How to avoid misinterpreting lung function tests in children: a few practical tips

The Practical Significance of Measurement Error in Pulmonary Function Testing Conducted in Research Settings

Conventional spirometry produces measurement error by using repeatability criteria (RC) to discard acceptable data and terminating tests early when RC are met. These practices also implicitly assume that there is no variation across maneuvers within each test. This has implications for air pollution regulations that rely on pulmonary function tests to determine adverse effects or set standards. We perform a Monte Carlo simulation of 20,902 tests of forced expiratory volume in 1 second (FEV₁ ), each with eight maneuvers, for an individual with empirically obtained, plausibly normal pulmonary function. Default coefficients of variation for inter- and intratest variability (3% and 6%, respectively) are employed. Measurement error is defined as the difference between results from the conventional protocol and an unconstrained, eight-maneuver alternative. In the default model, average measurement error is shown to be ∼5%. The minimum difference necessary for statistical significance at p < 0.05 for a before/after comparison is shown to be 16%. Meanwhile, the U.S. Environmental Protection Agency has deemed single-digit percentage decrements in FEV₁ sufficient to justify more stringent national ambient air quality standards. Sensitivity analysis reveals that results are insensitive to intertest variability but highly sensitive to intratest variability. Halving the latter to 3% reduces measurement error by 55%. Increasing it to 9% or 12% increases measurement error by 65% or 125%, respectively. Within-day FEV₁ differences ≤5% among normal subjects are believed to be clinically insignificant. Therefore, many differences reported as statistically significant are likely to be artifactual. Reliable data are needed to estimate intratest variability for the general population, subpopulations of interest, and research samples. Sensitive subpopulations (e.g., chronic obstructive pulmonary disease or COPD patients, asthmatics, children) are likely to have higher intratest variability, making it more difficult to derive valid statistical inferences about differences observed after treatment or exposure.

Natural variability of lung function in young healthy school children

Knowledge about long-term variability of lung function in healthy children is essential when monitoring and treating those with respiratory disease over time. The aim of this study was to define the natural variability in spirometry in young children after an interval of 12 months.The Size and Lung function In Children study was a prospective study designed to assess spirometry and body size, shape and composition in a multi-ethnic population of London school children. 14 schools with a wide range of socioeconomic circumstances were recruited. Spirometric and anthropometric assessments and parental questionnaires pertaining to respiratory symptoms, previous medical history, pubertal status and socioeconomic circumstances were completed at baseline and ∼1 year later.Technically acceptable spirometry data on two occasions ∼1 year apart (range 9-16 months) were available in 758 children (39% boys, mean±sd age 8.1±1.6 years), 593 of whom were classified as "healthy". Mean±sd within-subject between-test variability was 0.05±0.6 z-scores, with 95% of all the children achieving a between-test variability within ±1.2 z-scores (equating to ∼13% predicted).Natural variations of up to 1.2 z-scores occur in healthy children over ∼1 year. These must be considered when interpreting results from annual reviews in those with lung disease who are otherwise stable, if unnecessary further investigations or changes in treatment are to be avoided.

Improvement of Asthma and Gastroesophageal Reflux Disease With Oral Pulvis stomachicus cum Belladonna, a Combination of Matricaria recutita, Atropa belladonna, Bismuth, and Antimonite: A Pediatric Case Report

The association between gastroesophageal reflux disease (GERD) and asthma, although well established in adults, is less strong in the pediatric age group. Benefits of proton pump therapy are limited across age ranges. While there is a growing body of literature on the use of complementary treatments for both asthma and GERD, few studies have focused on treatment benefits for the GERD-asthma association. We present the case of a 2-year-old boy with asthma and GERD who was not responding to inhaled, low-dose corticosteroids, beta-mimetic therapy, and a 6-week course of proton pump inhibitor treatment. We noted a gradual disappearance of symptoms when he was given an oral preparation of Pulvis stomachicuscum Belladonna, an anthroposophic medication containing Matricaria recutita, Atropa belladonna, bismuth, and antimonite. Matricaria recutita and bismuth have known gastric protective properties, and Atropa belladonna contains anticholinergic agents that have a bronchodilatory effect. These complementary medications appear promising in terms of relieving the symptoms of GERD-associated asthma.

Self-reported race/ethnicity in the age of genomic research: its potential impact on understanding health disparities

This review explores the limitations of self-reported race, ethnicity, and genetic ancestry in biomedical research. Various terminologies are used to classify human differences in genomic research including race, ethnicity, and ancestry. Although race and ethnicity are related, race refers to a person's physical appearance, such as skin color and eye color. Ethnicity, on the other hand, refers to communality in cultural heritage, language, social practice, traditions, and geopolitical factors. Genetic ancestry inferred using ancestry informative markers (AIMs) is based on genetic/genomic data. Phenotype-based race/ethnicity information and data computed using AIMs often disagree. For example, self-reporting African Americans can have drastically different levels of African or European ancestry. Genetic analysis of individual ancestry shows that some self-identified African Americans have up to 99% of European ancestry, whereas some self-identified European Americans have substantial admixture from African ancestry. Similarly, African ancestry in the Latino population varies between 3% in Mexican Americans to 16% in Puerto Ricans. The implication of this is that, in African American or Latino populations, self-reported ancestry may not be as accurate as direct assessment of individual genomic information in predicting treatment outcomes. To better understand human genetic variation in the context of health disparities, we suggest using "ancestry" (or biogeographical ancestry) to describe actual genetic variation, "race" to describe health disparity in societies characterized by racial categories, and "ethnicity" to describe traditions, lifestyle, diet, and values. We also suggest using ancestry informative markers for precise characterization of individuals' biological ancestry. Understanding the sources of human genetic variation and the causes of health disparities could lead to interventions that would improve the health of all individuals.