Numerous diagnostic tests report their results quantitatively, using continuous scales. Receiver operating characteristic curve (ROC) analysis provides a statistical method for the assessment of the diagnostic accuracy of these tests, being used for three specific purposes: determine of the cutoff value with the highest sensitivity and specificity, evaluate the discriminative capacity of the diagnostic test, in other words, its ability to differentiate healthy versus sick individuals, and compare the discriminative capacity of two or more diagnostic tests that express their results as continuous scales. Based on a real clinical investigation, this article illustrates theoretical aspects regarding the construction of ROC curves, being its objective to help readers and investigators interpret correctly their results.
Asthma is no longer considered a single disease, but a common label for a set of heterogeneous conditions with shared clinical symptoms but associated with different cellular and molecular mechanisms. Several wheezing phenotypes coexist at preschool age but not all preschoolers with recurrent wheezing develop asthma at school-age; and since at the present no accurate single screening test using genetic or biochemical markers has been developed to determine which preschooler with recurrent wheezing will have asthma at school age, the asthma diagnosis still needs to be based on clinical predicted models or scores. The purpose of this review is to summarize the existing and most frequently used asthma predicting models, to discuss their advantages/disadvantages, and their accomplishment on all the necessary consecutive steps for any predictive model. Seven most popular asthma predictive models were reviewed (original API, Isle of Wight, PIAMA, modified API, ucAPI, APT Leicestersher, and ademAPI). Among these, the original API has a good positive LR~7.4 (increases the probability of a prediction of asthma by 2–7 times), and it is also simple: it only requires four clinical parameters and a peripheral blood sample for eosinophil count. It is thus an easy model to use in any rural or urban health care system. However, because its negative LR is not good, it cannot be used to rule out the development of asthma.
The GRADE system: a change in the way of assessing the quality of evidence and the strength of recommendations L as diferentes personas y grupos que toman decisiones en salud no solo deben considerar la magnitud de los efectos de diferentes cursos de acción (intervenciones) sino también la confianza que es posible tener en dichas estimaciones, ya sea en el contexto de una revisión sistemática o en la elaboración de recomendaciones para una guía de práctica clínica. El concepto "calidad de la evidencia" refleja la confianza que podemos tener en que conocemos los efectos de una intervención. La "fuerza de la recomendación" distingue situaciones en donde la evidencia muestra que una alternativa es claramente superior y, en consecuencia, como clínicos debiéramos tomar esa alternativa con todos o casi todos nuestros pacientes, de situaciones donde hay incertidumbre respecto de cuál es la mejor alternativa y, por tanto, debiéramos considerar los valores y preferencias de los pacientes y las circunstancias clínicas para tomar una decisión (idealmente utilizando un enfoque de decisiones compartidas).Hasta hace poco tiempo existían decenas de sistemas para clasificar la calidad de la evidencia y la fuerza de las recomendaciones 1 . Muchos de ellos utilizados únicamente por el grupo u organización que los había desarrollado. Afortunadamente,
The objective of this study was to identify wheezing recurrences and related risk factors in two groups of infants with bronchiolitis: respiratory syncytial virus (RSV)+ and RSV- as determined by RSV enzyme immunoassay. A 1-year prospective cohort study was conducted with infants younger than 2 years old. Follow-up was made monthly, by a clinical visit and/or by telephone, checking the number of wheezing episodes per month and possible related risk factors. There were 96 subjects enrolled, of whom 77 reached complete follow-up: 36 were RSV+ (46.8%), and 41 were RSV- (53.2%). In the RSV+ group, there were 17 males (47%), vs. RSV- with 30 males (73%) (P < 0.05); 22 RSV+ (61%) were admitted to hospital, vs.14 RSV- (34%) (P < 0.05). Mean age was not significantly different in both groups. The mean number of recurrences was 3.36 episodes/infant/year in the RSV+ and 2.34 in the RSV- group (P = 0.06). Crude relative risk (RR) for a new recurrence of an obstructive episode was 1.33 (95% CI, 0.99-1.79). After adjustment for several potential confounders, the RR was 1.41 (95% CI, 1.03-1.93). Hospitalization stay was longer in the RSV+ than the RSV- group (P < 0.05). In the RSV+ group, patients who had been hospitalized showed more recurrences (4.18) than those with outpatient treatment (2.07) (P < 0.05); this difference did not exist in the RSV- group. The related risk factors for recurrent wheeze in the RSV- group were male gender, number of siblings, and daycare attendance (P < 0.05). In the RSV+ group, the risk of recurrent wheeze was only increased by admission to hospital during the acute bronchiolitis episode (P < 0.05). We speculate that there may be a higher rate of increased airway reactivity and/or preexisting diminished lung function in RSV+ infants requiring hospitalization for their initial illness. In conclusion, RSV-proven bronchiolitis, particularly in those infants who are hospitalized, is associated with a higher recurrence of wheezing episodes in the subsequent 12 months. Other factors appear to account for recurrent wheeze in the RSV- group.
Vitamin D (VD) deficiency has been associated with increased incidence and severity of atopic dermatitis (AD), but the mechanisms through which VD may ameliorate AD are unclear. We compared the phenotypic characteristics of circulating myeloid and plasmacytoid dendritic cells (mDCs and pDCs, respectively) of children with AD vs healthy controls (HC) and evaluated if VD can modulate the allergic phenotype of circulating DCs in AD patients. Although there was no difference in frequency of circulating DCs between groups, among children with AD there was an inverse correlation between SCORAD and circulating total DCs and mDCs. In AD, serum IgE concentration correlated with FcεRI and surface‐bound IgE expression on mDCs and pDCs; pDCs expressing FcεRI and IgE were significantly increased compared to HC. Ex vivo, 1,25(OH)2D3 significantly decreased FcεRI expression on mDCs and surface‐bound IgE on mDCs and pDCs. Oral VD supplementation reduced expression of surface‐bound IgE on pDCs in children with AD. In summary, VD decreases the allergic phenotype of circulating DCs in children with AD, a potential mechanism for how VD supplementation may improve AD severity. Future studies are needed to further assess the role of VD supplementation as an immunomodulatory therapy for AD.
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