Evidence Of Variation In Rates Research Articles

Socioeconomic and ethnic disparities in preterm births in an English maternity setting: a population-based study of 1.3 million births

BackgroundPreterm birth is a major cause of infant mortality and morbidity and accounts for 7–8% of births in the UK. It is more common in women from socially deprived areas and from minority ethnic groups, but the reasons for this disparity are poorly understood. To inform interventions to improve child survival and their quality of life, this study examined the socioeconomic and ethnic inequalities in preterm births (< 37 weeks of gestation at birth) within Health Trusts in England.MethodsThis study investigated socioeconomic and ethnic inequalities in preterm birth rates across the National Health Service (NHS) in England. The NHS in England can be split into different units known as Trusts. We visualised between-Trust differences in preterm birth rates. Health Trusts were classified into five groups based on their standard deviation (SD) variation from the average national preterm birth rate. We used modified Poisson regression to compute risk ratios (RR) and 95% confidence intervals (95% CI) with generalised estimating equations.ResultsThe preterm birth rate ranged from 6.8/100 births for women living in the least deprived areas to 8.8/100 births for those living in the most deprived areas. Similarly, the preterm birth rate ranged from 7.8/100 births for white women, up to 8.6/100 births for black women. Some Health Trusts had lower than average preterm birth rates in white women whilst concurrently having higher than average preterm birth rates in black and Asian women. The risk of preterm birth was higher for women living in the most deprived areas and ethnicity (Asian).ConclusionsThere was evidence of variation in rates of preterm birth by ethnic group, with some Trusts reporting below average rates in white ethnic groups whilst concurrently reporting well above average rates for women from Asian or black ethnic groups. The risk of preterm birth varied substantially at the intersectionality of maternal ethnicity and the level of socioeconomic deprivation of their residency. In the absence of other explanations, these findings suggest that even within the same Health Trust, maternity care may vary depending on the women’s ethnicity and/or whether she lives in an area of high socioeconomic deprivation. Thus, social factors are likely key determinants of inequality in preterm birth rather than provision of maternity care alone.

Optimizing Outcomes in Regionalized Perinatal Care: Integrating Maternal and Neonatal Emergency Referral, Triage, and Transport

The purpose of integrating emergency maternal referral and triage capability into a neonatal retrieval service is to improve the effectiveness of regionalized perinatal care and to ensure opportunities for in utero transfer are maximized. Evidence for the effectiveness of regionalized perinatal care is presented, emphasizing the striking difference in survival of outborn extremely preterm (EPT) infants compared with inborn EPT infants. Barriers to achieving high rates of in utero transfer are identified and strategies to address preventable factors discussed. There is evidence of variation in rates of outborn extremely preterm births. As birth in transit is a rare event, this variation suggests there are opportunities for significant improvement in areas with high rates of outborn extremely preterm births. Variation in the level of risk aversion by triaging obstetricians and transport platform providers may be a significant preventable factor in deciding if a particular high-risk pregnant woman is deemed safe to transfer. Collaboration between obstetricians triaging these referrals and their neonatal retrieval colleagues within an integrated service is proposed as a model to address such issues. The integrated perinatal emergency referral and retrieval service is a key component of a system structured to support regionalized care. We propose this service should sit below the regional entity responsible for clinical governance that provides an imprimatur to ensure timely and equitable access to perinatal services for high-risk women and their newborn infants.

Seasonal patterns in permeable sediment and water-column biogeochemical properties on the inner shelf of the Middle Atlantic Bight

Abstract This study examines the responsiveness of permeable shelf sediments to seasonal factors affecting cycles of organic matter deposition and erosion. At a site on the inner continental shelf within the Middle Atlantic Bight (39°27′N, 74°14′W; water depth 13 m), sediment inventories of chlorophyll, phaeopigments, and fine particles enriched in organic matter are reported from SCUBA diver-collected cores retrieved during six cruises conducted over 2 years. These measurements provide little evidence for substantial seasonal variation in rates of organic matter accumulation, in spite of the potential for the sinking of large phytoplankton blooms associated with summer upwelling/downwelling events, or for wave orbital motion to cause both phytodetritus and benthic algae to be trapped in sand ripples. Sediment permeability, porosity, grain size, and extracellular proteolytic activity in both coarse and fine fractions showed little seasonality. Instead, a negative correlation between chlorophyll in surface sediments and bottom-water pools ( r 2 =0.56) was observed. Furthermore, overlays of other water-column properties with results of a principal component analysis of sediment variables suggest benthic–pelagic biogeochemical cycling is forced primarily by sediment resuspension events. Wave and current observations made during this study and during previous long-term experiments in the study area show that sediment resuspension stems from bottom stresses produced by both persistent irregular wind-waves and by very intense storm waves that occur in all seasons.

Body size, metabolic rate, generation time, and the molecular clock.

There is increasing evidence for variation in rates of nucleotide substitution among divergent taxonomic groups. Here, we summarize published rate data and show a strong relationship between substitution rate and body size. For instance, rates of nuclear and mtDNA evolution are slow in whales, intermediate in primates, and fast in rodents. A similar relationship exists for poikilothermic vertebrates. However, these taxa have slower mtDNA substitution rates overall than do homeotherms of similar size. A number of physiological and life history variables are highly correlated with body size. Of these, generation time and metabolic rate explain some patterns of rate heterogeneity equally well. In many cases, however, differences in metabolic rate explain important exceptions to the generation time model. Correlation between metabolic rate and nucleotide substitution may be mediated by (i) the mutagenic effects of oxygen radicals that are abundant by-products of aerobic respiration, and (ii) increased rates of DNA synthesis and nucleotide replacement in organisms with higher metabolic rates. Both of these factors increase mutation rate by decreasing the "nucleotide generation time," the average length of time before a nucleotide is copied either through replication or repair. Reconsideration of the generation time hypothesis to include physiological effects such as metabolic rate improves the theoretical underpinnings of molecular evolution.

So, what about the molecular clock hypothesis?

Recent studies have provided strong evidence for significant variation in rates of nucleotide substitution among evolutionary lineages. They have also provided evidence for germ-cell division as a major source of mutation (i.e. the generation-time effect hypothesis). Moreover, they have suggested the importance of differences in metabolic rate as a cause of rate variation.

Determination of Resistance to Abrasive Wear. VII. Uniformity of Results Obtained with the Du Pont Machine

Abstract (1) Tests have been made to investigate the variability of the abrasive papers used on the du Pont abrasion machine; the data obtained have also been examined to detect any variation in rate of abrasion during one test, and differences between the right- and left-hand specimens. (2) Differences in abrasiveness of 13 per cent were found between the different sheets of emery paper, even when compared with the differences between the rubber specimens, and it is considered that a solid disc of bonded abrasive, as used on the Akron machine, would be preferable to emery papers. (3) As there is no evidence of variation in rate of abrasion during a 20-minute run, there seems to be no objection to using different test-periods for different rubbers if circumstances render this desirable. (4) There are small, but not consistent, differences between the abrasion losses on the right- and left-hand specimens, which may arise from the 8-lb. load not being equally distributed between them. It is considered that the machine could be improved by making the arm that carries the specimens free to oscillate in a plane perpendicular to the abrasive, so that the loads on the specimens would be automatically equalized. The practice of rigidly fixing the arm parallel to the plane of the abrasive seems unsound because, if the parallelism were really rigid, the rates of wear on the two specimens would of necessity be equal, even if the rubbers had different abrasion resistances. Moreover, any suggestion to test the sample under examination and a standard rubber simultaneously is clearly unsound unless a freely oscillating arm is provided.