Protein Recovery of Tra Catfish (Pangasius hypophthalmus) Protein-Rich Side Streams by the pH-Shift Method

Increasing protein demand has led to growing attention being given to the full utilization of proteins from side streams in industrial fish processing. In this study, proteins were recovered from three protein-rich side streams during Tra catfish (Pangasius hypophthalamus) processing (dark muscle; head-backbone; and abdominal cut-offs) by an optimized pH-shift process. Physicochemical characteristics of the resulting fish protein isolates (FPIs) were compared to industrial surimi from the same raw material batch. The pH had a significant influence on protein extraction, while extraction time and the ratio of the extraction solution to raw material had little effect on the protein and dry matter recoveries. Optimal protein extraction conditions were obtained at pH 12, a solvent to raw material ratio of 8, and an extraction duration of 150 min. The resulting FPI contained <10% of the fat and <15% of the ash of the raw material, while the FPI protein recovery was 83.0−88.9%, including a good amino acid profile. All FPIs had significantly higher protein content and lower lipid content than the surimi, indicating the high efficiency of using the pH-shift method to recover proteins from industrial Tra catfish side streams. The FPI made from abdominal cut-offs had high whiteness, increasing its potential for the development of a high-value product.

Receiver operating characteristic plot and area under the curve with binary classifiers: pragmatic analysis of cognitive screening instruments

Aim: To examine whether receiver operating characteristic plots and area under the curve (AUC) values may be potentially misleading when assessing cognitive screening instruments as binary predictors rather than as categorical or continuous scales. Materials & methods: AUC was calculated using different methods (rank-sum, diagnostic odds ratio) using data from test accuracy studies of two binary classifiers of cognitive status (applause sign, attended with sign), a screener producing categorical data (Codex), and a continuous scale screening test (Mini-Addenbrooke's Cognitive Examination). Results: For all screeners, AUC calculated using diagnostic odds ratio method was greater than using rank-sum method. When Codex and Mini-Addenbrooke's Cognitive Examination were analyzed as binary (single fixed threshold) tests, AUC using rank-sum method was lower than when screeners were analyzed as categorical or continuous scales, respectively. Conclusion: If cognitive screeners producing categorical or continuous measures are dichotomized, calculated AUC may be an underestimate, thus affecting screening test accuracy.

Tumour markers with clinically controlled cut-offs for suspected cancer

BACKGROUND

Due to insufficient scientific evidence, panels of tumour markers (TMs) are currently not recommended for use in suspected cancer. However, recent well-designed studies have revealed a potential clinical value in lung cancer. We analysed the diagnostic accuracy of a panel of 11 circulating TMs with clinically controlled thresholds in the differentiation of cancer from nonmalignant diseases.

METHODS

We prospectively recruited 4776 consecutive patients presenting with focal or nonspecific symptoms suggestive of cancer who underwent testing for 11 serum TMs before diagnosis was known. The study abided by 2015 STARD guidelines. Tumour markers included, among others, carbohydrate antigen 19-9, carcinoembryonic antigen, alpha-fetoprotein, squamous cell carcinoma-associated antigen, prostate-specific antigen (males), neuron-specific enolase, progastrin-releasing peptide and carbohydrate antigen 125. Thresholds were adjusted for the presence of kidney failure, liver disease, effusions and dermatological disorders. Results showing ≥1 TMs with concentrations above threshold were considered positive.

RESULTS

Benign diseases were diagnosed in 3281 (68.7%) patients and cancer in 1495 (31.3%), with epithelial cancers in 1214 (77% at stage IV). When applying criteria for controlled thresholds, overall specificity was 98%. Overall sensitivity of the panel in epithelial cancers was 72.2%, positive predictive value 93% and negative predictive value 90.5%. The area under the receiver operating characteristic curve was 0.920 (95% confidence interval, 0.902-0.924).

CONCLUSIONS

By using clinically controlled cut-offs, the combined panel demonstrated an excellent ability to discriminate epithelial cancers from nonmalignant diseases. However, its use in clinical practice would need formal validation through a multicentre controlled trial assessing a panel-guided strategy vs. standard diagnosis.

A New Classification of the Severity of Psoriasis: What's Moderate Psoriasis?

The purpose of this study is to propose a ranking system for the severity of psoriasis. The consensus method of selecting the indices to include and the classification of real patient profiles by an expert panel to create a gold standard of severity were used. The performance of potential cut-offs was evaluated to create a ranking algorithm. The combined use of PASI, BSA, and sPGA may allow the classification of the severity of psoriatic patients. The final algorithm identifies severe patients in a single step (2 out 3 are met: PASI ≥ 11 or BSA ≥ 10 or sPGA ≥ 3), while two steps are required for mild ((2 out 3 are met: PASI ≤ 3 or BSA ≤ 5 or sPGA ≤ 2) and DLQI < 5) and moderate forms (the patient does not meet 2 out 3 (PASI ≥ 11 or BSA ≥ 10 or sPGA ≥ 3) but has a DLQI ≥ 5. A ranking algorithm is presented, consisting of different measures of disease which classifies psoriatic patients into three categories: mild, moderate, and severe.

Comparison of standard versus population-specific handgrip strength cut-off points in the detection of probable sarcopenia after launch of EWGSOP2

OBJECTIVE

We aimed to compare European Working Group on Sarcopenia in Older People (EWGSOP2)-suggested and population-specific handgrip strength (HGS) thresholds to detect probable sarcopenia and their associations with physical-performance measures and frailty.

METHODS

A retrospective cross-sectional observational-study included geriatrics outpatients applied to a university-hospital. HGS, timed up and go test (TUG), and usual gait speed (UGS) were assessed. Frailty was screened by FRAIL-scale.

RESULTS

A total of 1825 older adults were included (mean age, 74.5 + 7.0 years; 68.8% female). Prevalence of low-HGS were 12.2% by the EWGSOP2-recommended (27/16 kg) cut-offs and 37.5% by population-specific cut-offs (35/20 kg) (p<.001). When low-HGS was defined by EWGSOP2 suggested cut-offs, low-HGS was associated with impaired UGS, (odds ratio [OR] = 3.8, 95% confidence interval [CI]: 2.0-6.9, p<.001); impaired TUG, (OR = 4.6, 95% CI: 2.4-8.8, p<.001); and frailty (OR = 20.9, 95% CI: 8.3-53.0, p<.001). Similarly, low HGS determined by population-specific cut-off points was associated with impaired UGS (OR = 3.1, 95% CI: 2.1-6.9, p<.001); impaired TUG (OR = 6.0, 95% CI: 3.0-11.8, p<.001); and frailty (OR = 7.3, 95% CI: 4.1-13.0, p<.001).

CONCLUSIONS

Application of EWGSOP2-recommended standard HGS-cut-offs showed successful application in-practice. However, use of standard HGS cut-offs may result in underdiagnosis of probable sarcopenia. Therefore, we suggest that, whenever available, use of population-specific cut-offs for HGS may be better for correctly identifying older adults at risk.

Defining 'optimal' test cut-off using global test metrics: evidence from a cognitive screening instrument

Aim: To examine the variation of several global metrics of test accuracy with test cut-off for the diagnosis of dementia. These metrics included some based on the receiver operating characteristic curve, such as Youden index, and some independent of receiver operating characteristic curve, such as correct classification accuracy. Materials & methods: Data from a test accuracy study of Mini-Addenbrooke's Cognitive Examination were used to calculate and plot each global measure against test cut-off. Results: Different 'optimal' cut-points were identified for the different global measures, with a spread of ten points in observed optimal cut-off in the 30-point Mini-Addenbrooke's Cognitive Examination scale. Using these optima gave a large variation in test sensitivity from very high (diagnostic odds ratio) to very low (likelihood to be diagnosed or misdiagnosed), but all had high negative predictive value. Conclusion: The method used to determine the cut-off of cognitive screening instruments may have significant implications for test performance.

Longitudinal Stability of Reading Difficulties: Examining the Effects of Measurement Error, Cut-Offs, and Buffer Zones in Identification

This study examined the stability of reading difficulties (RD) from grades 2 to 6 and focused on the effects of measurement error and cut-off selection in the identification of RD and its stability with the use of simulations. It addressed methodological limitations of prior studies by (a) applying a model-based simulation analysis to examine the effects of measurement error and cut-offs in the identification of RD, (b) analyzing a non-English and larger sample, and (c) examining RD in both reading fluency and reading comprehension. Reading fluency and reading comprehension of 1,432 Finnish-speaking children were assessed in grades 2 and 6. In addition to the use of single cut-off points on observed data, we used a simulation approach based on an estimated structural equation model (SEM) in order to examine the effect of measurement error on RD identification stability. We also examined the effect of single cut-offs by using a simulation-based buffer zone. Our results showed that measurement error affects the identification of RD over time. The use of a simulation-based buffer zone could control both the effects of measurement error and the arbitrariness of single cut-offs and lead to more accurate classification into RD groups, especially for those with scores close to the cut-offs. However, even after controlling for measurement error and using buffer zones, RD was not stable over time for all children, but both resolving and late-emerging groups existed. The findings suggest that reading development needs to be followed closely beyond the early grades and that reading instruction should be planned according to individual needs at specific time points. There is a clear need for further consideration of the mechanisms underlying the stability and instability of RD.

Need to re-look cut-off of Aspergillus-specific IgE levels in children with ABPA

The cut-offs for total and specific IgE used for diagnosing ABPA in children have been adopted from adult literature and have not been validated in the paediatric population. To establish the ideal cut-offs of total IgE and Aspergillus-specific IgE for the diagnosis of ABPA in children. This study was a prospective observational case-control study, conducted in a tertiary care hospital in North India, enrolling 140 children with partly controlled and uncontrolled asthma. Seventy children had ABPA based on the Rosenberg-Patterson Criteria (Cases) whereas 70 children were without ABPA (Controls). All children were subjected to clinical examination and investigations such as absolute eosinophil count, total IgE, Aspergillus-specific IgE, Aspergillus skin prick test and radiological tests. ROC curve analysis was done to determine the ideal cut-offs of total and specific IgE to diagnose ABPA. The ROC curve analysis determined 1204IU/L as the cut-off value of total IgE with a sensitivity of 79.7% (95%CI 68.31% to 88.44%) and specificity of 53.1% (95%CI 40.23 to 65.7). The ROC analysis of specific IgE levels of children with ABPA determined the cut-off value of 0.49 KAU/L with a sensitivity of 94.03% (95%CI 85.41 to 98.35) and specificity of 88.89% (95%CI 75.94% to 96.29%). We propose that the cut-offs of total and specific IgE need to be relooked in the paediatric population. Cut-offs of total IgE as 1204 IU/L and for Aspergillus-specific IgE as 0.49KAU/L seem appropriate. Large multicentric studies should be conducted to determine the ideal values for diagnosing paediatric ABPA.

Comparing Approaches to Optimize Cut-off Scores for Short Cognitive Screening Instruments in Mild Cognitive Impairment and Dementia

BACKGROUND

Although required to improve the usability of cognitive screening instruments (CSIs), the use of cut-off scores is controversial yet poorly researched.

OBJECTIVE

To explore cut-off scores for two short CSIs: the Standardized Mini-Mental State Examination (SMMSE) and Quick Mild Cognitive Impairment (Qmci) screen, describing adjustments in scores for diagnosis (MCI or dementia), age (≤, >75 years), and education (<, ≥12 years), comparing two methods: the maximal accuracy approach, derived from receiver operating characteristic curves, and Youden's Index.

METHODS

Pooled analysis of assessments from patients attending memory clinics in Canada between 1999-2010 : 766 with mild cognitive impairment (MCI) and 1,746 with dementia, and 875 normal controls.

RESULTS

The Qmci was more accurate than the SMMSE in differentiating controls from MCI or cognitive impairment (MCI and dementia). Employing the maximal accuracy approach, the optimal SMMSE cut-off for cognitive impairment was <28/30 (AUC 0.86, sensitivity 74%, specificity 88%) versus <63/100 for the Qmci (AUC 0.93, sensitivity 85%, specificity 85%). Using Youden's Index, the optimal SMMSE cut-off remained <28/30 but fell slightly to <62/100 for the Qmci (sensitivity 83%, specificity 87%). The optimal cut-off for MCI was <29/30 for the SMMSE and <67/100 for the Qmci, irrespective of technique. The maximal accuracy approach generally produced higher Qmci cut-offs than Youden's Index, both requiring adjustment for age and education. There were no clinically meaningful differences in SMMSE cut-off scores by age and education or method employed.

CONCLUSION

Caution should be exercised selecting cut-offs as these differ by age, education, and method of derivation, with the extent of adjustment varying between CSIs.

Mid-upper arm circumference in detection of weight-for-height Z-score below -3 in children aged 6-59 months

OBJECTIVE

To evaluate the predictive ability of mid-upper arm circumference (MUAC) for detecting severe wasting (weight-for-height Z-score (WHZ) <-3) among children aged 6-59 months.

DESIGN

Cross-sectional survey.

SETTING

Rural Uttar Pradesh, India.

SUBJECTS

Children (n 18 456) for whom both WHZ (n 18 463) and MUAC were available.

RESULTS

The diagnostic test accuracy of MUAC for severe wasting was excellent (area under receiver-operating characteristic curve = 0·933). Across the lower range of MUAC cut-offs (110-120 mm), specificity was excellent (99·1-99·9 %) but sensitivity was poor (13·4-37·2 %); with higher cut-offs (140-150 mm), sensitivity increased substantially (94·9-98·8 %) but at the expense of specificity (37·6-71·9 %). The optimal MUAC cut-off to detect severe wasting was 135 mm. Although the prevalence of severe wasting was constant at 2·2 %, the burden of severe acute malnutrition, defined as either severe wasting or low MUAC, increased from 2·46 to 17·26 % with cut-offs of <115 and <135 mm, respectively. An MUAC cut-off <115 mm preferentially selected children aged ≤12 months (OR=11·8; 95 % CI 8·4, 16·6) or ≤24 months (OR=23·4; 95 % CI 12·7, 43·4) and girls (OR=2·2; 95 % CI 1·6, 3·2).

CONCLUSIONS

Based on important considerations for screening and case detection in the community, modification of the current WHO definition of severe acute malnutrition may not be warranted, especially in the Indian context.

A time-adjusted cortisol cut-off can reduce referral rate for Synacthen stimulation test whilst maintaining diagnostic performance

OBJECTIVE

Cortisol cut-offs can predict requirement for Synacthen stimulation tests (SST). We assessed the performance of a standard cortisol cut-off (375 nmol/L) across the morning and compared this with a time-adjusted cut-off.

DESIGN

Retrospective audit PATIENTS: Community reference set (n=12 550) and SST patients (n=757).

MEASUREMENTS

In the reference population, time-specific cortisol medians were calculated and used to convert cortisol to time-adjusted Multiples of the Median (MoM). In 757 SST patients, the predictive performance of a standard cortisol cut-off (375 nmol/L) and its time-adjusted MoM equivalent were compared.

RESULTS

Median cortisol decreased by ~30 nmol/L per hour between 0700 and 1200h. In the reference population, proportions below the 375 nmol/L cut-off increased throughout the morning (range 35%-64%), whereas using the time-adjusted MoM cut-off proportions were consistent (range 46%-50%), with a 17% maximal difference in referral rates between the two cut-offs after 1100h. A similar pattern was noted in the SST cohort. When a cortisol MoM cut-off was used to predict SST success, the excess proportion of patients tested and misclassification rates were lower and more consistent than when the standard cut-off was used. A median cortisol of 375 nmol/L equated to 444 and 313 nmol/L before 0800 and after 1100 h, respectively.

CONCLUSION

The use of a standard cortisol cut-off results in 17% more patients being referred for SST later in the morning. A time-adjusted cortisol cut-off provides consistent and lower referral rates, whilst maintaining similar or better performance than a standard single cut-off in predicting outcome of SST.

Neck Circumference to Assess Obesity in Preschool Children

OBJECTIVE

Limited information is available about the use of neck circumference (NC) to assess obesity in preschool children. This study aims to provide NC percentiles and determine the cut-off levels of NC as a measure to assess obesity in preschool children.

METHODS

The data were obtained from the Anthropometry of Turkish Children aged 0-6 years (ATCA-06) study database. A total of 21 family health centers were chosen and children aged 2-6 years old from all socioeconomic levels were randomly selected from the lists of district midwives; 1766 children (874 male and 892 female; 88.3% of sample size) were included in the study. The smoothed centile curves of NC were constructed by the LMS method. Receiver operating characteristic (ROC) analysis was performed to calculate cut-off points for NC using body mass index ≥95^th percentile.

RESULTS

Mean NC was greater in males than females. Cut-off values for obesity were found to be statistically significant in both genders other than 3 years old boys. The NC percentiles of Turkish preschool children were slightly greater than those of other European preschool children in both genders. This difference disappeared around the adiposity rebound period. The 97th percentile values for Turkish preschool children continue to be greater in both genders.

CONCLUSION

NC may be useful to define obesity in preschool children. Since ethnic and various other factors may have a role in incidence of obesity, local reference data are important in assessment of obesity.