Statistical inference for continuous variables.
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Bayes Theorem↗
Biomedical subjects
Lawrence Joseph
Publications and source records attributed to Lawrence Joseph.
Statistical inference for proportions.
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Bayes Theorem↗
Estimating the intensity of infection with Schistosoma japonicum in villagers of leyte, Philippines. Part I: a Bayesian cumulative logit model. The schistosomiasis transmission and ecology project (STEP).
Intensity profiles for helminths are used to describe population infection status, monitor effectiveness of control programs, and provide accurate data to validate transmission models. This study aims to accurately predict age/gender specific intensity profiles of endemic schistosomiasis japonica infection in the Philippines. Poor sensitivity of the Kato-Katz test and large heterogeneity in infection levels across villages complicate these predictions. Data from 1,989 individuals living in three endemic villages were analyzed with a Bayesian cumulative-logit model adjusting for nonproportional odds, variation between villages, and measurement error. The posterior uncertainty regarding the proportion of individuals in each egg category was high compared with that estimated using a model ignoring measurement error and villages' heterogeneity. The intensity profiles were very different in children less than 7 years old compared with older children and adults. This model could easily be adapted to other parasitic infections or outcomes where an analysis by category would be recommended.
Animals↗
Risk factors associated with incident clinical vertebral and nonvertebral fractures in postmenopausal women: the Canadian Multicentre Osteoporosis Study (CaMos).
Utilizing data from the Canadian Multicentre Osteoporosis Study (CaMos), we examined the association between potential risk factors and incident vertebral and nonvertebral fractures. A total of 5,143 postmenopausal women were enrolled. Information collected during the study included data from the CaMos baseline and annually mailed fracture questionnaires, the Short Form 36 (SF-36), the Health Utilities Index, and physical measurements. Participants were followed for 3 years. Postmenopausal women were classified into four groups according to their incident fracture status since baseline: those without a new fracture; those with a new clinically recognized vertebral fracture; those with an incident nonvertebral fracture at the wrist, hip, humerus, pelvis, or ribs (main nonvertebral fracture group); and those with any new nonvertebral fracture (any-nonvertebral-fracture group). We performed multivariate Cox proportional hazard analysis using all possible risk factors to determine the association between risk factors and the time to the first minimal trauma fracture. Best predictive models were also determined using variables that were included in the full models. The Bayesian information criterion was used for model selection. For all analyses, relative risks and associated 95% confidence intervals were calculated. During the follow-up period, 34, 163, and 280 women developed a vertebral, a main nonvertebral, or any nonvertebral fracture, respectively. The best predictive models indicated that a five point lower quality of life as measured by the SF-36 physical component summary score was associated with relative risks of 1.21 (95% CI, 1.02 to 1.44), 1.17 (95% CI, 1.07 to 1.28), and 1.19 (95% CI, 1.11 to 1.27) for incident vertebral, main nonvertebral, and all nonvertebral fractures, respectively. In addition, for a one standard deviation (SD=0.12) lower femoral neck BMD, the relative risks for incident vertebral, main nonvertebral, and any nonvertebral fractures increased by 2.73 (95% CI, 1.74 to 4.28), 1.39 (95% CI, 1.06 to 1.82), and 1.34 (95% CI, 1.09 to 1.65), respectively. Furthermore, various anthropometric measures, disease conditions, and medications are associated with a new fracture. Identifying postmenopausal women at risk is important given that fracture prevention therapies are now available.
Adult↗
Diversity of Mycobacterium tuberculosis isolates in an immigrant population: evidence against a founder effect.
Population-based studies have used DNA typing of Mycobacterium tuberculosis organisms to estimate the extent of ongoing tuberculosis transmission in various communities and to characterize associated risk factors. The finding of matched DNA "fingerprints" among isolates from an immigrant subgroup may reflect transmission in the adopted country but could also reflect limited diversity among M. tuberculosis organisms within that immigrant community. The authors sought to determine which hypothesis is more likely to explain the high frequency of matched isolates among Haitian-born tuberculosis patients in Montreal, Quebec, Canada. The authors determined the number of different bacterial genotypes in this community as compared with other foreign-born tuberculosis patients and applied a recently described measure of genetic similarity between M. tuberculosis organisms ("genetic distance"). Among 76 Haitian-born tuberculosis patients diagnosed during 1996-1998, the authors identified 47 distinct genotypes on the basis of standard IS6110 DNA typing and categorical analysis. In genetic distance analysis, these 47 genotypes showed as great a genetic diversity as that observed among the 191 distinct genotypes identified in 216 other foreign-born tuberculosis patients. A mycobacterial "founder effect" is unlikely to account for the high proportion of shared isolates among Haitian-born Montrealers. Recent transmission remains the most likely explanation.
Adolescent↗
Selection bias found in interpreting analyses with missing data for the prehospital index for trauma.
OBJECTIVE: To evaluate the effects of missing data on analyses of data from trauma databases, and to verify whether commonly used techniques for handling missing data work well in theses settings. STUDY DESIGN AND SETTING: Measures of trauma severity such as the Pre-Hospital Index (PHI) are used for triage and the evaluation of trauma care. As conditions of trauma patients can rapidly change over time, estimating the change in PHI from the arrival at the emergency room to hospital admission is important. We used both simulated and real data to investigate the estimation of PHI data when some data are missing. Techniques compared include complete case analysis, single imputation, and multiple imputation. RESULTS: It is well known that complete case analyses and single imputation methods often lead to highly misleading results that can be corrected by multiple imputation, an increasingly popular method for missing data situations. In practice, unverifiable assumptions may not hold, meaning that it may not be possible to draw definitive conclusions from any of the methods. CONCLUSION: Great care is required whenever missing data arises. This is especially true in trauma databases, which often have much missing data and where the data may not missing at random.
Database Management Systems↗
Bayesian statistics for parasitologists.
Bayesian statistical methods are increasingly being used in the analysis of parasitological data. Here, the basis of differences between the Bayesian method and the classical or frequentist approach to statistical inference is explained. This is illustrated with practical implications of Bayesian analyses using prevalence estimation of strongyloidiasis and onchocerciasis as two relevant examples. The strongyloidiasis example addresses the problem of parasitological diagnosis in the absence of a gold standard, whereas the onchocerciasis case focuses on the identification of villages warranting priority mass ivermectin treatment. The advantages and challenges faced by users of the Bayesian approach are also discussed and the readers pointed to further directions for a more in-depth exploration of the issues raised. We advocate collaboration between parasitologists and Bayesian statisticians as a fruitful and rewarding venture for advancing applied research in parasite epidemiology and the control of parasitic infections.
Animals↗
Health-related quality of life in cardiac patients with dyslipidemia and hypertension.
BACKGROUND: Hypertension is associated with lower health-related quality of life (HRQOL). Similar association may be found for dyslipidemia. However, controversies exist regarding the HRQOL with dyslipidemia. We evaluated the HRQOL of cardiac patients with and without dyslipidemia and hypertension. METHODS: In a cross-sectional study, 284 cardiac patients rated their HRQOL using SF-36 Health Survey (SF-36), and three preference-based measures (Rating Scale, Time Trade-off and Standard Gamble). RESULTS: Compared to those without dyslipidemia, those with dyslipidemia reported better HRQOL on all preference-based measures and most SF-36 scales particularly on the physical health scales. Adjusted mean differences and 95% confidence interval (95% CI) were equal to 4.5 (0.5, 8.5), 10.8 (2.8, 18.8), and 2.2 (0.2, 4.2) on the Physical Functioning, the Role-Physical and the Physical Component Summary scales, respectively. Exactly the opposite trends were observed among patients with hypertension. The adjusted mean differences (95% CI) were equal to -2.7 (-6.7, 1.4), -10.9 (-19.1, -2.8), and -2.9 (-4.9, -0.9) on the Physical Functioning, the Role-Physical and the Physical Component Summary scales, respectively. CONCLUSION: Cardiac patients with hypertension reported lower physical health than those without hypertension while cardiac patients with dyslipidemia reported better physical health than those without dyslipidemia. The reason for these different trends is not known. Possible explanations are discussed.
Adult↗
Bayesian sample size determination for prevalence and diagnostic test studies in the absence of a gold standard test.
Planning studies involving diagnostic tests is complicated by the fact that virtually no test provides perfectly accurate results. The misclassification induced by imperfect sensitivities and specificities of diagnostic tests must be taken into account, whether the primary goal of the study is to estimate the prevalence of a disease in a population or to investigate the properties of a new diagnostic test. Previous work on sample size requirements for estimating the prevalence of disease in the case of a single imperfect test showed very large discrepancies in size when compared to methods that assume a perfect test. In this article we extend these methods to include two conditionally independent imperfect tests, and apply several different criteria for Bayesian sample size determination to the design of such studies. We consider both disease prevalence studies and studies designed to estimate the sensitivity and specificity of diagnostic tests. As the problem is typically nonidentifiable, we investigate the limits on the accuracy of parameter estimation as the sample size approaches infinity. Through two examples from infectious diseases, we illustrate the changes in sample sizes that arise when two tests are applied to individuals in a study rather than a single test. Although smaller sample sizes are often found in the two-test situation, they can still be prohibitively large unless accurate information is available about the sensitivities and specificities of the tests being used.
Bayes Theorem↗
Antiphospholipid antibodies and thrombosis: association with acquired activated protein C resistance in venous thrombosis and with hyperhomocysteinemia in arterial thrombosis.
Although antiphospholipid antibodies (aPL) are associated with thrombosis, it is not known who with aPL is at higher risk for thrombosis. It was the aim of this cross-sectional study to investigate how thrombophilic factors contribute to venous or arterial thrombosis in aPL-positive individuals. In outpatient test centres at two tertiary care hospitals, two hundred and eight (208) persons requiring aPL testing were matched by age, gender and centre to 208 persons requiring a complete blood count. Persons were classified as aPL-positive (having anticardiolipin, lupus anticoagulant and/or anti-beta(2)-glycoprotein I antibodies) or aPL-negative. Several thrombophilic factors were studied using logistic regression modelling. Results showed that the aPL-positive group had three-fold more events (37%) than the aPL-negative group (12%). In unadjusted analyses, clinically important associations were observed between factor V Leiden and venous thrombosis, hyperhomocysteinemia and arterial thrombosis, and activated protein C resistance (APCR) and venous thrombosis (OR, 95% CI = 4.00, 1.35-11.91; 4.79, 2.03-11.33; and 2.03, 1.03-3.97, respectively). After adjusting for recruitment group, persons with both APCR and aPL had a three-fold greater risk (OR, 95% CI = 3.31, 1.30-8.41) for venous thrombosis than those with neither APCR nor aPL. Similarly, after adjusting for hypertension, family history of cardiovascular disease, gender and recruitment group, persons with both hyperhomocysteinemia and aPL had a five-fold increased risk (OR, 95% CI = 4.90, 1.37-17.37) for arterial thrombosis compared to those with neither risk factor. In conclusion, APCR phenotype and hyperhomocysteinemia are associated with a higher risk of venous and arterial thrombosis, respectively, in the presence of aPL.
Activated Protein C Resistance↗
Risk factors for hospitalization and infection in Canadian Inuit infants over the first year of life--a pilot study.
OBJECTIVES: Inuit infants experience higher mortality and poorer health than other Canadian infants, and suffer disproportionately from bacterial and viral infections. A wide range of inter-related factors affect their health and susceptibility to infection. The objective of the study was to describe hospitalization and morbidity patterns in a cohort of 46 healthy Inuit infants from Iqaluit, Nunavut, over their first year of life. STUDY DESIGN: Risk factors for hospitalization and infections were assessed using multiple linear regression. RESULTS: Infants experienced an average of four respiratory tract infections (RTIs) annually, which accounted for half of the hospitalizations in the cohort. Some interesting trends were evident from the assessment of risk factors using multiple linear regression. Adoption was associated with adverse health effects in addition to those that would be expected due to lack of breast-freeding alone; among infants who were not breast-fed, adopted infants had three more RTIs per year than non-adopted infants. CONCLUSION: The results of this pilot study provide support for undertaking larger epidemiological studies in order to clarify the role of these risk factors, so that future preventive efforts can be informed and effective.
Adoption↗
Magnetic resonance cholangiopancreatography: a meta-analysis of test performance in suspected biliary disease.
BACKGROUND: Magnetic resonance cholangiopancreatography (MRCP) is one of many newer noninvasive tests that can image the biliary tree. PURPOSE: To precisely estimate the overall sensitivity and specificity of MRCP in suspected biliary obstruction and to evaluate clinically important subgroups. DATA SOURCES: MEDLINE search (January 1987 to March 2003) for studies in English or French, bibliographies, and subject matter experts. STUDY SELECTION: Studies were included if they allowed construction of 2x2 contingency tables of MRCP compared with a reasonable gold standard for at least 1 of the following: the presence, level, or cause of biliary obstruction. DATA EXTRACTION: Two independent observers graded study quality, which included consecutive enrollment, blinding, use of a single (versus composite) gold standard, and nonselective use of the gold standard. Logistic regression was used to examine the influence of publication year, quality score, proportion of patients having a "direct" gold standard, and clinical context on diagnostic performance. DATA SYNTHESIS: Of 498 studies identified, 67 were included (4711 patients). Mixed-effect models were used to estimate the sensitivity and specificity, and quantitative receiver-operating characteristic analysis was performed. Magnetic resonance cholangiopancreatography had a high overall pooled sensitivity (95% [+/-1.96 SD: spread of SD, 75% to 99%]) and specificity (97% [spread of SD, 86% to 99%]). The procedure was less sensitive for stones (92%; odds ratio, 0.51 [CI, 0.35 to 0.75]) and malignant conditions (88%; odds ratio, 0.28 [CI, 0.18 to 0.44]) than for the presence of obstruction. In addition, diagnostic performance was higher in studies that were larger, did not use consecutive enrollment, and did not use gold standard assessment for some patients. CONCLUSIONS: Magentic resonance cholangiopancreatography is a noninvasive imaging test with excellent overall sensitivity and specificity for demonstrating the level and presence of biliary obstruction; however, it seems less sensitive for detecting stones or differentiating malignant from benign obstruction.
Bile Duct Neoplasms↗
Prediction of community prevalence of human onchocerciasis in the Amazonian onchocerciasis focus: Bayesian approach.
OBJECTIVE: To develop a Bayesian hierarchical model for human onchocerciasis with which to explore the factors that influence prevalence of microfilariae in the Amazonian focus of onchocerciasis and predict the probability of any community being at least mesoendemic (>20% prevalence of microfilariae), and thus in need of priority ivermectin treatment. METHODS: Models were developed with data from 732 individuals aged > or =15 years who lived in 29 Yanomami communities along four rivers of the south Venezuelan Orinoco basin. The models' abilities to predict prevalences of microfilariae in communities were compared. The deviance information criterion, Bayesian P-values, and residual values were used to select the best model with an approximate cross-validation procedure. FINDINGS: A three-level model that acknowledged clustering of infection within communities performed best, with host age and sex included at the individual level, a river-dependent altitude effect at the community level, and additional clustering of communities along rivers. This model correctly classified 25/29 (86%) villages with respect to their need for priority ivermectin treatment. CONCLUSION: Bayesian methods are a flexible and useful approach for public health research and control planning. Our model acknowledges the clustering of infection within communities, allows investigation of links between individual- or community-specific characteristics and infection, incorporates additional uncertainty due to missing covariate data, and informs policy decisions by predicting the probability that a new community is at least mesoendemic.
Adolescent↗
Evidence for use of coronary stents. A hierarchical bayesian meta-analysis.
BACKGROUND: Coronary stents are widely used in interventional cardiology, but a current quantitative systematic overview comparing routine coronary stenting with standard percutaneous transluminal coronary angioplasty (PTCA) and restricted stenting (provisional stenting) has not been published. PURPOSE: To summarize results from all randomized clinical trials comparing routine coronary stenting with standard PTCA. DATA SOURCES: Electronic databases were searched by using the key words angioplasty and stent. References from identified articles were also reviewed. In addition, several prominent general medical and cardiology journals were searched and agencies known to perform systematic reviews were consulted. STUDY SELECTION: All comparative randomized clinical trials were included, except those involving primary angioplasty for the treatment of acute myocardial infarction. DATA EXTRACTION: A specified protocol was followed, and two of the authors independently extracted the data. Outcomes assessed were total mortality, myocardial infarction, angiographic restenosis, coronary artery bypass surgery, repeated PTCA, and freedom from angina. DATA SYNTHESIS: The results were synthesized by using a Bayesian hierarchical random-effects model. A total of 29 trials involving 9918 patients were identified. There was no evidence for a difference between routine coronary stenting and standard PTCA in terms of deaths or myocardial infarctions (odds ratio, 0.90 [95% credible interval [CrI], 0.72 to 1.11]) or the need for coronary artery bypass surgery (odds ratio, 1.01 [CrI, 0.79 to 1.31]). Coronary stenting reduced the rate of restenosis (odds ratio, 0.52 [CrI, 0.37 to 0.69]) and the need for repeated PTCA (odds ratio, 0.59 [CrI, 0.50 to 0.68]). The trials showed a wide range of crossover rates from PTCA to stenting. By use of a multiplicative model, each 10% increase in crossover rate decreased the need for repeated angioplasty by approximately 8% (odds ratio multiplying factor, 1.08 [CrI, 0.98 to 1.18]). Routine stenting probably reduces the need for repeated angioplasty by fewer than 4 to 5 per 100 treated persons compared with PTCA with provisional stenting. Studies were not blinded and suggest a bias with a possible overestimation of this benefit. CONCLUSIONS: In the controlled environment of randomized clinical trials, routine coronary stenting is safe but probably not associated with important reductions in rates of mortality, acute myocardial infarction, or coronary artery bypass surgery compared with standard PTCA with provisional stenting. Coronary stenting is associated with substantial reductions in angiographic restenosis rates and the subsequent need for repeated PTCA, although this benefit may be overestimated because of trial designs. The incremental benefit of routine stenting for reducing repeated angioplasty diminishes as the crossover rate of stenting with conventional PTCA increases.
Aged↗
Clinical outcomes following institution of universal leukoreduction of blood transfusions for premature infants.
CONTEXT: Leukocytes present in stored blood products can have a variety of biological effects, including depression of immune function, thereby increasing nosocomial infections and possibly resulting in organ failure and death. Premature infants, given their immature immune state, may be uniquely predisposed to the effects of transfused leukocytes. OBJECTIVE: To evaluate the clinical outcomes following implementation of a universal prestorage red blood cell (RBC) leukoreduction program in premature infants admitted to neonatal intensive care units (NICUs). DESIGN AND SETTING: Retrospective before-and-after study conducted in 3 Canadian tertiary care NICUs from January 1998 to December 2000. PATIENTS: A total of 515 premature infants weighing less than 1250 g who were admitted to the NICU, received at least 1 RBC transfusion, and survived at least 48 hours were enrolled. The intervention group consisted of infants admitted in the 18-month period following the introduction of universal leukoreduction (n = 247) and the control group consisted of infants admitted during the 18 months prior to the introduction of universal leukoreduction (n = 268). MAIN OUTCOME MEASURES: Primary outcomes were nosocomial bacteremia and NICU mortality, compared before and after implementation of universal leukoreduction using multivariate regression. Secondary outcomes included bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, and intraventricular hemorrhage. RESULTS: The proportion of infants who acquired bacteremia after an RBC transfusion was 79/267 (29.6%) in the nonleukoreduction period and 63/246 (25.6%) in the leukoreduction period. For NICU mortality, there were 45 deaths (16.8%) in the nonleukoreduction period and 44 deaths (17.8%) in the leukoreduction period. The adjusted odds ratio (OR) for bacteremia was 0.59 (95% confidence interval [CI], 0.34-1.01) and for mortality was 1.22 (95% CI, 0.59-2.50). The adjusted ORs for bronchopulmonary dysplasia and retinopathy of prematurity were 0.42 (95% CI, 0.25-0.70) and 0.56 (95% CI, 0.33-0.93), respectively. The adjusted ORs for necrotizing enterocolitis and grade 3 or 4 intraventricular hemorrhage were 0.39 (95% CI, 0.17-0.90) and 0.65 (95% CI, 0.35-1.19), respectively. The adjusted OR for a composite measure of any major neonatal morbidity was 0.31 (95% CI, 0.17-0.56). Crude and adjusted rates for all secondary outcomes suggest that leukoreduction was associated with improved outcomes. CONCLUSION: Implementation of universal prestorage leukoreduction was not associated with significant reductions in NICU mortality or bacteremia but was associated with improvement in several clinical outcomes in premature infants requiring RBC transfusions.
Bacteremia↗
Prevalence of peanut allergy in primary-school children in Montreal, Canada.
BACKGROUND: Peanut allergy is receiving increasing attention. Only one study has estimated the prevalence in North America, but it did not corroborate history with diagnostic testing. OBJECTIVE: We estimated the prevalence of peanut allergy in Montreal by administering questionnaires regarding peanut ingestion to children in kindergarten through grade 3 in randomly selected schools. METHODS: Respondents were stratified as follows: (1). peanut tolerant, (2). never-rarely ingest peanut, (3). convincing history of peanut allergy, and (4). uncertain history of peanut allergy. Groups 2, 3, and 4 underwent peanut skin prick tests (SPTs), and if the responses were positive in groups 2 or 4, measurement of peanut-specific IgE were undertaken. Children in group 3 with a positive SPT response were considered allergic to peanut without further testing. Children in groups 2 and 4 with peanut-specific IgE levels of less than 15 kU/L underwent oral peanut challenges. RESULTS: Of the 7768 children surveyed, 4339 responded, 94.6% in group 1. The prevalence of peanut allergy was 1.50% (95% CI, 1.16%-1.92%). When multiple imputation was used to incorporate data on those responding to the questionnaire but withdrawing before testing, the estimated prevalence increased to 1.76% (95% CI, 1.38%-2.21%). When data regarding the peanut allergy status of nonresponders (as declared to the school before the study) were also incorporated, the estimated prevalence was 1.34% (95% CI, 1.08%-1.64%). CONCLUSION: Our prevalence study is the first in North America to corroborate history with confirmatory testing and the largest worldwide to incorporate these techniques. We have shown that, even with conservative assumptions, prevalence exceeds 1.0%.
Arachis↗
Universal health insurance coverage does not eliminate inequities in access to cardiac procedures after acute myocardial infarction.
BACKGROUND: It remains unclear whether socioeconomic status (SES) influences access to invasive cardiac procedures after acute myocardial infarction (AMI) in a universal health care system. The objective of this study was to evaluate the effect of SES on access to cardiac procedure after AMI in a universal health care system. METHODS: This was an observational cohort study of all patients with a first AMI in the province of Quebec, Canada, between 1985 to 1995. Information on treatment was obtained from the discharge and physicians' claims databases. SES was obtained from census data by linking postal codes. SES-independent predictors of use were identified, then incorporated in hierarchical models to predict use in low, medium, and high SES areas. The main outcome measures were rates of cardiac catheterization, percutaneous coronary intervention (PCI), and coronary artery bypass graft surgery (CABG) as a function of SES. RESULTS: SES data were available for 62,364 individuals with a first AMI. Of these, 65% were men and the mean age was 64 +/- 13 years. Rates of cardiac procedures rose with an increase in several SES measures. After adjustment for individual-level predictors of use of cardiac catheterization, average rent, (odds ratio per $100 difference: 1.57, 95% credible interval: 1.36 to 1.80) and proportion of renters, (odds ratio, 2.2; 95% CI: 1.21 to 3.73) in the area were independent SES predictors. Patients in low SES areas (median family income: $ 30,809 CDN) were less likely to undergo cardiac catheterization than patients in high SES areas ($92,169 CDN) (men: 33%; compared with 47%; women: 18%; compared with 47%). However, among patients with cardiac catheterization, SES was not associated with the use of revascularization procedures. For example, PCI rates for men within 90 days after AMI were 26%, compared with 25% in low and high SES areas, respectively. CABG rates were 15%, compared with 19%. CONCLUSIONS: We found that in the universal health care system of Canada, access to cardiac catheterization after AMI varied according to SES. Among those with cardiac catheterization, SES did not appear to influence further use of revascularization procedures.
Aged↗
The predictive value of a positive prick skin test to peanut in atopic, peanut-naïve children.
BACKGROUND: Although allergy testing before food ingestion is generally not recommended, many peanut-naive children undergo prick skin tests (PSTs) to peanut because of atopy. Children with positive PSTs are generally advised to avoid peanuts either indefinitely or until a definitive diagnosis is made through challenge. OBJECTIVE: To describe peanut challenges in atopic, peanut-naive children with PST to peanuts > or = 3 mm and the PST properties in this population. METHODS: Between 1994 and 2001, 47 patients were identified who had a positive peanut PST, no previous peanut ingestion, and had undergone a peanut challenge. RESULTS: Forty-nine percent of the challenges were positive. The mean of the largest wheal diameter (95% confidence interval [CI]) of the PST in children having a negative and positive challenge was 6.3 mm (CI, 5.3 to 7.3) and 10.3 mm (CI, 8.9 to 11.8), respectively. At a PST cutoff of > or = 5 mm, the sensitivity and negative predictive value (95% CI) was 100% (85.2 to 100) and 100% (29.2 to 100), whereas the specificity and positive predictive value (95% CI) was 12.5% (2.7 to 32.4) and 52.3% (36.7 to 67.5), respectively. CONCLUSIONS: We show that 49% of atopic, peanut-naïve children sensitized to peanut developed allergic symptoms during oral provocation with peanut. Although the sensitivity of the PST at > or = 5 mm for the detection of peanut allergy in this study was 100%, our small sample size limits the applicability of this value. Further investigation is needed to determine whether children with wheal diameters of 3 or 4 mm, perhaps coupled with low peanut-specific IgE, could undergo less resource-intensive, accelerated challenges.
Antibody Specificity↗