Measuring beverage consumption in US children and adolescents: a systematic review.

Beverage consumption habits are associated with weight outcomes for children and adolescents. Many studies have examined youth's beverage consumption, but little is known about what methods are commonly used to assess youth beverage consumption and whether these strategies are valid and reliable. This study aimed to systematically review articles assessing beverage consumption among children and adolescents. We searched PubMed and Scopus for English-language articles published between February 2007 and February 2017 that measured and reported on American youth's (ages 2-18 years) beverage consumption. Searches yielded 17,165 articles, of which 589 articles describing 615 measures were extracted. We examined the types of assessment methods used, characteristics of these methods (e.g. validity, reliability, and literacy level), characteristics of study samples, and beverages assessed. The most common assessment methods were questionnaires/screeners (used by 65.4% of articles) and recalls (24.4%). About three-quarters of articles did not address validity (70.5%) or reliability (79.5%) of any measures used. Study populations were diverse: 54.7% of articles included low-income children, and 90.2% included non-White children. The most commonly assessed beverage category was sugar-sweetened beverages. Findings suggest that improved measurement techniques and reporting are both needed to track progress towards a goal of ensuring all youth have healthy beverage consumption.

International variation in reported livebirth prevalence rates of Down syndrome, adjusted for maternal age.

Reported livebirth prevalence of Down syndrome (DS) may be affected by the maternal age distribution of the population, completeness of ascertainment, accuracy of diagnosis, extent of selective prenatal termination of affected pregnancies, and as yet unidentified genetic and environmental factors. To search for evidence of the latter, we reviewed all published reports in which it was possible to adjust both for effects of maternal age and for selective termination (where relevant). We constructed indices that allowed direct comparisons of prevalence rates after standardising for maternal age. Reference rates were derived from studies previously identified as having near complete ascertainment. An index value significantly different from 1 may result from random fluctuations, as well as from variations in the factors listed above. We found 49 population groups for which an index could be calculated. Methodological descriptions suggested that low values could often be attributed to under-ascertainment. A possible exception concerned African-American groups, though even among these most acceptable studies were compatible with an index value of 1. As we have reported elsewhere, there was also a suggestive increase in rates among US residents of Mexican or Central American origin. Nevertheless, our results suggest that "real" variation between population groups reported to date probably amounts to no more than +/-25%. However, reliable data in many human populations are lacking including, surprisingly, some jurisdictions with relatively advanced health care systems. We suggest that future reports of DS livebirth prevalence should routinely present data that allow calculation of an index standardised for maternal age and adjusted for elective prenatal terminations.

Elevated maternal age-specific rates of Down syndrome liveborn offspring of women of Mexican and Central American origin in California.

BACKGROUND: Maternal age-specific rates of Down syndrome livebirths are widely utilized in personal and policy decisions concerning provision of and election of prenatal cytogenetic diagnostic services. The only extensive reference data available are on those of primarily European ancestral origin. In the absence of definitive evidence of any ethnic, racial or environmental influence upon rates (other than those associated with age) these rate schedules have been widely applied to those of all national origins. METHODS: Available material age-specific data on livebirths from intensive studies on those of Hispanic (primarily of Mexican and Central American background) and of other origin in populations in the U.S.A. with likely complete ascertainment were analysed. The numbers observed were compared with (i) those predicted from established published rate schedules in those of primarily European origin, and (ii) with the observations on livebirths of non-Hispanic European origin in the same population as the Hispanic live births. RESULTS: In comparisons with the numbers predicted from published rates, observed numbers of case among Hispanic live births were increased by 19 per cent (SE 0.06) in younger mothers, 23 per cent in older mothers (SE 0.07) and 20 per cent (SE 0.04) in those of all ages. Comparisons with observed rates in those of Hispanic origin with those observed in non-Hispanic births in the same time intervals and populations indicated that the excess rates in Hispanics were not attributable to some local factor increasing rates in all ethnic groups at least among those under 35. CONCLUSIONS: Data on mothers of Mexican and Central American origin residing in the U.S.A. indicate maternal age-specific rates of Down syndrome in live births about 20 per cent greater than those in published rate schedules on Down syndrome, widely used in decisions concerning election or provison of prenatal diagnostic services. The reason for this difference remains unknown.

Rates of Down syndrome at livebirth by one-year maternal age intervals in studies with apparent close to complete ascertainment in populations of European origin: a proposed revised rate schedule for use in genetic and prenatal screening.

Precision and accuracy in determining rates of Down syndrome at livebirth are indispensible to algorithms which determine eligibility for prenatal cytogenetic diagnostic services. We derived Down syndrome rates by single year of maternal age which we propose as a revised rate schedule for background risk. Data on European-origin populations were obtained from 5 sources judged most likely to have complete ascertainment of cases. A "constant plus exponent" regression model and variants extending the analysis to higher powers of maternal age were applied to several ranges of maternal age. Confidence intervals about the rates were calculated. This analysis results in rates significantly higher than those in widespread use though the confidence intervals show a need for caution in assuming precision. Sources of variation in rates are also considered.

The imprecision in rates of Down syndrome by 1-year maternal age intervals: a critical analysis of rates used in biochemical screening.

Current algorithms to determine eligibility for prenatal cytogenetic diagnostic services depend critically on the accuracy and precision of the underlying rates of cytogenetic abnormality used in the calculations. We examine the maternal age-specific rates of Down syndrome livebirths in eight studies of European-origin populations, pooled rates from which are widely used for baseline calculations in biochemical screening. These studies vary significantly in such factors as methods of ascertainment of cases, likelihood of complete ascertainment, and methods of correction, if any, for underascertainment. Restriction of analysis to those two studies among the eight whose methods suggest the greatest likelihood of complete ascertainment for Down syndrome generates rates significantly higher than those in widespread use. Confidence intervals about previously reported and currently derived rates indicate that even with large-scale data, there is considerable residual uncertainty in derived rates.