Negative Post-test Probability Research Articles

Diagnostic Performance of 18F-Fluorodeoxyglucose in 162 Small Pulmonary Nodules Incidentally Detected in Subjects Without a History of Malignancy

Solitary pulmonary nodule (SPN) still represents a diagnostic challenge. The aim of our study was to evaluate the diagnostic performance of (18)F-fluorodeoxyglucose positron emission tomography-computed tomography in one of the largest samples of small SPNs, incidentally detected in subjects without a history of malignancy (nonscreening population) and undetermined at computed tomography. One-hundred and sixty-two small (>0.8 to 1.5 cm) and, for comparison, 206 large nodules (>1.5 to 3 cm) were retrospectively evaluated. Diagnostic performance of (18)F-fluorodeoxyglucose visual analysis, receiver-operating characteristic (ROC) analysis for maximum standardized uptake value (SUVmax), and Bayesian analysis were assessed using histology or radiological follow-up as a golden standard. In 162 small nodules, (18)F-fluorodeoxyglucose visual and ROC analyses (SUVmax = 1.3) provided 72.6% and 77.4% sensitivity and 88.0% and 82.0% specificity, respectively. The prevalence of malignancy was 38%; Bayesian analysis provided 78.8% positive and 16.0% negative posttest probabilities of malignancy. In 206 large nodules (18)F-fluorodeoxyglucose visual and ROC analyses (SUVmax = 1.9) provided 89.5% and 85.1% sensitivity and 70.8% and 79.2% specificity, respectively. The prevalence of malignancy was 65%; Bayesian analysis provided 85.0% positive and 21.6% negative posttest probabilities of malignancy. In both groups, malignant nodules had a significant higher SUVmax (p < 0.0001) than benign nodules. Only in the small group, malignant nodules were significantly larger (p = 0.0054) than benign ones. (18)F-fluorodeoxyglucose can be clinically relevant to rule in and rule out malignancy in undetermined small SPNs, incidentally detected in nonscreening population with intermediate pretest probability of malignancy, as well as in larger ones. Visual analysis can be considered an optimal diagnostic criterion, adequately detecting a wide range of malignant nodules with different metabolic activity.

A Systematic Review of the Diagnostic Value of CT Imaging in Diagnosing Otosclerosis.

To evaluate the diagnostic value of computed tomography (CT) in detecting otosclerosis in patients with conductive hearing loss and a clinical suspicion of otosclerosis. PubMed, Embase, and the Cochrane Library. A systematic search was conducted. Studies reporting original study data were included. Relevance and risk of bias of the selected articles were assessed. Studies with low relevance, high risk of bias, or both were excluded. Prevalences, sensitivities, specificities, and post-test probabilities were extracted from the included articles. Seven studies characterized by a moderate to high relevance and moderate to low risk of bias were included for data extraction. The prevalence of otosclerosis was high (up to 100%) in the majority of the included studies. In those studies with a high prevalence of disease, both positive and negative post-test probabilities were (relatively) high: 99% and between 51% and 67% respectively. In one study with a low prevalence of disease (9%), both positive and negative post-test probabilities were low (23% and 3% respectively). Overall, reported sensitivities ranged between 60% and 95%. Preoperative CT has little to add in establishing otosclerosis and may not be necessary to confirm the diagnosis. We would recommend reserving CT for those patients with suspected additional abnormalities, for specific preoperative planning, or out of legal necessity.

The diagnostic performance of coronary artery angiography with 64-MSCT and post 64-MSCT: systematic review and meta-analysis.

PurposeTo comprehensively investigate the diagnostic performance of coronary artery angiography with 64-MDCT and post 64-MDCT.Materials and MethodsPubMed was searched for all published studies that evaluated coronary arteries with 64-MDCT and post 64-MDCT. The clinical diagnostic role was evaluated by applying the likelihood ratios (LRs) to calculate the post-test probability based on Bayes' theorem.Results91 studies that met our inclusion criteria were ultimately included in the analysis. The pooled positive and negative LRs at patient level were 8.91 (95% CI, 7.53, 10.54) and 0.02 (CI, 0.01, 0.03), respectively. For studies that did not claim that non-evaluable segments were included, the pooled positive and negative LRs were 11.16 (CI, 8.90, 14.00) and 0.01 (CI, 0.01, 0.03), respectively. For studies including uninterruptable results, the diagnostic performance decreased, with the pooled positive LR 7.40 (CI, 6.00, 9.13) and negative LR 0.02 (CI, 0.01, 0.03). The areas under the summary ROC curve were 0.98 (CI, 0.97 to 0.99) for 64-MDCT and 0.96 (CI, 0.94 to 0.98) for post 64-MDCT, respectively. For references explicitly stating that the non-assessable segments were included during analysis, a post-test probability of negative results >95% and a positive post-test probability <95% could be obtained for patients with a pre-test probability of <73% for coronary artery disease (CAD). On the other hand, when the pre-test probability of CAD was >73%, the diagnostic role was reversed, with a positive post-test probability of CAD >95% and a negative post-test probability of CAD <95%.ConclusionThe diagnostic performance of post 64-MDCT does not increase as compared with 64-MDCT. CTA, overall, is a test of exclusion for patients with a pre-test probability of CAD<73%, while for patients with a pre-test probability of CAD>73%, CTA is a test used to confirm the presence of CAD.

Valeur diagnostique des critères de suspicion d’infection néonatale précoce : bilan dix ans après les recommandations de l’Anaes

Because clinical symptoms and biological markers are neither sensitive nor specific, newborns are frequently suspected of having an infection. In France, 30-50% of newborns are suspected of having early-onset sepsis (EOS) and many of them undergo laboratory tests and empirical antibiotic treatments while awaiting results. The aim of this study was to evaluate the diagnostic value of various suspicion criteria for EOS as recommended by the Anaes since 2002, and the value of umbilical cord blood procalcitonin (PCT), currently assayed in our maternity ward. This 4-year retrospective study in the CHU of Nantes included hospitalized newborns with suspected early neonatal infection. Infection status was established according to the Anaes definitions and clinical evolution. The study included 2151 newborns. Among anamnestic criteria, only prematurity significantly increased the risk of EOS (relative risk of 3.1; 95% CI 1.4-7.0). The relative risk of infection for a symptomatic newborn was 12.2 (95% CI 4.9-30.2; P<0.0001). Laboratory test results were the most predictive criteria. The relative risk to be infected was 291.6 (95% CI 70.7-1,214.0; P<0.0001) with a blood cord PCT value>0.6 ng/L. The positive post-test probability was 28% (95% CI: 23-33) and the negative post-test probability was close to 0 (95% CI: 0-0). Clinical criteria of postnatal life adaptation are more predictive of early-onset neonatal infection than anamnestic criteria are. The blood cord PCT value could be a helpful marker in the identification of infected newborns. PCT measured in umbilical cord blood could be included in a general algorithm in order to identify as soon as possible newborns with a high risk of EOS.

Hits and Misses

To evaluate joint task force criteria-based screening for severe obstructive sleep apnea (s-OSA) in commercial drivers. Among a community-based cohort of licensed commercial vehicle drivers, we assessed utility of the joint task force criteria. We conducted full, 14-channel overnight polysomnography in all drivers, defining s-OSA as an apnea-hypopnea index of 30 or more per hour. One hundred of 104 drivers with successful polysomnography studies were predominantly obese (median body mass index = 32.8 kg/m; interquartile range = 26.8 to 37.4) and had a median apnea-hypopnea index of 20.6 per hour (interquartile range = 10.0 to 34.2). Examination-based criteria were more effective (sensitivity = 80%; negative posttest probability [nPTP] = 17%) than symptom-based criteria (sensitivity = 63%; nPTP = 23%). Examination and symptom-based criteria combined had high sensitivity (97%) and low nPTP (7%), but poor specificity (19%). Examination-based criteria missed 20% of s-OSA cases. Combining examination with confidentially reported symptoms improved sensitivity but required confirmatory polysomnography in 86%, supporting universal screening of all drivers.

Diagnosis of Femoral Neck Fracture Associated With Femoral Shaft Fracture

Femoral neck fractures that are associated with femoral shaft fractures have historically been associated with high rates of missed diagnosis. Despite the potentially serious consequences of a missed femoral neck fracture, little work has been conducted to rigorously evaluate the ability of commonly used imaging studies to detect such fractures. Our hypothesis was that axial-view computed tomography is superior to plain radiography at detecting femoral neck fractures. Blinded assessment of a randomized image set that included axial-view computed tomographic scans of the pelvis, anteroposterior-view radiographs of the pelvis, and anteroposterior-view radiographs of the femur. Academic trauma center. Twenty-eight patients who had femoral shaft fractures with femoral neck fractures and 60 patients who had femoral shaft fractures without femoral neck fractures. Images that were stripped of demographic data were independently viewed in random order on computer workstations by 5 trauma fellowship-trained orthopaedic surgeons who were blinded to treatment and diagnosis. Sensitivity, specificity, positive post-test probability, and 1 minus negative post-test probability were calculated for diagnosing femoral neck fracture based on each image type. Interobserver reliability showed "substantial agreement" (kappa > 0.65) for all imaging modalities, indicating that the surgeons had a high level of agreement. All 3 imaging sets had high specificity (>94%) and 1 minus negative post-test probability (>95%) but had poor sensitivity (<65%) and positive post-test probability (<58%). False positives and false negatives were equally likely for all imaging modalities (P > 0.2). Plain radiography and computed tomography have rates of missed femoral neck fractures that are similar and substantial, with a sensitivity of only 56%-64%. Our data emphasize the importance of intraoperative and postoperative imaging in detecting nondisplaced femoral neck fractures in association with femoral shaft fractures.

C-Reactive Protein in Prediction of Ventriculoperitoneal Shunt-Related Infection in High-Risk Patients

C-reactive protein (CRP) is an inflammatory marker believed to be of value in the early detection of meningitis. We evaluated its potential as a marker for prediction of shunt-related infection in high-risk subjects. We conducted a prospective pilot study in 26 ventriculoperitoneal shunt procedures; 18 of the patients were considered to be at high risk of infection at the time of shunt insertion. All patients were screened for other disease that could cause, an increase in CRP. The serum CRP medians were 3.90 mg/L in the whole sample and 5.36 mg/L in the high-risk participants. All four shunt infections occurred in the high-risk group (22.2% of the group), three (75%) of which were in patients with meningitis. The logistic regression model showed that CRP concentrations above the cut-off value of ≥ 7 mg/L were related to shunt infection (p=0.042). The receiving-operating characteristic curve revealed a cutoff point at ≥ 10.1 mg/L (sensitivity 0.75, 1 - specificity 0.18). The calculated area under the curve was 0.744. The sensitivity and specificity in the whole sample and high-risk group were not different (75% and 79%-80%, respectively). The positive post-test probability was 40% in the whole sample and 50% in the high-risk group. The negative post-test probability was 5% and 7%, respectively. Our data suggest that in a patient at high risk of shunt-related infection, the serum CRP concentration can be a valuable predictor of the risk of infection. Further studies in larger samples would be worthwhile.

Screening for Severe Obstructive Sleep Apnea Syndrome in Hypertensive Outpatients

The authors attempted to validate a 2-stage strategy to screen for severe obstructive sleep apnea syndrome (s-OSAS) among hypertensive outpatients, with polysomnography (PSG) as the gold standard. Using a prospective design, outpatients with hypertension were recruited from medical outpatient clinics. Interventions included (1) assessment of clinical data; (2) home sleep testing (HST); and (3) 12-channnel, in-laboratory PSG. The authors developed models using clinical or HST data alone (single-stage models) or clinical data in tandem with HST (2-stage models) to predict s-OSAS. For each model, area under receiver operating characteristic curves (AUCs), sensitivity, specificity, negative likelihood ratio, and negative post-test probability (NPTP) were computed. Models were then rank-ordered based on AUC values and NPTP. HST used alone had limited accuracy (AUC=0.727, NPTP=2.9%). However, models that used clinical data in tandem with HST were more accurate in identifying s-OSAS, with lower NPTP: (1) facial morphometrics (AUC=0.816, NPTP=0.6%); (2) neck circumference (AUC=0.803, NPTP=1.7%); and Multivariable Apnea Prediction Score (AUC=0.799, NPTP=1.5%) where sensitivity, specificity, and NPTP were evaluated at optimal thresholds. Therefore, HST combined with clinical data can be useful in identifying s-OSAS in hypertensive outpatients, without incurring greater cost and patient burden associated with in-laboratory PSG. These models were less useful in identifying obstructive sleep apnea syndrome of any severity.

Concordance between hysteroscopic impression and endometrial histopathological diagnosis

ObjectiveThe aim of this study was to evaluate the accuracy of hysteroscopic impression for diagnosing benign and malignant endometrial pathology. MethodThis is a retrospective cross-sectional study involving case records of 412 patients who underwent hysteroscopy with diagnostic dilatation and curettage (D&C) at the University of Malaya Medical Centre from January 2009 to August 2011, and cases with records of previous hysteroscopies (2007–2008). Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values, likelihood ratios (LR) and post-test probabilities of hysteroscopy were calculated. D&C was set as the ‘gold standard’. ResultsHysteroscopy and histology results were concordant in 366 (88.8%) subjects. Sensitivity, specificity, PPV and NPV were high exceeding 80%. Moderate sensitivity for endometrial hyperplasia (64.4%, 95% CI=49.8%–76.8%) with moderate PPV for malignancy (62.1%, 95% CI=44.0%–77.3%) due to misdiagnosing hyperplasia as malignant was observed. PPV for leiomyoma was reduced (83.3%, 95% CI=60.8%–94.2%) despite 100% sensitivity, due to D&C false negatives. High positive LR (>10) and low negative LR (<0.2) were observed generally except for endometrial hyperplasia (0.36). Hysteroscopy had moderate positive post-test probability for malignancy (0.62) but effective in ruling out malignancy (negative post-test probability=0.00). ConclusionHysteroscopy is accurate for diagnosing focal and malignant endometrial pathology but only moderate for hyperplasia. Endometrial sampling is recommended for all cases especially when suspecting hyperplasia or malignancy.

Diagnostic Accuracy of Elevated Serum Carcinoembryonic Antigen for Recurrence in Postoperative Stage II Colorectal Cancer Patients: Comparison With Stage III

PurposeElevated levels of serum carcinoembryonic antigen (CEA) following a curative resection of colorectal cancer (CRC) indicate recurrence; however, the levels of CEA may be elevated above the normal limit without recurrence. The aim of this study is to analyze the diagnostic accuracy of elevated serum CEA for predicting recurrence in postoperative stage II and stage III CRC patients.MethodsA total of 336 stage II and stage III CRC patients who underwent a curative resection between January 2005 and October 2009 were enrolled. Sensitivities, specificities, positive predictive values (PPVs), negative predictive values (NPVs), likelihood ratios and post-test probabilities of recurrence associated with elevated CEA were analyzed and compared.ResultsThe median follow-up duration was 45 months (36 to 134 months). Twenty-seven of 189 stage II patients (14.3%) and 52 of 147 stage III patients (35.4%) developed recurrence during the follow-up period. Sensitivities, specificities, PPVs, and NPVs of elevated CEA were 37.0%, 91.4%, 41.7%, and 89.7%, respectively, in stage II patients and 46.2%, 90.5%, 72.7%, and 75.4% in stage III patients. Post-test probabilities of recurrence associated with elevated CEA were 41.8% in stage II patients and 71.9% in stage III patients.ConclusionThe predictive performance of the probability of recurrence associated with elevated serum CEA after a curative resection in stage II CRC patients is lower than that in stage III CRC patients.

Validation of a serological test for the diagnosis of canine rickettsial disease

Canine vector borne diseases include a variety of illnesses affecting domestic dogs worldwide. Clinical abnormalities are often nonspecific during rickettsial infections, and coinfections caused by other tick-transmitted agents may be common. The aim of this study was to validate a differential serological assay for the diagnosis of rickettsial infections by the indirect fluorescent antibody (IFA) test. Sensitivity (DSe), specificity (Dsp), accuracy (Acc), positive and negative predictive values (PPV and NPV), positive and negative likelihood ratios (LR+ and LR−), Cohen's Kappa agreement, Youden's J index and odds values were calculated in order to define the positive and negative post-test probability and to establish a link between clinical signs compatible with a rickettsial infections and serological confirmation.

High prevalence of undiagnosed obstructive sleep apnoea in the general population and methods for screening for representative controls

Undiagnosed obstructive sleep apnoea (OSA) in the community makes comparisons of OSA subjects with control samples from the general population problematic. This study aims to estimate undiagnosed moderate to severe OSA in a general population sample and to determine the capacity of questions from the Berlin questionnaire (BQ) to identify subjects without diagnosed OSA of this severity. Using a general population sample (n = 793) with no history of OSA, case and control status for moderate-severe OSA was determined by home-based nasal flow and oximetry-derived apnoea-hypopnoea index using a cut-off value of ≥ 15 events/h to define cases. The diagnostic accuracy of the complete BQ and its component questions in identifying cases was assessed by calculating sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios and post-test probabilities. The age-standardised prevalence estimate of moderate-severe OSA was 9.1 % (12.4 % in men, 5.7 % in women). Sensitivity of the BQ in this population was 54 %, and specificity, 70 %. A combination of questions regarding snoring frequency and hypertension provided maximal post-test probability of OSA and greatest post-screen sample size. Undiagnosed OSA is highly prevalent in the Western Australian general population. While the complete BQ is a sub-optimal screening instrument for the general population, snoring frequency or hypertension can be used to screen out moderate-severe OSA from general population samples with limited reduction in sample size. As there are few general population samples available for epidemiological or genetic studies of OSA and its associated phenotypes, these results may usefully inform future case-control studies.

In-Home, Self-Assembled Sleep Studies Are Useful in Diagnosing Sleep Apnea in the Elderly

Obstructive sleep apnea (OSA) is common and treatable among the elderly. Yet, few older adults seek evaluation for OSA at sleep disorders centers. The authors assessed the feasibility of a two-stage screening procedure for obstructive sleep apnea syndrome (OSAS) in a community-based sample of older adults. Prospective cohort study. Participants' domicile (in-home) and academic sleep research center. There were 452 Medicare recipients residing in the greater Philadelphia metropolitan area with the complaint of daytime sleepiness. None. All participants underwent in-home unattended sleep studies that recorded airflow, and standard in-laboratory polysomnography. Additional measures included symptoms of sleep apnea, body mass index, neck circumference, age, and sex. When comparing diagnostic approaches, the best-performing single-stage model was one that combined apnea symptoms with age and neck circumference. This model had an area under the receiver operating characteristic curve (AUC) of 0.774 and negative posttest probability of 1.2%. The best-performing two-stage model combined symptoms, neck circumference, age, and sex in the first stage, followed by an unattended portable study with a corresponding AUC of 0.85 and negative posttest probability of 0.5%. Unattended, self-assembled, in-home sleep studies recording airflow and respiratory effort are most useful if applied in tandem with clinical data, including a carefully obtained sleep history. This two-stage model is accurate in identifying severe OSAS in older adults and represents a practical diagnostic approach for older adults. Incorporating clinical data was vital and increased accuracy well above that of unattended studies of airflow and effort alone.

Severe bronchiolitis in infancy: Can asthma in adolescence be predicted?

Bronchiolitis in infancy is a risk factor for development of asthma in the first decades of life, although the majority may be asymptomatic at school age. Respiratory symptoms are common in early life, and prediction of later asthma may be challenging. We aimed to study if simple clinical variables assessed at 2 years of age could predict asthma at 11 years of age and thereby provide a basis for follow-up and treatment after bronchiolitis in infancy. The study included 105 children hospitalized for bronchiolitis during their first year of life. Of these, 101 (96.2%) participated in the first follow-up at 2 years of age and 93 (88.6%) in the second follow-up at age 11. The overall prevalence of asthma at 11 years of age was 22.6%. Among the risk factors assessed at 2 years of age, recurrent wheeze appeared most important (odds ratio for later asthma: 7.2; 95% confidence interval: 1.3, 41.6; P = 0.015). Tested separately, recurrent wheeze had high sensitivity (90.5%), but low specificity (58.3%), low negative likelihood ratio (LR) (0.2) and low negative post-test probability (4.5%); indicating that absence of recurrent wheeze was better suited to exclude than to predict asthma at 11 years of age. Combining recurrent wheeze with either parental atopy, parental asthma or atopic dermatitis improved the specificity (>80), positive LR (>3) and positive post-test probability (∼50%), rendering the combinations more appropriate for the prediction of later asthma. In conclusion, after bronchiolitis in infancy, simple clinical non-invasive variables assessed at 2 years of age could predict asthma at 11 years of age with reasonable accuracy. However, the data were better suited to exclude than to predict later asthma.

Diagnostic performance of ultrasound in patients with suspected brachial plexus lesions in adults: a multicenter retrospective study with MRI, surgical findings and clinical follow-up as reference standard

To evaluate brachial plexus ultrasound (US) performance in a large multicenter study. The research was approved by the Institutional Review Boards, and all patients gave written informed consent. A multicenter retrospective trial including three centers was performed between March, 2006 and April, 2011. A total of 204 patients who received a brachial plexus ultrasound requested by the referring physician were enrolled: magnetic resonance imaging, surgical findings and clinical follow-up of at least 12 months were used as the reference standard. Sensitivity, specificity with 95 % confidence intervals (CIs), positive predictive value (PPV), pre-test-probability (the prevalence), negative predictive value (NPV), pre- and post- test odds (OR), likelihood ratio for positive results (LH+), likelihood ratio for negative results (LH-), accuracy and post-test probability (post-P) were reported on a per-patient basis. The overall sensitivity and specificity with 95 % CIs were: 0.76 (0.75-0.97); 0.96 (0.77-0.89). Overall PPV, pre-test probability, NPV, pre-OR, post-OR, LH+, LH-, Accuracy and post-P were: 0.93/0.43/0.84/0.75/0.75/13.4/17.6/0.25/0.88/0.93, respectively. The specificity of brachial plexus US in patients suspected of having a brachial plexus lesion is very high.

How low is low enough? Evaluation of various risk-assessment models for lymph node metastasis in endometrial cancer: a Korean multicenter study

ObjectiveThe aim of this study was to identify a standard for the evaluation of future models for prediction of lymph node metastasis in endometrial cancer through estimation of performance of well-known surgicopathological models.MethodsUsing the medical records of 947 patients with endometrial cancer who underwent surgical management with lymphadenectomy, we retrospectively assessed the predictive performances of nodal metastasis of currently available models.ResultsWe evaluated three models included: 1) a model modified from the Gynecologic Oncology Group (GOG) pilot study; 2) one from the GOG-33 data; and 3) one from Mayo Clinic data. The three models showed similar negative predictive values ranging from 97.1% to 97.4%. Using Bayes' theorem, this can be translated into 2% of negative post-test probability when 10% of prevalence of lymph node metastasis was assumed. In addition, although the negative predictive value was similar among these models, the proportion that was classified as low-risk was significantly different between the studies (56.4%, 44.8%, and 30.5%, respectively; p<0.001).ConclusionThe current study suggests that a false negativity of 2% or less should be a goal for determining clinical usefulness of preoperative or intraoperative prediction models for low-risk of nodal metastasis.

Breast MRI at 3.0 T in a high-risk familial breast cancer screening cohort: comparison with 1.5 T screening studies

The sensitivity of X-ray mammography for the detection of breast malignancy in younger females is lower than that of breast MRI; consequently, guidelines recommend annual MRI for patients with a significantly elevated lifetime risk. The improved signal-to-noise ratio obtainable at 3.0 T should result in data superior to those obtainable at 1.5 T. However, breast imaging on higher field strength systems poses specific problems. As a result, caution has been urged in the implementation of breast MRI at 3.0 T. The aim of this study was to determine if it is appropriate to use 3.0 T MRI in the screening of patients by comparing the summary statistics achieved by this 3.0 T MRI programme against the published results of 1.5 T screening studies. Over a 20-month period, 291 patients referred with an elevated familial risk of breast cancer were examined at 3.0 T. Resulting images were scored based on the Royal College of Radiologists Breast Group imaging classification. The reference standard was a combination of histology and follow-up imaging. Follow-up data were available in 267 patients. Analysis revealed positive and negative post-test probabilities of 28% [95% confidence intervals (CI); range, 10-60%] and 1% (95% CI; range, 0-2%), respectively. These results compared favourably against those of a recent meta-analysis [25.3% (95% CI; range, 18.4-33.8%) and 0.4% (95% CI; range, 0.2-0.9%), respectively]. Given the similar summary statistics between this work and the 1.5 T results, it would appear that screening of high-risk patients at 3.0 T has potential. Further studies should be undertaken to verify this result.

US Cannot Be Used to Predict the Presence or Severity of Hepatic Steatosis in Severely Obese Adolescents

To evaluate the diagnostic accuracy of ultrasonography (US) for the assessment of hepatic steatosis in severely obese adolescents, with proton magnetic resonance (MR) spectroscopy as the reference standard, and to provide insight on the influence of prevalence on predictive values by calculating positive and negative posttest probabilities. This prospective study was institutional review board approved. All participants, and/or their legal representatives, gave written informed consent. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for the overall presence of steatosis and for the presence of substantial (moderate to severe) steatosis. Positive and negative posttest probabilities were calculated and plotted against prevalence. A total of 104 children (47 male, 57 female) were prospectively included. Mean age was 14.5 years (range, 8.3-18.9 years) and mean age-adjusted standard deviation body mass index (BMI) score (BMI z score) was 3.3 (range, 2.6-4.1). The overall prevalence of hepatic steatosis was 46.2% (48 of 104). Sensitivity of US was 85.4% (41 of 48), specificity was 55.4% (31 of 56), PPV was 62.1% (41 of 66), and NPV was 81.6% (31 of 38). The prevalence of substantial steatosis was 15.4% (16 of 104), with US sensitivity of 75.0% (12 of 16) and specificity of 87.5% (77 of 88). PPV was 52.2% (12 of 23) and NPV was 95.1% (77 of 81). Plotting of posttest probabilities against prevalence for both disease degrees demonstrated how disease prevalence influences US accuracy. Positive US results in severely obese adolescents cannot be used to accurately predict the presence and severity of hepatic steatosis, and additional imaging is required. Negative US results exclude the presence of substantial steatosis with acceptable accuracy. Steatosis prevalence differs among specific populations, strongly influencing posttest probabilities.

Diagnostic accuracy of MRI in adults with suspect brachial plexus lesions: A multicentre retrospective study with surgical findings and clinical follow-up as reference standard

ObjectiveTo evaluate brachial plexus MRI accuracy with surgical findings and clinical follow-up as reference standard in a large multicentre study. Materials and methodsThe research was approved by the Institutional Review Boards, and all patients provided their written informed consent. A multicentre retrospective trial that included three centres was performed between March 2006 and April 2011. A total of 157 patients (men/women: 81/76; age range, 18–84 years) were evaluated: surgical findings and clinical follow-up of at least 12 months were used as the reference standard. MR imaging was performed with different equipment at 1.5T and 3.0T. The patient group was divided in five subgroups: mass lesion, traumatic injury, entrapment syndromes, post-treatment evaluation, and other.Sensitivity, specificity with 95% confidence intervals (CIs), positive predictive value (PPV), pre-test-probability (the prevalence), negative predictive value (NPV), pre- and post-test odds (OR), likelihood ratio for positive results (LH+), likelihood ratio for negative results (LH−), accuracy and post-test probability (post-P) were reported on a per-patient basis. ResultsThe overall sensitivity and specificity with 95% CIs were: 0.810/0.914; (0.697–0.904). Overall PPV, pre-test probability, NPV, LH+, LH−, and accuracy: 0.823, 0.331, 0.905, 9.432, 0.210, 0.878. ConclusionsThe overall diagnostic accuracy of brachial plexus MRI calculated on a per-patient base is relatively high. The specificity of brachial plexus MRI in patients suspected of having a space-occupying mass is very high. The sensitivity is also high, but there are false-positive interpretations as well.

Is Routine Pregnancy Testing Necessary in Women with Suspected UTI?

Objective: To determine if women of reproductive age who present to the Emergency Department (ED) with urinary tract infection (UTI) symptoms can accurately predict their pregnancy status. Methods: We performed a retrospective study of women who presented to the ED with UTI symptoms (dysuria, fre- quency, or urgency). Consecutive females aged 18-49 years were referred from triage to a computer kiosk in the waiting room. The kiosk asked all patients in oral and written format: Are you pregnant, worried you might be pregnant or have you missed your last period? Patient responses about pregnancy risk were compared to urine pregnancy test results. Test characteristics and post-test probabilities were calculated. Results: From a total of 300 eligible subjects, 216 received a pregnancy test, of which 10 were positive, giving a preg- nancy prevalence of 5%. Of 196 patients who reported no pregnancy risk, 4 were found to be pregnant, yielding a nega- tive posttest probability of pregnancy = 2.0% (95%CI 0.8-5.1). Among the 155 women diagnosed with a UTI, 6 were pregnant, giving a prevalence of 4%. Of the 144 patients who reported no pregnancy risk, 2 were found to be pregnant, yielding a negative posttest probability of 1.4% (95% CI 0.4-4.9). Conclusions: Adult women presenting to the ED with UTI symptoms who report no pregnancy risk have a 2% or lower probability of actually being pregnant. We believe this level of accuracy to be sufficient for routine clinical practice, and consider it is reasonable to initiate empiric antibiotic therapy without diagnostic pregnancy testing in such patients.