The conventional cutoff for small
The conventional cutoff for small for gestational age is based on birthweight, which is suitable for infants born at term but is far less appropriate for those born preterm. Preterm birth is itself pathological, and ultrasound-based estimates of fetal weight show that infants born preterm are much smaller than their peers who remain in utero at the same gestational age. Thus, at preterm gestational ages, the poorly sensitive cutoff of lower than the 10th centile for birthweight will be even less sensitive for identification of suboptimum fetal growth when it ras inhibitor is based on the distribution of birthweights, rather than estimated fetal weights. The ongoing Intergrowth study will provide improved ultrasound-based estimates for identification of growth-restricted preterm newborn babies.
What is the public health use of any indicator of gestational age or fetal growth? Although findings of randomised trials of balanced energy–protein and micronutrient supplementation show some effects of reducing preterm birth and small-for-gestational-age births, most countries (including those of high, middle, and low income) have seen important reductions in infant mortality despite rises in preterm birth (mostly attributable to increases in obstetric intervention) and only modest reductions in small-for-gestational-age birth. Most recent progress in reducing infant mortality has been achieved by lowering mortality across the entire range of gestational ages and birthweights, including that of term infants of normal birthweight, not by preventing preterm or small-for-gestational-age birth. In other words, a focus on reducing infant mortality and severe morbidity is likely to pay higher dividends for public health than are attempts to prevent preterm or small-for-gestational-age birth.
Cataract accounts for half of all blindness worldwide. WHO statistics from 2004 suggest that about 18 million people were so visually impaired by cataract that they were unable to walk around independently, with poor and socially marginalised people disproportionately affected. Cataract surgery is now a highly effective intervention, restoring visual function, improving quality of life for patients, and increasing household incomes. In the absence of any effective, proven strategy for prevention of cataract, surgery remains the mainstay of management. The effective delivery of cataract surgical services to the many people who need them faces numerous challenges, including low awareness, fear of surgery, and fatalistic attitudes to the irreversibility of blindness in old age. The quality and patient experience of surgery are increasingly attracting attention as important determinants of uptake and measures of the performance of coordinated cataract surgical programmes. Competent surgeons are a key component in the delivery of high-quality services. Inadequate numbers of surgeons who can independently do surgery of acceptable quality is a serious practical obstacle in some regions. Monitoring the quality of cataract surgery training programmes largely depends on accurate assessment of visual outcomes. However, little research has investigated practical, effective approaches to assess surgical quality in developing countries, where assessment of outcomes is often challenging because of poor follow-up. Nathan Congdon and colleagues investigated the validity of using early outcomes of all cases, or of using late outcomes of only the patients who returned for final follow-up assessment, to monitor final overall visual outcomes of cataract surgery. They report that early postoperative visual acuity, measured within 3 days after surgery, is closely correlated with vision assessed at final follow-up visits (Spearman\'s =0·74, p<0·0001). Additionally, late visual outcomes (measured at 40 days or more after surgery) of those who returned for postoperative follow-up were representative of overall final outcomes (=0·86, p<0·0001). This large study, which covered an impressive 40 centres across 11 developing countries in Asia, Latin America, and Africa, is a welcome addition to the published work on latitudinal diversity gradient topic. These findings are especially important for planners and designers of blindness-prevention programmes.