Browsing by keyword "False Negative Reactions"
Now showing items 1-6 of 6
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Acylcarnitines in plasma and blood spots of patients with long-chain 3-hydroxyacyl-coenzyme A dehydrogenase defiencyThe acylcarnitines in plasma and blood spots of 23 patients with proven deficiency of long-chain 3-hydroxyacylcoenzyme A dehydrogenase were reviewed. Long-chain 3-hydroxyacylcarnitines of C14:1, C14, C16 and C18:1 chain length, and long-chain acylcarnitines of C12, C14:1, C14, C16, C18:2 and C18:1 chain length were elevated. Acetylcarnitine was decreased. In plasma, elevation of hydroxy-C18:1 acylcarnitine over the 95th centile of controls, in combination with an elevation of two of the three acylcarnitines C14, C14:1 and hydroxy-C16, identified over 85% of patients with high specificity (less than 0.1% false positive rate). High endogenous levels of long-chain acylcarnitines in normal erythrocytes reduced the diagnostic specificity in blood spots compared with plasma samples. The results were also diagnostic in asymptomatic patients, and were not influenced by genotype. Treatment with diet low in fat and high in medium-chain triglyceride decreased all disease-specific acylcarnitines, often to normal, suggesting that this assay is useful in treatment monitoring.
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Diagnostic dilemmas resulting from the immunoreactive trypsinogen/DNA cystic fibrosis newborn screening algorithmOBJECTIVE: To quantitate the proportion of infants identified through cystic fibrosis (CF) newborn screening (NBS) by an immunoreactive trypsinogen (IRT)/DNA screening algorithm who have an unclear diagnosis as defined by the findings of an elevated IRT level and either 1) 2 CF gene (CFTR) mutations detected and sweat chloride level <60 mEq/L; or 2) 0 or 1 CFTR mutations and a "borderline" sweat chloride level >or=30 and <60 mEq/L. STUDY DESIGN: Using the 4-year cohort of CF-affected infants recently described by the Massachusetts CF NBS program, we identified and described the number of infants with the diagnostic characteristics (diagnostic dilemmas) aforementioned. RESULTS: Of infants with positive results on CF NBS who had 1 CFTR mutation detected and a borderline sweat chloride concentration, nearly 20% displayed a second CFTR mutation on further evaluation. Of all infants with positive CF NBS results considered affected with CF, 11% had a diagnosis that fell into 1 of the diagnostic dilemma categories aforementioned. CONCLUSIONS: Four problematic diagnostic categories generated by CF NBS are defined. In the absence of data on the natural history of such infants, careful follow-up is recommended for infants in whom a definitive diagnosis is elusive.
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Likelihood of missed and recurrent adenomas in the proximal versus the distal colonBACKGROUND: Colonoscopy may be less efficacious in reducing colorectal cancer mortality in the proximal compared with the distal colon. A greater likelihood for missed and recurrent adenomas in the proximal colon may contribute to this phenomenon. OBJECTIVE: To examine whether a proximal adenoma is associated with the risk and location of missed and recurrent adenomas. DESIGN: Prospective. SETTING: Polyp Prevention Trial. PARTICIPANTS: A total of 1864 patients with an adenoma at baseline underwent a follow-up colonoscopy 4 years later (adenoma recurrence). Of these, 1731 underwent a clearing colonoscopy 1 year after the baseline examination (missed adenoma). MAIN OUTCOME MEASUREMENTS: Association of baseline adenoma location with the risk and location of adenomas found at colonoscopy performed 1 year and 4 years later. RESULTS: At the year 1 colonoscopy, 598 patients (34.6%) had an adenoma (missed adenoma). Compared with those with a distal-only adenoma at baseline, patients with a proximal-only adenoma at baseline were more likely to have any missed adenomas (relative risk [RR] 1.28; 95% CI, 1.09-1.49) and a proximal-only missed adenoma (RR 2.05; 95% CI, 1.49-2.80). At the year 4 colonoscopy, 733 patients (39.3%) had adenoma recurrence. Patients with a baseline proximal-only adenoma were more likely to have any adenoma recurrence (RR 1.14; 95% CI, 1.00-1.31) and a proximal-only adenoma recurrence (RR 1.52; 95% CI, 1.15-2.02). Sensitivity analyses involving missed adenomas did not materially affect the risk or location of recurrent adenomas at year 4 colonoscopy. LIMITATION: Lesions may still be missed on repeated colonoscopies. CONCLUSIONS: Missed and recurrent adenomas are more likely to be in the proximal colon. Published by Mosby, Inc. All rights reserved.
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Management of axilla in breast cancer - The saga continuesProspective trials investigating the accuracy of SLNB for cN0 (primary surgical therapy) and cN1 patients (neoadjuvant chemotherapy) have not utilized likelihood ratios (LR) to assess the impact of false negative SLNB. This review evaluates the evidence on accuracy of SLNB using STARD and QUADAS-2 (revised) criteria for patients undergoing primary surgical therapy and primary chemotherapy. It utilizes the: (i) Reported rates for pre-test probabilities of node positive disease from Surveillance, Epidemiology, and End Results (SEER) database for the cN0 patients (primary surgical therapy) for each T stage; calculates the negative LR from cumulative evidence; and uses the Bayesian nomogram to compute the post-test probability of missing the metastatic axillary node based on negative SLNB. (ii) Reported rates of complete axillary response in ACOSOG-Z1071 trial for cN1 patients to calculate the pre-test probabilities of residual nodal disease for each biological tumor sub-type; calculates the negative LR from ACOSOG-Z1071, and SENTINA trial data; and uses the Bayesian nomogram to compute the post-test probability of missing the residual metastatic axillary node based on negative SLNB. For cN0 disease, the odds of missing axillary disease based on negative SLNB for each T stage are: T1a = 0.7%; T1b = 1.5%; T1c = 3%; T2 = 7%; T3 = 18%. For cN1 disease, the odds of missing residual axillary disease based on negative SLNB for each biological subtype are: HER2neu+ = 8%; Triple negative = 15%; ER+/PR+/HER2neu- = 45%. Negative LR is more accurate and superior to false negative rate for determining the clinical utility of SLNB by taking into account the changing pre-test probability of disease.
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Stereotactic core needle biopsy of nonpalpable breast lesions: initial experience with a promising techniqueOBJECTIVES: To evaluate the correlation between the pathological findings of stereotactic core needle biopsy (SCNB) and the prebiopsy mammographic findings, as well as the pathological findings of lesions that were subsequently removed by surgical excision. DESIGN: A retrospective review of 97 consecutive patients who underwent 100 SCNBs of suspicious nonpalpable mammographic lesions. The criterion standard is surgical excisional biopsy with needle localization. Mammographic findings were graded according to the American College of Radiology Breast Imaging Reporting and Data System. The pathological findings of SCNB were categorized into 4 groups: benign and specific, benign and nonspecific, premalignant, and malignant. Surgical excision of the lesion was performed if the pathological finding on SCNB was nonconcordant with the prebiopsy mammogram and when premalignant or malignant lesions were found. The pathological findings of lesions that were subsequently removed by surgical excision were compared with those of SCNB. SETTING: Community-based private multispecialty ambulatory practice. PATIENTS: A population-based sample composed of 97 patients who had grade III, IV, or V lesions on routine screening mammograms. INTERVENTION: Stereotactic core needle biopsy of nonpalpable mammographic lesions. MAIN OUTCOME MEASURES: Percentage of patients whose SCNB results were concordant with the mammographic findings and the pathological findings on subsequent surgical excision. RESULTS: Concordance between SCNB and mammography occurred in 97% of biopsy specimens. Concordance between the pathological findings of SCNB and those of surgically excised lesions occurred in 92.5% of biopsy specimens. We had 1 false-negative result. We had no false-positive diagnosis of cancer with SCNB. CONCLUSION: On the basis of accumulating literature and our own initial experience, SCNB is a promising, safe, and cost-effective procedure.
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Sweat testing infants detected by cystic fibrosis newborn screeningOBJECTIVE: Describe and define limitations of early pilocarpine iontophoresis (sweat testing) for cystic fibrosis (CF) newborn screening (NBS). STUDY DESIGN: Population-based results from follow-up of CF NBS-positive newborns. RESULTS: Insufficient quantity of sweat is more likely if the sweat test is done too early, but testing is generally successful after 2 weeks of age. Sweat chloride levels drop over the first weeks of life. CF carriers have higher sweat chloride concentrations than non-carriers. CONCLUSIONS: Sweat testing can be performed effectively after 2 weeks of age for CF NBS-positive newborns. Earlier testing has a higher risk of insufficient sweat for completing testing.