medium, and large effect-size, using G*Power software. Long-run expected PPV and NPV of critical care research field findings were then calculated.

RESULTS

With α 0.05, post-hoc power for small effect-size was very low in all RCT-cohorts (eg, median 24% in Adult-RCTs). For medium effect-size, post-hoc power was low, except for Adult-RCTs (eg, median 9% in Pediatric-RCTs). For large effect-size, post-hoc power for non-human-animal Consecutive-RCTs was low (median 32%). With α 0.005, post-hoc power was even lower. The corollary was that both PPV and NPV were poor for small effect-size, unless α 0.005 was used. Even with α 0.005, with realistic (vs. optimistic) prior probability of the alternative hypothesis, the PPV was low (eg, in Adult-RCTs 57.1% vs. 92.3%). Adding mild bias (0.1) reduced the PPV even further. For medium effect-size both PPV and NPV were better; nevertheless, with α 0.05 and realistic prior probability of the alternative hypothesis the PPV was poor, and with α 0.005 and mild bias (0.1) the PPV was very low (eg, Adult-RCTs median 44.1%).

CONCLUSIONS

To improve the predictive value of findings in the critical care research field, RCTs should be designed to have 80% power for realistic effect-size at α 0.005.

Nomogram predicting prostate cancer in patients with negative prebiopsy multiparametric magnetic resonance

Aim: To build two nomograms for predicting the possibilities of prostate cancer (PCa) and clinically significant PCa (csPCa) in patients with negative prebiopsy multiparametric MRI (mpMRI). Methods: The independent predictors associated with PCa or csPCa in patients with negative mpMRI were determined and served in the construction of the two nomograms. Results: The nomogram predicting PCa consisted of age, positive digital rectal examination, free/total prostate-specific antigen (PSA) ratio and PSA density, while age, positive digital rectal examination and PSA density comprised the nomogram predicting csPCa. The negative predictive value of mpMRI for PCa and csPCa improved from 77.1 and 87.5% to 90.4 and 96.1%, respectively, in the training cohort (n = 376) and from 81.9 and 89.0% to 91.8 and 96.5%, respectively, in the validation cohort (n = 127) when combined with the two nomograms. Conclusion: The negative predictive value of negative mpMRI for the detection of PCa or csPCa was improved with the results of the nomograms.

Reappraisal of CSF-specific oligoclonal bands in Asia

The prevalence of cerebrospinal fluid-specific oligoclonal bands (CSF-OCBs) was reported to be low in Asian people with multiple sclerosis (pwMS) compared to that in Western pwMS. It is yet to be determined whether it is a genuine feature of Asian pwMS or a misapprehension owing to past mis-classification of MS-mimicking diseases as MS. We aimed to reappraise the prevalence of CSF-OCBs in Korean pwMS after carefully excluding other central nervous system-inflammatory demyelinating diseases since 2017. Among 88 subjects, 78 (88.6%) were positive for CSF-OCBs, which suggests the prevalence of CSF-OCBs is not different between Korean and Western pwMS.

Assigning readers to cases in imaging studies using balanced incomplete block designs

In many imaging studies, each case is reviewed by human readers and characterized according to one or more features. Often, the inter-reader agreement of the feature indications is of interest in addition to their diagnostic accuracy or association with clinical outcomes. Complete designs in which all participating readers review all cases maximize efficiency and guarantee estimability of agreement metrics for all pairs of readers but often involve a heavy reading burden. Assigning readers to cases using balanced incomplete block designs substantially reduces reading burden by having each reader review only a subset of cases, while still maintaining estimability of inter-reader agreement for all pairs of readers. Methodology for data analysis and power and sample size calculations under balanced incomplete block designs is presented and applied to simulation studies and an actual example. Simulation studies results suggest that such designs may reduce reading burdens by >40% while in most scenarios incurring a <20% increase in the standard errors and a <8% and <20% reduction in power to detect between-modality differences in diagnostic accuracy and κ statistics, respectively.

D-dimer level for ruling out peripherally inserted central catheter-associated upper extremity deep vein thrombosis and superficial vein thrombosis

AIMS

To examine the effectiveness of D-dimer values to be used as an independent diagnostic marker for excluding peripherally inserted central catheter-associated upper extremity deep vein thrombosis and superficial vein thrombosis.

DESIGN

This was a retrospective case-cohort study.

METHODS

Records were reviewed for 281 patients who underwent peripherally inserted central catheter insertion between 1 October 2017 and 1 October 2019. According to the modified Wells score after peripherally inserted central catheter insertion, the patients who had low vein thrombosis risk underwent a D-dimer test and colour Doppler ultrasound.

RESULTS

Among 281 patients, 180 patients (64%, 95% CI: 58.2%-69.4%) had negative D-dimer results and 39 of 180 patients had vein thrombosis despite having a negative D-dimer result, resulting in a failure rate of 21.7% (95% CI: 16.3%-28.3%). The negative predictive value of peripherally inserted central catheter-associated vein thrombosis in the cancer group (80.0%, 95% CI: 73.2%-85.4%) was higher than that of the non-cancer group (60.0%, 95% CI: 35.7%-80.2%). The negative predictive value of peripherally inserted central catheter-associated deep venous thrombosis (84.9%, 95% CI: 78.7%-89.6%) was lower than that of the PICC-associated superficial venous thrombosis (91.0%, 95% CI: 85.4%-94.6%).

CONCLUSION

The D-dimer levels maybe should not be used as a diagnostic index to rule out peripherally inserted central catheter-associated upper extremity vein thrombosis.

Evaluation of the reliability of MRSA screens in patients undergoing universal decolonization

PURPOSE

Colonization of methicillin-resistant Staphylococcus aureus (MRSA) can be detected via nasal screens. Evidence indicates that negative MRSA nasal screens may be used to de-escalate anti-MRSA antibiotics in pulmonary infections. In the ICU, universal decolonization with intranasal mupirocin is implemented to reduce MRSA infection risk. This study aimed to determine whether mupirocin administration affects the reliability of MRSA PCR nasal screens.

METHODS

This retrospective study divided subjects based on timing of intranasal mupirocin administration-before and after MRSA screen. Subjects with confirmed pulmonary infection that received vancomycin, blood/respiratory cultures, and had MRSA PCR screen collected were included. Subjects with concurrent infection requiring vancomycin or MRSA infection in prior 30 days were excluded. Primary outcome of this non-inferiority study was the negative predictive value (NPV) of the screen. Secondary outcomes included the positive predictive value (PPV), sensitivity, and specificity of the screen and duration of vancomycin.

RESULTS

Ultimately, 125 subjects were included in each group. The NPV in the group receiving mupirocin before screen was 95.2%, whereas the NPV in the group receiving mupirocin after screen was 99%. The difference between groups was -3.8% (90% CI -7.8%-0.2%; p=0.31), which failed to meet non-inferiority criteria. The secondary outcomes of PPV, sensitivity and specificity of the screen were similar in both groups. The duration of vancomycin was significantly longer in subjects receiving mupirocin before screen (3 days vs. 2 days; p<0.05).

CONCLUSION

Intranasal mupirocin prior to the screen may reduce NPV in pulmonary infections. Approach de-escalation of vancomycin based on screen results with caution.

C-Reactive Protein, Procalcitonin, and White Blood Count to Rule Out Neonatal Early-onset Sepsis Within 36 Hours: A Secondary Analysis of the Neonatal Procalcitonin Intervention Study

BACKGROUND

Neonatal early-onset sepsis (EOS) is one of the main causes of global neonatal mortality and morbidity, and initiation of early antibiotic treatment is key. However, antibiotics may be harmful.

METHODS

We performed a secondary analysis of results from the Neonatal Procalcitonin Intervention Study, a prospective, multicenter, randomized, controlled intervention study. The primary outcome was the diagnostic accuracy of serial measurements of C-reactive protein (CRP), procalcitonin (PCT), and white blood count (WBC) within different time windows to rule out culture-positive EOS (proven sepsis).

RESULTS

We analyzed 1678 neonates with 10 899 biomarker measurements (4654 CRP, 2047 PCT, and 4198 WBC) obtained within the first 48 hours after the start of antibiotic therapy due to suspected EOS. The areas under the curve (AUC) comparing no sepsis vs proven sepsis for maximum values of CRP, PCT, and WBC within 36 hours were 0.986, 0.921, and 0.360, respectively. The AUCs for CRP and PCT increased with extended time frames up to 36 hours, but there was no further difference between start to 36 hours vs start to 48 hours. Cutoff values at 16 mg/L for CRP and 2.8 ng/L for PCT provided a sensitivity of 100% for discriminating no sepsis vs proven sepsis.

CONCLUSIONS

Normal serial CRP and PCT measurements within 36 hours after the start of empiric antibiotic therapy can exclude the presence of neonatal EOS with a high probability. The negative predictive values of CRP and PCT do not increase after 36 hours.

Sensitivity of long-term EEG monitoring as a second diagnostic step in the initial diagnosis of epilepsy

In this retrospective study, we aimed to evaluate the sensitivity and negative predictive value of long-term EEG (L-EEG) in patients being assessed for epilepsy, who had already undergone non-specific standard EEG(s) (S-EEG). Secondary endpoints of this study were: (1) the correlation of non-specific changes on EEG with epileptiform patterns on L-EEG; and (2) the correlation of clinical parameters such as subjective frequency of seizures or epileptogenic lesions on cerebral imaging with epileptiform changes on L-EEG. We retrospectively analysed clinical and electrophysiological data of 75 patients, assessed for epilepsy at the University Hospital Zurich, who had undergone an L-EEG for at least 48 hours, between 2010 and 2015. All patients had already undergone S-EEG(s) before L-EEG, which showed no epileptic changes. Furthermore, the association with clinical parameters, such as frequency of presumptive seizures, abnormalities on standard-EEG, AED intake and cerebral imaging with the final diagnosis, was analysed. Out of 75 patients, 14 (19%) patients were finally diagnosed with epilepsy. In eight of these patients, L-EEGs showed typical ictal/interictal patterns, with a sensitivity of 57% and negative predictive value of 91%. Neither the subjective frequency of seizures nor potentially epileptogenic lesions on cerebral imaging were associated with a positive epilepsy diagnosis. In this preselected cohort of patients, who had already undergone a non-diagnostic S-EEG, the sensitivity of L-EEG remained considerable. Nonetheless, our study also revealed a significant false-negative rate. Based on the high negative predictive value in this study, L-EEG appears to be most useful at excluding epilepsy. Nevertheless, thorough evaluation of seizure history and clinical findings remain crucial for a reliable diagnosis.

The Accuracy of Envelope Following Responses in Predicting Speech Audibility

OBJECTIVES

The present study aimed to (1) evaluate the accuracy of envelope following responses (EFRs) in predicting speech audibility as a function of the statistical indicator used for objective response detection, stimulus phoneme, frequency, and level, and (2) quantify the minimum sensation level (SL; stimulus level above behavioral threshold) needed for detecting EFRs.

DESIGN

In 21 participants with normal hearing, EFRs were elicited by 8 band-limited phonemes in the male-spoken token /susa∫i/ (2.05 sec) presented between 20 and 65 dB SPL in 15 dB increments. Vowels in /susa∫i/ were modified to elicit two EFRs simultaneously by selectively lowering the fundamental frequency (f0) in the first formant (F1) region. The modified vowels elicited one EFR from the low-frequency F1 and another from the mid-frequency second and higher formants (F2+). Fricatives were amplitude-modulated at the average f0. EFRs were extracted from single-channel EEG recorded between the vertex (Cz) and the nape of the neck when /susa∫i/ was presented monaurally for 450 sweeps. The performance of the three statistical indicators, F-test, Hotelling's T, and phase coherence, was compared against behaviorally determined audibility (estimated SL, SL ≥0 dB = audible) using area under the receiver operating characteristics (AUROC) curve, sensitivity (the proportion of audible speech with a detectable EFR [true positive rate]), and specificity (the proportion of inaudible speech with an undetectable EFR [true negative rate]). The influence of stimulus phoneme, frequency, and level on the accuracy of EFRs in predicting speech audibility was assessed by comparing sensitivity, specificity, positive predictive value (PPV; the proportion of detected EFRs elicited by audible stimuli) and negative predictive value (NPV; the proportion of undetected EFRs elicited by inaudible stimuli). The minimum SL needed for detection was evaluated using a linear mixed-effects model with the predictor variables stimulus and EFR detection p value.

RESULTS

of the 3 statistical indicators were similar; however, at the type I error rate of 5%, the sensitivities of Hotelling's T (68.4%) and phase coherence (68.8%) were significantly higher than the F-test (59.5%). In contrast, the specificity of the F-test (97.3%) was significantly higher than the Hotelling's T (88.4%). When analyzed using Hotelling's T as a function of stimulus, fricatives offered higher sensitivity (88.6 to 90.6%) and NPV (57.9 to 76.0%) compared with most vowel stimuli (51.9 to 71.4% and 11.6 to 51.3%, respectively). When analyzed as a function of frequency band (F1, F2+, and fricatives aggregated as low-, mid- and high-frequencies, respectively), high-frequency stimuli offered the highest sensitivity (96.9%) and NPV (88.9%). When analyzed as a function of test level, sensitivity improved with increases in stimulus level (99.4% at 65 dB SPL). The minimum SL for EFR detection ranged between 13.4 and 21.7 dB for F1 stimuli, 7.8 to 12.2 dB for F2+ stimuli, and 2.3 to 3.9 dB for fricative stimuli.

CONCLUSIONS

EFR-based inference of speech audibility requires consideration of the statistical indicator used, phoneme, stimulus frequency, and stimulus level.

Can Prostate-Specific Antigen Density Be an Index to Distinguish Patients Who Can Omit Repeat Prostate Biopsy in Patients with Negative Magnetic Resonance Imaging?

Purpose

We evaluated the negative predictive value (NPV) of multiparametric magnetic resonance imaging (mpMRI) in detecting clinically significant prostate cancer (csPCa) according to biopsy setting and prostate-specific antigen density (PSAD) using transperineal template-guided saturation prostate biopsy (TPB) as the reference standard.

Methods

A total of 161 patients with biopsy histories and negative pre-biopsy mpMRI (Prostate Imaging Reporting and Data System version 2 scores of less than 3) participated in the study. TPB was performed on the following indications: “prior negative biopsy” in patients with persistent suspicion of prostate cancer (n = 91) or “confirmatory biopsy” in patients who were candidates for active surveillance (n = 70). The csPCa was defined as a Gleason score of 3 + 4 or greater. We calculated the NPV of mpMRI in detecting csPCa according to biopsy history and prostate-specific antigen density (PSAD) and conducted a logistic regression analysis to determine the clinical predicator for the absence of csPCa.

Results

The detection rate of csPCa was 5.5% in the prior negative biopsy group and 14.3% in the confirmatory biopsy group (P = 0.057). None of the variables in the logistic regression models including PSAD <0.15 ng/mL/cc and prior negative biopsy could predict the absence of csPCa. The NPV of mpMRI in detecting csPCa in patients with a prior negative biopsy worsen from 94.5% to 93.3% when combined with PSAD <0.15 ng/mL/cc.

Conclusion

Patients with negative mpMRI findings may not omit repeat biopsy even if their prior biopsy histories are negative and PSADs are <0.15 ng/mL/cc.

Reliability and validity of D-dimer monitoring for pulmonary thromboembolism in patients with unresectable, advanced or recurrent colorectal cancer treated with bevacizumab

Pulmonary thromboembolism (PTE) is one of the leading causes of death among cancer outpatients. The aim of the present study was to investigate the reliability and validity of D-dimer monitoring for PTE in patients with unresectable, advanced or recurrent colorectal cancer treated with bevacizumab. A total of 25 patients with advanced colorectal cancer who received bevacizumab combination chemotherapy as primary treatment were retrospectively reviewed. The selection criteria included that D-dimer tests were performed repetitively, and that chest and abdominal contrast-enhanced CT scans were completed. The D-dimer levels and the presence or absence of PTE on CT images were retrospectively examined. Four cases (16%) were detected as having asymptomatic PTE. The D-dimer values at the onset of PTE were 14.2, 4.6, 1.1 and 0.9 µg/ml. The negative predictive value was 90.5% when 3.0 µg/ml was set as the D-dimer level cutoff value. The incidence of PTE, including asymptomatic PTE, in the present study was higher compared with that reported in previous studies on various types of cancer, of various stages and treated with different chemotherapy regimens. In patients with bevacizumab-treated unresectable, advanced or recurrent colorectal cancer, the D-dimer test was found to be less useful for exclusion diagnosis; however, along with chest CT, it may be useful in the detection and diagnosis of PTE. However, the determination of the optimal reference values and appropriate measurement timing of D-dimer testing requires further study.

Role of pre-revision tissue biopsy in evaluation of painful shoulder arthroplasty: a systematic review and meta-analysis

BACKGROUND

Pre-revision tissue biopsy (PTB) for culture has been used as a diagnostic tool in the evaluation for periprosthetic joint infection among patients with a painful shoulder arthroplasty. The purpose of this study was to (1) determine the sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of PTB culture results compared with results of "gold-standard" tissue biopsy for culture taken at the time of subsequent revision surgery (TBR), and (2) report the current indications and protocols described for use of PTB. The hypothesis was that PTB culture results would correlate highly with results of TBR and that protocols for PTB would vary by institution.

METHODS

By use of Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, a systematic review and meta-analysis of English-language literature were performed using the Embase, MEDLINE, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and Cochrane databases from inception through March 2020. Methodological Index for Non-randomized Studies (MINORS) validated grading criteria were used to summarize the quality and bias of included studies. Studies were included if an arthroscopic or open tissue biopsy was performed in patients who had previously undergone anatomic total shoulder arthroplasty, shoulder hemiarthroplasty, or reverse total shoulder arthroplasty as a separate procedure prior to revision of components, if applicable. Meta-analysis to identify the sensitivity, specificity, NPV, and PPV of PTB was performed. Analysis was performed by first defining 1 positive PTB culture result as infection and then defining 2 positive culture results as infection.

RESULTS

A total of 1751 titles were screened, and 66 full-text articles were reviewed for inclusion. Four total studies encompassing 72 cases met the inclusion criteria. All studies were small (N = 13 to N = 23), retrospective series, with all but 12 biopsies performed arthroscopically. Sixty-five patients (90.2%) underwent subsequent revision surgery and TBR. Of these patients, 23 (35.4%) had ≥1 positive culture result with PTB and TBR. By this definition, the sensitivity of PTB was 92.0% (95% confidence interval [CI], 72.5%-98.6%); specificity, 70.0% (95% CI, 53.3%-82.9%); PPV, 65.7% (95% CI, 47.7%-80.3%); and NPV, 93.3% (95% CI, 76.5%-98.8%). For 2 positive PTB results, the sensitivity of PTB was 100% (95% CI, 51.7%-100%); specificity, 50.0% (95% CI, 31.4%-68.6%); PPV, 33.3% (95% CI, 14.4%-58.8%); and NPV, 100% (95% CI, 69.9%-100%). No complications of PTB were reported. The mean Methodological Index for Non-randomized Studies (MINORS) grade was 11.4 (range, 8.5-14).

CONCLUSION

PTB is a sensitive diagnostic modality with a high NPV that may aid in the diagnosis of shoulder periprosthetic joint infection in patients with a painful shoulder arthroplasty. Given the disparate biopsy protocols, greater standardization of clinical best practices and broader prospective studies are necessary to define the future role of PTB in dictating treatment.

SARS-CoV-2 infection: use and effectiveness of antigenic swab for the health surveillance of healthcare workers

Background:

The gold standard to identify SARS-CoV-2 infections is the Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) on rhino-pharyngeal swabs, but faster and cheaper methods such as antigenic swabs have been developed. A retrospective observational study on antigenic swabs included in the extraordinary health surveillance protocol of a large Hospital in Turin was aimed to assess their performance validity.

Methods:

From 30 October 2020 to 4 May 2021, 4000 antigenic swabs were carried out in three groups of healthcare workers (HCWs), respectively (i) asymptomatic, (ii) cohabiting with a positive case, and (iii) not recently exposed to the virus.

Results:

Overall sensitivity and specificity associated with a prevalence of 1.30% were 26.9%, 97.2%, respectively, the corresponding positive (PPV) and negative predictive value (NPV) being 11.29% and 99.02% [95% IC (99.00 - 99.04)] respectively; a prevalence of 0.29% was observed in the asymptomatic group, among whom sensitivity and specificity were 25.0% and 98.9%, respectively, the corresponding PPV and NPV being 6.25% and 99.78% [95% IC (99.76 - 99.81)], respectively; the cohabitant group showed a prevalence of 21.11%, sensitivity and specificity were 47.4%, 81.7%, respectively, giving rise to a PPV of 40.91% and NPV of 85.29% [95% IC (85.18 – 85.41)] respectively. The prevalence in the not exposed group was 0.77%, sensitivity and specificity were 29.2%, 97.4%, respectively, and PPV and NPV 8.05% and 99.44% [95% IC (99.42 - 99.46)] respectively.

Conclusions:

Antigenic swabs reduced costs and provided reliable diagnostic results. In the cohabitant group, the higher-prevalence groups showed poor test performances, likely because of the high prevalence of pre-symptomatic illness in this group. Owing to the relatively low NPV, a negative result would still require confirmation with a molecular test to be acceptable for a surveillance program that effectively reduces the virus’s intra-hospital spread.

Diagnostic value of probe-based confocal laser endomicroscopy versus conventional endoscopic biopsies of non-muscle invasive bladder tumors: a pilot study

PURPOSE

The standard procedure for diagnostics and follow-up for non-muscle invasive bladder cancer (NMIBC) is cystoscopy in the outpatient clinic. Suspicious lesions are biopsied for histopathological assessment. This pilot study aimed to evaluate the ability of Confocal Laser Endomicroscopy (CLE) to rule out High Grade Urothelial Carcinoma (HGUC) to select patients for in-office fulguration.

MATERIALS AND METHODS

We performed a prospective non-randomized, single surgeon study. Intraoperative CLE was performed independently by the surgeon and a blinded on-site uropathologist. Following the procedure, a CLE evaluation was performed by another blinded urologist. Lesions were classified as normal/inflammatory, Low Grade Urothelial Carcinoma (LGUC) or HGUC. With the histological evaluations as the gold standard we calculated sensitivity, specificity, PPV and NPV for HGUC and the accuracy for each CLE assessor. The primary outcome was the NPV for HGUC for the surgeon.

RESULTS

Twelve patients with a total of 34 lesions were included. Six lesions were flat and 28 were exophytic. On histopathology, 25 lesions were classified as normal/inflammatory or LGUC, while nine were classified as HGUC. For the surgeon, the uropathologist and the second urologist, the sensitivity was 44%, 78% and 22%, respectively. Specificities for the three observers were 84%, 68% and 96%. This corresponded to PPVs for HGUC of 50%, 47% and 67% and NPV for HGUC of 81%, 89% and 77%.

CONCLUSIONS

In our hands the NPV of CLE is not high enough for it to be considered an alternative to histopathological assessment of bladder lesions.

Prediction of dementia of Alzheimer type by different types of subjective cognitive decline

INTRODUCTION

Subjective cognitive decline (SCD) is a risk condition for dementia, including dementia of Alzheimer type (DAT).

METHODS

We report sensitivity, specificity, positive and negative predictive values (PPV, NPV) for conversion to all-cause dementia, and DAT in different SCD types (decline in memory, assocated worries, longitudinal consitency, of the AgeCoDe study (n = 2.402, 12 years follow-up).

RESULTS

82.7% of those converting to any dementia and 84.4% of those converting with DAT at follow-up, reported memory decline and fulfilled criteria of SCD at least at one time point before. SCD with worries at two consecutive time points showed a specificity of 92.2% for any dementia and also for DAT as well as a PPV of 44.3% for any dementia and of 36.9% for DAT at follow-up at the expense of low sensitivity.

DISCUSSION

Different SCD subtypes were either sensitive or specific for future all-cause dementia and DAT in cognitively unimpaired individuals. Modest PPV of the most specific SCD subtypes were achieved in this low prevalence population.

Unexpected Ground-Glass Opacities on Abdominopelvic CT of a Patient With a Negative SARS-CoV-2 Antigen Test Result and No Respiratory Symptoms Upon Admission

One of the biggest challenges during the coronavirus disease 2019 (COVID-19) pandemic continues to be the detection of asymptomatic and presymptomatic persons infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Persons infected with SARS-CoV-2 who do not have symptoms of COVID-19 may transmit the virus to others and may have subclinical lung abnormalities. Some hospitals use SARS-CoV-2 antigen tests for pre-admission screening testing because they are relatively inexpensive, have a rapid turnaround time, and can be performed at the point of care; however, antigen tests are generally less sensitive than nucleic acid amplification tests with reverse transcription polymerase chain reaction (RT-PCR) assay. Moreover, as the local COVID-19 prevalence increases, the negative predictive value of antigen tests may decrease, meaning that the probability of having false-negative results may increase. We present a case of a patient who, prior to admission for a surgical procedure, had a negative antigen test result for SARS-CoV-2, had no respiratory symptoms, and had no suspected or known exposure to SARS-CoV-2; however, she tested positive for SARS-CoV-2 RNA after admission. The only factor that led the healthcare team to suspect SARS-CoV-2 infection was an unexpected finding of bilateral ground-glass opacities on an abdominopelvic computed tomography (CT), which was performed to assess the extent of a perianal abscess the patient presented. This case highlights the importance of using highly sensitive SARS-CoV-2 tests for pre-admission screening testing in the hospital setting.

Laboratory Assay Evaluation Demystified: A Review of Key Factors Influencing Interpretation of Test Results Using Different Assays for SARS-CoV-2 Infection Diagnosis

Laboratory tests are an integral part of the diagnosis and management of patients; however, these tests are far from perfect. Their imperfections can be due to patient health condition, specimen collection, and/or technological difficulty with performing the assay and/or interpretation. To be useful clinically, testing requires calculation of positive predictive values (PPVs) and negative predictive values (NPVs). During the current global pandemic of COVID-19 (coronavirus disease 2019), multiple assays with unknown clinical sensitivity and specificity have been rapidly developed to aid in the diagnosis of the disease. Due to a lack of surveillance testing, the prevalence of COVID-19 remains unknown. Hence, using this situation as an clinical example, the goal of this article is to clarify the key factors that influence the PPV and NPV yielded by diagnostic testing, By doing so, we hope to offer health-care providers information that will help them better understand the potential implications of utilizing these test results in clinical patient management.

Mutual Information as a Performance Measure for Binary Predictors Characterized by Both ROC Curve and PROC Curve Analysis

The predictive receiver operating characteristic (PROC) curve differs from the more well-known receiver operating characteristic (ROC) curve in that it provides a basis for the evaluation of binary diagnostic tests using metrics defined conditionally on the outcome of the test rather than metrics defined conditionally on the actual disease status. Application of PROC curve analysis may be hindered by the complex graphical patterns that are sometimes generated. Here we present an information theoretic analysis that allows concurrent evaluation of PROC curves and ROC curves together in a simple graphical format. The analysis is based on the observation that mutual information may be viewed both as a function of ROC curve summary statistics (sensitivity and specificity) and prevalence, and as a function of predictive values and prevalence. Mutual information calculated from a 2 × 2 prediction-realization table for a specified risk score threshold on an ROC curve is the same as the mutual information calculated at the same risk score threshold on a corresponding PROC curve. Thus, for a given value of prevalence, the risk score threshold that maximizes mutual information is the same on both the ROC curve and the corresponding PROC curve. Phytopathologists and clinicians who have previously relied solely on ROC curve summary statistics when formulating risk thresholds for application in practical agricultural or clinical decision-making contexts are thus presented with a methodology that brings predictive values within the scope of that formulation.

Clinical Performance of SARS-CoV-2 Molecular Tests

Molecular testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the gold standard for diagnosis of coronavirus disease 2019 (COVID-19), but the clinical performance of these tests is still poorly understood, particularly with regard to disease course, patient-specific factors, and viral shedding. From 10 March to 1 May 2020, NewYork-Presbyterian laboratories performed 27,377 SARS-CoV-2 molecular assays from 22,338 patients. Repeat testing was performed for 3,432 patients, of which 2,413 had initial negative and 802 had initial positive results.

Molecular testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the gold standard for diagnosis of coronavirus disease 2019 (COVID-19), but the clinical performance of these tests is still poorly understood, particularly with regard to disease course, patient-specific factors, and viral shedding. From 10 March to 1 May 2020, NewYork-Presbyterian laboratories performed 27,377 SARS-CoV-2 molecular assays from 22,338 patients. Repeat testing was performed for 3,432 patients, of which 2,413 had initial negative and 802 had initial positive results. Repeat-tested patients were more likely to have severe disease and low viral loads. The negative predictive value of the first-day result among repeat-tested patients was 81.3% The clinical sensitivity of SARS-CoV-2 molecular assays was estimated between 58% and 96%, depending on the unknown number of false-negative results in single-tested patients. Conversion to negative was unlikely to occur before 15 to 20 days after initial testing or 20 to 30 days after the onset of symptoms, with 50% conversion occurring at 28 days after initial testing. Conversion from first-day negative to positive results increased linearly with each day of testing, reaching 25% probability in 20 days. Sixty patients fluctuated between positive and negative results over several weeks, suggesting that caution is needed when single-test results are acted upon. In summary, our study provides estimates of the clinical performance of SARS-CoV-2 molecular assays and suggests time frames for appropriate repeat testing, namely, 15 to 20 days after a positive test and the same day or next 2 days after a negative test for patients with high suspicion for COVID-19.

On the Binormal Predictive Receiver Operating Characteristic Curve for the Joint Assessment of Positive and Negative Predictive Values

The predictive receiver operating characteristic (PROC) curve is a diagrammatic format with application in the statistical evaluation of probabilistic disease forecasts. The PROC curve differs from the more well-known receiver operating characteristic (ROC) curve in that it provides a basis for evaluation using metrics defined conditionally on the outcome of the forecast rather than metrics defined conditionally on the actual disease status. Starting from the binormal ROC curve formulation, an overview of some previously published binormal PROC curves is presented in order to place the PROC curve in the context of other methods used in statistical evaluation of probabilistic disease forecasts based on the analysis of predictive values; in particular, the index of separation (PSEP) and the leaf plot. An information theoretic perspective on evaluation is also outlined. Five straightforward recommendations are made with a view to aiding understanding and interpretation of the sometimes-complex patterns generated by PROC curve analysis. The PROC curve and related analyses augment the perspective provided by traditional ROC curve analysis. Here, the binormal ROC model provides the exemplar for investigation of the PROC curve, but potential application extends to analysis based on other distributional models as well as to empirical analysis.

Assessment of a Multiplex Serological Test for the Diagnosis of Prosthetic Joint Infection: a Prospective Multicentre Study

Introduction: The diagnosis of prosthetic joint infections (PJIs) can be difficult in the chronic stage and is based on clinical and paraclinical evidence. A minimally invasive serological test against the main pathogens encountered during PJI would distinguish PJI from mechanical loosening. Methods: We performed a prospective, multicentre, cross-sectional study to assess the contribution of serology in the diagnosis of PJI. Over a 2-year period, all patients undergoing prosthesis revision were included in the study. A C-reactive protein assay and a serological test specifically designed against 5 bacterial species (Staphylococcus aureus, S. epidermidis, S. lugdunensis, Streptococcus agalactiae, Cutibacterium acnes) were performed preoperatively. Five samples per patient were taken intraoperatively during surgery. The diagnosis of PJI was based on clinical and bacteriological criteria according to guidelines. Results: Between November 2015 and November 2017, 115 patients were included, 49 for a chronic PJI and 66 for a mechanical problem. Among patients with PJI, a sinus tract was observed in 32.6% and a C-reactive protein level ≥10 mg/L in 74.5%. The PJI was monomicrobial in 43 cases (targeted staphylococci, 24; S. agalactiae, 1; C. acnes, 2; others, 16), and polymicrobial in 6 cases (12.2%). Sensitivity, specificity, positive predictive value and negative predictive value were 75.0%, 82.1%, 58.3% and 90.8%, respectively, for targeted staphylococci. Specificity/negative predictive value was 97.3%/100% for S. agalactiae and 83.8% /96.9% for C. acnes. Conclusions: The serological tests are insufficient to affirm the diagnosis of PJI for the targeted bacteria. Nevertheless, the excellent NPV may help clinicians to exclude PJI.

Information Graphs Incorporating Predictive Values of Disease Forecasts

Diagrammatic formats are useful for summarizing the processes of evaluation and comparison of forecasts in plant pathology and other disciplines where decisions about interventions for the purpose of disease management are often based on a proxy risk variable. We describe a new diagrammatic format for disease forecasts with two categories of actual status and two categories of forecast. The format displays relative entropies, functions of the predictive values that characterize expected information provided by disease forecasts. The new format arises from a consideration of earlier formats with underlying information properties that were previously unexploited. The new diagrammatic format requires no additional data for calculation beyond those used for the calculation of a receiver operating characteristic (ROC) curve. While an ROC curve characterizes a forecast in terms of sensitivity and specificity, the new format described here characterizes a forecast in terms of relative entropies based on predictive values. Thus it is complementary to ROC methodology in its application to the evaluation and comparison of forecasts.

An exact test for comparing two predictive values in small-size clinical trials

Positive and negative predictive values describe the performance of a diagnostic test. There are several methods to test the equality of predictive values in paired designs. However, these methods were premised on large sample theory, and they may not be suitable for small-size clinical trials because of inflation of the type 1 error rate. In this study, we propose an exact test to control the type 1 error rate strictly for conducting a small-size clinical trial that investigates the equality of predictive values in paired designs. In addition, we execute simulation studies to evaluate the performance of the proposed exact test and existing methods in small-size clinical trials. The proposed test can calculate the exact P value, and as a result of simulations, the empirical type 1 error rate for the proposed test did not exceed the significance level regardless of the setting, and the empirical power for the proposed test is not much different from the other methods based on large-sample theory. Therefore, it is considered that the proposed exact test is useful when the type 1 error rate needs to be controlled strictly.

Determination of the optimal volume of ascitic fluid for the precise diagnosis of malignant ascites

BACKGROUND/AIMS

The aim of this study was to determine the optimal volume of peritoneal effusion required to diagnose malignant ascites.

PATIENTS AND METHODS

The authors recruited 123 patients with shifting dullness and obtained 123 peritoneocentesis fluid samples. The samples were divided into seven aliquots of 10, 50, 100, 150, 200, 250, and 300 mL for cytopathological examination. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were calculated for each aliquot.

RESULTS

The sensitivity for the diagnosis of malignant ascites gradually increased as the sample volume increased and reached a constant value at a volume of 200 mL. The sensitivity and NPV for the 10-, 100-, and 150-mL volumes were significantly different from those for the 200-mL sample. However, the sensitivity and NPV for the 250- and 300-mL volumes were not significantly different. The sensitivity for the diagnosis of malignant ascites is closely related to the volume of peritoneal fluid that is extracted by peritoneocentesis.

CONCLUSION

We suggest a volume of 200 mL as the optimal minimum volume to confirm malignant ascites in patients with shifting dullness.

Predicting nonroutine discharge after elective spine surgery: external validation of machine learning algorithms

OBJECTIVE

Nonroutine discharge after elective spine surgery increases healthcare costs, negatively impacts patient satisfaction, and exposes patients to additional hospital-acquired complications. Therefore, prediction of nonroutine discharge in this population may improve clinical management. The authors previously developed a machine learning algorithm from national data that predicts risk of nonhome discharge for patients undergoing surgery for lumbar disc disorders. In this paper the authors externally validate their algorithm in an independent institutional population of neurosurgical spine patients.

METHODS

Medical records from elective inpatient surgery for lumbar disc herniation or degeneration in the Transitional Care Program at Brigham and Women's Hospital (2013-2015) were retrospectively reviewed. Variables included age, sex, BMI, American Society of Anesthesiologists (ASA) class, preoperative functional status, number of fusion levels, comorbidities, preoperative laboratory values, and discharge disposition. Nonroutine discharge was defined as postoperative discharge to any setting other than home. The discrimination (c-statistic), calibration, and positive and negative predictive values (PPVs and NPVs) of the algorithm were assessed in the institutional sample.

RESULTS

Overall, 144 patients underwent elective inpatient surgery for lumbar disc disorders with a nonroutine discharge rate of 6.9% (n = 10). The median patient age was 50 years and 45.1% of patients were female. Most patients were ASA class II (66.0%), had 1 or 2 levels fused (80.6%), and had no diabetes (91.7%). The median hematocrit level was 41.2%. The neural network algorithm generalized well to the institutional data, with a c-statistic (area under the receiver operating characteristic curve) of 0.89, calibration slope of 1.09, and calibration intercept of -0.08. At a threshold of 0.25, the PPV was 0.50 and the NPV was 0.97.

CONCLUSIONS

This institutional external validation of a previously developed machine learning algorithm suggests a reliable method for identifying patients with lumbar disc disorder at risk for nonroutine discharge. Performance in the institutional cohort was comparable to performance in the derivation cohort and represents an improved predictive value over clinician intuition. This finding substantiates initial use of this algorithm in clinical practice. This tool may be used by multidisciplinary teams of case managers and spine surgeons to strategically invest additional time and resources into postoperative plans for this population.