Simple methods for comparing two predictive values with incomplete data

Statistical methods have been well developed for comparing the predictive values of two binary diagnostic tests under a paired design. However, existing methods do not make allowance for incomplete data. Although maximum likelihood based method can be used to deal with incomplete data, it requires iterative algorithm for implementation. A simple and easily implemented statistical method is therefore needed. Simple methods exist for comparing two sensitivities or specificities with incomplete data but such simple methods are not available for comparing two predictive values with incomplete data. In this paper, we propose two simple methods for comparing two predictive values with incomplete data. The test statistics derived by these two methods are simple to compute, only involving some minor modification of the existing weighted generalized score statistics with complete data. Simulation results demonstrate that the proposed methods are more efficient than the ad-hoc method that only uses the subjects wit complete data. As an illustration, the proposed methods are applied to an observational study comparing two non-invasive methods in detecting endometriosis.

Predictive values of ultrasound characters associated with malignant thyroid nodules in Yaoundé: a cross-sectional study

Introduction

most ultrasound criteria are defined in developed countries and commonly used in practice to assess the malignancy risk of thyroid nodules. This practice does not take into consideration some aspects of our context as delay of consultation and insufficient iodine intake. The objective of this study was to determine the predictive values of ultrasound characters associated with malignant thyroid nodules in our environment.

Methods

we conducted a cross-sectional, prospective, and analytical study in three hospitals in Yaoundé over a six-month period in 2022. Our sample consisted of thyroid nodules with ultrasound, cytopathological, and histopathological data. The ultrasound characters and histology status of category III thyroid nodules and higher in Bethesda score were analysed in univariate and multivariate statistics to determine their predictive values.

Results

eighty-nine nodules were obtained according to our inclusion criteria. The sex ratio was 0.46 and the average age of the patients was 46 years (IQR=42-59). The cancer prevalence in our sample was 22.47%. On ultrasound assessment, the characters associated to malignant histology (p<0.05) were nodules count, echogenicity, echostructure, presence or absence of microcalcifications, margins, and type of vascularization. Positive predictive values ranged from 26.15 to 57.14%, while negative predictive values ranged from 12.5 to 33.3%.

Conclusion

taken alone, the ultrasound characters of suspected thyroid nodules have poor predictive values. There was a high variability in sensitivity but that was generally good (60-95%) while specificity was low. The prediction of malignant thyroid nodules is correlated with the association of at least two ultrasound criteria supported by clinical arguments.

Validation of ICD-9-CM codes for major genitourinary birth defects in Military Health System administrative data, 2006-2014

BACKGROUND

The Department of Defense Birth and Infant Health Research program is dedicated to birth defects research and surveillance among military families. Here, we assess and refine the validity of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for selected genitourinary birth defects in the Military Health System (MHS). We additionally outline methods for the calculation of positive predictive value (PPV) and negative predictive value (NPV), sensitivity, and specificity using a stratified sampling design.

METHODS

Among military infants born from 2006 through 2014, a random sample of ICD-9-CM screen-positive cases (for six genitourinary birth defects) and screen-negative cases were selected for chart review. PPV, NPV, sensitivity, and specificity were calculated for individual defects and any included defect (i.e., overall); measures were weighted by the inverse probability of being sampled.

RESULTS

Of 461,557 infants, 686 were sampled for chart review. Bladder exstrophy was accurately reported (PPV: >90%), while the accuracy of renal dysplasia, renal agenesis/hypoplasia, and hypospadias was moderate (PPVs: 66%-68%) and congenital hydronephrosis was low (PPV: 20%). Specificity and NPVs always exceeded 98%. The overall PPV was 50%; however, excluding congenital hydronephrosis screen-positive cases and requiring at least two inpatient or outpatient diagnostic codes resulted in a PPV of 85%.

CONCLUSIONS

The validity of major genitourinary birth defect codes varied in MHS administrative data. The accuracy of an overall defect measure improved by omitting congenital hydronephrosis and requiring at least two diagnostic codes. Although PPV is generally useful for research, additional calculation of NPV, sensitivity, and specificity better informs the identification of appropriate selection criteria across surveillance and research settings.

Validation of diagnosis codes for chorioamnionitis in medical encounter data, 2013-2018

PURPOSE

Chorioamnionitis refers to intrauterine infection/inflammation that can be diagnosed clinically or from laboratory testing. This study aimed to validate chorioamnionitis International Classification of Diseases (ICD) codes using reference standards for clinical and histologic cases.

METHODS

Department of Defense Birth and Infant Health Research program data identified a cohort of live deliveries at two United States military hospitals from 2013 to 2018. Deliveries were screened for chorioamnionitis using ICD codes from maternal delivery records; a sample of screen positive and negative deliveries was selected for chart review. Primary analyses validated deliveries using a reference standard for clinical chorioamnionitis; secondary analyses employed a reference standard that also included histologic cases, but were limited by temporal differences in availability of laboratory data. Sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values were calculated with 95% confidence intervals (CIs).

RESULTS

Overall, 1857 deliveries (465 screen positive, 1392 screen negative) were eligible for analysis and 336 met the reference standard for clinical chorioamnionitis, yielding a PPV of 0.68 (95% CI 0.63, 0.72) and sensitivity of 0.76 (95% CI 0.72, 0.81). In secondary analyses, 390 deliveries met the reference standard for clinical or histologic chorioamnionitis, resulting in an overall PPV of 0.75 (95% CI 0.71, 0.79); in 2018, when more laboratory results were available, the PPV was 0.91 (95% CI 0.84, 0.97). NPV and specificity were ≥0.97 across reference standards.

CONCLUSIONS

Chorioamnionitis ICD codes exhibited moderate correlation with clinical disease, suggesting challenges in using medical encounter data to isolate clinical cases from those only identified through laboratory testing.

Intelligence is a poor predictor of nonrestorability of competence to stand trial

Criminal defendants found incompetent to stand trial (IST) may only be committed for competency restoration if their restoration success is considered likely and when this aim can be met within a "reasonable" period of time. In this study, we evaluated the predictive validity and test accuracy of standardized intelligence testing on the classification of nonrestorability in a sample of 293 male patients adjudicated IST and committed for inpatient restoration. At 90 days, 17.0% of cases with FSIQ scores within one standard deviation of the mean were unrestored, and nonrestoration rates increased with each additional FSIQ standard deviation decrement to 29.5%, 38.8%, and 59.5%. Time-to-event analyses found that whereas half of patients with FSIQ scores of 56 or higher would be predicted to be restored within 64 days, the median restoration timeline was 145 days for patients with FSIQ scores of 55 or below. Positive predictive values associated with the range of possible FSIQ scores were uniformly low at modeled nonrestoration prevalence rates of 5%, 15%, and 25%, rarely exceeding chance levels. We conclude that although FSIQ scores are relevant to predictions of nonrestorability, particularly when scores are at least three standard deviations below average, the accuracy of individual FSIQ-based predictions of nonrestorability are limited.

Associations of miRNA-146a and miRNA-223 with Rheumatoid Arthritis and Their Predictive Values

Purpose

To analyze the independent associations of miRNA-146a and miRNA-223 with rheumatoid arthritis (RA) and evaluate their predictive values for RA.

Patients and Methods

A total of 68 RA patients were selected as cases, and meanwhile 68 patients with a traumatic knee condition were selected as controls by matching to the cases according to sex and age at the ratio of 1:1. The independent associations of miRNA-146a and miRNA-223 with RA were identified by binary logistic regression analysis. Receiver operating characteristic (ROC) curve was used to evaluate their predictive values for RA.

Results

MiRNA-146a and miRNA-223 expression levels in both synovial tissues and serums were statistically higher in cases than in controls, and their expression levels in serums were not statistically different from those in synovial tissues in both cases and controls. The expression levels of miRNA-146a and miRNA-223 in synovial tissues were independently associated with RA, as well as the expression levels of miRNA-146a and miRNA-223 in serums. The area under curve (AUC) of combination of miRNA-146a and miRNA-223 in synovial tissues for the prediction of RA was 0.910 [95% confidence interval (CI): 0.863-0.962], and the AUC of combination of miRNA-146a and miRNA-223 in serums was 0.904 (95% CI: 0.851-0.957). Their difference was not statistically significant (P=0.873), but the AUC of combination prediction was statistically higher than those of individual predictions (synovial tissues: 0.910 vs 0.773, P=0.005, 0.910 vs 0.788, P=0.009; serums: 0.904 vs 0.766, P=0.005, 0.904 vs 0.784, P=0.011).

Conclusion

MiRNA-146a and miRNA-223 in both synovial tissues and serums could be applied in predicting RA, and their combination could elevate the predictive value significantly.

Comparison of Four Tests for Preterm Birth Prediction in Symptomatic Singleton Women: A Prospective Cohort Study

Background and Purpose: It is challenging to predict preterm births accurately. We sought to compare the diagnostic performance of cervical length in predicting preterm birth to those of contraction recording in cardiotocography (CTG), cervical funneling, and Bishop score. Methods: A total of 371 women with singleton pregnancies and threatened preterm labor admitted to tertiary hospitals of northwestern Iran were included in this prospective cohort study and followed up until childbirth. Transvaginal ultrasound was utilized to assess the cervical length and funneling. Also, a CTG test and digital vaginal examination were performed. The data of 218 women were analyzed in the STATA software. The sensitivity and other diagnostic performances, and 95% confidence intervals, were reported. Results: The CTG uterine contraction recording had the highest sensitivity for predicting birth within the next 2 days, whereas a Bishop score ≥6 revealed the highest specificity, positive predictive value, and positive likelihood ratio. Inadequate cervical length for gestational age exhibited a high negative predictive value and the lowest negative likelihood ratio. Conclusion: The cervical length test has good diagnostic and prognostic performance among the four tests for preterm birth. Cervical funneling and CTG tests have poor predictive value, whereas the Bishop score has a superior diagnostic performance to the other tests.

Evaluation of test-day milk somatic cell count to predict intramammary infection in late lactation grazing dairy cows

Use of selective dry cow antimicrobial therapy requires to precisely differentiate cows with an intramammary infection (IMI) from uninfected cows close to drying-off to enable treatment allocation. Milk somatic cell count (SCC) is an indicator of an inflammatory response in the mammary gland and is usually associated with IMI. However, SCC can also be influenced by cow-level variables such as milk yield, lactation number and stage of lactation. In recent years, predictive algorithms have been developed to differentiate cows with IMI from cows without IMI based on SCC data. The objective of this observational study was to explore the association between SCC and subclinical IMI, taking cognizance of cow-level predictors on Irish seasonal spring calving, pasture-based systems. Additionally, the optimal test-day SCC cut-point (maximized sensitivity and specificity) for IMI diagnosis was determined. A total of 2,074 cows, across 21 spring calving dairy herds with an average monthly milk weighted bulk tank SCC of ≤200,000 cells/mL were enrolled in the study. Quarter-level milk sampling was carried out on all cows in late lactation (interquartile range = 240-261 d in milk) for bacteriological culturing. Bacteriological results were used to define cows with IMI, when ≥1 quarter sample resulted in bacterial growth. Cow-level test-day SCC records were provided by the herd owners. The ability of the average, maximum and last test-day SCC to predict infection were compared using receiver operator curves. Predictive logistic regression models tested included parity (primiparous or multiparous), yield at last test-day and a standardized count of high SCC test-days. In total, 18.7% of cows were classified as having an IMI, with first parity cows having a higher proportion of IMI (29.3%) compared with multiparous cows (16.1%). Staphylococcus aureus accounted for the majority of these infections. The last test-day SCC was the best predictor of infection with the highest area under the curve. The inclusions of parity, yield at last test-day, and a standardized count of high SCC test-days as predictors did not significantly improve the ability of last test-day SCC to predict IMI. The cut-point for last test-day SCC which maximized sensitivity and specificity was 64,975 cells/mL. This study indicates that in Irish seasonal pasture-based dairy herds,with low bulk tank SCC control programs, the last test-day SCC (interquartile range days in milk = 221-240) is the best predictor of IMI in late lactation.

Fetal Doppler Evaluation to Predict NEC Development

Antenatal factors play a role in NEC pathogenesis. This study aimed to investigate the predictive value of fetal ductus venosus doppler (DV) for NEC in fetal growth restriction fetuses (FGRF) and to assess the predictive accuracy of IG21 and Fenton curves in NEC development. Data from FGRF, postnatal findings, and Doppler characteristics were collected between 2010 and 2020 at a single center. Patients were then divided into two groups (i.e., with and without NEC). Bivariate and multivariate analyses were performed. We identified 24 cases and 30 controls. Absent or reversed end-diastolic flow (AREDF) and increased resistance in the DV were more impaired in cases (p < 0.05). Although the median birthweight was not different, the Fenton z-score was lower in NEC (p < 0.05). Fetal cardiopulmonary resuscitation, synchronized intermittent mandatory ventilation, neonatal respiratory distress, persistent patent ductus arteriosus (PDA), and inotropic support were more frequent in the NEC group. Furthermore, NEC patients had lower white blood cells (WBC) (p < 0.05). The predictive model for NEC (model 4), including Fenton z-score, WBC, PDA, and DV had an AUC of 84%. Fetal Doppler findings proved effective in predicting NEC in FGR. The Fenton z-score was the most predictive factor considering the fetal growth assessment showing high sensitivity.

Correlation between hysterosalpingography diagnosis and final hysterolaparoscopy with dye-test diagnosis in women with utero-tubal infertility: A cross-sectional study of the implication for which test should be the first-line investigation

Objective:

To assess the accuracy of hysterosalpingography in diagnosis of uterine and/or tubal factor infertility, using hysterolaparoscopy with dye test as the gold standard with an implication for which test should be the first-line investigation.

Methods:

A prospective cross-sectional study of 96 women who underwent hysterosalpingography and hysterolaparoscopy with dye test. All women within reproductive age group with utero-tubal infertility who underwent both hysterosalpingography and hysterolaparoscopy with dye-test procedure were included. The outcome measures were proportions of tubal blockage and intrauterine pathology. Individual and overall mean accuracy were calculated for hysterosalpingography, using hysterolaparoscopy with dye test as the gold standard. Patient had procedure of hysterosalpingography first and both laparoscopic surgeons and patients were blinded to the outcome of hysterolaparoscopy with dye test until analysis. Statistical significance was set at p < 0.05.

Results:

Overall, 128 women were assessed for eligibility while 96 women finally completed the study. Hysterosalpingography demonstrated diagnostic accuracy of 77.8% (p < 0.001), 76.3% (p < 0.001) and 78.3% (p < 0.001) for right, left and bilateral tubal blockage, respectively. Overall accuracy of hysterosalpingography tubal factor assessment was 77.4 ± 0.8% (95% confidence interval = 76.5% to 78.4%). Hysterosalpingography showed an accuracy of 85.7%, 86.6% and 76.7% for right, left and bilateral hydrosalpinx, respectively, given overall diagnostic accuracy of 83.0 ± 5.1% (95% confidence interval = 77.9% to 88.1%). Overall accuracy of hysterosalpingography in diagnosing intrauterine pathology was 68.5 ± 9.8% (95% confidence interval = 53.9% to 83.1%).

Conclusion:

Hysterosalpingography detects tubal blockade and intrauterine pathology poorly compared to hysterolaparoscopy with dye test. Hysterosalpingography may face unpredictable clinical situations biased by technological error, leading to unsuccessful evaluation and uncertain diagnosis. Although the cost-effectiveness, risk of surgery or anaesthesia flaws hysterolaparoscopy with dye test. Hysterosalpingography should not be the first-line utero-tubal assessment tool rather hysterolaparoscopy with dye test.

The Predictive Values of Five Sarcopenia Screening Tools on Clinical Outcomes Following Surgery in Patients with Gastric Cancer: A Prospective Cohort Study

BACKGROUND

The association between strength, assistance with walking, rise from a chair, climb stairs and falls (SARC-F), strength, assistance with walking, rise from a chair, climb stairs, falls and calf circumference (SARC-CalF), Ishii score chart, the short version of mini sarcopenia risk assessment (MSRA-5), the full version of mini sarcopenia risk assessment (MSRA-7) and clinical outcomes in patients with gastric cancer were unclear. We aimed to investigate the predictive values of the above five sarcopenia screening tools on clinical outcomes following surgery in patients with gastric cancer.

METHODS

The clinical data of consecutive patients who would undergo gastrectomy from May 2020 to October 2020 at the First Affiliated Hospital of Nanjing Medical University were prospectively collected. On the first admission day, patients' characteristics, Nutrition risk screening 2002 (NRS 2002), the above five sarcopenia screening tools and anthropometric measurements were preoperatively collected. Within 24 hours after discharge, operation information, tumor-node-metastasis (TNM) stage and clinical outcomes in hospital (postoperative complications, hospitalization expenditures and postoperative hospital stay) were collected. Three months after discharge, clinical outcomes out of hospital (hospital readmissions and mortality) were collected. Multivariate analyses were conducted to identify the independent predictors for clinical outcomes.

RESULTS

A total of 263 patients were finally included in the study, with the average age being 62.44 years. The prevalence of sarcopenia risk ranged from 3.42% to 73.76%. For the above five sarcopenia screening tools, multivariate analyses showed that sarcopenia risk indicated by SARC-CalF was an independent predictor for postoperative complications (OR=3.145 [95%CI: 0.594, 16.665], P=0.037), prolonged postoperative hospital stay (B=2.383 [95%CI: 0.377, 4.388], P=0.020), increased hospitalization expenditures (B=1.305 [95%CI: 0.402, 2.208], P=0.005) and 3-month hospital readmissions (HR=3.626 [95%CI: 1.126, 11.676], P=0.031). Sarcopenia risk indicated by Ishii score chart was an independent predictor for postoperative complications (OR=6.491 [95%CI: 1.514, 27.840], P=0.012) and hospitalization expenditures (B=0.767 [95%CI: 0.065, 1.469], P=0.032). Sarcopenia risk indicated by MSRA-7 was an independent predictor for prolonged postoperative hospital stay (B=1.636 [95%CI: 0.119, 3.153], P=0.035)and increased hospitalization expenditures (B=0.831 [95%CI: 0.146, 1.516], P=0.018).

CONCLUSION

Among the above five sarcopenia screening tools, SARC-CalF seemed to have better predictive values on clinical outcomes. Preoperative gastric cancer patients with sarcopenia risk indicated by SARC-CalF could have a higher risk of postoperative complications, prolonged postoperative hospital stay, increased hospitalization expenditures and 3-month hospital readmissions.

Statistics in diagnostic medicine

This tutorial gives an introduction into statistical methods for diagnostic medicine. The validity of a diagnostic test can be assessed using sensitivity and specificity which are defined for a binary diagnostic test with known reference or gold standard. As an example we use Procalcitonin with a cut off value ≥ 0.5 g/L as a test and Sepsis-2 criteria as a reference standard for the diagnosis of sepsis. Next likelihood ratios are introduced which combine the information given by sensitivity and specificity. For these measures the construction of confidence intervals is demonstrated. Then, we introduce predictive values using Bayes' theorem. Predictive values are sometimes difficult to communicate. This can be improved using natural frequencies which are applied to our example. Procalcitonin is actually a continuous biomarker, hence we introduce the use of receiver operator curves (ROC) and the area under the curve (AUC). Finally we discuss sample size estimation for diagnostic studies. In order to show how to apply these concepts in practice we explain how to use the freely available software R.

The predictive value of disability at 2 weeks after plating of distal radial fractures: a prospective study of 101 patients

Assuming that some patients may benefit from early supervised rehabilitation after distal radial fractures, we investigated to what extent self-reported measures of disability, pain and performance of daily activities 2 weeks after anterior locking plating of distal radial fractures could predict long-lasting disability. We included 101 patients in a prediction study and recorded the scores of the Disability of the Arm, Shoulder and Hand questionnaire, visual analogue scales for pain and the Canadian Occupational Performance Measure. We found that the Disability of the Arm, Shoulder and Hand scores with a cut-off score of 50 were the best at predicting disability at 6 months in patients who did not receive early supervised therapy. The positive predictive value was 65% and the negative predictive value was 71%. We conclude that these scores could be used as a single measure to predict patient disability, although the predictive value was rather weak.Level of evidence: II.

Evaluation of Predictive Values of Naples Prognostic Score in Patients with Unresectable Stage III Non-Small Cell Lung Cancer

Background

Naples prognosis score (NPS) is a new prognostic score according to host inflammatory and nutritional state, and it could be useful for predicting tumor prognosis based on albumin level, total cholesterol level, neutrophil-to-lymphocyte ratio, and lymphocyte-to-monocyte ratio. This study aimed to evaluate the clinical significance of Naples prognostic score (NPS) in stage III non-small cell lung cancer patients (NSCLC).

Patients and Methods

In this study, 206 patients diagnosed with locally advanced NCCLC receiving chemoradiotherapy were retrospectively reviewed from January 2013 to January 2017. The included patients were divided into 3 groups according to NPS (group 0, group 1, and group 2), and the associations of the NPS with clinical characteristics and outcomes were evaluated among the groups. Survival curves for the NPS were analyzed using the Kaplan-Meier method. Univariate and multivariate analyses were performed using the Cox proportional hazards regression model to evaluate the prognostic value of overall survival (OS) and progression-free survival (PFS).

Results

The median follow-up time of this study was 37.0 (range, 13-59) months. The median OS was 27 months in group 0, 23 months in group 1, and 21 months in group 2, and median PFS was 15, 12 and 13 in group 0, group 1 and group 2, respectively. Age was significantly different among the 3 groups. The NPS was superior to other host inflammatory and nutritional indexes for prognostic risk stratification. In the multivariate analysis, NPS was identified as an independent prognostic indicator for OS and PFS (all P<0.05).

Conclusion

The NPS system is considered to be a useful predictor of outcomes in patients with stage III NSCLC.

Positive predictive values in clinical screening for developmental dysplasia of the hip

AIM

To establish the positive predictive value (PPV) of clinical hip examinations performed by referrers in the Danish screening programme for Developmental Dysplasia of the Hip (DDH) utilising three definitions of true positive DDH diagnosis.

METHODS

We retrospectively identified 290 children (169 female) referred during a 4-year period to the orthopaedic outpatient clinic at our institution with a positive clinical hip examination. Positive predictive value was calculated for clinical hip examinations across three definitions of a true positive clinical hip examination for all referrers and subgroups consisting of general practitioners, midwives and paediatricians. The PPV for clinical hip examinations was calculated for paediatric orthopaedic surgeons using one of the three definitions.

RESULTS

Positive predictive value of clinical hip examinations for all referrers were 5.4%, 3.6% and 1.8% with the definition of a true positive DDH diagnosis defined as clinical instability found by orthopaedic surgeon, ultrasound classification ≥Graf IIc or both definitions combined, respectively. Positive predictive value of clinical hip examinations performed by orthopaedic surgeons was 33.3% with a true positive clinical examination defined as an ultrasound classification ≥Graf IIc.

CONCLUSION

We conclude that the positive predictive value of clinical hip examinations made by referrers in the Danish screening programme for DDH is low.

Problems associated with mass border testing of COVID-19

We evaluated the yield of exit screening for SARS-Cov-2 performed in order for travellers to meet entry requirements to Sweden. Among 472 people screened, no infectious case of COVID-19 was detected, while two previously known cases were redetected after having already completed isolation. Our data suggest that depending on the epidemiological situation in the area of departure, border screening can lead to very low positive predictive values and very high costs per relevant case detected.

Development and Validation of a Healthcare Utilization-Based Algorithm to Identify Acute Exacerbations of Chronic Obstructive Pulmonary Disease

Introduction

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are important events that may precipitate other adverse outcomes. Accurate AECOPD event identification in electronic administrative data is essential for improving population health surveillance and practice management.

Objective

Develop codified algorithms to identify moderate and severe AECOPD in two US healthcare systems using administrative data and electronic medical records, and validate their performance by calculating positive predictive value (PPV) and negative predictive value (NPV).

Methods

Data from two large regional integrated health systems were used. Eligible patients were identified using International Classification of Diseases (Ninth Edition) COPD diagnosis codes. Two algorithms were developed: one to identify potential moderate AECOPD by selecting outpatient/emergency visits associated with AECOPD-related codes and antibiotic/systemic steroid prescriptions; the other to identify potential severe AECOPD by selecting inpatient visits associated with corresponding codes. Algorithms were validated via patient chart review, adjudicated by a pulmonologist. To estimate PPV, 300 potential moderate AECOPD and 250 potential severe AECOPD events underwent review. To estimate NPV, 200 patients without any AECOPD identified by the algorithms (100 patients each without moderate or severe AECOPD) during the two years following the index date underwent review to identify AECOPD missed by the algorithm (false negatives).

Results

The PPVs (95% confidence interval [CI]) for both moderate and severe AECOPD were high: 293/298 (98.3% [96.1–99.5]) and 216/225 (96.0% [92.5–98.2]), respectively. NPV was lower for moderate AECOPD (75.0% [65.3–83.1]) than for severe AECOPD (95.0% [88.7–98.4]). Results were consistent across both healthcare systems.

Conclusion

This study developed healthcare utilization-based algorithms to identify moderate and severe AECOPD in two separate healthcare systems. PPV for both algorithms was high; NPV was lower for the moderate algorithm. Replication and consistency of results across two healthcare systems support the external validity of these findings.

Utility of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening in patients with acute myeloid leukemia (AML)

BACKGROUND

Current literature has demonstrated the utility of the MRSA nasal screen as a de-escalation tool to decrease unnecessary anti-MRSA antibiotic therapy. However, data on the applicability of this test in patients with hematologic malignancy is lacking.

METHODS

This is a single-center, retrospective cohort study of patients with acute myeloid leukemia (AML) with or without a history of hematopoietic cell transplant (HCT), with pneumonia and MRSA nasal screening with respiratory cultures obtained. The primary outcome was to determine the negative predictive value (NPV) of the MRSA nasal screen for MRSA pneumonia. Secondary outcomes included sensitivity, specificity, positive predictive value (PPV) of the MRSA nasal screen and prevalence of MRSA pneumonia.

RESULTS

Of 98 patients with AML and pneumonia, the prevalence of MRSA pneumonia was 4.1% with confirmed positive MRSA respiratory cultures observed in 4 patient cases. In patients with confirmed MRSA pneumonia, 3 had positive MRSA nasal screens while 1 had a false negative result, possibly due to a long lag time (21 days) between MRSA nasal screen and pneumonia diagnosis. Overall, the MRSA nasal screen demonstrated 75% sensitivity and 100% specificity, with a PPV of 100% and a NPV of 98.9%.

CONCLUSIONS

Given the low prevalence, empiric use of anti-MRSA therapy in those AML and HCT patients with pneumonia may not be warranted in clinically stable patients. For patients in whom empiric anti-MRSA antibiotics are initiated, nasal screening for MRSA may be utilized to de-escalate anti-MRSA antibiotics in patients with AML with or without HCT.

Predictive Values of the SeLECT Score and IL-1β for Post-Stroke Epilepsy

PURPOSE

To establish a new prognostic tool for the prediction of post-stroke epilepsy (PSE) through combining the SeLECT score with IL-1β.

PATIENTS AND METHODS

This prospective observational study included 915 patients with acute ischemic stroke. The SeLECT score was calculated, and serum IL-1β levels were measured within 24 h of their admission. One unprovoked late seizure following the acute phase of stroke was diagnosed as PSE. All patients were divided into PSE group and non-PSE group according to the occurrence of PSE. Multivariate analysis was performed to determine the independent associations between the SeLECT score, IL-1β and PSE. Receiver operating characteristic (ROC) curve was employed to assess the predictive values of the SeLECT score, IL-1β and their combination for PSE.

RESULTS

Fifty-three patients occurred PSE within 1 year after stroke onset (5.8%). Multivariate analysis demonstrated that the SeLECT score [odds ratio (OR): 1.416, 95% confidence interval (CI): 1.191-1.863, P=0.013] and IL-1β (OR: 1.457, 95% CI: 1.215-1.894, P<0.001) were independent risk factors for PSE after adjusting for more than one comorbidity, stroke laterality, large-artery atherosclerosis, thrombolysis, age and use of statins. The AUC of the SeLECT score and IL-1β for predicting PSE was 0.756 (SE: 0.033, 95% CI: 0.692-0.819) and 0.811 (SE: 0.032, 95% CI: 0.748-0.875), respectively. The AUC of their combination was 0.933 (SE: 0.027, 95% CI: 0.880-0.985). Z test showed that the AUC of their combination was significantly higher than that of the SeLECT score or IL-1β alone (0.933 vs 0.756, Z=4.151, P<0.01; 0.933 vs 0.811, Z=2.914, P<0.01). Combination prediction of the SeLECT score and IL-1β for PSE had a high predictive value with a sensitivity of 88.06% and specificity of 82.37%.

CONCLUSION

The combination of the SeLECT score and IL-1β had a potential to act as a new prognostic tool for the prediction of PSE.

Characterization of a Pan-Immunoglobulin Assay Quantifying Antibodies Directed against the Receptor Binding Domain of the SARS-CoV-2 S1-Subunit of the Spike Protein: A Population-Based Study

Pan-immunoglobulin assays can simultaneously detect IgG, IgM and IgA directed against the receptor binding domain (RBD) of the S1 subunit of the spike protein (S) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 S1-RBD Ig). In this work, we aim to evaluate a quantitative SARS-CoV-2 S1-RBD Ig electrochemiluminescence immunoassay (ECLIA) regarding analytical, diagnostic, operational and clinical characteristics. Our work takes the form of a population-based study in the principality of Liechtenstein, including 125 cases with clinically well-described and laboratory confirmed SARS-CoV-2 infection and 1159 individuals without evidence of coronavirus disease 2019 (COVID-19). SARS-CoV-2 cases were tested for antibodies in sera taken with a median of 48 days (interquartile range, IQR, 43-52) and 139 days (IQR, 129-144) after symptom onset. Sera were also tested with other assays targeting antibodies against non-RBD-S1 and -S1/S2 epitopes. Sensitivity was 97.6% (95% confidence interval, CI, 93.2-99.1), whereas specificity was 99.8% (95% CI, 99.4-99.9). Antibody levels linearly decreased from hospitalized patients to symptomatic outpatients and SARS-CoV-2 infection without symptoms (p < 0.001). Among cases with SARS-CoV-2 infection, smokers had lower antibody levels than non-smokers (p = 0.04), and patients with fever had higher antibody levels than patients without fever (p = 0.001). Pan-SARS-CoV-2 S1-RBD Ig in SARS-CoV-2 infection cases significantly increased from first to second follow-up (p < 0.001). A substantial proportion of individuals without evidence of past SARS-CoV-2 infection displayed non-S1-RBD antibody reactivities (248/1159, i.e., 21.4%, 95% CI, 19.1-23.4). In conclusion, a quantitative SARS-CoV-2 S1-RBD Ig assay offers favorable and sustained assay characteristics allowing the determination of quantitative associations between clinical characteristics (e.g., disease severity, smoking or fever) and antibody levels. The assay could also help to identify individuals with antibodies of non-S1-RBD specificity with potential clinical cross-reactivity to SARS-CoV-2.

Multi-Platform Comparison of SARS-CoV-2 Serology Assays for the Detection of COVID-19

BACKGROUND

COVID-19 is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel beta-coronavirus that is responsible for the 2019 coronavirus pandemic. Acute infections should be diagnosed by polymerase chain reaction (PCR) based tests, but serology tests can demonstrate previous exposure to the virus.

METHODS

We compared the performance of the Diazyme, Roche, and Abbott SARS-CoV-2 serology assays using 179 negative participants to determine negative percentage agreement (NPA) and in 60 SARS-CoV-2 PCR-confirmed positive patients to determine positive percentage agreement (PPA) at 3 different time frames following a positive SARS-CoV-2 PCR result.

RESULTS

At ≥15 days, the PPA (95% CI) was 100 (86.3-100)% for the Diazyme IgM/IgG panel, 96.0 (79.7-99.9)% for the Roche total Ig assay, and 100 (86.3-100)% for the Abbott IgG assay. The NPA (95% CI) was 98.3 (95.2-99.7)% for the Diazyme IgM/IgG panel, 99.4 (96.9-100)% for the Roche total Ig assay, and 98.9 (96.0-99.9)% for the Abbott IgG assay. When the Roche total Ig assay was combined with either the Diazyme IgM/IgG panel or the Abbott IgG assay, the positive predictive value was 100% while the negative predictive value remained greater than 99%.

CONCLUSIONS

Our data demonstrates that the Diazyme, Roche, and Abbott SARS-CoV-2 serology assays have similar clinical performances. We demonstrated a low false-positive rate across all 3 platforms and observed that false positives observed on the Roche platform are unique compared to those observed on the Diazyme or Abbott assays. Using multiple platforms in tandem increases the PPVs, which is important when screening populations with low disease prevalence.

Calculating Sensitivity, Specificity, and Predictive Values for Correlated Eye Data

Purpose

To describe and demonstrate appropriate statistical approaches for estimating sensitivity, specificity, predictive values and their 95% confidence intervals (95% CI) for correlated eye data.

Methods

We described generalized estimating equations (GEE) and cluster bootstrap to account for inter-eye correlation and applied them for analyzing the data from a clinical study of telemedicine for the detection of retinopathy of prematurity (ROP).

Results

Among 100 infants (200 eyes) selected for analysis, 20 infants had referral-warranted ROP (RW-ROP) in both eyes and 9 infants with RW-ROP only in one eye based on clinical eye examination. In the per-eye analysis that included both eyes of an infant, the image evaluation for RW-ROP had sensitivity of 83.7% and specificity of 86.8%. The 95% CI's from the naïve approach that ignored the inter-eye correlation were narrower than those of the GEE approach and cluster bootstrap for both sensitivity (width of 95% CI: 22.4% vs. 23.2% vs. 23.9%) and specificity (11.4% vs. 12.5% vs. 11.6%). The 95% CIs for sensitivity and specificity calculated from left eyes and right eyes separately were wider (35.2% and 30.8% respectively for sensitivity, 25.4% and 17.3% respectively for specificity).

Conclusions

When an ocular test is performed in both eyes of some or all of the study subjects, the statistical analyses are best performed at the eye-level and account for the inter-eye correlation by using either the GEE or cluster bootstrap. Ignoring the inter-eye correlation results in 95% CIs that are inappropriately narrow and analyzing data from two eyes separately are not efficient.

Meta-analysis of diagnostic performance of serological tests for SARS-CoV-2 antibodies up to 25 April 2020 and public health implications

We reviewed the diagnostic accuracy of SARS-CoV-2 serological tests. Random-effects models yielded a summary sensitivity of 82% for IgM, and 85% for IgG and total antibodies. For specificity, the pooled estimate were 98% for IgM and 99% for IgG and total antibodies. In populations with ≤ 5% of seroconverted individuals, unless the assays have perfect (i.e. 100%) specificity, the positive predictive value would be ≤ 88%. Serological tests should be used for prevalence surveys only in hard-hit areas.

Diagnostic Accuracy of the Ambulatory EEG vs. Routine EEG for First Single Unprovoked Seizures and Seizure Recurrence: The DX-Seizure Study

Background: The DX-Seizure study aims to evaluate the diagnostic accuracy (sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio) of the ambulatory EEG in comparison with the first routine EEG, and a second routine EEG right before the ambulatory EEG, on adult patients with first single unprovoked seizure (FSUS) and define the utility of ambulatory EEG in forecasting seizure recurrence in these patients after 1-year follow-up.

Methods: The DX-Seizure study is a prospective cohort of 113 adult patients (≥18-year-old) presenting with FSUS to the Single Seizure Clinic for evaluation. These patients will be assessed by a neurologist/epileptologist with the first routine EEG (referral EEG) and undergo a second routine EEG and ambulatory EEG. The three EEG (first routine EEG as gold standard) will be compared and evaluated their diagnostic accuracy (sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratios) with respect of epileptiform activity and other abnormalities. One-year follow-up of each patient will be used to assess recurrence of seizures after a FSUS and the utility of the ambulatory EEG to forecast these recurrences.

Discussion: To the best of our knowledge, this will be the first study to prospectively examine the use of ambulatory EEG for a FSUS in adults and its use for prediction of recurrence of seizures. The overarching goal is to improve diagnostic accuracy with the use of ambulatory EEG in patients with their FSUS. We anticipate that this will decrease incorrect or uncertain diagnoses with resulting psychological and financial cost to the patient. We also anticipate that an improved method to predicting the recurrence of seizures will reduce the chances of repeated seizures and their consequences.

How helpful are the European AIDS Clinical Society cognitive screening questions in predicting cognitive impairment in an aging, well-treated HIV-positive population?

Objectives

Diagnosing neurocognitive impairment (NCI) in HIV infection requires time‐consuming neuropsychological assessment. Screening tools are needed to identify when neuropsychological referral is indicated. We examined the positive and negative predictive values (PPVs and NPVs, respectively) of the three European AIDS Clinical Society (EACS) screening questions in identifying NCI.

Methods

The Neurocognitive Assessment in the Metabolic and Aging Cohort (NAMACO) study recruited patients aged ≥45 years enrolled in the Swiss HIV Cohort Study between 1 May 2013 and 30 November 2016. NAMACO participants (1) answered EACS screening questions, (2) underwent standardized neuropsychological assessment and (3) completed self‐report forms [Center for Epidemiologic Studies Depression Scale (CES‐D)] rating mood. NCI categories were defined using Frascati criteria. PPVs and NPVs of the EACS screening questions in identifying NCI categories were calculated.

Results

Of 974 NAMACO participants with complete EACS screening question data, 244 (25.1%) expressed cognitive complaints in answer to at least one EACS screening question, of whom 51.3% had NCI (26.1% HIV‐associated and 25.2% related to confounding factors). The PPV and NPV of the EACS screening questions in identifying HIV‐associated NCI were 0.35 and 0.7, respectively. Restricting analysis to NCI with functional impairment or related to confounding factors, notably depression, the NPV was 0.90. Expressing cognitive complaints for all three EACS screening questions was significantly associated with depression (P < 0.001).

Conclusions

The EACS screening questions had an NPV of 0.7 for excluding patients with HIV‐associated NCI as defined by Frascati criteria. The PPV and NPV may improve if NCI diagnoses are based on new criteria.

Accuracy of single molecular biomarkers in saliva for the diagnosis of periodontitis: A systematic review and meta-analysis

AIM

To analyse, using a meta-analytical approach, the diagnostic accuracy of single molecular biomarkers in saliva for the detection of periodontitis in systemically healthy subjects.

MATERIALS AND METHODS

Articles on molecular biomarkers in saliva providing a binary contingency table (or sensitivity and specificity values and group sample sizes) in individuals with clinically diagnosed periodontitis were considered eligible. Searches for candidate articles were conducted in six electronic databases. The methodological quality was assessed through the tool Quality Assessment of Diagnostic Studies. Meta-analyses were performed using the Hierarchical Summary Receiver Operating Characteristic model.

RESULTS

Meta-analysis was possible for 5 of the 32 biomarkers studied. The highest values of sensitivity for the diagnosis of periodontitis were obtained for IL1beta (78.7%), followed by MMP8 (72.5%), IL6 and haemoglobin (72.0% for both molecules); the lowest sensitivity value was for MMP9 (70.3%). In terms of specificity estimates, MMP9 had the best result (81.5%), followed by IL1beta (78.0%) and haemoglobin (75.2%); MMP8 had the lowest specificity (70.5%).

CONCLUSIONS

MMP8, MMP9, IL1beta, IL6 and Hb were salivary biomarkers with good capability to detect periodontitis in systemically healthy subjects. MMP8 and IL1beta are the most researched biomarkers in the field, both showing clinically fair effectiveness for the diagnosis of periodontitis.

Volumetric imaging parameters are significant for predicting the pathological complete response of preoperative concurrent chemoradiotherapy in local advanced rectal cancer

Preoperative concurrent chemoradiotherapy (CCRT) as the standard treatment for locally advanced rectal cancer (LARC) has been widely used in clinic. Its efficiency influences the prognosis and the selection of subsequent treatment. The current criteria for evaluating the prognosis of patients with extremely sensitive preoperative CCRT include the clinical complete remission response (cCR) and pathological complete response (pCR), but those with cCR may not necessarily achieve pCR, and the pCR can be confirmed only after surgery. Some scholars believe that patients with pCR after CCRT can be categorized as 'watch and wait'. Therefore, it is extremely important to find a way to predict the pCR status of patients before therapy. In this study, we examined the expression of stem cell markers and obtained direct and derivative volumetric imaging parameters before treatment. Subsequently, these factors and the general clinical data were adopted into a regression model, and the correlation between them and the pCR was analyzed. We found that the pCR of LARC was positively correlated with tumor compactness (TC), whereas it was negatively correlated with approximate tumor volume (ATV), real tumor volume (RTV), total surface area of the tumor (TSA) and tumor maximum longitudinal length (TML). In these meaningful predictors, the positive predictive values and the negative predictive values of TC were 74.73% and 94.61%, respectively. Compared with other possible predictors, TC is the most encouraging predictor of pCR. Our findings provide a way for clinicians to predict the sensitivity of preoperative CCRT and will help to select individualized treatment options for LARC patients.

Hematologic profile in reverse total shoulder arthroplasty: perioperative and postoperative blood loss

BACKGROUND

Few studies have investigated the amount of blood loss during reverse total shoulder arthroplasty (RTSA). The purpose of this study was to investigate blood loss in patients who underwent RTSA for massive irreparable rotator cuff tear (MIRCT) using the hemoglobin (Hb) balance method and total Hemovac amount and to identify predictors of blood transfusion in these patients.

METHODS

We retrospectively reviewed 121 patients who underwent RTSA for MIRCT. The mean age was 71.2 ± 6.9 years, and 75 were women. Age, sex, body mass index, use of anticoagulants, American Society of Anesthesiologists physical status score, comorbidities (eg, hypertension, diabetes mellitus, cerebrovascular accident), preoperative Hb level, preoperative hematocrit level, preoperative prothrombin time/international normalized ratio, use of cement, and operative time were evaluated as values predicting blood transfusion.

RESULTS

The overall blood loss was 846.6 ± 527.6 mL, which included 346 ± 231.2 mL of intraoperative blood loss and 500.3 ± 196.4 mL of postoperative blood loss. Values predicting blood transfusion were a lower preoperative Hb level (P < .001), hematocrit level (P < .001), hypertension (P = .018), and cerebrovascular accident (P = .008). Receiver operating characteristic analysis identified the following cutoff values for predicting transfusion: preoperative Hb level of 13.5 g/dL (90.3% sensitivity) and hematocrit of 40% (90.3% sensitivity).

CONCLUSIONS

RTSA for MIRCT is associated with blood loss during and after surgery. The amount of blood loss should be noted, and blood transfusion could be predicted by calculating the blood loss and predictive values. Lower preoperative Hb level, hematocrit, hypertension, and cerebrovascular accident are predictors of blood transfusion. Blood transfusion should be considered if a patient with preoperative Hb level <13.5 g/dL and hematocrit <40% has a history of hypertension or cerebrovascular accident.

The End of the Beginning of the Alzheimer's Disease Nightmare: A Devil's Advocate's View

Although there have been so many failures in Alzheimer's disease (AD) modifying trials, there are still many compounds in the pipeline and the hope still remains that the entrance of disease-modifying treatment (DMT) for AD will positively and dramatically change the whole situation of AD treatment. However, if DMT does enter the market, it will be the beginning of a great number of challenges and problems. The current infrastructure for diagnostics of early (pre-dementia) AD does not have the capacity to meet the demands and expectations of the population. Neither is there capacity for treatment monitoring and follow-ups. If screening is considered, there will be a great risk for false positive cases and a great number of people who will have to undergo diagnostics. There will be high costs for diagnostics and treatment initially, while potential benefits will occur much later in other sectors than where the payers for treatment are. Although there are great hopes that prevention of cardiovascular risk factors and changes in lifestyle might impact the risk for dementia, there is still no consensus that this is the case. Finally, the relevance of different AD paradigms such as amyloid and tau is still a matter of discussion, particularly regarding the oldest old.

DNA methylation-mediated Klotho silencing is an independent prognostic biomarker of head and neck squamous carcinoma

Purpose

To study the prognostic value of klotho (KL) and its promoter DNA methylation in head and neck squamous cell carcinoma (HNSCC) and to assess their associations with the autophagy gene LC3 and the RNA transferase gene NSUN2.

Materials and methods

Upper quartile normalized RNA-seq V2 RSEM values of KL mRNA and beta value for KL methylation were retrieved from The Cancer Genome Atlas HNSCC dataset. Kaplan–Meier survival curves were used to assess the associations of KL expression and methylation with patient survival; multivariate Cox proportional hazards regression models were used to estimate the HRs and their 95% CIs.

Results

There is a negative relationship between KL gene expression and its promoter DNA methylation in HNSCC. KL gene expression was positively correlated with overall survival, while KL methylation was inversely correlated with the overall survival of HNSCC patients. Furthermore, KL methylation was significantly associated with gender (P=0.012), tumor grade (P=0.0009) and tumor site (P<0.0001). Finally, HNSCC patients with high KL gene expression or low KL DNA methylation had high LC3 but low NSUN2.

Conclusion

KL methylation silenced its gene expression in HNSCC. Low KL expression and high KL methylation can be potential biomarkers for worse prognosis in HNSCC. As the downstream targets, LC3 and NSUN2 could be responsible for the KL expression in HNSCC.

Effectiveness of bladder tumor antigen quantitative test in the diagnosis of bladder carcinoma in a schistosoma endemic area

Introduction:

Bladder carcinoma is the most common male cancer in our environment due to endemicity of schistosomiasis. Squamous-cell carcinoma is the most common histological type and patients present at an advanced stage. The objective of this study is to compare the sensitivity, specificity, and predictive values of the bladder tumor antigen quantitative test (BTA TRAK) and urine cytology in the diagnosis of bladder carcinoma in a schistosoma endemic area.

Materials and Methods:

This is a 12-month cross-sectional study of 88 patients, 52 of them with features of bladder carcinoma as study group, and 36 of them with hematuria from other urologic conditions, and benign urologic conditions and healthy volunteers as control group (CG). The mean ages of patients in the study and CGs were 47.17 ± 17.00 and 44.19 ± 18.89 years, respectively (P = 0.412). Bladder tumor antigen was assayed using enzyme-linked immunosorbent assay. Data were analyzed using SPSS version 20.0 for Windows.

Results:

The sensitivity of urine cytology and BTA TRAK in the study was 29.1% and 98.8%, respectively. The specificity of urine cytology and BTA TRAK was 95.5% and 13.6%, respectively (P = 0.05). The positive predictive values of urine cytology and BTA TRAK in the study were 96.2% and 81.7%, respectively. The negative predictive values were 25.0% and 75.0% for urine cytology and BTA TRAK, respectively.

Conclusion:

BTA TRAK is more sensitive but poorly specific as compared to that of the urine cytology for bladder cell carcinoma detection in a schistosoma endemic area.

Predictive values of alpha-gal IgE levels and alpha-gal IgE: Total IgE ratio and oral food challenge-proven meat allergy in a population with a high prevalence of reported red meat allergy

BACKGROUND

Severe meat allergy with anaphylaxis may be caused by sensitization to alpha-gal. Levels of alpha-gal sensitization that correlate with high risk of meat allergy are currently unknown. We have identified an area with a high prevalence of reported red meat allergy which offered the opportunity to evaluate the diagnostic value of IgE antibody tests.

METHODS

To determine levels of alpha-gal IgE and alpha-gal:total IgE ratio in a large cohort of subjects with challenge-proven meat allergy compared with control subjects from the same environment, we conducted fieldwork assessing 131 participants who reported adverse reactions to meat, and 26 control subjects, by questionnaires, IgE sensitization to alpha-gal and oral food challenge to beef sausage.

RESULTS

Eighty-four participants were diagnosed with alpha-gal allergy. Alpha-gal IgE ranged between 0.7 and 344.5 kU/L. Alpha-gal:total IgE ratio ranged from 0.1% to 67.6%. Logistic regression analysis showed both alpha-gal IgE and alpha-gal:total IgE ratio strongly correlated with meat allergy, with AUC of 0.95. The values giving the best correct classification were IgE of 2.00 kU/L and ratio of 0.75%. The value above which there is a 95% probability of meat allergy is IgE>5.5 kU/L and ratio of 2.12%.

CONCLUSION

Alpha-gal allergy in a population with a high prevalence of reported red meat allergy showed a more rapid onset of symptoms than previously described and a high prevalence of isolated subjective gastrointestinal manifestations. Cutoff values are described for levels of sensitization to alpha-gal IgE and alpha-gal:total IgE ratio that are highly likely to result in clinically significant meat allergy.

A Bayesian model to estimate the cutoff and the clinical utility of a biomarker assay

To enable targeted therapies and enhance medical decision-making, biomarkers are increasingly used as screening and diagnostic tests. When using quantitative biomarkers for classification purposes, this often implies that an appropriate cutoff for the biomarker has to be determined and its clinical utility must be assessed. In the context of drug development, it is of interest how the probability of response changes with increasing values of the biomarker. Unlike sensitivity and specificity, predictive values are functions of the accuracy of the test, depend on the prevalence of the disease and therefore are a useful tool in this setting. In this paper, we propose a Bayesian method to not only estimate the cutoff value using the negative and positive predictive values, but also estimate the uncertainty around this estimate. Using Bayesian inference allows us to incorporate prior information, and obtain posterior estimates and credible intervals for the cut-off and associated predictive values. The performance of the Bayesian approach is compared with alternative methods via simulation studies of bias, interval coverage and width and illustrations on real data with binary and time-to-event outcomes are provided.

High Negative Predictive Value of Normal Body Mass Index for Obstructive Sleep Apnea in the Lateral Sleeping Position

STUDY OBJECTIVES

Obesity is a major risk factor for obstructive sleep apnea (OSA). Patients who are not obese and who have OSA usually present with a low apnea-hypopnea index (AHI) in the lateral sleeping position. Hence, sleep-disordered breathing (SDB) seems more dependent on body mass index (BMI) in the lateral sleeping position than the supine sleep position. This makes obesity a better predictor of SDB in the lateral sleeping position. The objective of this study was to find a negative predictive value of normal BMI for SDB in relation to sleep positions, thus defining a group of patients who could be treated by positional intervention, and prioritizing the use of polysomnography diagnostics.

METHODS

This study comprises a retrospective and prospective part run on groups of 1,181 and 821 consecutive patients, respectively. All had been referred to the university-based sleep laboratory because of suspected OSA and underwent polysomnography.

RESULTS

In the retrospective study, areas under the receiver operating characteristic curves for normal BMI at AHI ≥ 5 and AHI ≥ 15 events/h were found to be larger in the lateral sleeping positing than supine: 0.79 versus 0.69 and 0.80 versus 0.68, respectively (P < .05). Comparable results were obtained in the prospective study. For normal BMI, the negative predictive value for AHI < 15 events/h in the lateral sleep position was 97.5% and 97.1% in the retrospective and prospective study, respectively.

CONCLUSIONS

Normal BMI offers a high negative predictive value for moderate or severe OSA in the lateral sleeping position.

Adaptation and validation of the disruptive behaviour disorders teacher rating scale as a screening tool for early detection of disruptive behaviour disorders in schools in a lower-middle income setting

Background Despite the need to curb the menace resulting from the negative trajectory of disruptive behaviour disorders (DBD) in societies of the world today, there is yet a dearth of locally standardised tools for the early detection of these disorders in Nigeria. This study was aimed at standardising the DBD teacher rating scale (DBD-TRS) to be culturally specific using teachers' ratings of their students. Objectives To establish norm scores for the three categories of DBD on the DBD-TRS, to evaluate the reliability, validity, predictive power, sensitivity and specificity of DBD-TRS items for identifying DBD symptoms amongst children/adolescents between the ages of 4 and 16 years. Methods A cross-sectional survey of the five divisions of Lagos was conducted using multi-stage sampling technique. A randomly selected sample of teachers from a selection of regular schools across the five divisions of Lagos retrospectively rated systematically selected samples of their students in absentia; by referring to the names in their class registers for the recently concluded school session. The DBD-TRS and the previously validated strengths and difficulties questionnaire (SDQ) were used for the ratings. Results Ratings were completed for 1508 children/adolescents by 197 teachers from 30 regular schools. The norm scores for the three categories of DBD were determined by gender, age, and grade/class. Satisfactory psychometric properties were established for the DBD rating scale. All DBD items had high negative predictive power and positive predictive power, high specificity, and low false positive rates. However, ADHD items had lower PPP (0.23-0.55). Conclusion The DBD rating scale demonstrated sufficient technical merits to be used as a preliminary tool for identifying children that may require further clinical evaluation by mental health experts for behavioural disorders.

Yield and Efficiency of Mental Disorder Screening at Intake to Prison: A Comparison of DIA-X Short- and Long-Screening-Protocols in Compensation Prisoners

Background: Inmates are several times more likely to suffer from mental disorders than the general population.In order to take appropriate curative or preventive measures, a precise psychiatric diagnosis at detention start would therefore be imperative, but is frequently not carried out for reasons of time. The computer-aided expert system DIA-X enables a rapid and reliable diagnosis of psychiatric disorders. DIA-X is available as a short screening questionnaire with a processing time of a few minutes and as a standardized interview, which takes ~1 h to complete. Objective: The aim of this study was to assess the efficiency and accuracy of the DIA-X short screening questionnaire. Methods: One hundred detainees were recruited randomly from compensation prisoners, who were imprisoned because they were unwilling or unable to pay a fine for committing a criminal offence, from the penal institution Berlin-Plötzensee in 2017. Both the short screening questionnaire and the standardized interview from the DIA-X expert system were used for diagnosing mental disorders. Based on the results of the standardized interview from four study populations of compensation prisoners from 1999, 2004, 2010, and 2017, the sensitivity, specificity and the predictive values of the screening form were inferred. Results: More than half of the compensation prisoners suffered from mental and behavioral disorders caused by the abuse of alcohol or psychoactive substances. Phobic anxiety disorders were detected in one out of ten compensation prisoners and two out of ten compensation prisoners suffered from major depressive disorders. The DIA-X screening questionnaire was able to detect all mental illnesses with a sensitivity of 100%. However, specificities were low for nicotine dependency, drug and alcohol abuse. High specificities and high predictive values were obtained for psychoses and anxiety disorders. Conclusions: As the main test quality criteria of the DIA-X screening forms were so low, we cannot recommend the application of the DIA-X screening form for obtaining a valid diagnosis. Therefore, we explicitly recommend using the long form DIA-X for the detection of the most serious cases of mental illness. Then, these prisoners could receive either therapy or special social training.

Common pitfalls in statistical analysis: Understanding the properties of diagnostic tests - Part 1

In this article in our series on common pitfalls in statistical analysis, we look at some of the attributes of diagnostic tests (i.e., tests which are used to determine whether an individual does or does not have disease). The next article in this series will focus on further issues related to diagnostic tests.

International variation in the prevalence of preclinical colorectal cancer: Implications for predictive values of noninvasive screening tests and potential target populations for screening

Screening for colorectal cancer (CRC) is implemented in an increasing number of countries. We aimed to assess international variation in the prevalence of preclinical CRC and the resulting variation in positive and negative predictive values (PPVs, NPVs) of existing and potential CRC screening tests in various countries. Using age‐ and sex‐specific CRC incidence data and transition rates from preclinical to clinical CRC we estimated overall and age‐ and sex‐specific prevalence of preclinical CRC in the target population aged 50–74 years in different parts of the world. These prevalence estimates were used to derive PPVs and NPVs for existing and potential noninvasive screening tests with varying levels of sensitivity and specificity. Within all regions and countries, prevalence strongly increases with age and is higher in men than in women. In addition, major variation was seen between regions and countries, with overall prevalence varying between 1 and 0.1%. As a result, PPVs are expected to strongly vary between ∼10% for men in high incidence countries, such as Australia and Germany, and 1% for women in low incidence countries, whereas NPVs are expected to be consistently well above 99%. Variation in CRC prevalence profoundly affects expected PPVs of screening tests, and PPVs should be carefully considered when decisions on screening tests and strategies are made for specific populations and health care systems. Here, we provide estimates of preclinical CRC and expected PPVs and NPVs of noninvasive screening tests, which may enhance the empirical basis for planning of population‐based CRC screening strategies.

What's new?

Colorectal cancer (CRC) screening is implemented in an increasing number of countries, usually in a two‐step approach consisting in a noninvasive test followed by colonoscopy in case of a positive result. Prevalence of preclinical colorectal cancer strongly affects screening efficiency, but such data is scarce. Here, the authors provide detailed age‐ and sex‐specific preclinical CRC prevalence estimates for various countries and geographical regions and show their implications on expected positive and negative predictive values of existing and potential noninvasive screening tests. Knowledge of these predictive values should enhance the empirical basis for decisions on CRC screening tests and target populations.

Prediction of neonatal respiratory morbidity by quantitative ultrasound lung texture analysis: a multicenter study

BACKGROUND

Prediction of neonatal respiratory morbidity may be useful to plan delivery in complicated pregnancies. The limited predictive performance of the current diagnostic tests together with the risks of an invasive procedure restricts the use of fetal lung maturity assessment.

OBJECTIVE

The objective of the study was to evaluate the performance of quantitative ultrasound texture analysis of the fetal lung (quantusFLM) to predict neonatal respiratory morbidity in preterm and early-term (<39.0 weeks) deliveries.

STUDY DESIGN

This was a prospective multicenter study conducted in 20 centers worldwide. Fetal lung ultrasound images were obtained at 25.0-38.6 weeks of gestation within 48 hours of delivery, stored in Digital Imaging and Communication in Medicine format, and analyzed with quantusFLM. Physicians were blinded to the analysis. At delivery, perinatal outcomes and the occurrence of neonatal respiratory morbidity, defined as either respiratory distress syndrome or transient tachypnea of the newborn, were registered. The performance of the ultrasound texture analysis test to predict neonatal respiratory morbidity was evaluated.

RESULTS

A total of 883 images were collected, but 17.3% were discarded because of poor image quality or exclusion criteria, leaving 730 observations for the final analysis. The prevalence of neonatal respiratory morbidity was 13.8% (101 of 730). The quantusFLM predicted neonatal respiratory morbidity with a sensitivity, specificity, positive and negative predictive values of 74.3% (75 of 101), 88.6% (557 of 629), 51.0% (75 of 147), and 95.5% (557 of 583), respectively. Accuracy was 86.5% (632 of 730) and positive and negative likelihood ratios were 6.5 and 0.3, respectively.

CONCLUSION

The quantusFLM predicted neonatal respiratory morbidity with an accuracy similar to that previously reported for other tests with the advantage of being a noninvasive technique.

How to diagnose mould allergy? Comparison of skin prick tests with specific IgE results

BACKGROUND

Diagnosis of mould allergy is complicated due to the heterogeneity of the test material and the decrease in the number of commercial mould skin test solutions that are currently available.

OBJECTIVES

The aim of this study was to compare skin prick tests (SPT) from different manufacturers to one another and concurrently with sIgE tests for Aspergillus fumigatus (Asp f), Cladosporium herbarum (Cla h), Penicillium chrysogenum (Pen ch), Alternaria alternata (Alt a) and Aspergillus versicolor (Asp v) to ascertain a feasible diagnostic procedure for mould sensitization.

METHODS

In this multi-centre study, 168 patients with mould exposure and/or mould-induced respiratory symptoms were included. Mould SPT solutions were analysed biochemically and tested in duplicate on patients' arms. Specific IgE (sIgE) concentrations to corresponding mould species and mould mix (mx1) were measured by ImmunoCAP. SPTs in accordance with one another and with sIgE were further considered. The test efficiency was calculated using receiver-operating characteristic (ROC) analysis.

RESULTS

Mould sensitization was more frequently detected by the SPT (90 of 168) than by the sIgE tests (56 of 168). Concordances of double SPT positives were only sufficient (≥ 80%) for environmental allergens, two Asp f and three Alt a SPT solutions, whereas all other mould solutions revealed concordances < 80%. The antigen content of SPT solutions was positively associated with concordant SPT double values as well as with sIgE. Taking sIgE as the 'positive standard', all mould SPT solutions revealed test efficiencies > 80%, but varied up to 20% in sensitivity and positive predictive value with the exception of Alt a.

CONCLUSIONS

SPT solutions are sensitive and essential diagnostic tools for the detection of mould sensitization. Our recommendation for diagnosis would be to test at least Alt a, Asp f and Pen ch using SPT and additional sIgE test to mx1.

Water Holding as Determinant for the Elastically Stored Energy in Protein-Based Gels

To evaluate the importance of the water holding capacity for the elastically stored energy of protein gels, a range of gels were created from proteins from different origin (plant: pea and soy proteins, and animal: whey, blood plasma, egg white proteins, and ovalbumin) varying in network morphology set by the protein concentration, pH, ionic strength, or the presence of specific ions. The results showed that the observed positive and linear relation between water holding (WH) and elastically stored energy (RE) is generic for globular protein gels studied. The slopes of this relation are comparable for all globular protein gels (except for soy protein gels) whereas the intercept is close to 0 for most of the systems except for ovalbumin and egg white gels. The slope and intercept obtained allows one to predict the impact of tuning WH, by gel morphology or network stiffness, on the mechanical deformation of the protein-based gel. Addition of charged polysaccharides to a protein system leads to a deviation from the linear relation between WH and RE and this deviation coincides with a change in phase behavior.

Utility of features of the patient's history in the diagnosis of atraumatic shoulder pain: a systematic review

BACKGROUND

Whereas physical examination tests for shoulder disorders have numeric values that describe the utility of the test and its effect on the probability of having a diagnosis, this information is lacking for elements of the history. The purpose of this study was to conduct a systematic review of the literature to determine numeric data (sensitivity, specificity, predictive values, and likelihood or odds ratios) for elements of the history with regard to diagnoses in patients with chronic atraumatic shoulder pain.

METHODS

We performed a systematic review to extract information from the existing literature regarding the numeric utility of different features of the patient history as they pertain to chronic atraumatic shoulder pain. Data sources were MEDLINE through PubMed (1946-January 2012) and EMBASE through Ovid (1980-January 2012).

RESULTS

Twenty-one studies met inclusion criteria. A diagnosis of rotator cuff tear was more likely with a history of hypercholesterolemia, having a relative with rotator cuff disease, excessive lifting, above-shoulder work, hand-held vibration work, or age older than 60 years. Acromioclavicular arthritis was more likely in weightlifters. Glenohumeral arthritis was more likely if the patient has a history of prior dislocation, age >75 years, or a diagnosis of knee osteoarthritis. Adhesive capsulitis was more likely with a history of diabetes or thyroid disorder. Posterior labral tear was more likely in football players.

CONCLUSIONS

The numeric values for the utility of these history features will help establish numeric probabilities for diagnoses in patients with shoulder pain.

Value of the use of absolute lymphocyte as surrogate for CD4 count in resource poor situations

BACKGROUND

The initiation of antiretroviral (ARV) drugs and monitoring of human immunodeficiency virus (HIV) treatment in developing nations such as sub-Sahara Africa is based on the clinical stage and level of CD4 count. Clinical stages can easily be determined using the World Health Organisation (WHO) criteria, this is not so with CD4 count where the right equipment and expertise are not easily available. This lead to various studies being carried out in search of surrogates for CD4 count with use of total lymphocyte count (TLC) being suggested by some studies.

OBJECTIVE

In situation where determination of CD4 cell count is not available or feasible, lymphocyte count is believed to be one alternative method for immunological classification of Acquired Immunodeficiency Syndrome (AIDS). Such assumption may not be true of every population. The objective is, therefore, to examine the correlation between the absolute lymphocyte count and the CD4+ lymphocyte count in HIV positive patients.

MATERIALS AND METHODS

One hundred and sixty-five consecutive HIV positive patients were recruited for the study before the commencement of ARV drugs over a period of 13 months. The haemotological parameters such as the CD4 count was done by flow cytometry using Partec cyflow counter machine made in Germany, with strict adherence to the manufacturer's standard operating procedure. TLC were also determined using Sysmex haematology blood analyser, following the manufacturer's standard operating procedure. Patients were then grouped into CD4 and Total lymphocyte (TLC) categories. These were then compared to determine if there is any correlation as shown in previous studies. Statistical analysis of data was done using Statistical Package for Social Sciences (SPSS) and statistical significance of data was based on P value of less than 0.05. There was significant positive correlation (P value 0.000) between TLC and CD4 count.

RESULTS

Majority of the patients with TLC less than 1000/mm([3]) had CD4 count <200 cells/μl. Using TLC <1000/mm([3]) threshold, there was high sensitivity of 81.8% but low specificity and positive predictive value of 47.5% and 19.4%, respectively, for CD4 count <200 cells/μl. Further assessment using TLC of <1,200/mm([3]) for the currently accepted CD4 count cut-off of <350 cells/μl for initiation of antiretroviral drugs, the sensitivity, specificity, positive predictive value were found to be 76.5%, 26.7%, 21.3%, respectively.

CONCLUSIONS

Considering the low specificity and positive predictive value, it was concluded that the use of TLC of as a surrogate for CD4 count is unreliable. However, where there is no alternative, it could be used with caution bearing in mind its limitations.

Visual presentation of statistical concepts in diagnostic testing: the 2 × 2 diagram

OBJECTIVE

The purpose of this article is to present a visual conceptual framework for important statistical concepts in radiology, and to provide an online application to facilitate this visualization.

CONCLUSION

Statistical measures such as sensitivity, specificity, and predictive values are ubiquitous in medical literature, yet thinking fluidly about these concepts is not always easy. The 2 × 2 diagram is a helpful guide.

Impact of body mass index on the detection of radiographic localized pleural thickening

RATIONALE AND OBJECTIVES

Subpleural fat can be difficult to distinguish from localized pleural thickening (LPT), a marker of asbestos exposure, on chest radiographs. The aims of this study were to examine the influence of body mass index (BMI) on the performance of radiograph readers when classifying LPT and to model the risk of false test results with varying BMI.

MATERIALS AND METHODS

Subjects (n = 200) were patients being screened or treated for asbestos-related health outcomes. A film chest radiograph, a digital chest radiograph, and a high-resolution computed tomography (HRCT) chest scan were collected from each subject. All radiographs were independently read by seven B readers and scored using the International Labour Office system. HRCT scans, read by three experienced thoracic radiologists, served as the gold standard for the presence of LPT. We calculated measures of radiograph reader performance, including sensitivity and specificity, for each image modality. We also used logistic regression to estimate the probability of a false-positive and a false-negative result while controlling for covariates.

RESULTS

The proportion of false-positive readings correlated with BMI. While controlling for covariates, regression modeling showed the probability of a false-positive result increased with increasing BMI category, younger age, not having pleural calcification, and among subjects not reporting occupational or household contact asbestos exposure.

CONCLUSIONS

Clinicians should be cautious when evaluating radiographs of younger obese persons for the presence of asbestos-related pleural plaque, particularly in populations having an anticipated low or background prevalence of LPT.

Prospective parallel randomized trial of the MultiCyte™ ThinPrep(®) imaging system: the Scottish experience

BACKGROUND

Computer-assisted screening of cervical liquid-based cytology (LBC) preparations using the ThinPrep® Imaging System (TIS) has shown improved qualitative and quantitative gains. The use of Multicyte™ has not been described in a well-established national screening programme with a low incidence of high-grade dyskaryosis.

OBJECTIVES

To assess the impact of computer-assisted screening within the Scottish Cervical Screening Programme (SCSP).

METHODS

Two groups of three laboratories, each sharing a ThinPrep® Imager, screened 79 366 slides randomized to test and 90 551 to control arms by laboratory accession. Screeners were not blinded. Standard laboratory reporting profiles of the SCSP, sensitivity, specificity and false-negative rates of all grades of LBC abnormalities with respect to final cytology reports, predictive value for cervical intraepithelial neoplasia grade 2 or worse (CIN2+) on histology; and screening rates were compared for both arms.

RESULTS

Inadequate and negative reporting rates were significantly lower and low-grade reporting rates significantly higher in the imager arm. Imager-assisted screening showed significantly better specificity than manual screening with respect to the final cytology result. There was no evidence of a significant difference in the detection of CIN2+ or CIN3 +. Positive, abnormal and total predictive values (high-grade, low-grade and all abnormal cytology found to be CIN2+, respectively) were similar in both arms. Productivity was significantly higher in the imager arm.

CONCLUSION

  Computer-assisted screening in a well established screening programme showed significantly improved productivity without loss of quality. These findings should inform future policy for cervical screening programmes.

Assessment of intrapartum antibiotic prophylaxis for the prevention of early-onset group B Streptococcal disease

BACKGROUND

Most early-onset group B streptococcal (GBS) disease in recent years has occurred in newborns of prenatally GBS-negative mothers who missed intrapartum antibiotic prophylaxis (IAP). We aimed to assess the accuracy of prenatal culture in predicting GBS carriage during labor, the IAP use, and occurrence of early-onset GBS disease.

METHODS

We obtained vaginal-rectal swabs at labor for GBS culture from 5497 women of ≥ 32 weeks' gestation and surface cultures at birth from newborns between February 5, 2008 and February 4, 2009 at 3 hospitals in Houston, TX and Oakland, CA. Prenatal cultures were performed by a healthcare provider during routine care, and culture results were obtained from medical records. The accuracy of prenatal culture in predicting intrapartum GBS carriage was assessed by positive and negative predictive values. Mother-to-newborn transmission of GBS was assessed. Newborns were monitored for early-onset GBS disease.

RESULTS

GBS carriage was 24.5% by prenatal and 18.8% by labor cultures. Comparing prenatal with labor GBS cultures of 4696 women, the positive predictive value was 50.5% and negative predictive value was 91.7%. IAP, administered to 93.3% of prenatally GBS-positive women, was 83.7% effective in preventing newborn's GBS colonization. Mother-to-newborn transmission of GBS occurred in 2.6% of elective cesarean deliveries. Two newborns developed early-onset GBS disease (0.36/1000 births); the prenatal GBS culture of one was negative, the other's was unknown.

CONCLUSIONS

IAP was effective in interrupting mother-to-newborn transmission of GBS. However, approximately 10% of prenatally GBS-negative women were positive during labor and missed IAP, whereas approximately 50% of prenatally GBS-positive women were negative during labor and received IAP. These findings emphasize the need for rapid diagnostics during labor.

Measures of Diagnostic Accuracy: Basic Definitions

Diagnostic accuracy relates to the ability of a test to discriminate between the target condition and health. This discriminative potential can be quantified by the measures of diagnostic accuracy such as sensitivity and specificity, predictive values, likelihood ratios, the area under the ROC curve, Youden's index and diagnostic odds ratio. Different measures of diagnostic accuracy relate to the different aspects of diagnostic procedure: while some measures are used to assess the discriminative property of the test, others are used to assess its predictive ability. Measures of diagnostic accuracy are not fixed indicators of a test performance, some are very sensitive to the disease prevalence, while others to the spectrum and definition of the disease. Furthermore, measures of diagnostic accuracy are extremely sensitive to the design of the study. Studies not meeting strict methodological standards usually over- or under-estimate the indicators of test performance as well as they limit the applicability of the results of the study. STARD initiative was a very important step toward the improvement the quality of reporting of studies of diagnostic accuracy. STARD statement should be included into the Instructions to authors by scientific journals and authors should be encouraged to use the checklist whenever reporting their studies on diagnostic accuracy. Such efforts could make a substantial difference in the quality of reporting of studies of diagnostic accuracy and serve to provide the best possible evidence to the best for the patient care. This brief review outlines some basic definitions and characteristics of the measures of diagnostic accuracy.