Urbanisation but not biomass fuel smoke exposure is associated with asthma prevalence in four resource-limited settings

Determinants of asthma among adults in Tigray, Northern Ethiopia: a facility-based case-control study

Background

Asthma is a public health concern affecting millions of productive age groups. Several studies were conducted on the determinants of asthma in children. However, little is known about the determinants of asthma among adults in Ethiopia. Understanding the determinants of asthma among adults can help reduce its burden. This study was aimed at identifying determinant factors for developing asthma among adults in Tigray hospitals.

Methods

A facility-based, unmatched case-control study design was conducted from January 1 to April 26, 2019. A total of 698 participants (228 cases and 470 controls) completed their guided interviews using structured and pretested questionnaires by trained data collectors. A modified standard questionnaire from the European Community Respiratory Health Survey II (ECRHS II) was used to collect the data. The case definition was patients having asthma, and the control definition was patients without asthma. Data were entered and cleaned using Epi Data Manager Version 3.1 software and imported to statistical packages for social sciences Version 25 software for analysis. To identify asthma determinants, bivariate and multivariable logistic regression models were fitted.

Results

The response rate for both cases and controls was 95.9%. The odds of developing asthma was nearly twice higher among those who resided in urban (AOR = 1.68; 95% CI [1.13-2.50]), more than twice higher among those who have income less than 1000 ETB (AOR = 2.3; 95% CI [1.17-4.56]), twice higher among those who had history of skin allergy (AOR = 2.09; 95% CI [1.14-3.86]), over four times higher among those with family history of asthma (AOR = 4.26; 95% CI [2.63-6.91]), three times higher among those having house dust or smoke exposure (AOR = 3.01; 95% CI [1.96-4.64]), over five times higher among those lifetime firewood users (AOR = 5.39; 95% CI [3.34-8.72]), door opening while cooking (AOR = 0.35; 95% CI [0.26-0.55]), nearly two times higher among those having house dampness (AOR = 1.98; 95% CI [1.069-3.68]), over seven times higher among pet owners (AOR = 7.46; 95% CI [4.04-13] and almost twice higher among those who were physically inactive (AOR = 1.75; 95% CI [1.11-2.85]).

Conclusion

Asthma has been associated with urbanization, low income, a history of allergic diseases, indoor smoke or dust, firewood use, pet ownership, and a sedentary lifestyle. The community should be informed about the known risks and implement preventive steps like opening a door while cooking to lower the risk of asthma.

Ambient particulate matter associates with asthma in high altitude region: A population-based study

Background

Exposure to particulate matter (PM) has been a major public health threat, but the potentially differential effects on asthma of PM remain largely unknown in high altitude settings. We evaluated the effects of ambient PM on asthma in high altitude settings.

Methods

The study recruited a representative sample from high altitude settings using a multistage stratified sampling procedure. Asthma was defined by a self-reported history of diagnosis by a physician or by wheezing symptoms in the preceding 12 months. The annual mean PM_2.5 and PM₁₀ concentrations were calculated for each grid cell at 1-km spatial resolution based on the geographical coordinates.

Results

We analyzed data for participants (mean age 39.1 years, 51.4% female) and 183 (3.7%, 95% confidence interval (CI): 3.2-4.2) of the participants had asthma. Prevalence was higher in women (4.3%, 95% CI 3.5-5.1) than in men (3.1%, 2.4-3.8) and increasing with higher concentration of PM exposures. For an interquartile range (IQR) difference (8.77 μg/m³) in PM_2.5 exposure, the adjusted odds ratio (OR) was 1.64 (95% CI 1.46-1.83, P < 0.001) for risk of asthma. For PM₁₀, there was evidence for an association with risk of asthma (OR 2.34, 95% CI: 1.75-3.15, P < 0.001 per IQR of 43.26 μg/m³). Further analyses showed that household mold or damp exposure may aggravate PM exposure associated risks of asthma.

Conclusions

This study identified that PM exposure could be a dominate environmental risk factor for asthma but largely unconsidered in the high-altitude areas. The association between PM exposure and asthma should be of interest for planners of national policies and encourage programs for prevention of asthma in residents living at high altitudes.

Asthma, COPD, Respiratory, and Allergic Health Effects in an Adult Population Living near an Italian Refinery: A Cross-Sectional Study

BACKGROUND AND AIM

Asthma and chronic obstructive pulmonary disease (COPD) are leading causes of morbidity and mortality worldwide. Globally, 545 million people suffer from chronic respiratory diseases with a wide geographical variability. Risk factors for asthma are both genetic and related to several environmental factors (internal and external pollutants); these also have an important role in the occurrence of COPD. The aim of this study was to describe the prevalence of asthma, COPD, and asthma/COPD overlap (ACO) in an adult population living in two municipalities located in the Po Valley.

METHODS

A standardized questionnaire on respiratory symptoms and sociodemographic characteristics was self-administered to a random sample of the adult population aged 20-64 years, living near a refinery in Northern Italy during the period between 2016 and 2019. Logistic and multinomial regression were implemented to explore factors associated with asthma, COPD, and ACO.

RESULTS

In total, 1108 subjects filled out the questionnaire, the mean age was 48.02 ± 12.34 years (range 21-68), and 53% of the respondents/participants were female. Half of the responders were non-smokers, but the frequency of current and former smokers was significantly greater in men than in women (p < 0.001). The likelihood of being a probable case of asthma decreased with increasing age and increased for smokers. Tobacco smoke was associated with the presence of COPD and ACO.

CONCLUSION

Respiratory diseases such as asthma and COPD are common in the general population, with differences among countries worldwide. Our findings show, on the basis of the main confirmed risk factor, namely smoking, that it is useful to plan target programs and actions in order to reduce smoking, thus improving the quality of life in public health.

Subjective socioeconomic status: an alternative to objective socioeconomic status

BACKGROUND

Subjective "ladder" measurements of socio-economic status (SES) are easy-to-administer tools that ask respondents to rate their own SES, allowing them to evaluate their own material resources and determine where it places them relative to their community. Here, we sought to compare the MacArthur Scale of Subjective Social status to the WAMI, an objective measure of SES that includes data on water and sanitation, asset ownership, education, and income.

METHODS

Leveraging a study of 595 tuberculosis patients in Lima, Peru, we compared the MacArthur ladder score to the WAMI score using weighted Kappa scores and Spearman's rank correlation coefficient. We identified outliers that fell outside the 95^th percentile and assessed the durability of the inconsistencies between scores by re-testing a subset of participants. We then used Akaike information criterion (AIC) to compare the predictability of logistic regression models evaluating the association between the two SES scoring systems and history of asthma.

RESULTS

The correlation coefficient between the MacArthur ladder and WAMI scores was 0.37 and the weighted Kappa was 0.26. The correlation coefficients differed by less than 0.04 and the Kappa ranged from 0.26 to 0.34, indicating fair agreement. When we replaced the initial MacArthur ladder scores with retest scores, the number of individuals with disagreements between the two scores decreased from 21 to 10 and the correlation coefficient and weighted Kappa both increased by at least 0.03. Lastly, we found that when we categorized WAMI and MacArthur ladder scores into three groups, both had a linear trend association with history of asthma with effect sizes and AICs that differed by less than 15% and 2 points, respectively.

CONCLUSION

Our findings demonstrated fair agreement between the MacArthur ladder and WAMI scores. The agreement between the two SES measurements increased when they were further categorized into 3-5 categories, the form in which SES is often used in epidemiologic studies. The MacArthur score also performed similarly to WAMI in predicting a socio-economically sensitive health outcome. Researchers should consider subjective SES tools as an alternative method for measuring SES, particularly in large health studies where data collection is a burden.

Global Considerations in Asthma Treatment: Management in Low Resource Settings

Low-resource settings have a disproportionately higher burden of asthma due to factors that include environmental triggers, access to healthcare, availability of medications, and uncoordinated health systems. The application of guideline-based management can vary, which further impacts the treatment delivered. This chapter aims to outline the global landscape of asthma management, including cultural and social factors, with suggestions for interventions.

Determinants of asthma in Ethiopia: age and sex matched case control study with special reference to household fuel exposure and housing characteristics

BACKGROUND

Asthma is a chronic inflammatory disorder characterized by airway obstruction and hyper-responsiveness. Studies suggest that household fuel exposure and housing characteristics are associated with air way related allergy. But there remains to be a considerable uncertainty about whether that reflects an association with asthma. This study endeavored to bridge the gap by identifying factors associated with asthma, with special reference to household fuel exposure and housing characteristics in selected public hospitals in Addis Ababa, Ethiopia.

METHODS

We conducted a hospital-based matched case-control study. A total of 483 study participants were selected from two Ethiopian referral hospitals using a sequential sampling technique, with 161 cases and 322 controls. Standard questionnaire from the European Community Respiratory Health Survey II (ECRHS II) and the American Thoracic Society Division of Lung Disease (ATS-DLD-78) were used to collect household related data. Conditional logistic regression model was applied to identify the determinants of asthma. Both crude and adjusted odds ratios with 95% confidence interval (CI) were used to identify predictors of asthma.

RESULTS

The response rate for both cases and controls was 99.17%. The odds of developing asthma was about four times higher among those who used agricultural residues for cooking (AOR: 3.81, 95% CI: 1.05, 13.79)., about five times higher among those who used wood for cooking (AOR: 4.95, 95% CI: 2.1, 11.69), nearly five times higher among those who had family history of asthma (AOR: 4.72, 95% CI: 1.54, 14.45), just over six times higher among those who smoke tobacco (AOR: 6.16, 95% CI: 1.31, 29.09) and over ten times higher among those who do not practice door opening, while cooking (AOR: 10.25, 95% CI: 3.97, 26.49).

CONCLUSION

Family history of asthma, tobacco smoking, use of solid fuels including, woods and agricultural residues were associated with development of asthma. To reduce the risk of asthma, people should practice door opening, while cooking, and must avoid using wood and agricultural residues for cooking and should also refrain from tobacco smoking.

Understanding socio-economic inequalities in the prevalence of asthma in India: an evidence from national sample survey 2017-18

Background

Today, over 300 million people reside with asthma worldwide and India alone is home for 6% of children and 2% of adults suffering from this chronic disease. A common notion of disparity persists in terms of health outcomes across the poor and better-off section of the society. Thus, there is a need to explore socio-economic inequality in the contribution of various factors associated with asthma prevalence in India.

Methods

Data for the study were carved out from the 75th round of National Sample Survey (NSS), collected by the National Sample Survey Organization (NSSO) during 2017–18. The sample size for this study was 555,289 individuals, for which data was used for the analysis. Descriptive statistics were used to show the distribution of the study population. Further, bivariate and multivariate analysis was performed to identify the factors associated with Asthma prevalence. The concentration index was used to measure the inequality. Further, we used decomposition analysis to find the contribution of factors responsible for socio-economic status-related inequality in asthma prevalence.

Results

The prevalence of asthma was 2 per 1000 in the whole population; however, the prevalence differs by age groups in a significant manner. Age, sex, educational status, place of residence, cooking fuel, source of drinking water, household size and garbage disposal facility were significantly associated with asthma prevalence in India. It was found that asthma was more concentrated among individuals from higher socioeconomic status (concentration index: 0.15; p < 0.05). While exploring socio-economic inequality for asthma, richest wealth status (53.9%) was the most significant contributor in explaining the majority of the inequality followed by the urban place of residence (37.9%) and individual from age group 45–65 years (33.3%). Additionally, individual aged 65 years and above (27.9%) and household size less than four members (14.7%) contributed in explaining socio-economic inequality for asthma.

Conclusion

Due to the heterogeneous nature of asthma, associations between different socio-economic indicators and asthma can be complex and may point in different directions. Hence, considering the concentration of asthma prevalence in vulnerable populations and its long-term effect on general health, a comprehensive programme to tackle chronic respiratory diseases and asthma, in particular, is urgently needed.

The effects of indoor and outdoor air pollution on the prevalence of adults' respiratory diseases in four Chinese cities: a comparison between 2017-2018 and 1993-1996

Background

Over the past decades, both ambient and household air pollution have changed in several aspects, including the emission sources and the concentrations of pollutants, in many Chinese cities. It is unknown whether these changes are associated with changes in health conditions, especially given changes in other factors due to rapid economic growth.

Methods

Two cross-sectional surveys were conducted in two periods spanning more than twenty years (1993–1996 vs. 2017–2018) in four Chinese cities of Chongqing, Wuhan, Lanzhou, and Guangzhou. Data were collected regarding adults’ respiratory disease, smoking status, education, occupation, and household characteristics. Ambient air pollution data were obtained for each study. We first used logistic regression models to construct the district-specific adjusted disease prevalences. In the second stage, first-difference regression models were employed to examine whether the change in respiratory diseases prevalences was associated with the change in outdoor air pollution and indoor air pollution surrogates.

Results

A total of 7,557 and 9,974 households were participating in Period 1 (1993–1996) and Period 2 (2017–2018), respectively. Compared to Period 1, we found substantial reductions in the ambient air pollution concentrations, and a suggestive improvement in cooking-related indoor air pollution in Period 2. We observed decreases in the district-specific covariate-adjusted prevalences of both asthma and chronic bronchitis among participants, with an average reduction of 3.6% (range: 0.0% to 24.3%). From Period 1 to Period 2, one percent decrease in the proportion of cooking with coal was associated with a 19.0% (95% CI, 0.96–37.04%) decrease in the prevalence of males’ chronic bronchitis and a 1.86% (0.69–3.04%) increase in the prevalence of females’ asthma. Little evidence was observed regarding the potential health benefits associated with the decreases in ambient air pollution levels.

Conclusions

The substantial reduction in household use of coal for cooking might be an important contributor to the decrease in adults’ respiratory disease prevalence from 1993–1996 to 2017–2019 in four Chinese cities. Changes in this indoor air pollution source, along with other risk factors for respiratory diseases, may have masked respiratory health benefits associated with reductions in outdoor air pollution levels.

Understanding Asthma and Allergies by the Lens of Biodiversity and Epigenetic Changes

Exposure to different organisms (bacteria, mold, virus, protozoan, helminths, among others) can induce epigenetic changes affecting the modulation of immune responses and consequently increasing the susceptibility to inflammatory diseases. Epigenomic regulatory features are highly affected during embryonic development and are responsible for the expression or repression of different genes associated with cell development and targeting/conducting immune responses. The well-known, "window of opportunity" that includes maternal and post-natal environmental exposures, which include maternal infections, microbiota, diet, drugs, and pollutant exposures are of fundamental importance to immune modulation and these events are almost always accompanied by epigenetic changes. Recently, it has been shown that these alterations could be involved in both risk and protection of allergic diseases through mechanisms, such as DNA methylation and histone modifications, which can enhance Th2 responses and maintain memory Th2 cells or decrease Treg cells differentiation. In addition, epigenetic changes may differ according to the microbial agent involved and may even influence different asthma or allergy phenotypes. In this review, we discuss how exposure to different organisms, including bacteria, viruses, and helminths can lead to epigenetic modulations and how this correlates with allergic diseases considering different genetic backgrounds of several ancestral populations.

Reported Neighborhood Traffic and the Odds of Asthma/Asthma-Like Symptoms: A Cross-Sectional Analysis of a Multi-Racial Cohort of Children

Asthma in children poses a significant clinical and public health burden. We examined the association between reported neighborhood traffic (a proxy for traffic-related air pollution) and asthma among 855 multi-racial children aged 4-8 years old who participated in the Environmental Influences on Child Health Outcomes (ECHO) cohort. We hypothesized that high neighborhood traffic density would be associated with the prevalence of asthma. Asthma/asthma-like symptoms (defined as current and/or past physician diagnosed asthma, past wheezing, or nighttime cough or wheezing in the past 12 months) was assessed by parental report. The relationship between neighborhood traffic and asthma/asthma-like symptoms was assessed using logistic regression. The prevalence of asthma/asthma-like symptoms among study participants was 23%, and 15% had high neighborhood traffic. Children with significant neighborhood traffic had a higher odds of having asthma/asthma-like symptoms than children without neighborhood traffic [adjusted OR = 2.01 (95% CI: 1.12, 3.62)] after controlling for child's race-ethnicity, age, sex, maternal education, family history of asthma, play equipment in the home environment, public parks, obesity and prescribed asthma medication. Further characterization of neighborhood traffic is needed since many children live near high traffic zones and significant racial/ethnic disparities exist.

Measuring urbanicity as a risk factor for childhood wheeze in a transitional area of coastal ecuador: a cross-sectional analysis

Background

The urbanisation process has been associated with increases in asthma prevalence, an observation supported largely by studies comparing urban with rural populations. The nature of this association remains poorly understood, likely because of the limitations of the urban–rural approach to understand what a multidimensional process is.

Objective

This study explored the relationship between the urbanisation process and asthma prevalence using a multidimensional and quantitative measure of urbanicity.

Methods

A cross-sectional analysis was conducted in 1843 children living in areas with diverse levels of urbanisation in the district of Quinindé, Ecuador in 2013–2015. Categorical principal components analysis was used to generate an urbanicity score derived from 18 indicators measured at census ward level based on data from the national census in 2010. Indicators represent demographic, socioeconomic, built environment and geographical dimensions of the urbanisation process. Geographical information system analysis was used to allocate observations and urban characteristics to census wards. Logistic random effects regression models were used to identify associations between urbanicity score, urban indicators and three widely used definitions for asthma.

Results

The prevalence of wheeze ever, current wheeze and doctor diagnosis of asthma was 33.3%, 13% and 6.9%, respectively. The urbanicity score ranged 0–10. Positive significant associations were observed between the urbanicity score and wheeze ever (adjusted OR=1.033, 95% CI 1.01 to 1.07, p=0.05) and doctor diagnosis (adjusted OR=1.06, 95% CI 1.02 to 1.1, p=0.001). For each point of increase in urbanicity score, the prevalence of wheeze ever and doctor diagnosis of asthma increased by 3.3% and 6%, respectively. Variables related to socioeconomic and geographical dimensions of the urbanisation process were associated with greater prevalence of wheeze/asthma outcomes.

Conclusions

Even small increases in urbanicity are associated with a higher prevalence of asthma in an area undergoing the urban transition. The use of a multidimensional urbanicity indicator has greater explanatory power than the widely used urban–rural dichotomy to improve our understanding of how the process of urbanisation affects the risk of asthma.

Risk factors associated with rhinitis, allergic conjunctivitis and eczema among schoolchildren in Uganda

Background

The prevalence of allergy-related diseases (ARDs), including rhinitis, allergic conjunctivitis and eczema, is on the increase globally. The causes of this increase are not well established.

Objectives

To investigate the risk factors associated with ARDs among schoolchildren in Uganda.

Methods

We conducted a secondary data analysis of a large asthma case–control study involving 1700 schoolchildren, 5–17 years, in urban Uganda. ARDs were defined according to the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Skin prick testing (SPT) was conducted using standard procedures and allergen-specific IgE (asIgE) using ImmunoCAP^®. We employed inverse probability weighted analysis to generate estimated prevalence data and weighted odds ratios.

Results

The lifetime estimated weighted prevalence of reported rhinitis, allergic conjunctivitis and eczema was 43.3%, 39.5% and 13.5%; weighted prevalence in 12 months was 10.1%, 9.1% and 2.3%, respectively. There was overlap of ARDs, with 66.3% of 1193 schoolchildren who reported having ever an ARDs (including asthma) reporting two or more. Risk factors associated with reported rhinitis in the last 12 months were city residence at birth [adjusted odds ratio (95% confidence interval) 2.66 (1.42–4.99) compared to rural]; father’s [2.62 (1.79–3.83)] and mother’s history of allergic disease [2.12 (1.48–3.02)]; frequent de-worming in the last 12 months [2.01 (1.30–3.11), ≥2 versus none]; current high frequency of ‘trucks passing on the street near home’ [2.59 (1.48–4.52), ‘almost all the time’ versus rarely] and positive SPT [1.54 (1.09–2.18)] but not asIgE [1.38 (0.60–3.15)]. The same pattern of risk factors was observed for allergic conjunctivitis and eczema.

Conclusion

We found extensive multi-morbidity of, and overlap in the risk factors for, rhinitis, conjunctivitis and eczema—similar to asthma risk factors—among schoolchildren in urban Uganda. This suggests a similar underlying cause for all ARDs, associated with exposure to urban lifestyles and environment in Uganda.

Ambient Air Pollution and Variation in Multiple Domains of Asthma Morbidity among Peruvian Children

RATIONALE

A large portion of asthma morbidity occurs in low- and middle-income countries, and Peru suffers particularly high asthma prevalence. Ambient air exposures are also high, and likely play a role. Most studies of environmental exposures focus on understanding contributors to health care utilization or mortality risk; however, less severe outcomes may still impact quality of life (QOL).

OBJECTIVES

To study the association between multiple pollutants and several asthma domains in Peruvian children.

METHODS

A total of 484 children aged 9-19 years with asthma were followed for 6-9 months, and evaluated for asthma control, asthma-related QOL, missed school days, and health care utilization. We used geographically distributed monitors to estimate air pollutant concentrations and multivariable generalized linear mixed models to model asthma outcomes as a function of pollutants.

RESULTS

A total of 67% of children had moderate to severe persistent asthma. In multipollutant models, higher particulate matter less than 2.5 μm in aerodynamic diameter (PM_2.5), black carbon, and nitrogen dioxide concentrations were independently associated with worse asthma control. For each interquartile range increase in PM_2.5 or nitrogen dioxide concentration, there was a 59% or 34% higher odds of uncontrolled asthma, respectively. If the proportion of PM_2.5 that was black carbon increased, there were increased odds of uncontrolled asthma. Similarly, pollutants were independently associated with worse asthma-related QOL, and PM exposure was associated with increased risk of health care utilization.

CONCLUSIONS

Our study highlights the importance of pollutant exposures on multiple domains of asthma morbidity among Peruvian children, including not only acute exacerbations, but also on general asthma burden, such as worse asthma symptom control and QOL.

Prevalence of chronic obstructive pulmonary disease at high altitude: a systematic review and meta-analysis

Background and objective

Recently, several studies have investigated the prevalence of chronic obstructive pulmonary disease (COPD) at high altitude (>1,500 m). However, much remains to be understood about the correlation between altitude and COPD. We aimed to summarize the prevalence of COPD at high-altitudes and find out if altitude could be a risk factor for COPD.

Methods

We searched PubMed/Medline, Cochrane Library, Web of Science, SCOPUS, OVID, Chinese Biomedical Literature Database (CBM) and Embase databases from inception to April 30th, 2019, with no language restriction. We used STATA 14.0 to analyze the extracted data. A random-effect model was used to calculate the combined OR and 95% CI. Heterogeneity was assessed by the I² statistic versus P-value. We performed a subgroup analysis to analyze possible sources of heterogeneity. The Egger’s test and the Begg’s test were used to assess any publication bias.

Results

We retrieved 4,574 studies from seven databases and finally included 10 studies (54,578 participants). Males ranged from 18.8% to 49.3% and the population who smoked ranged from 3.3% to 53.3%. The overall prevalence of COPD at high-altitude was 10.0% (95% CI [0.08–0.12], P < 0.001). In a subgroup analysis, based on different regions, the results showed that the prevalence in Asia was higher than that in Europe and America. Seven studies compared the relationship between the prevalence of COPD at high-altitudes and the lowlands. The results showed that altitude was not an independent risk factor for the prevalence of COPD (OR_adj = 1.18, 95% CI [0.85–1.62], P = 0.321). There was no publication bias among the studies.

Conclusions

Our study found a higher prevalence of COPD at high-altitudes than those from average data. However, altitude was not found to be an independent risk factor for developing COPD (PROSPERO Identifier: CRD42019135012).

Risk factors for asthma among schoolchildren who participated in a case-control study in urban Uganda

Data on asthma aetiology in Africa are scarce. We investigated the risk factors for asthma among schoolchildren (5–17 years) in urban Uganda. We conducted a case-control study, among 555 cases and 1115 controls. Asthma was diagnosed by study clinicians. The main risk factors for asthma were tertiary education for fathers (adjusted OR (95% CI); 2.32 (1.71–3.16)) and mothers (1.85 (1.38–2.48)); area of residence at birth, with children born in a small town or in the city having an increased asthma risk compared to schoolchildren born in rural areas (2.16 (1.60–2.92)) and (2.79 (1.79–4.35)), respectively; father’s and mother’s history of asthma; children’s own allergic conditions; atopy; and cooking on gas/electricity. In conclusion, asthma was associated with a strong rural-town-city risk gradient, higher parental socio-economic status and urbanicity. This work provides the basis for future studies to identify specific environmental/lifestyle factors responsible for increasing asthma risk among children in urban areas in LMICs.

Asthma is a chronic disease of the airways that leads to breathing difficulty and sometimes death: the condition affects about 235 million people worldwide, especially children. Scientists still do not know exactly what causes asthma, but studies in Europe and North America suggest that individuals born or raised in rural areas are less likely to be affected. However, few studies have examined asthma in African countries, where urbanization is often quickly increasing. Examining the factors associated with the disease as more people move to cities may provide new clues about how asthma emerges, and how to prevent it.

To this end, Mpairwe et al. conducted a study with over 1,670 schoolchildren in Uganda. Those born or raised in rural areas were least likely to have asthma, but the risk doubled among children from small towns, and tripled in those born or who grew up in the city. Children whose parents had a higher education and socioeconomic status had the highest asthma risk, but more work is required to understand why this is the case.

The study by Mpairwe et al. is the first step towards identifying environmental and lifestyle factors associated with increased asthma risk in Africa. Further studies may help scientists to understand how beginning life in a more urban area plays a role in the development of the disease.

Urbanisation and asthma in low-income and middle-income countries: a systematic review of the urban-rural differences in asthma prevalence

BACKGROUND

Urbanisation has been associated with temporal and geographical differences in asthma prevalence in low-income and middle-income countries (LMICs). However, little is known of the mechanisms by which urbanisation and asthma are associated, perhaps explained by the methodological approaches used to assess the urbanisation-asthma relationship.

OBJECTIVE

This review evaluated how epidemiological studies have assessed the relationship between asthma and urbanisation in LMICs, and explored urban/rural differences in asthma prevalence.

METHODS

Asthma studies comparing urban/rural areas, comparing cities and examining intraurban variation were assessed for eligibility. Included publications were evaluated for methodological quality and pooled OR were calculated to indicate the risk of asthma in urban over rural areas.

RESULTS

Seventy articles were included in our analysis. Sixty-three compared asthma prevalence between urban and rural areas, five compared asthma prevalence between cities and two examined intraurban variation in asthma prevalence. Urban residence was associated with a higher prevalence of asthma, regardless of asthma definition: current-wheeze OR:1.46 (95% CI:1.22 to 1.74), doctor diagnosis OR:1.89 (95% CI:1.47 to 2.41), wheeze-ever OR:1.44 (95% CI:1.15 to 1.81), self-reported asthma OR:1.77 (95% CI:1.33 to 2.35), asthma questionnaire OR:1.52 (95% CI:1.06 to 2.16) and exercise challenge OR:1.96 (95% CI:1.32 to 2.91).

CONCLUSIONS

Most evidence for the relationship between urbanisation and asthma in LMICs comes from studies comparing urban and rural areas. These studies tend to show a greater prevalence of asthma in urban compared to rural populations. However, these studies have been unable to identify which specific characteristics of the urbanisation process may be responsible. An approach to understand how different dimensions of urbanisation, using contextual household and individual indicators, is needed for a better understanding of how urbanisation affects asthma.

PROSPERO REGISTRATION NUMBER

CRD42017064470.

Educational and health outcomes of children treated for asthma: Scotland-wide record linkage study of 683 716 children

Background

The global prevalence of childhood asthma is increasing. The condition impacts physical and psychosocial morbidity; therefore, wide-ranging effects on health and education outcomes are plausible.

Methods

Linkage of eight Scotland-wide databases, covering dispensed prescriptions, hospital admissions, maternity records, death certificates, annual pupil census, examinations, school absences/exclusions and unemployment, provided data on 683 716 children attending Scottish schools between 2009 and 2013. We compared schoolchildren on medication for asthma with peers, adjusting for sociodemographic, maternity and comorbidity confounders, and explored effect modifiers and mediators.

Results

The 45 900 (6.0%) children treated for asthma had an increased risk of hospitalisation, particularly within the first year of treatment (incidence rate ratio 1.98, 95% CI 1.93–2.04), and increased mortality (HR 1.77, 95% CI 1.30–2.40). They were more likely to have special educational need for mental (OR 1.76, 95% CI 1.49–2.08) and physical (OR 2.76, 95% CI 2.57–2.95) health reasons, and performed worse in school exams (OR 1.11, 95% CI 1.06–1.16). Higher absenteeism (incidence rate ratio 1.25, 95% CI 1.24–1.26) partially explained their poorer attainment.

Conclusions

Children with treated asthma have poorer education and health outcomes than their peers. Educational interventions that mitigate the adverse effects of absenteeism should be considered.

Asthmatic children experience significant disadvantage in addition to poor health. Adverse effects on other aspects of their life, such as education, need to be recognised and addressed.bit.ly/2W5K4Nib

Rural to urban migration contributes to the high burden of asthma in the urban area

INTRODUCTION

It is unknown whether rural-urban migration contributes to worse the burden of asthma in the cities.

OBJECTIVES

The aim of this study was to evaluate whether subjects with asthma that migrated from rural areas to a large urban center in Brazil have more severe disease than asthmatic subjects that was born and always lived in the urban area.

METHODS

This is a case-control study. We enrolled two groups of subjects with asthma currently living in a large urban center in Brazil: 486 subjects with moderate-severe asthma and 432 subjects with mild asthma.

RESULTS

Rural-urban migrants had higher odds of moderate-severe asthma [adjusted OR 1.57, 95% CI (1.18-2.01)] and uncontrolled symptoms of asthma [adjusted OR 1.80, 95% CI (1.16-2.76)] than urban-born subjects.

CONCLUSIONS

Rural-urban migrants in Brazil have more severe asthma than urban-born subjects. Our results suggest that rural-urban migration is associated with the high burden of asthma in the urban area.

Prevalence, risk factors, and management of asthma in China: a national cross-sectional study

BACKGROUND

Asthma is a common chronic airway disease worldwide. Despite its large population size, China has had no comprehensive study of the national prevalence, risk factors, and management of asthma. We therefore aimed to estimate the national prevalence of asthma in a representative sample of the Chinese population.

METHODS

A representative sample of 57 779 adults aged 20 years or older was recruited for the national cross-sectional China Pulmonary Health (CPH) study using a multi-stage stratified sampling method with parameters derived from the 2010 census. Ten Chinese provinces, representative of all socioeconomic settings, from six geographical regions were selected, and all assessments were done in local health centres. Exclusion criteria were temporary residence, inability to take a spirometry test, hospital treatment of cardiovascular conditions or tuberculosis, and pregnancy and breastfeeding. Asthma was determined on the basis of a self-reported history of diagnosis by a physician or by wheezing symptoms in the preceding 12 months. All participants were assessed with a standard asthma questionnaire and were classed as having or not having airflow limitation through pulmonary function tests before and after the use of a bronchodilator (400 μg of salbutamol). Risk factors for asthma were examined by multivariable-adjusted analyses done in all participants for whom data on the variables of interest were available. Disease management was assessed by the self-reported history of physician diagnosis, treatments, and hospital visits in people with asthma.

FINDINGS

Between June 22, 2012, and May 25, 2015, 57 779 participants were recruited into the CPH study. 50 991 (21 446 men and 29 545 women) completed the questionnaire survey and had reliable post-bronchodilator pulmonary function test results and were thus included in the final analysis. The overall prevalence of asthma in our sample was 4·2% (95% CI 3·1-5·6), representing 45·7 million Chinese adults. The prevalence of asthma with airflow limitation was 1·1% (0·9-1·4), representing 13·1 million adults. Cigarette smoking (odds ratio [OR] 1·89, 95% CI 1·26-2·84; p=0·004), allergic rhinitis (3·06, 2·26-4·15; p<0·0001), childhood pneumonia or bronchitis (2·43, 1·44-4·10; p=0·002), parental history of respiratory disease (1·44, 1·02-2·04; p=0·040), and low education attainment (p=0·045) were associated with prevalent asthma. In 2032 people with asthma, only 28·8% (95% CI 19·7-40·0) reported ever being diagnosed by a physician, 23·4% (13·9-36·6) had a previous pulmonary function test, and 5·6% (3·1-9·9) had been treated with inhaled corticosteroids. Furthermore, 15·5% (11·4-20·8) people with asthma reported at least one emergency room visit and 7·2% (4·9-10·5) at least one hospital admission due to exacerbation of respiratory symptoms within the preceding year.

INTERPRETATION

Asthma is prevalent but largely undiagnosed and undertreated in China. It is crucial to increase the awareness of asthma and disseminate standardised treatment in clinical settings to reduce the disease burden.

FUNDING

National Key R&D Program of China, Ministry of Science and Technology of China; the Special Research Foundation for Public Welfare of Health, Ministry of Health of China; the Chinese National Research Program for Key Issues in Air Pollution Control; and the National Natural Science Foundation of China.

The health and social implications of household air pollution and respiratory diseases

Approximately three billion individuals are exposed to household air pollution (HAP) from the burning of biomass fuels worldwide. Household air pollution is responsible for 2.9 million annual deaths and causes significant health, economic and social consequences, particularly in low- and middle-income countries. Although there is biological plausibility to draw an association between HAP exposure and respiratory diseases, existing evidence is either lacking or conflicting. We abstracted systematic reviews and meta-analyses for summaries available for common respiratory diseases in any age group and performed a literature search to complement these reviews with newly published studies. Based on the literature summarized in this review, HAP exposure has been associated with acute respiratory infections, tuberculosis, asthma, chronic obstructive pulmonary disease, pneumoconiosis, head and neck cancers, and lung cancer. No study, however, has established a causal link between HAP exposure and respiratory disease. Furthermore, few studies have controlled for tobacco smoke exposure and outdoor air pollution. More studies with consistent diagnostic criteria and exposure monitoring are needed to accurately document the association between household air pollution exposure and respiratory disease. Better environmental exposure monitoring is critical to better separate the contributions of household air pollution from that of other exposures, including ambient air pollution and tobacco smoking. Clinicians should be aware that patients with current or past HAP exposure are at increased risk for respiratory diseases or malignancies and may want to consider earlier screening in this population.

Prevalence of chronic respiratory disease in urban and rural Uganda

Objective

To determine the prevalence of chronic respiratory diseases in urban and rural Uganda and to identify risk factors for these diseases.

Methods

The population-based, cross-sectional study included adults aged 35 years or older. All participants were evaluated by spirometry according to standard guidelines and completed questionnaires on respiratory symptoms, functional status and demographic characteristics. The presence of four chronic respiratory conditions was monitored: chronic obstructive pulmonary disease (COPD), asthma, chronic bronchitis and a restrictive spirometry pattern.

Findings

In total, 1502 participants (average age: 46.9 years) had acceptable, reproducible spirometry results: 837 (56%) in rural Nakaseke and 665 (44%) in urban Kampala. Overall, 46.5% (698/1502) were male. The age-adjusted prevalence of any chronic respiratory condition was 20.2%. The age-adjusted prevalence of COPD was significantly greater in rural than urban participants (6.1 versus 1.5%, respectively; P < 0.001), whereas asthma was significantly more prevalent in urban participants: 9.7% versus 4.4% in rural participants (P < 0.001). The age-adjusted prevalence of chronic bronchitis was similar in rural and urban participants (3.5 versus 2.2%, respectively; P = 0.62), as was that of a restrictive spirometry pattern (10.9 versus 9.4%; P = 0.82). For COPD, the population attributable risk was 51.5% for rural residence, 19.5% for tobacco smoking, 16.0% for a body mass index < 18.5 kg/m² and 13.0% for a history of treatment for pulmonary tuberculosis.

Conclusion

The prevalence of chronic respiratory disease was high in both rural and urban Uganda. Place of residence was the most important risk factor for COPD and asthma.

Environmental exposures and systemic hypertension are risk factors for decline in lung function

BACKGROUND

Chronic lung disease is a leading contributor to the global disease burden; however, beyond tobacco smoke, we do not fully understand what risk factors contribute to lung function decline in low-income and middle-income countries.

METHODS

We collected sociodemographic and clinical data in a randomly selected, age-stratified, sex-stratified and site-stratified population-based sample of 3048 adults aged ≥35 years from four resource-poor settings in Peru. We assessed baseline and annual pre-bronchodilator and post-bronchodilator lung function over 3 years. We used linear mixed-effects models to assess biological, socioeconomic and environmental risk factors associated with accelerated lung function decline.

RESULTS

Mean±SD enrolment age was 55.4±12.5 years, 49.2% were male and mean follow-up time was 2.36 (SD 0.61) years. Mean annual pre-bronchodilator FEV1 decline was 30.3 mL/year (95% CI 28.6 to 32.0) and pre-bronchodilator FVC decline was 32.2 mL/year (30.0 to 34.4). Using multivariable linear mixed-effects regression, we found that urban living, high-altitude dwelling and having hypertension accounted for 25.9% (95% CI 15.7% to 36.1%), 21.3% (11.1% to 31.5%) and 15.7% (3.7% to 26.9%) of the overall mean annual decline in pre-bronchodilator FEV1/height2, respectively. Corresponding estimates for pre-bronchodilator FVC/height2 were 42.1% (95% CI% 29.8% to 54.4%), 36.0% (23.7% to 48.2%) and 15.8% (2.6% to 28.9%) of the overall mean annual decline, respectively.

CONCLUSION

Urbanisation, living at high altitude and hypertension were associated with accelerated lung function decline in a population with low daily smoking prevalence.

Association between exhaled carbon monoxide and asthma outcomes in Peruvian children

BACKGROUND

Asthma prevalence continues to increase in low and middle-income countries, presenting challenges in assessing asthma control in resource-poor settings. Previous studies suggest that exhaled carbon monoxide (eCO) is higher with asthma severity and lower with treatment. We hypothesized that eCO levels may be elevated in children with asthma, particularly in children with partially controlled or uncontrolled asthma in a low-resource setting in Lima, Peru.

METHODS

We compared average eCO levels between 248 children with asthma and 221 healthy controls as well as the odds of asthma by eCO quartiles (0-1, 2, 3, and ≥4 ppm) using multivariable linear and logistic regression. eCO quartiles were also used to compare the odds of partially controlled or uncontrolled asthma (score ≤19 on the Asthma Control Test) in a multivariable logistic regression model.

FINDINGS

Average adjusted eCO level was 0.56 ppm (95% CI 0.07-1.05) higher in children with asthma. The adjusted odds of asthma were 1.22 (95% CI 0.75-1.97), 1.46 (0.81-2.63), and 1.76 (0.96-3.23) in the second, third, and fourth eCO quartiles compared to the first eCO quartile, respectively. Among children with asthma, the adjusted odds of partially controlled or uncontrolled asthma in those in the second, third, and fourth eCO quartiles, compared to the first, were 1.61 (95% CI 0.74-3.48), 3.66 (95% CI 1.51-8.87), and 2.50 (95% CI 1.06-5.90), respectively.

INTERPRETATION

eCO may serve as an inexpensive biomarker for asthma control, particularly in low-resource settings.

Patterns of Body Composition Relating to Chronic Respiratory Diseases Among Adults in Four Resource-Poor Settings in Peru

PURPOSE

Body composition is known to influence the development and progression of chronic respiratory diseases (CRDs). We sought to characterize the unique anthropometric phenotypes that present with asthma, chronic obstructive pulmonary disease (COPD), and chronic bronchitis across four distinct settings in Peru.

METHODS

We collected sociodemographic, clinical history, and spirometry data from 2959 participants from Lima, Tumbes, and rural and urban Puno. We compared the prevalence of CRDs among different study sites and described disease phenotypes. We used single and multivariable linear regression to model the influence of CRD status on various descriptors of body composition.

RESULTS

Overall prevalence of CRDs varied across sites with the highest prevalence of asthma in Lima (14.5%) and the highest prevalence of COPD in rural Puno (9.9%). Measures of body composition also varied across sites, with highest mean body mass index (BMI) in Lima (28.4 kg/m²) and the lowest mean BMI in rural Puno (25.2 kg/m²). Participants with COPD had the lowest mean fat mass index (FMI) (10.5 kg/m²) and waist circumference (88.3 cm), whereas participants with asthma had the highest mean FMI (14.5 kg/m²), and waist circumference (94.8 cm). In multivariable analysis, participants with COPD had a lower waist circumference (adjusted mean - 2.97 cm, 95% CI 4.62 to - 1.32 cm) when compared to non-CRD participants.

CONCLUSIONS

Our findings provide evidence that asthma and chronic bronchitis are more likely to be associated with obesity and higher fat mass, while COPD is associated with being underweight and having less lean mass.

Asthma and Allergic Disorders in Uganda: A Population-Based Study Across Urban and Rural Settings

BACKGROUND

Allergic diseases are increasing in sub-Saharan Africa, but few studies have characterized the burden among adults.

OBJECTIVE

We conducted a study to evaluate the prevalence and risk factors of allergic disorders in urban and rural Uganda.

METHODS

We present a cross-sectional analysis of enrollment data from a population-based cohort study of adults aged ≥35 years in urban and rural Uganda. Sociodemographic and both lifetime and 12-month respiratory symptoms data were collected and spirometry was conducted following standard guidelines.

RESULTS

In 1,308 adults (median age 43.8 years and 52.3% female), we found an age-adjusted prevalence of 6.8% for asthma (9.8% urban, 4.3% rural; P < .001), 11.9% for allergic rhinitis (16.4% urban, 7.8% rural; P < .001), and 8.2% for eczema (9.9% urban, 7.8% rural; P = .15). Urbanization was the primary driver of asthma, accounting for 61.4% of cases (95% confidence interval [CI] 22.0% to 83.4%), and was the strongest risk factor for any allergic illness (odds ratio [OR] = 1.87, 95% CI 1.39-2.51). Parental asthma was not associated with allergic illness. Asthma was associated with a lower forced expiratory volume in 1 second (FEV₁) by 0.56 z scores (95% CI 0.33-0.80). We found a dose-response association between lower quintiles of the FEV₁/forced vital capacity ratio and both hospitalization (OR = 1.77, 95% CI 1.21-2.59) and impairment in daily activities (1.65, 1.20-2.27).

CONCLUSIONS

Asthma and allergic rhinitis were twice as prevalent in urban settings. Asthma was associated with greater impairment and worse lung function outcomes. We identified a high prevalence of allergic disorders in Uganda, which can be expected to increase due to urbanization and resultant exposures throughout early development.

Asthma prevalence and severity in low-resource communities

PURPOSE OF REVIEW

The prevalence of asthma was thought to be low in most low-income countries, but several reports have indicated this is not always true. This is a narrative review of recent publications on the burden of asthma in low and middle-income countries (LMIC) and underprivileged communities from developed countries.

RECENT FINDINGS

Several studies have reported a low prevalence of asthma is LMIC, but indicate it is increasing. In the last few years, however, many surveys demonstrated this may not always be true. An analysis of the International Study for Asthma and Allergy in Childhood phase III database indicated although the prevalence of asthma among children and adolescents is higher in the developed countries, symptoms of asthma are often more severe in less affluent nations. The rate of uncontrolled asthma is also higher among underprivileged communities of developed countries. Secondary analysis of data generated by the WHO's world health survey performed among adults of 70 countries indicate symptoms of asthma are less frequent in middle-income countries and more frequent in the extremes, low income and high income. This sort of U shaped distribution suggests the disease (or syndrome) comprise more than one major phenotype related to diverse underlying mechanisms. In fact, recent reports show symptoms of asthma among the poor are associated with unhygienic living conditions, which may reduce the risk of atopy but increase the risk of nonatopic wheezing. Urbanization and exposure to air pollution also seem to contribute to an increasing prevalence severity of asthma in LMIC. Access to proper diagnosis and treatment with controller medications for asthma, specially with inhaled corticosteroids is feasible and cost-effective, reduce symptoms, health resource utilization, improves quality of life, and reduce mortality in low-resource settings.

SUMMARY

Prevalence of asthma was thought to be low in low-income countries, but several reports have indicated this is not always true. Under diagnosis, under treatment, exposure to air pollution, and unhygienic living conditions may contribute to a higher frequency and severity of symptoms of asthma among the poor. Proper diagnosis and treatment with controller medications for asthma is feasible and cost-effective in low-resource settings.

ERS/ATS workshop report on respiratory health effects of household air pollution

Exposure to household air pollution (HAP) from solid fuel combustion affects almost half of the world population. Adverse respiratory outcomes such as respiratory infections, impaired lung growth and chronic obstructive pulmonary disease have been linked to HAP exposure. Solid fuel smoke is a heterogeneous mixture of various gases and particulates. Cell culture and animal studies with controlled exposure conditions and genetic homogeneity provide important insights into HAP mechanisms. Impaired bacterial phagocytosis in exposed human alveolar macrophages possibly mediates several HAP-related health effects. Lung pathological findings in HAP-exposed individuals demonstrate greater small airways fibrosis and less emphysema compared with cigarette smokers. Field studies using questionnaires, air pollution monitoring and/or biomarkers are needed to better establish human risks. Some, but not all, studies suggest that improving cookstove efficiency or venting emissions may be associated with reduced respiratory symptoms, lung function decline in women and severe pneumonia in children. Current studies focus on fuel switching, stove technology replacements or upgrades and air filter devices. Several governments have initiated major programmes to accelerate the upgrade from solid fuels to clean fuels, particularly liquid petroleum gas, which provides research opportunities for the respiratory health community.

A rural environment does not protect against asthma or other allergic diseases amongst Mexican children

INTRODUCTION

The commonly held notion that a rural environment decreases the frequency of allergic diseases has proven to be inconsistent amongst children.

OBJECTIVE

Our objective was to contrast the prevalence of bronchial asthma (BA), allergic rhinitis (AR), and atopic dermatitis (AD) between children that live in a rural environment and those that live in urban areas.

METHODS

We carried out a cross-sectional study amongst children aged six to seven; they were selected through probabilistic, stratified and conglomerated sampling. The prevalence of BA, AR, and AD was identified with the use of the questionnaire provided by The International Study of Asthma and Allergies in Childhood, additionally, we inquired about each child's family history of atopy, their exposure to farm animals, the intake of unpasteurised cow's milk, and the number of siblings related to every child. We used logistic regression and multivariate analysis to determine the correlation between asthma, allergic diseases, and rural environment.

RESULTS

We included 189/1003 (18.8%) children from a rural environment, and 814/1003 (81.2%) from an urban area. BA and AR were associated to a family history of atopy (OR=2.15, p=0.001; OR=2.58, p=0.002, respectively). BA was more prevalent in males (OR=1.92, p=0.007). Notably, a higher number of siblings seems to protect against AR (OR=0.45, p=0.008). A paternal history of allergies was associated to AD.

CONCLUSIONS

In our study, we were unable to find protective factors in a rural environment that might decrease the prevalence of asthma or allergic diseases.

Childhood abuse and adult-onset asthma among Peruvian women

OBJECTIVE

Childhood abuse has been found to be associated with adult-onset asthma; however, this association has not been studied in low- and middle-income countries with a high burden of gender-based violence, including childhood abuse. We examined the odds of asthma diagnosed at age 18 or older in relation to history of physical and sexual abuse among Peruvian pregnant women.

METHODS

This cross-sectional study collected demographic characteristics, history of abuse and asthma diagnoses from 3081 pregnant women. Logistic regression procedures estimated adjusted odds ratios and 95% confidence intervals (aOR, [95% CI]) for asthma diagnoses in relation to abuse.

RESULTS

Overall, 71% of the women reported a history of abuse (<18 years), and asthma was diagnosed among 2.6% of the cohort participants. The prevalence of physical only, sexual only and both physical and sexual childhood abuse was 38, 8 and 25%, respectively. The history of physical only (1.16, [0.63-2.17]), sexual only (2.11, [0.92-4.84]) or both physical and sexual childhood abuse (1.75, [0.94-3.29]) was positively associated with increased odds of asthma, although the associations were not statistically significant in the multivariate analysis. However, the odds of asthma increased with increasing numbers of abuse events (p_trend = 0.01). Women who reported ≥3 abuse events had an increased odds of asthma (1.88, [1.06-3.34]).

CONCLUSION

Our results do not provide convincing evidence that childhood abuse is associated with asthma among pregnant Peruvian women; however, we were able to demonstrate that an increased number of abuse events are associated with asthma. Further research is required to better understand the effects of abuse on asthma.

Estimating pediatric asthma prevalence in rural senegal: A cross-sectional survey

RATIONALE

In Senegal, the prevalence of childhood asthma and utilization of appropriate asthma therapies is unknown.

METHODOLOGY

We used the International Study of Asthma and Allergies in Childhood (ISAAC) survey instrument to assess childhood respiratory health in rural Senegal. We interviewed the caregivers of children aged 5 through 8 years of age in the four largest Niakhar villages in August 2012.

RESULTS

We interviewed 1,103 primary caregivers for 1,513 children, representing 91% of all age-eligible children in the study area. Overall, 206 (14%) children had wheeze at any time in the past, 130 (9%) had wheeze within the past year, and only 41 (3%) reported a clinical diagnosis of asthma. Among children with wheeze within the past year, 81 (62%) had symptoms of severe asthma. Nocturnal cough was reported in 186 (14%) children who denied any history of wheezing illness. Only four (3%) children with wheeze in the past year had ever received bronchodilator therapy. Children with wheeze in the past year were significantly more likely to seek medical care for respiratory symptoms and to be perceived as less healthy than their peers. Children of lower socioeconomic status were significantly more likely to have wheeze.

CONCLUSIONS

Nearly one in ten children in Niakhar, Senegal had symptoms suggestive of asthma; however, few children have a diagnosis of asthma or use appropriate therapies. This study highlights an opportunity to raise community awareness of asthma in rural Senegal and to increase access to appropriate medical therapies. Pediatr Pulmonol. 2017;52:303-309. © 2016 Wiley Periodicals, Inc.

Cross-Sectional Comparison of Sleep-Disordered Breathing in Native Peruvian Highlanders and Lowlanders

Pham, Luu V., Christopher Meinzen, Rafael S. Arias, Noah G. Schwartz, Adi Rattner, Catherine H. Miele, Philip L. Smith, Hartmut Schneider, J. Jaime Miranda, Robert H. Gilman, Vsevolod Y. Polotsky, William Checkley, and Alan R. Schwartz. Cross-sectional comparison of sleep-disordered breathing in native Peruvian highlanders and lowlanders. High Alt Med Biol. 18:11-19, 2017.

BACKGROUND

Altitude can accentuate sleep disordered breathing (SDB), which has been linked to cardiovascular and metabolic diseases. SDB in highlanders has not been characterized in large controlled studies. The purpose of this study was to compare SDB prevalence and severity in highlanders and lowlanders.

METHODS

170 age-, body-mass-index- (BMI), and sex-matched pairs (age 58.2 ± 12.4 years, BMI 27.2 ± 3.5 kg/m2, and 86 men and 84 women) of the CRONICAS Cohort Study were recruited at a sea-level (Lima) and a high-altitude (Puno, 3825 m) setting in Peru. Participants underwent simultaneous nocturnal polygraphy and actigraphy to characterize breathing patterns, movement arousals, and sleep/wake state. We compared SDB prevalence, type, and severity between highlanders and lowlanders as measured by apnea-hypopnea index (AHI) and pulse oximetry (SPO2) during sleep.

RESULTS

Sleep apnea prevalence was greater in highlanders than in lowlanders (77% vs. 54%, p < 0.001). Compared with lowlanders, highlanders had twofold elevations in AHI due to increases in central rather than obstructive apneas. In highlanders compared with lowlanders, SPO2 was lower during wakefulness and decreased further during sleep (p < 0.001). Hypoxemia during wakefulness predicted sleep apnea in highlanders, and it appears to mediate the effects of altitude on sleep apnea prevalence. Surprisingly, hypoxemia was also quite prevalent in lowlanders, and it was also associated with increased odds of sleep apnea.

CONCLUSIONS

High altitude and hypoxemia at both high and low altitude were associated with increased SDB prevalence and severity. Our findings suggest that a large proportion of highlanders remain at risk for SDB sequelae.

Clinical Roles of Lung Volumes Detected by Body Plethysmography and Helium Dilution in Asthmatic Patients: A Correlation and Diagnosis Analysis

Roles of lung volumes in asthma remain controversial. We aimed to evaluate the efficacy of lung volumes in differentiating asthma severity levels. Consecutive outpatients with chronic persistent asthma were enrolled, and body plethysmography (BP) and helium dilution (HD) were performed simultaneously to extract RV%pred, TLC%pred, and RV/TLC. Significant negative correlations were found between FEV₁%pred and RV%pred (r = -0.557, P < 0.001), TLC%pred (r = -0.387, P < 0.001), and RV/TLC (r = -0.485, P < 0.001) measured by BP, as well as difference in volumes between these two techniques (ΔRV%pred, ΔTLC%pred and ΔRV/TLC). In mild and moderate asthma, AUC of RV%pred detected by BP and ΔTLC%pred was 0.723 (95%CI 0.571-0.874, P = 0.005) and 0.739 (95%CI 0.607-0.872, P = 0.002) with sensitivity and specificity being 79.41% and 88.24%, and 65.22% and 56.52% at cut-off of 145.40% and 14.23%, respectively. In moderate and severe asthma, AUC of RV%pred detected by BP and ΔTLC%pred was 0.782 (95%CI 0.671-0.893, P < 0.001) and 0.788 (95%CI 0.681-0.894, P < 0.002) with sensitivity and specificity being 77.78% and 97.22%, and 73.53% and 52.94% at cut-off of 179.85% and 20.22%, respectively. In conclusion, lung volumes are reliable complement of FEV₁ in identifying asthma severity levels.

Short-Term Fluctuations in Air Pollution and Asthma in Scania, Sweden. Is the Association Modified by Long-Term Concentrations?

Background and aims

Asthma is one of the most common respiratory diseases in the world. Research has shown that temporal increases in air pollution concentrations can aggravate asthma symptoms. The aim of this study was to assess whether individuals living in areas with higher air pollution concentrations responded differently to short-term temporal exposure to air pollution than those living in lower air pollution areas.

Method

The study was designed as a case-crossover study in Scania, Sweden. Outcome data was visits to primary health care clinics with asthma as the main complaint during the years 2007 to 2010. Nitrogen dioxide levels were obtained from 21 different air pollution monitoring stations. Short-term exposure was defined as the average concentration four days prior to the visit. Data was pooled for areas above and below a two-year average NO2 concentration of 10 μg/m3, dispersion modelled with an emission database.

Results

The short-term association between NO2 and asthma visits seemed stronger in areas with NO2 levels below 10 μg/m3, with an odds ratio (OR) of 1.15 (95% confidence interval (CI): 1.08–1.23) associated with a 10 μg/m3 increase in NO₂ compared to areas above 10 μg/m3 NO2 levels, where corresponding OR of 1.09 (95% CI: 1.02–1.17). However, this difference was not statistically significant. (p = 0.13)

Conclusions

The study provided some evidence, although not statistically significant, that short-term associations between air pollution and asthma may depend on background air pollution levels. However, we cannot rule out that the association is due to other spatially dependent factors in Scania. The study should be reproduced in other study areas.

Job strain, bullying and violence at work and asthma in Peruvian cleaners-a cross-sectional analysis

OBJECTIVES

An increased asthma prevalence was found in cleaners. Many of them work in precarious employment conditions, potentially leading to stress, a known risk factor for asthma. We aimed to analyze whether asthma in cleaners might partly be explained by psychosocial working conditions.

METHODS

The study population of this cross-sectional study included 199 cleaners employed at regional public health services in Puno Province (Peru). They were compared to 79 unexposed workers from Lima, Peru (response 83%). Both groups answered the short version of the European Working Condition Survey and a modified version of the European Community Respiratory Health screening questionnaire. After multiple imputation, the association between psychosocial working conditions and asthma (wheeze without cold or use of asthma medication) was assessed.

RESULTS

The 12-months prevalence of asthma was 22% among cleaners versus 5% among unexposed workers (pChi(2) = .001). Cleaners were more likely than unexposed workers to work with temporary or sub-contracts, have a high employment insecurity, high strain working conditions and low social support (all pChi(2) < .05). Twenty-six percent vs. 10% reported a high bullying score; 39% vs. 8% had experienced violence at work (both pChi(2) < .001). High bullying score (adjusted Odds Ratio 5.6; 95% Confidence Interval 1.5-21.4) and violence (2.4; 1.1-5.4) were the main predictors of asthma. Taking these factors into account, being a cleaner was not statistically significantly associated with the outcome (3.5; 0.9-13.8).

CONCLUSIONS

Poor psychosocial working conditions of cleaners may partly explain the high prevalence of asthma. The underlying mechanism might be a stress-induced inflammatory immune response.