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Objective: To examine the utility of using external estimates of within-person variation to adjust usual nutrient intake distributions.Design: Analyses of the prevalence of inadequate intake of an example nutrient by the Estimated Average Requirement (EAR) cut-point method using three different methods of statistical adjustment of the usual intake distribution of a single 24-hour recall in Russian children in 1996, using the Iowa State University method for adjustment of the distribution. First, adjusting the usual intake distribution with day 2 recalls from the same 1996 sample (the correct method); second, adjusting the distribution using external variance estimates derived from US children in 1996; and third, adjusting the distribution using external estimates derived from Russian children of the same age in 2000. We also present prevalence estimates based on naive statistical analysis of the unadjusted distribution of intakes.Setting/subjects: Children drawn from the Russia Longitudinal Monitoring Survey in 1996 and 2000 and from the 1996 Continuing Survey of Food Intakes by Individuals.Results: When the EAR cut-point method is applied to a single recall, the resulting prevalence estimate in this study is inflated by 100-1300%. When the intake distribution is adjusted using an external variance estimate, the prevalence estimate is much less biased, suggesting that any adjustment may give less biased estimates than no adjustment.Conclusions: In moderately large samples, adjusting distributions with external estimates of variances results in more reliable prevalence estimates than using 1-day data. [ABSTRACT FROM AUTHOR]

Objective: To examine the utility of using external estimates of within-person variation to adjust usual nutrient intake distributions.Design: Analyses of the prevalence of inadequate intake of an example nutrient by the Estimated Average Requirement (EAR) cut-point method using three different methods of statistical adjustment of the usual intake distribution of a single 24-hour recall in Russian children in 1996, using the Iowa State University method for adjustment of the distribution. First, adjusting the usual intake distribution with day 2 recalls from the same 1996 sample (the correct method); second, adjusting the distribution using external variance estimates derived from US children in 1996; and third, adjusting the distribution using external estimates derived from Russian children of the same age in 2000. We also present prevalence estimates based on nave statistical analysis of the unadjusted distribution of intakes.Setting/subjects: Children drawn from the Russia Longitudinal Monitoring Survey in 1996 and 2000 and from the 1996 Continuing Survey of Food Intakes by Individuals.Results: When the EAR cut-point method is applied to a single recall, the resulting prevalence estimate in this study is inflated by 1001300%. When the intake distribution is adjusted using an external variance estimate, the prevalence estimate is much less biased, suggesting that any adjustment may give less biased estimates than no adjustment.Conclusions: In moderately large samples, adjusting distributions with external estimates of variances results in more reliable prevalence estimates than using 1-day data. [ABSTRACT FROM AUTHOR]

Objective: Pregnancy and postpartum iron status is of great public health importance, yet few studies have examined predictors of haemoglobin (Hb) concentration during this time. We identified predictors of Hb from 24 weeks' gestation until delivery and from 4 to 25 weeks postpartum.Design: Blood was drawn as many as four times during care: at the initial visit, at 24-29 weeks' gestation, at delivery and postpartum. A longitudinal, multivariable linear regression model was used to predict Hb concentration.Setting: A public health clinic in Raleigh, North Carolina.Subjects: n=520 women who participated in the Iron Supplementation Study.Results: Hb concentration at the previous blood draw, short stature, non-Hispanic white ethnicity/race, >12 years of education and smoking were positive predictors of pregnancy and postpartum Hb concentrations. Iron supplement use was a positive predictor, while inadequate weight gain and severe nausea/vomiting were negative predictors of gestational Hb. A high infant birth weight and postpartum haemorrhage were negative predictors of postpartum Hb. Pre-pregnancy body mass index had a slight positive relationship with gestational Hb, but had a strong negative relationship with postpartum Hb. The longitudinal model also confirmed the typical pattern of gestational Hb concentration. As the number of weeks between the initial visit and the 24- to 29-week visit increased, Hb at 24-29 weeks' gestation decreased. As gestational age increased from 24 weeks until delivery, Hb concentration increased as well.Conclusions: The predictors identified here could be used in clinical settings to target high-risk women for intervention. [ABSTRACT FROM AUTHOR]

Objective: Pregnancy and postpartum iron status is of great public health importance, yet few studies have examined predictors of haemoglobin (Hb) concentration during this time. We identified predictors of Hb from 24 weeks' gestation until delivery and from 4 to 25 weeks postpartum.Design: Blood was drawn as many as four times during care: at the initial visit, at 24–29 weeks' gestation, at delivery and postpartum. A longitudinal, multivariable linear regression model was used to predict Hb concentration.Setting: A public health clinic in Raleigh, North Carolina.Subjects:n=520 women who participated in the Iron Supplementation Study.Results: Hb concentration at the previous blood draw, short stature, non-Hispanic white ethnicity/race, >12 years of education and smoking were positive predictors of pregnancy and postpartum Hb concentrations. Iron supplement use was a positive predictor, while inadequate weight gain and severe nausea/vomiting were negative predictors of gestational Hb. A high infant birth weight and postpartum haemorrhage were negative predictors of postpartum Hb. Pre-pregnancy body mass index had a slight positive relationship with gestational Hb, but had a strong negative relationship with postpartum Hb. The longitudinal model also confirmed the typical pattern of gestational Hb concentration. As the number of weeks between the initial visit and the 24- to 29-week visit increased, Hb at 24–29 weeks' gestation decreased. As gestational age increased from 24 weeks until delivery, Hb concentration increased as well.Conclusions: The predictors identified here could be used in clinical settings to target high-risk women for intervention. [ABSTRACT FROM AUTHOR]

Objective: In resource-constrained facilities or during resuscitation, immediate paediatric weight estimation remains a fundamental challenge. We aimed to develop and validate weight estimation models based on ulna length and forearm width and circumference measured by simple and portable tools; and to compare them against previous methods (advanced paediatric life support (APLS), Theron and Traub-Johnson formulas).Design: Cross-sectional analysis of anthropometric measurements. Four ulna- and forearm-based weight estimation models were developed in the training set (n 1016). Assessment of bias, precision and accuracy was examined in the validation set (n 457).Setting: National Children's Study-Formative Research in Anthropometry (2011-2012).Subjects: Multi-racial/ethnic infants and children aged <6 years (n 1473).Results: Developed Models 1-4 had high predictive precision (R 2=0·91-0·97). Mean percentage errors between predicted and measured weight were significantly smaller across the developed models (0·1-0·7 %) v. the APLS, Theron and Traub-Johnson formulas (-1·7, 9·2 and -4·9 %, respectively). Root-mean-squared percentage error was overall smaller among Models 1-4 v. the three existing methods (range=7·5-8·7 v. 9·8-13·3 %). Further, Models 1-4 were within 10 and 20 % of actual weight in 72-87 and 95-99 % of the weight estimations, respectively, which outperformed any of the three existing methods.Conclusions: Ulna length, forearm width and forearm circumference by simple and portable tools could serve as valid and reliable surrogate measures of weight among infants and children aged <6 years with improved precision over the existing age- or length-based methods. Further validation of these models in physically impaired or non-ambulatory children is warranted. [ABSTRACT FROM AUTHOR]