A comparison of double-blind, placebo-controlled food challenge and open food challenge

BACKGROUND

Double-blind, placebo-controlled food challenge (DBPCFC) remains the gold standard for diagnosing food allergy, despite sparse comparisons to open food challenges (OpenFCs). The objective of this retrospective study was to compare severity of symptoms and threshold values (cumulative dose of food allergen eliciting a clinical reaction) in children and adults with peanut allergy, challenged in an open and/or double-blind, placebo-controlled protocol.

METHODS

This study included patients from the Allergy Centre, Odense University Hospital with a positive oral food challenge, defined as strict objective signs, with peanut during the period 2001-2022. Severity of symptoms was graded using the Sampson's severity score. Distribution models of threshold values were calculated using log-normal interval-censored survival analysis, and the number of placebo reactions was evaluated.

RESULTS

In total, 318 positive OpenFCs and 86 DBPCFCs were included. There was no difference in severity of symptoms nor threshold values comparing the two challenge types, neither when stratified for age groups. However, a higher proportion of children experienced Grade 3 symptoms in the double-blind group. Only one patient had a positive reaction to a placebo challenge.

CONCLUSION

Our findings do not advocate for DBPCFC being superior to OpenFC, if the latter is performed with strict objective stop criteria by trained staff.

Stair Climbing Ability and Identification of the Nine Stairs Ascent and Descent Test Cut-Off Points in Hip Osteoarthritis Patients: A Retrospective Study

Objectives As the prevalence and incidence of hip osteoarthritis (hip OA) continue to rise, measuring the impact of hip OA severity on a patient's functionality is essential. Stair walking is a particularly relevant task to assess hip OA patients, as difficulty with stair ascent is one of the driving factors in deciding to undergo a total hip arthroplasty. Although stairs tests often arise in post-arthroplasty measures, there is a lack of reported stairs performance time in hip OA patients. Therefore, this retrospective study aimed to report the stair performance time of hip OA patients categorized by disease severity and determine cut-off points that differentiate between severity grades. Materials and methods The patient selection was based on the review of de-identified data from our research laboratory database. 254 hip OA patients (aged ≥ 50 years) were divided according to the Kellgren-Lawrence classification system into three groups: Grade 2 (n=68), Grade 3 (n=109), and Grade 4 (n= 68). The stair-walking ability was evaluated using the 9S-A/D test. The time taken to ascend and descend the stairs was measured separately, and the total time (9S-A/D) was also recorded. The one-way ANOVA model, Welch test, Games-Howell posthoc test, Chi-Square tests, and Two-Way ANOVA model were used for the statistical analysis of the data. The cut-off points were obtained by receiver operating curve (ROC) analysis. The statistical significance was set at p<0.05. Results Homogeneity was found between the three groups regarding demographic and clinical characteristics, except age and gender (p<0.001). The comparison of the variables (9S-ascent, 9S-descent, and 9S-A/D) between groups, adjusted for gender and age, showed significant differences: Grade 2 individuals had shorter performance times compared to those in Grade 3 and Grade 4 (p<0.005). Simultaneously, patients with Grade 3 hip OA have a shorter performance time than those with Grade 4 hip OA (p<0.005). Regarding ROC analysis of Grade 2 versus Grade 3: The AUCs of 9S-ascend, 9S-descent, and 9S-A/D were 0.742 (95%CI 0.67-0.81), 0.734 (95%CI 0.66-0.81), and 0.745 (95%CI 0.54-0.90), respectively (all p values <0.005). The cut-off points of 9S-ascend, 9S-descent, and 9S-A/D were 8.7 s (sensitivity 56%, specificity 88%), 7.1 s (sensitivity 58%, specificity 80%), and 16.25 s (sensitivity 54%, specificity 90%), respectively. Concerning ROC analysis of Grade 3 versus Grade 4: The AUCs of 9S-ascend, 9S-descent, and 9S-A/D were 0.702 (95%CI 0.62-0.78), 0.711 (95%CI 0.63-0.79), and 0.715 (95%CI 0.64-0.80), respectively (all p values <0.005). The cut-off points of 9S-ascend, 9S-descent, and 9S-A/D were 11.5 s (sensitivity 66%, specificity 65%), 8.3 s (sensitivity 71%, specificity 62%), and 19.05 s (sensitivity 71%, specificity 61%), respectively. Conclusions The study provides evidence that the progression of hip OA affected stair walking; the performance time of 9S-ascent, 9S-ascent, and 9S-A/D tests was significantly longer as the severity of hip OA worsened. ROC analysis results show tests' ability to distinguish the cut-off point between different hip OA grades. However, further research is required for the reporting and classification of stair performance time values in hip OA patients and to further investigate the ability of 9S-ascent, 9S-descent, and 9S-A/D tests to predict the grade of hip OA.

Determining Tipping Points and Responses of Macroinvertebrate Traits to Abiotic Factors in Support of River Management

Although the trait concept is increasingly used in research, quantitative relations that can support in determining ecological tipping points and serve as a basis for environmental standards are lacking. This study determines changes in trait abundance along a gradient of flow velocity, turbidity and elevation, and develops trait-response curves, which facilitate the identification of ecological tipping points. Aquatic macroinvertebrates and abiotic conditions were determined at 88 different locations in the streams of the Guayas basin. After trait information collection, a set of trait diversity metrics were calculated. Negative binomial regression and linear regression were applied to relate the abundance of each trait and trait diversity metrics, respectively, to flow velocity, turbidity and elevation. Tipping points for each environmental variable in relation to traits were identified using the segmented regression method. The abundance of most traits increased with increasing velocity, while they decreased with increasing turbidity. The negative binomial regression models revealed that from a flow velocity higher than 0.5 m/s, a substantial increase in abundance occurs for several traits, and this is even more substantially noticed at values higher than 1 m/s. Furthermore, significant tipping points were also identified for elevation, wherein an abrupt decline in trait richness was observed below 22 m a.s.l., implying the need to focus water management in these altitudinal regions. Turbidity is potentially caused by erosion; thus, measures that can reduce or limit erosion within the basin should be implemented. Our findings suggest that measures mitigating the issues related to turbidity and flow velocity may lead to better aquatic ecosystem functioning. This quantitative information related to flow velocity might serve as a good basis to determine ecological flow requirements and illustrates the major impacts that hydropower dams can have in fast-running river systems. These quantitative relations between invertebrate traits and environmental conditions, as well as related tipping points, provide a basis to determine critical targets for aquatic ecosystem management, achieve improved ecosystem functioning and warrant trait diversity.

An overview of bitter compounds in foodstuffs: Classifications, evaluation methods for sensory contribution, separation and identification techniques, and mechanism of bitter taste transduction

The bitter taste is generally considered an undesirable sensory attribute. However, bitter-tasting compounds can significantly affect the overall flavor of many foods and beverages and endow them with various beneficial effects on human health. To better understand the relationship between chemical structure and bitterness, this paper has summarized the bitter compounds in foodstuffs and classified them based on the basic skeletons. Only those bitter compounds that are confirmed by human sensory evaluation have been included in this paper. To develop food products that satisfy consumer preferences, correctly ranking the key bitter compounds in foodstuffs according to their contributions to the overall bitterness intensity is the precondition. Generally, three methods were applied to screen out the key bitter compounds in foods and beverages and evaluate their sensory contributions, including dose-over-threshold factors, taste dilution analysis, and spectrum descriptive analysis method. This paper has discussed in detail the mechanisms and applications of these three methods. Typical procedures for separating and identifying the main bitter compounds in foodstuffs have also been summarized. Additionally, the activation of human bitter taste receptors (TAS2Rs) and the mechanisms of bitter taste transduction are outlined. Ultimately, a conclusion has been drawn to highlight the current problems and propose potential directions for further research.

Cut Points of Chair Stand Test for Poor Physical Function and Its Association With Adverse Health Outcomes in Community-Dwelling Older Adults: A Cross-Sectional and Longitudinal Study

OBJECTIVES

To identify the optimal cutoff points for poor physical function [measured by a 5-times sit-to-stand (5-STS) test] associated with slowness in community-dwelling older adults and to validate the 5-STS cut points by determining whether they predicted future slowness and clinically relevant health outcomes over a 2-year-follow-up period.

DESIGN

Cross-sectional and longitudinal analyses of a cohort study.

SETTING AND PARTICIPANTS

We conducted cross-sectional (n = 2977) and prospective 2-year follow-up analyses (n = 2515) among participants aged 70-84 years enrolled in the nationwide Korean Frailty and Aging Cohort Study (KFACS).

METHODS

Classification and regression tree (CART) analysis was used to identify the 5-STS cut points for poor performance in terms of slowness (eg, gait speed ≥1.0 m/s, gait speed >0.8 m/s and <1.0 m/s, gait speed ≤0.8 m/s) at baseline. Multinomial logistic regression models were used to evaluate the prevalence and incidence of slowness and clinical outcomes according to the three 5-STS categories (normal, intermediate, and poor) in the cross-sectional and longitudinal analyses.

RESULTS

The overall prevalence of slowness in our study sample was 9.0% for a gait speed of ≤0.8 m/s and 32.1% for a gait speed of <1.0 m/s. The CART model identified 5-STS cut points of 10.8 seconds and 12.8 seconds for intermediate and poor physical function, respectively. In the adjusted model, the cut point of 12.8 seconds had a significantly increased likelihood of incident slowness and clinically relevant health outcomes (ie, mobility limitation, disability, frailty, sarcopenia risk, and falls) over the 2-year-follow-up period (all, P < .05).

CONCLUSIONS AND IMPLICATIONS

Our study established 5-STS test cutoff points for poor physical function. Thresholds of 10.8 and 12.8 seconds (intermediate and poor physical function, respectively) for a 5-STS test might help identify individuals at risk of physical function impairments and, thus, help design preventive interventions in community health care settings.

Timed Up and Go (TUG) Reference Values and Predictive Cutoffs for Fall Risk and Disability in Singaporean Community-Dwelling Adults: Yishun Cross-Sectional Study and Singapore Longitudinal Aging Study

OBJECTIVES

The "timed up and go" (TUG) test is a simple and widely used test of overall functional mobility. There is a paucity of TUG normative data among Asian individuals who differ in habitual gait speed and fall risk from Western population. The objectives of this study were to determine TUG reference values and optimum cutoffs predicting prevalent and incident disability for community-dwelling adults.

DESIGN

One cross-sectional (Study 1-Yishun Study) and one longitudinal (Study 2-Singapore Longitudinal Aging Study) study in Singapore.

SETTING AND PARTICIPANTS

Study 1 comprised 538 nondisabled, community-dwelling adults aged between 21 and 90 years. Study 2 comprised 1356 community-dwelling older adults aged ≥55 years followed for 3 years.

METHODS

Study 1 collected TUG reference values and assessed physiological fall risk (PFR) using the Physiological Profile Assessment (PPA). Study 2 assessed association of TUG with disability with the Barthel Index and the Lawton scale at baseline and follow-up.

RESULTS

From Study 1, mean TUG time for individuals aged 60 to 74 years was 9.80 seconds, shorter than values reported for Westerners of 12.30 seconds. It was significantly associated with high PFR [odds ratio (OR) 1.14, 95% confidence interval (CI) 1.03-1.27], 74.0% agreement, Cohen's kappa = 0.314 (95% CI 0.238-0.390); area under the curve = 0.85 (95% CI 0.80-0.90). A TUG cutoff of 10.2 seconds discriminated high PFR from low PFR with 84.4% sensitivity and 72.6% specificity. In Study 2, the threshold for observing significantly increased risk of disability was ≥9.45 seconds for prevalent disability (OR 2.98, 95% CI 1.41-6.78), functional decline (OR 2.68, 95% CI 1.33-5.80), and incidental disability (OR 2.25, 95% CI 1.08-4.97).

CONCLUSIONS AND IMPLICATIONS

TUG reference values and cutoff predicting disability for community-dwelling older adults in Singapore are consistent with Asian data and lower than for Western individuals. TUG could be used to guide development and evaluation of risk screening of adverse health outcomes across the life span in Singapore.

A Somatic Coliphage Threshold Approach To Improve the Management of Activated Sludge Wastewater Treatment Plant Effluents in Resource-Limited Regions

Effective wastewater management is crucial to ensure the safety of water reuse projects and effluent discharge into surface waters. Multiple studies have demonstrated that municipal wastewater treatment with conventional activated sludge processes is inefficient for the removal of a wide spectrum of viruses in sewage. In this study, a well-accepted statistical approach was used to investigate the relationship between viral indicators and human enteric viruses during wastewater treatment in a resource-limited region. Influent and effluent samples from five urban wastewater treatment plants (WWTPs) in Costa Rica were analyzed for somatic coliphage and human enterovirus, hepatitis A virus, norovirus genotypes I and II, and rotavirus. All WWTPs provide primary treatment followed by conventional activated sludge treatment prior to discharge into surface waters that are indirectly used for agricultural irrigation. The results revealed a statistically significant relationship between the detection of at least one of the five human enteric viruses and somatic coliphage. Multiple logistic regression and receiver operating characteristic curve analysis identified a threshold of 3.0 × 103 (3.5 log10) somatic coliphage PFU per 100 ml, which corresponded to an increased likelihood of encountering enteric viruses above the limit of detection (>1.83 × 102 virus targets/100 ml). Additionally, quantitative microbial risk assessment was executed for farmers indirectly reusing WWTP effluent that met the proposed threshold. The resulting estimated median cumulative annual disease burden complied with World Health Organization recommendations. Future studies are needed to validate the proposed threshold for use in Costa Rica and other regions.IMPORTANCE Effective wastewater management is crucial to ensure safe direct and indirect water reuse; nevertheless, few countries have adopted the virus log reduction value management approach established by the World Health Organization. In this study, we investigated an alternative and/or complementary approach to the virus log reduction value framework for the indirect reuse of activated sludge-treated wastewater effluent. Specifically, we employed a well-accepted statistical approach to identify a statistically sound somatic coliphage threshold value which corresponded to an increased likelihood of human enteric virus detection. This study demonstrates an alternative approach to the virus log reduction value framework which can be applied to improve wastewater reuse practices and effluent management.

Meteorological Variables and Synoptic Patterns Associated with Air Pollutions in Eastern China during 2013-2018

Steady meteorological conditions are important external factors affecting air pollution. In order to analyze how adverse meteorological variables affect air pollution, surface synoptic situation patterns and meteorological conditions during heavy pollution episodes are discussed. The results showed that there were 78 RPHPDs (regional PM_2.5 pollution days) in Jiangsu, with a decreasing trend year by year. Winter had the most stable meteorological conditions, thus most RPHPDs appeared in winter, followed by autumn and summer, with the least days in spring. RPHPDs were classified into three patterns, respectively, as equalized pressure (EQP), advancing edge of a cold front (ACF) and inverted trough of low pressure (INT) according to the SLP (sea level pressure). RPHPDs under EQP were the most (51%), followed by ACF (37%); INT was the minimum (12%). Using statistical methods and meteorological condition data on RPHPDs from 2013 to 2017 to deduce the thresholds and 2018 as an independent dataset to validate the proposed thresholds, the threshold values of meteorological elements are summarized as follows. The probability of RPHPDs without rain was above 92% with the daily and hourly precipitation of all RPHPDs below 2.1 mm and 0.8 mm. Wind speed, RHs, inversion intensity(ITI), height difference in the temperature inversion(ITK), the lower height of temperature inversion (LHTI) and mixed-layer height (MLH) in terms of 25%–75% high probability range were respectively within 0.5–3.6 m s⁻¹, 55%–92%, 0.7–4.0 °C 100 m ⁻¹, 42–576 m, 3–570 m, 200–1200 m. Two conditions should be considered: whether the pattern was EQP, ACF or INT and whether the eight meteorological elements are within the thresholds. If both criteria are met, PM_2.5 particles tend to accumulate and air pollution diffusion conditions are poor. Unfavorable meteorological conditions are the necessary, but not sufficient condition for RPHPDs.

[Determination of thresholds values for platelet serotonin and urinary 5-HIAA concentrations for the biological diagnosis of digestive neuroendocrine tumors]

OBJECTIVES

Platelet serotonin and its urinary metabolite 5-HIAA (5-hydroxyindolacetic acid) are the main biomarkers measured for the detection of neuroendocrine tumors (NET). We observe in our laboratory many false positives or false negatives for the 2 assays using threshold values given by the manufacturer. We aim to determine our own local threshold values for a better detection of gastrointestinal NETs.

METHODS

We studied patients with measurement of platelet serotonin and/or urinary 5-HIAA in University Hospital of Tours between January 2005 and June 2016. We established an « index » cohort with 75% of patients to determine local threshold value for the 2 parameters. A "validation" cohort constituted with 25% of remaining patients allowed us to compare the performances of manufacturer's values with local threshold values.

RESULTS

Two hundred ninety patients were included, with 19 suffering from NETs. Local threshold value for platelet serotonin was determined at 5.13 amol/platelet, the one for urinary 5-HIAA at 3.60 μmol/mmol urinary creatinine. Platelet serotonin specificity was better with local threshold value for identical sensibility (0.75). Urinary 5-HIAA sensibility was improved with local threshold value (1 vs 0.667) for identical specificity (0.902).

CONCLUSION

Using our local threshold value for platelet serotonin and urinary 5-HIAA improved diagnostic performances of these biochemical markers to detect NETs.

Impact of varying the definition of myopia on estimates of prevalence and associations with risk factors: time for an approach that serves research, practice and policy

BACKGROUND

Refractive error is an increasing global public health concern that requires robust and reliable research to identify modifiable risk factors and provide accurate estimates of population burden. We investigated the impact of reclassification of individuals when using different threshold values of spherical equivalent (SE) to define myopia, on estimates of frequency, distribution and associations with risk factors, to inform current international initiatives to standardise definitions.

METHODS

A random sample of 1985 individuals from the 1958 British birth cohort, at age 44, had autorefraction and self-reported on educational attainment and social class.Refraction status assigned in three different models using SE: (A) moderate to high myopia -3 diopters (D) or more extreme (≤-3.00D), (B) hypermetropia +1.00D or more extreme (≥+1.00D) and (C) mild myopia using three different thresholds: -1.00D, -0.75D or -0.50D, hence reciprocal changes in definition of emmetropia.

RESULTS

Frequency estimates and associations with risk factors altered significantly as the threshold value for myopia moved towards SE 0.0D: prevalence of mild myopia increased from 28% to 47%, the association with highest educational attainment attenuated and with higher social class strengthened, with changes in risk ratios of approximately 20%.

CONCLUSION

Even small changes in the threshold definition of myopia (±0.25D) can significantly affect the conclusions of epidemiological studies, creating both false-positive and false-negative associations for specific risk factors. An international classification for refractive error, empirically evidenced and cognisant of the question(s) being addressed and the population(s) being studied, is needed to serve better translational research, practice and policy.

Comparison of Dig-Labeled PCR, Nested PCR, and ELISA for the Detection of Clavibacter michiganensis subsp. sepedonicus in Field-Grown Potatoes

The sensitivity of digoxigenin- (dig-) labeled polymerase chain reaction (PCR) was compared with nested PCR and enzyme-linked immunosorbent assay (ELISA) for the detection of the potato ring rot bacterium, Clavibacter michiganensis subsp. sepedonicus, in seed potatoes and stem tissues. The bacterial DNA was extracted from chopped tuber or stem tissue by a modified hot alkaline DNA extraction method. C. michiganensis subsp. sepedonicus specific DNA sequence was amplified by dig-labeled PCR with the primer pair CMSIF1/CMSIR1 previously designed based on the insertion element IS1121 of C. michiganensis subsp. sepedonicus. Dig-labeled PCR products were then blotted on a nylon membrane and the signal was detected by a colorimetric assay using alkaline phosphatase. The new assay procedure has a detection sensitivity close to that of nested PCR and simplicity of the standard ELISA procedure commonly used commercially. The dig-labeled PCR assay was more sensitive than ELISA and can be used to detect C. michiganensis subsp. sepedonicus in symptomless field potato tubers.