scholarly journals The Mystery of the Z-Score

Aorta ◽  
2016 ◽  
Vol 04 (04) ◽  
pp. 124-130 ◽  
Author(s):  
Alexander Curtis ◽  
Tanya Smith ◽  
Bulat Ziganshin ◽  
John Elefteriades
Keyword(s):  
Thoracic Aorta ◽  
Normal Population ◽  
Pediatric Population ◽  
Treatment Strategies ◽  
Z Score ◽  
Web Based ◽  
Geographical Regions ◽  
Z Scores ◽  
American Society ◽  
Size Limits

AbstractReliable methods for measuring the thoracic aorta are critical for determining treatment strategies in aneurysmal disease. Z-scores are a pragmatic alternative to raw diameter sizes commonly used in adult medicine. They are particularly valuable in the pediatric population, who undergo rapid changes in physical development. The advantage of the Z-score is its inclusion of body surface area (BSA) in determining whether an aorta is within normal size limits. Therefore, Z-scores allow us to determine whether true pathology exists, which can be challenging in growing children. In addition, Z-scores allow for thoughtful interpretation of aortic size in different genders, ethnicities, and geographical regions. Despite the advantages of using Z-scores, there are limitations. These include intra- and inter-observer bias, measurement error, and variations between alternative Z-score nomograms and BSA equations. Furthermore, it is unclear how Z-scores change in the normal population over time, which is essential when interpreting serial values. Guidelines for measuring aortic parameters have been developed by the American Society of Echocardiography Pediatric and Congenital Heart Disease Council, which may reduce measurement bias when calculating Z-scores for the aortic root. In addition, web-based Z-score calculators have been developed to aid in efficient Z-score calculations. Despite these advances, clinicians must be mindful of the limitations of Z-scores, especially when used to demonstrate beneficial treatment effect. This review looks to unravel the mystery of the Z-score, with a focus on the thoracic aorta. Here, we will discuss how Z-scores are calculated and the limitations of their use.

Wall stress misrepresents afterload in children and young adults with abnormal left ventricular geometry

2002 ◽  
Vol 92 (3) ◽  
pp. 1053-1057 ◽  
Author(s):  
Thomas L. Gentles ◽  
Steven D. Colan
Keyword(s):  
Normal Population ◽  
Wall Stress ◽  
Left Ventricular ◽  
Left Ventricular Geometry ◽  
Z Score ◽  
Fiber Stress ◽  
Ventricular Geometry ◽  
Wide Range ◽  
Z Scores ◽  
The Difference

Wall stress, although commonly used as an index of afterload, fails to take into account forces generated within the wall of the left ventricle (LV) that oppose systolic fiber shortening. Wall stress may, therefore, misrepresent fiber stress, the force resisting fiber shortening, particularly in the presence of an abnormal LV thickness-to-dimension ratio ( h/ D). M-mode LV echocardiograms were obtained from 207 patients with a wide range of values for LV mass and/or h/ D. Diagnoses were valvar aortic stenosis, coarctation repair, anthracycline treated, and severe aortic and/or mitral regurgitation. End-systolic wall stress (WSes) and fiber stress (FSes) were expressed as age-corrected Z scores relative to a normal population. The difference between WSes and FSes was extreme when h/ D was elevated or reduced [WSes Z score − FSes Z score = 0.14 × ( h/ D)−1.47 − 2.13; r = 0.78, P < 0.001], with WSes underestimating FSes when h/ D was increased and overestimating FSes when h/ D was decreased. Analyses of myocardial mechanics based on wall stress have limited validity in patients with abnormal ventricular geometry.

scholarly journals Regional variations in the treatment of gallstone disease may affect patient outcome: A large, population-based register study in sweden

2020 ◽  
pp. 145749692096801
Author(s):  
L. Lindqvist ◽  
G. Sandblom ◽  
P. Nordin ◽  
O. Hemmingsson ◽  
L. Enochsson
Keyword(s):  
Population Density ◽  
Gallstone Disease ◽  
Large Population ◽  
Treatment Strategies ◽  
Population Based ◽  
Standards Of Care ◽  
Geographical Regions ◽  
Operative Complications ◽  
American Society ◽  
Post Operative Complications

Background: The lack of studies showing benefit from surgery in patients with symptoms of gallstone disease has led to a divergence in local practices and standards of care. This study aimed to explore regional differences in management and complications in Sweden. Furthermore, to study whether population density had an impact on management. Methods: Data were collected from the Swedish National Register for Gallstone Surgery and Endoscopic Retrograde Cholangiopancreatography (GallRiks). Cholecystectomies undertaken for gallstone disease between January 2006 and December 2017 were included. Age, sex, American Society of Anesthesiologists (ASA) classification, intra- and post-operative complications, and the proportion of patients with acute cholecystitis who underwent surgery within 2 days of hospital admission were analyzed. The 21 different geographical regions in Sweden were compared, and each variable was analyzed according to population density. Results: A total of 139,444 cholecystectomies cases were included in this study. There were large differences between regions regarding indications for surgery and intra- and post-operative complications. In the analyses, there were greater divergences than would be expected by chance for most of the variables analyzed. Age of the cholecystectomized patients correlated with population density of the regions (R2 = 0.310; p = 0.0088). Conclusion: There are major differences between the different regions in Sweden in terms of the treatment of gallstone disease and outcome, but these did not correlate to population density, suggesting that local routines are more likely to have an impact on treatment strategies rather than demographic factors. These differences need further investigation to reveal the underlying causes.

The following is the abstract of the article discussed in the subsequent letter:

2004 ◽  
Vol 97 (6) ◽  
pp. 2395-2397 ◽  
Author(s):  
Jeffrey H. Silber
Keyword(s):  
Normal Population ◽  
Wall Stress ◽  
Z Score ◽  
Fiber Stress ◽  
Lv Mass ◽  
Wide Range ◽  
Z Scores ◽  
The Difference ◽  
Range Of Values ◽  
Valvar Aortic Stenosis

Wall stress, although commonly used as an index of afterload, fails to take into account forces generated within the wall of the left ventricle (LV) that oppose systolic fiber shortening. Wall stress may, therefore, misrepresent fiber stress, the force resisting fiber shortening, particularly in the presence of an abnormal LV thickness-to-dimension ratio ( h/ D). M-mode LV echocardiograms were obtained from 207 patients with a wide range of values for LV mass and/or h/ D. Diagnoses were valvar aortic stenosis, coarctation repair, anthracycline treated, and severe aortic and/or mitral regurgitation. End-systolic wall stress (WSes) and fiber stress (FSes) were expressed as age-corrected Z scores relative to a normal population. The difference between WSes and FSes was extreme when h/ D was elevated or reduced [WSes Z score − FSes Z score = 0.14 × ( h/ D)−1.47 − 2.13; r = 0.78, P < 0.001], with WSes underestimating FSes when h/ D was increased and overestimating FSes when h/ D was decreased. Analyses of myocardial mechanics based on wall stress have limited validity in patients with abnormal ventricular geometry.

scholarly journals Individual Alpha Peak Frequency, an Important Biomarker for Live Z-Score Training Neurofeedback in Adolescents with Learning Disabilities

2021 ◽  
Vol 11 (2) ◽  
pp. 167
Author(s):  
Rubén Pérez-Elvira ◽  
Javier Oltra-Cucarella ◽  
José Antonio Carrobles ◽  
Minodora Teodoru ◽  
Ciprian Bacila ◽  
...  
Keyword(s):  
Learning Disabilities ◽  
Pediatric Population ◽  
Peak Frequency ◽  
Normative Values ◽  
Z Score ◽  
Absolute Power ◽  
The Individual ◽  
And Behavior ◽  
The Waves ◽  
Alpha Peak

Learning disabilities (LDs) have an estimated prevalence between 5% and 9% in the pediatric population and are associated with difficulties in reading, arithmetic, and writing. Previous electroencephalography (EEG) research has reported a lag in alpha-band development in specific LD phenotypes, which seems to offer a possible explanation for differences in EEG maturation. In this study, 40 adolescents aged 10–15 years with LDs underwent 10 sessions of Live Z-Score Training Neurofeedback (LZT-NF) Training to improve their cognition and behavior. Based on the individual alpha peak frequency (i-APF) values from the spectrogram, a group with normal i-APF (ni-APF) and a group with low i-APF (li-APF) were compared in a pre-and-post-LZT-NF intervention. There were no statistical differences in age, gender, or the distribution of LDs between the groups. The li-APF group showed a higher theta absolute power in P4 (p = 0.016) at baseline and higher Hi-Beta absolute power in F3 (p = 0.007) post-treatment compared with the ni-APF group. In both groups, extreme waves (absolute Z-score of ≥1.5) were more likely to move toward the normative values, with better results in the ni-APF group. Conversely, the waves within the normal range at baseline were more likely to move out of the range after treatment in the li-APF group. Our results provide evidence of a viable biomarker for identifying optimal responders for the LZT-NF technique based on the i-APF metric reflecting the patient’s neurophysiological individuality.

Dental Caries Severity and Nutritional Status of Nigerian Preschool Children

2021 ◽  
pp. 238008442110021
Author(s):  
O.O. Olatosi ◽  
A.A. Alade ◽  
T. Naicker ◽  
T. Busch ◽  
A. Oyapero ◽  
...  
Keyword(s):  
Early Childhood ◽  
Dental Caries ◽  
Nutritional Status ◽  
Early Childhood Caries ◽  
Z Score ◽  
Cross Sectional ◽  
Risk Of Death ◽  
Malnourished Children ◽  
Z Scores ◽  
Childhood Caries

Introduction: Malnutrition in children is one of the most prevalent global health challenges, and malnourished children have a higher risk of death from childhood diseases. Early childhood caries (ECC) is the most common chronic disease of childhood. Complications from ECC such as pain, loss of tooth/teeth, and infection can undermine a child’s nutrition and growth. Aim: This study aims to evaluate the severity of decay, missing, and filled tooth (dmft) by nutritional status using the z scores of the anthropometric measurements: height for age (HFA), weight for age (WFA), weight for height (WFH), and body mass index for age (BMIA) among children with ECC in Nigeria. Study Design: This is a cross-sectional study conducted in 5 local government areas (LGAs) in Lagos State, Nigeria. A multistage sampling technique was used. Results: A total of 273 cases of ECC were included in the analyses (mean age 4.19 ± 0.96 y). Overall, the mean dmft was 3.04 ± 2.28, and most (96%) were accounted for by untreated decay. The distribution of dmft within the different z score categories of BMIA (<–3 = severely wasted, –2 to –3 = wasted, –2 to +2 = normal, +2 to +3 = overweight and >+3 = obese) showed the highest dmft scores among the combined severely wasted and wasted groups, lowest among children with normal z scores, and intermediate in the overweight and obese groups. There was a significant negative correlation between BMIA z score, WFH z score, and dmft ( r = −0.181, P < 0.05 and r = −0.143, P < 0.05, respectively). However, the correlations between HFA z score, WFA z score, and dmft were positive but not significant ( r = 0.048, P = 0.44 and r = 0.022, P = 0.77, respectively). Conclusion: Our study showed an increased severity of dental caries among severely wasted or wasted children with ECC compared to those of normal or overweight. Knowledge Transfer Statement: The results from this study will raise awareness among clinicians and policy makers on the need for a primary prevention program for early childhood caries in countries with high burden of malnutrition and limited resources. Also, it will help draw the attention of clinicians to the caries status of malnourished children that can be managed to improve the nutritional outcomes.

scholarly journals Growth and nutritional status, and their association with lung function: a study from the international Primary Ciliary Dyskinesia Cohort

2017 ◽  
Vol 50 (6) ◽  
pp. 1701659 ◽  
Author(s):  
Myrofora Goutaki ◽  
Florian S. Halbeisen ◽  
Ben D. Spycher ◽  
Elisabeth Maurer ◽  
Fabiën Belle ◽  
...  
Keyword(s):  
Lung Function ◽  
Primary Ciliary Dyskinesia ◽  
Repeated Measurements ◽  
World Health ◽  
Z Score ◽  
Multilevel Regression ◽  
Growth And Nutrition ◽  
Diagnostic Certainty ◽  
Z Scores ◽  
Ciliary Dyskinesia

Chronic respiratory disease can affect growth and nutrition, which can influence lung function. We investigated height, body mass index (BMI), and lung function in patients with primary ciliary dyskinesia (PCD).In this study, based on the international PCD (iPCD) Cohort, we calculated z-scores for height and BMI using World Health Organization (WHO) and national growth references, and assessed associations with age, sex, country, diagnostic certainty, age at diagnosis, organ laterality and lung function in multilevel regression models that accounted for repeated measurements.We analysed 6402 measurements from 1609 iPCD Cohort patients. Height was reduced compared to WHO (z-score −0.12, 95% CI −0.17 to −0.06) and national references (z-score −0.27, 95% CI −0.33 to −0.21) in male and female patients in all age groups, with variation between countries. Height and BMI were higher in patients diagnosed earlier in life (p=0.026 and p<0.001, respectively) and closely associated with forced expiratory volume in 1 s and forced vital capacity z-scores (p<0.001).Our study indicates that both growth and nutrition are affected adversely in PCD patients from early life and are both strongly associated with lung function. If supported by longitudinal studies, these findings suggest that early diagnosis with multidisciplinary management and nutritional advice could improve growth and delay disease progression and lung function impairment in PCD.

scholarly journals The Childhood Growth of Twin Children

1995 ◽  
Vol 44 (3-4) ◽  
pp. 169-178 ◽  
Author(s):  
B. Luke ◽  
S. Leurgans ◽  
L. Keith ◽  
D. Keith
Keyword(s):  
Gestational Age ◽  
Growth Retardation ◽  
Z Score ◽  
Cross Sectional ◽  
Childhood Growth ◽  
Severe Stunting ◽  
Increased Risk ◽  
Z Scores ◽  
Twin Children ◽  
Current Weight

AbstractThe objective of this study was to assess the childhood growth of twin children in terms of the effects of intrauterine growth retardation (IUGR) and discordancy at birth on the incidence and severity of stunting and discordancy in current height and weight. The study was part of a cross-sectional field project conducted at the Annual Twins Days Festival in Twinsburg. Ohio, USA, during 1990, 1991, and 1993, and including all twin children between 2 and 12 years of age. Mothers of twins were interviewed regarding their children's birthweights and gestational age; the twin children were measured for their current heights and weights. The study population included 990 twin children, including 555 boys and 435 girls, of which there were 254 boy pairs and 194 girl pairs. Birthweight for gestational age and current weight and height were each converted into Z-scores and characterized as severe (Z-score <−2,0), or moderate IUGR or stunting (Z-score > −2.0 and < −1.2). For the present study discordancy in birthweight, and current height and weight was calculated for like-gender twin pairs. Only twin children with severe IUGR at birth showed an increased risk of stunting in their current height or weight, and this risk was only for moderate, not severe, stunting. Boy twins with severe IUGR at birth were at increased risk of moderate stunting in their current weight (OR 2.67, 95% CI 1.55, 4.58, P = 0.002), while girl twins with severe IUGR at birth were at increased risk of moderate stunting in their current height (OR 4,09, 95% CI 1.49, 10.99, p = 0.003). Among like-gender twin pairs, there were no differences in mean or categories of birthweight or current weight discordancy, but boy twin pairs did show a significantly greater proportion of current weight discordancy compared to girl twin pairs (p = 0.005). Overall, there was a significant tendency for differences in height and weight between like-gender twin pairs to disappear over time, with the effect being greater for boy twin pairs. We conclude from these findings that twin children tend to overcome growth retardation and discordancy present at birth, and although children who had severe IUGR or discordancy at birth were more likely to have some residual moderate stunting or discordancy in height or weight, they still tended to be within normal values for their gender and current age.

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