Comparison of clinical prediction rules for management of pharyngitis in settings with limited resources

OBJECTIVE: To compare the effectiveness of several clinical prediction rules for culture-positive streptococcal pharyngitis in a single group of patients in a setting in which clinicians routinely treat all cases of pharyngitis presumptively, without laboratory data. STUDY DESIGN: A MEDLINE search identified clinical prediction rules for streptococcal pharyngitis in children. Each rule was applied analytically to data from 410 children in Cairo, Egypt with clinical pharyngitis, in whom throat cultures were performed. The diagnostic effectiveness of these rules for predicting a positive culture were assessed and compared. RESULTS: Seven prediction rules were identified. Of these 7 rules, 4 were developed in North American children, 1 was recommended by the World Health Organization (WHO), and 2 were developed in Egypt. In the Cairo children, the WHO rule was the least sensitive, at 12%. The 6 other rules had sensitivities ranging from 81% to 99% and specificities ranging from 4% to 40%; 2 rules seemed to be effective, with diagnostic odds ratios of 5.2 and 6.1. CONCLUSIONS: The prediction rules demonstrated variable diagnostic effectiveness in the Egyptian children. Without laboratory testing, 2 clinical rules detected > 90% of cases of pharyngitis with positive culture for group A streptococcus and reduced overtreatment of culture-negative cases by approximately 40%. Selected clinical prediction rules have useful characteristics in settings of limited resources and need further validation.     

Understanding diagnostic tests 1: sensitivity, specificity and predictive values

The usefulness of diagnostic tests, that is their ability to detect a person with disease or exclude a person without disease, is usually described by terms such as sensitivity, specificity, positive predictive value and negative predictive value. In this article, the first of the series, a simple, practical explanation of these concepts is provided and their use and misuse discussed. It is explained that while sensitivity and specificity are important measures of the diagnostic accuracy of a test, they are of no practical use when it comes to helping the clinician estimate the probability of disease in individual patients. Predictive values may be used to estimate probability of disease but both positive predictive value and negative predictive value vary according to disease prevalence. It would therefore be wrong for predictive values determined for one population to be applied to another population with a different prevalence of disease. CONCLUSION: Sensitivity and specificity are important measures of the diagnostic accuracy of a test but cannot be used to estimate the probability of disease in an individual patient. Positive and negative predictive values provide estimates of probability of disease but both parameters vary according to disease prevalence.     

早期预测食物过敏高风险儿童方法探讨

目的探讨联合多种危险因素获得的过敏风险评分预测食物过敏高风险儿童的价值。方法采用问卷调查方式获得≤3岁婴幼儿的过敏危险因素信息,以多元logistic逐步回归分析婴幼儿食物过敏危险因素,计算各危险因素对食物过敏的阳性预测值,依据回归方程计算过敏风险评分,通过ROC曲线评价过敏风险评分在筛查食物过敏高风险儿童中的价值。结果获得78例确诊为食物过敏及156例非过敏性疾病的≤3岁婴幼儿的回顾性调查信息。其中过敏性疾病家族史、剖宫产、孕期使用抗生素或解热镇痛药、孕期吸烟或接触吸烟环境、孕期接触杀虫剂或驱蚊剂、家中饲养宠物均是婴幼儿发生食物过敏的危险因素(P0.05)。过敏家族史预测食物过敏的阳性预测值为63.2%,ROC曲线下面积(AUC)为0.696(95%CI:0.620～0.771)。当联合多因素获得的过敏风险评分≥2.85时,其预测食物过敏的AUC为0.804(95%CI:0.746～0.863),灵敏度为0.526,特异度为0.910,尤登指数为0.436。结论多危险因素联合指标筛查食物过敏高风险儿童的预测价值高于过敏家族史。     

Need for quantitative assessment of transglutaminase autoantibodies for celiac disease in screening-identified children

OBJECTIVES: To assess several transglutaminase autoantibody (TGAA) assays in their ability to distinguish celiac disease (CD) in screening-identified children with abnormal intestine biopsy specimens from those with normal biopsy specimens. STUDY DESIGN: Children at risk for CD (n = 54) composed of type 1 diabetics, first-degree relatives of type 1 diabetics or CD, and HLA-DQ2+ individuals followed from birth received intestine biopsy. Sera obtained at the time of biopsy were tested for TGAA, using the radioimmunoassay and 5 other commercially available enzyme-linked immunosorbent assays. RESULTS: False-positive rates ranged from 28% to 80%. The positive predictive value (PPV) of the tests ranged from 63% to 84% (lower than reported for symptomatic children). Setting a higher cutoff for each assay maximized PPV. CONCLUSIONS: There are significant quantitative differences among all TGAA assays that could affect interpretation of a positive test for CD. The overall false-positive rate for all assays was high in this population. Using the assay as a quantitative rather than qualitative tool by increasing the cutoff of positivity to indicate biopsy increases PPV. Multicenter workshops are needed to identify critical differences and to standardize TGAA assays among laboratories.     

Initial nutritional management of the preterm infant

Postnatal nutrition has a large impact on long-term outcome of preterm infants. Evidence is accumulating showing even a relationship between nutrient supply in the first week of life and later cognitive development in extremely low birth weight infants. Since enteral nutrition is often not tolerated following birth, parenteral nutrition is necessary. Yet, optimal parenteral intakes of both energy and amino acids are not well established. Subsequently, many preterm infants fail to grow well, with long-term consequences. Early and high dose amino acid administration has been shown to be effective and safe in very low birth weight infants, but the effect of additional lipid administration needs to be defined.     

Newborn screening for congenital adrenal hyperplasia has reduced sensitivity in girls

OBJECTIVES: To characterize Wisconsin-born infants with 21-hydroxylase deficiency-congenital adrenal hyperplasia (21-OH-D-CAH) who were not identified by the newborn screening for 21-OH-D-CAH, and to examine male and female screening 17-hydroxyprogesterone (17-OHP) levels. STUDY DESIGN: Information on infants with false-negative results was gathered. Results of the Wisconsin newborn screening for 21-OH-D-CAH from January 1, 2000, to June 30, 2003, were analyzed to detect possible differences between male (n=119,842) and female (n=114,951) infants. RESULTS: Six of 7 female infants with false-negative results had genital masculinization, and 4 of 8 infants with false-negative results had laboratory evidence of salt-wasting. None died, had a salt-wasting crisis, or was assigned the wrong sex. A significant difference in the mean 17-OHP levels between male (17.5 ng/mL) and female (15.4 ng/mL) infants (P <.0001) was detected. The sensitivity of newborn screening for female infants was 60%, compared with 80% for male infants. CONCLUSIONS: Male and female infants have significantly different mean 17-OHP levels on newborn screening, and female infants comprise most of the infants with false-negative results. Although health professionals should not assume that newborn screening for 21-OH-D-CAH is a means of identifying all affected infants, the primary goals of newborn screening for CAH (prevention of salt-wasting crises and sex misassignment) are fulfilled.     

Policy issues for expanding newborn screening programs: the cystic fibrosis newborn screening experience in the United States

OBJECTIVE: To describe the screening approaches and implementation strategies for cystic fibrosis newborn screening in the 12 programs that were offered in 11 states in 2002. STUDY DESIGN: Telephone interviews conducted in the spring of 2003 with program representatives in the 11 states. Screening approaches were defined in four overlapping categories: state mandated screening, state-wide offering, hospital based screening, and screening with informed consent. RESULTS: Screening was state mandated in seven states but was routinely offered to most infants in nine states. The primary care provider or hospital determined if screening was done in three states (four programs). Informed consent was explicitly documented in two states. In five programs, immunoreactive trypsinogen exclusively was used to identify at-risk infants. In seven programs, a second tier DNA test was also used, but these programs each had distinct strategies. In only two programs where DNA testing was performed and normal sweat tests indicated carrier status, were results routinely provided to parents "in person" at a CF center. CONCLUSION: The diversity of approaches for screening approaches and strategies has advantages for future policy decisions, provided that data about the clinical and psychosocial impact of screening from these programs are collected and disseminated. As additional states determine that the resources are available, programs can be designed with a more favorable benefit/risk balance as a result of the successes and challenges faced by other states.