Nara Tagiyeva

Changes in the prevalence of asthma, eczema and hay fever in pre‐pubertal children: a 40‐year perspective

Surveys of primary schools children in Aberdeen carried out in 1964, 1989, 1994 and 1999 suggested a slowing of the increase in parent-reported wheeze between 1994 and 1999. To assess whether this pattern had continued, questionnaires were distributed to 5712 children aged 7-12 years in the same schools in 2004. A total of 3271 (57.3%) completed questionnaires were returned. As in earlier surveys the results were divided into those for younger children (school years 3-4; age 7-9 years) and older children (school years 5-7; age 9-12 years). Compared with 1999, the 2004 results showed a decrease in the proportion of children with wheeze in the last 3 years from 30.1% to 23.3% (P < 0.001) in the younger group and from 27.6% to 25.1% (P = 0.052) in the older group. There was no significant change in the lifetime prevalence of asthma in either the younger or the older group, but the lifetime prevalence of eczema and hay fever increased by around 10% in both the younger and older groups (all P < 0.001). The differences in the time trends for the different conditions suggest that the causal factors for wheeze and asthma differ from those for other allergic diseases of childhood.

Parental occupation is a risk factor for childhood wheeze and asthma.

The present birth cohort study investigated whether or not childhood wheeze and asthma are associated with parental exposure to occupational sensitisers that cause asthma. Parental occupation, from the Avon Longitudinal Study of Parents and Children (ALSPAC), was related to wheeze, asthma, ventilatory function, airway responsiveness and atopic sensitisation in children aged 0–102 months. Occupation was recorded for 11,193 mothers and 9,473 fathers antenatally, and for 4,631 mothers and 5,315 fathers post-natally. Childhood respiratory outcomes were not associated with parental occupational exposure to diisocyanates, glues/resins, dyes, animal dust, solder, enzymes and wood dust. Maternal post-natal occupational exposure to latex and/or biocides/fungicides increased the likelihood of childhood wheeze and asthma. High levels of latex or biocide/fungicide exposure were associated with an OR (95% CI) of 1.26 (1.07–1.50) and 1.22 (1.02–2.05), respectively, for wheezing up to 81 months. Combined maternal latex and biocide/fungicide exposure increased the likelihood of childhood wheeze (1.22 (1.03–1.43)) and asthma. High paternal occupational flour dust exposure was associated with an increased likelihood of wheeze after 30 months (2.31 (1.05–5.10)) and asthma by 91 months (3.23 (1.34–7.79)). Maternal occupational exposure to latex and/or biocides and paternal exposure to flour dust increases the risk of childhood asthma. Further studies in this area are justified.

Volatile organic compounds and risk of asthma and allergy: a systematic review

Volatile organic compounds (VOCs) are ubiquitous domestic pollutants. Their role in asthma/allergy development and exacerbations is uncertain. This systematic review investigated whether domestic VOC exposure increases the risk of developing and/or exacerbating asthma and allergic disorders. We systematically searched 11 databases and three trial repositories, and contacted an international panel of experts to identify published and unpublished experimental and epidemiological studies. 8455 potentially relevant studies were identified; 852 papers were removed after de-duplication, leaving 7603 unique papers that were screened. Of these, 278 were reviewed in detail and 53 satisfied the inclusion criteria. Critical appraisal of the included studies indicated an overall lack of high-quality evidence and substantial risk of bias in this body of knowledge. Aromatics (i.e. benzenes, toluenes and xylenes) and formaldehyde were the main VOC classes studied, both in relation to the development and exacerbations of asthma and allergy. Approximately equal numbers of studies reported that exposure increased risks and that exposure was not associated with any detrimental effects. The available evidence implicating domestic VOC exposure in the risk of developing and/or exacerbating asthma and allergy is of poor quality and inconsistent. Prospective, preferably experimental studies, investigating the impact of reducing/eliminating exposure to VOC, are now needed in order to generate a more definitive evidence base to inform policy and clinical deliberations in relation to the management of the now substantial sections of the population who are either at risk of developing asthma/allergy or living with established disease. Investigation of VOCs in relation to developing or exacerbating asthma or allergy indicates new studies are required http://ow.ly/wEJ19

Changing trends in asthma in 9–12 year olds between 1964 and 2009

Introduction Childhood asthma is a common condition and the prevalence has increased in many countries during the late 20th century. The Aberdeen schools asthma surveys reported rising lifetime prevalence of asthma between 1964 and 2004 in children aged 9–12 years, but a fall in wheeze in the last 3 years between 1999 and 2004. The present study tested the hypothesis that lifetime childhood asthma prevalence has fallen since 2004. Methods Children aged 9–12 years who attended the same schools surveyed since 1964 were invited to participate. A lifetime history of asthma or eczema and also wheeze in the past 3 years and 12 months was ascertained from a questionnaire. Trends over 1999, 2004 and 2009 were analysed with adjustment for age, gender and an index of deprivation. Results There were 2253 eligible children and 1196 (53%) questionnaires were returned. The lifetime prevalence of asthma rose from 24.3% in 1999 to 28.4% in 2004 but fell to 22.1% in 2009 (p<0.001), while wheeze in the last 3 years fell from 27.9% in 1999 to 25.2% in 2004 and fell further to 22.2% in 2009 (p<0.001). The lifetime prevalence of eczema among 9–12 year olds was 21.4% in 1999, 34.1% in 2004 and 30.7% in 2009 (p<0.001). Reductions in symptom prevalences between 2004 and 2009 were significant for girls but not boys. Conclusion The prevalence of lifetime asthma and wheeze appear to have fallen in school children, especially girls, although the low response rate means some caution is required when interpreting the results. Asthma prevalence remains high and the underlying mechanisms remain incompletely understood.

Domestic exposure to volatile organic compounds in relation to asthma and allergy in children and adults.

Over the past decades, the prevalence of asthma, allergic disease and atopy has increased significantly and in parallel with the increased use of products and materials emitting volatile organic compounds (VOCs) in the indoor environment. The purpose of this review is to examine the evidence of the relationship between quantitatively measured domestic exposure to VOCs and allergic diseases and allergy in children and adults. Sources, potential immune-inflammatory mechanisms and risks for development and severity of asthma and allergy have been addressed. Available evidence is based on studies that have mainly used observational designs of variable quality. Total, aromatic, aliphatic, microbial VOCs and aldehydes have been the most widely investigated VOC classes, with formaldehyde being the most commonly examined single compound. Overall, the evidence is inadequate to draw any firm conclusions. However, given indicative evidence from a few high-quality studies and significant potential for improvements in asthma outcomes in those with established disease, there is a need to consider undertaking further investigation of the relationship between domestic VOC exposure and asthma/allergy outcomes that should encompass both high-quality, robust observational studies and ultimately clinical trials assessing the impact of interventions that aim to reduce VOC exposure in children and adults with asthma.

Two main subtypes of wheezing illness? Evidence from the 2004 Aberdeen schools asthma survey

To compare risk factors for wheezy bronchitis (WB) and multi‐trigger wheeze (MTW) in pre‐pubertal children along the spectrum of disease severity. Cross‐sectional survey of children aged 7–12 yr in Aberdeen city primary schools in 2004 using parent‐completed questionnaires as used in surveys in 1964, 1989, 1994, and 1999. Children were grouped into five categories: no wheeze in the past three years, non‐severe wheeze triggered only by a cold (non‐severe WB), non‐severe wheeze triggered by other factors (non‐severe MTW), severe WB, or severe MTW. Severe wheeze was defined as greater than four wheezing attacks, greater than or equal to one disturbed night per week, or speech limitation in the last 12 months. Questionnaires were returned by 3271 children (57.3%), of whom 7.4% had WB (6.1% non‐severe and 1.3% severe) and 17.2% had MTW (9.4% non‐severe and 7.8% severe). Severe disease was more frequent in children with MTW (31.8%) than in those with WB (5.1%). Whereas the prevalence of MTW had increased since 1964, the prevalence of WB had remained stable over this period. After adjustment for confounders, age had no influence on either wheeze type, and male sex was only associated with non‐severe WB [OR 1.44, 95% confidence intervals (1.03–2.02)]. In the WB group eczema or/and hay fever in the child were more strongly associated with severe wheeze [OR 3.28(1.49–7.23) vs. OR 1.84(1.31–2.60)]. In the MTW group, this association was noticeably higher than in the WB group, but did not differ much between non‐severe and severe wheeze [OR 5.46(3.70–7.20) and OR 6.01(4.1–8.75) respectively]. The presence of any allergic diseases in either parent increased the odds for non‐severe and severe MTW at the same level of magnitude [OR 1.92(1.38–2.68) and OR 1.92(1.34–2.76) respectively], and statistically non‐significantly for severe WB [OR 1.75(0.78–3.94)]. Living in a deprived area increased both severe WB and severe MTW, reaching statistical significance only for severe MTW [OR 1.96(1.39–2.78)]. Smoking in the house was associated with increased risk of WB and MTW of any severity. WB and MTW differ in prevalence trends and severity. Within severity levels, the influence of age, allergic diseases in children and parents also differed between these two wheezing subtypes.

Diverging prevalences and different risk factors for childhood asthma and eczema: a cross-sectional study

Objective To compare the prevalences of and risk factors for asthma, wheeze, hay fever and eczema in primary schoolchildren in Aberdeen in 2014. Design Cross-sectional survey. Setting Primary schools in Aberdeen, North-East Scotland. Participants Children in Scottish school years primary 1–7 were handed a questionnaire by their class teacher to be completed by their parents and returned to the researchers by post or online. Main outcome measures Lifetime history of asthma, eczema and hay fever, and recent history of wheeze. Results 41 schools agreed to participate (87%). 11 249 questionnaires were distributed and 3935 returned (35%). A parent-reported lifetime history of asthma, eczema and hay fever was present in 14%, 30% and 24% of children, respectively. The odds of lifetime asthma increased with age (OR 1.1 per year, 95% CI 1.1 to 1.2), male sex (OR 1.89, 95% CI 1.4 to 2.3), parental smoking (OR 1.7, 95% CI 1.2 to 2.3) and eczema (OR 6.6, 95% CI 5.2 to 8.4). Prevalence of recent wheeze was also reported to be 14% and was positively associated with male sex, parental smoking and eczema. In contrast, parental eczema was the only identified predictor of childhood eczema risk. Conclusions The lifetime prevalence of asthma in primary schoolchildren was 14% in this survey, approximately half the prevalence of eczema. We report diverging prevalences in relation to previous studies in our locality, and different risk factors for asthma and eczema. These findings suggest that asthma and eczema are unlikely to have a common origin.

Early-life residential exposure to soil components in rural areas and childhood respiratory health and allergy

The increase in asthma and allergies has been attributed to declining exposure to environmental microorganisms. The main source of these is soil, the composition of which varies geographically and which is a major component (40-45%) of household dust. Our hypothesis-generating study aimed to investigate associations between soil components, respiratory health and allergy in a Scottish birth cohort. The cohort was recruited in utero in 1997/8, and followed up at one, two and five years for the development of wheezing, asthma and eczema. Lung function, exhaled nitric oxide and allergic sensitization were measured at age five in a subset. The Scottish Soils Database held at The James Hutton Institute was linked to the birth cohort data by the residential postcode at birth and five years. The soil database contained information on size separates, organic matter concentration, pH and a range of inorganic elements. Soil and clinical outcome data were available for 869, 790 and 727 children at one, two and five years. Three hundred and fifty nine (35%) of children had the same address at birth and five years. No associations were found between childhood outcomes and soil content in the residential area at age five. The soil silt content (2-20 μm particle size) of the residential area at birth was associated with childhood wheeze (adjusted OR 1.20, 95% CI [1.05; 1.37]), wheeze without a cold (1.41 [1.18; 1.69]), doctor-diagnosed asthma (1.54 [1.04; 2.28]), lung function (FEV1: beta -0.025 [-0.047;-0.001]) and airway inflammation (FENO: beta 0.15 [0.03; 0.27]) at age five, but not with allergic status or eczema. Whilst residual confounding is the most likely explanation for the associations reported, the results of this study lead us to hypothesise that early life exposure to residential soil silt may adversely influence childhood respiratory health, possibly because of the organic components of silt.

Changes in the relationship between asthma and associated risk factors over fifty years

Childhood asthma is a common condition whose prevalence is changing. We hypothesized that the relationship between asthma and associated risk factors has changed over a 50‐year period.

Occupational exposure to asthmagens and adult onset wheeze and lung function in people who did not have childhood wheeze: A 50-year cohort study

BACKGROUND There are few prospective studies that relate the development of adult respiratory disease with exposure to occupational asthmagens. OBJECTIVE To evaluate the risk of adult onset wheeze (AOW) and obstructive lung function associated with occupational exposures over 50years. METHODS A population-based randomly selected cohort of children who had not had asthma or wheezing illness, recruited in 1964 at age 10-15years, was followed-up in 1989, 1995, 2001 and 2014 by spirometry and respiratory questionnaire. Occupational histories were obtained in 2014 and occupational exposures determined with an asthma-specific job exposure matrix. The risk of AOW and lung function impairment was analysed in subjects without childhood wheeze using logistic regression and linear mixed effects models. RESULTS All 237 subjects (mean age: 61years, 47% male, 52% ever smoked) who took part in the 2014 follow-up had completed spirometry. Among those who did not have childhood wheeze, spirometry was measured in 93 subjects in 1989, in 312 in 1995 and in 270 subjects in 2001 follow-up. For longitudinal analysis of changes in FEV1 between 1989 and 2014 spirometry records were available on 191 subjects at three time points and on 45 subjects at two time points, with a total number of 663 records. AOW and FEV1<LLN were associated with occupational exposure to food-related asthmagens (adjusted odds ratios (adjORs) 95% CI: 2.7 [1.4, 5.1] and 2.9 [1.1, 7.7]) and biocides/fungicides (adjOR 95% CI: 1.8 [1.1, 3.1] and 3.4 [1.1, 10.8]), with evident dose-response effect (p-trends<0.05). Exposure to food-related asthmagens was also associated with reduced FEV1, FVC and FEF25-75% (adjusted regression coefficients 95% CI: -7.2 [-12.0, -2.4], -6.2 [-10.9, -1.4], and -13.3[-23.4, -3.3]). Exposure to wood dust was independently associated with AOW, obstructive lung function and reduced FEF25-75%. Excess FEV1 decline of 6-8ml/year was observed with occupational exposure to any asthmagen, biocides/fungicides and food-related asthmagens (p<0.05). CONCLUSIONS This longitudinal study confirmed previous findings of increased risks of adult onset wheezing illness with occupational exposure to specific asthmagens. A novel finding was the identification of food-related asthmagens and biocides/fungicides as potential new occupational risk factors for lung function impairment in adults without childhood wheeze.