| 1. |
- Backman, Helena, et al.
(författare)
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Determinants of severe asthma : a long-term cohort study in northern Sweden
- 2022
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Ingår i: Journal of Asthma and Allergy. - : Dove press. - 1178-6965. ; 15, s. 1429-1439
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Tidskriftsartikel (refereegranskat)abstract
- Background: Risk factors for severe asthma are not well described. The aim was to identify clinical characteristics and risk factors at study entry that are associated with severe asthma at follow-up in a long-term prospective population-based cohort study of adults with asthma.Methods: Between 1986 and 2001, 2055 adults with asthma were identified by clinical examinations of population-based samples in northern Sweden. During 2012–2014, n = 1006 (71% of invited) were still alive, residing in the study area and participated in a follow-up, of which 40 were identified as having severe asthma according to ERS/ATS, 131 according to GINA, while 875 had other asthma. The mean follow-up time was 18.7 years.Results: Obesity at study entry and adult-onset asthma were associated with severe asthma at follow-up. While severe asthma was more common in those with adult-onset asthma in both men and women, the association with obesity was observed in women only. Sensitization to mites and moulds, but not to other allergens, as well as NSAID-related respiratory symptoms was more common in severe asthma than in other asthma. Participants with severe asthma at follow-up had lower FEV1, more pronounced FEV1 reversibility, and more wheeze, dyspnea and nighttime awakenings already at study entry than those with other asthma.Conclusion: Adult-onset asthma is an important risk factor for development of severe asthma in adults, and obesity increased the risk among women. The high burden of respiratory symptoms already at study entry also indicate long-term associations with development of severe asthma.
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| 2. |
- Backman, Helena, et al.
(författare)
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Eosinophilic inflammation and lung function decline in a long-term follow-up of a large population-based asthma cohort
- 2018
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Ingår i: European Respiratory Journal. - : European Respiratory Society. - 0903-1936 .- 1399-3003. ; 52
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The relationship between lung function decline and airway inflammation among asthmatics has important therapeutic implications, but has rarely been studied in large samples or in population-based asthma cohorts.A population-based adult asthma cohort (n=2055) was recruited during 1986-2001 and clinically examined including spirometry. In 2012-2014, all still eligible subjects (n=1425) were invited to a clinical follow-up including spirometry, blood sampling, and a structured interview, and n=1006 participated (55% women, mean age 59y, 32-92y). Linear regression was performed with age, sex, smoking habits, year of first examination, family history of asthma, socioeconomic status, eosinophils (EOS)>=0.3x109/L, and neutrophils (NEUT)>=5.0x109/L as independent variables and pre-bronchodilator FEV1 decline/year (ml and % of predicted [pp], respectively) as dependent. In secondary models, both ICS use at baseline and ICS use at follow-up were also included.The mean annual FEV1 decline in ml (pp) among asthmatics with EOS<0.3, 0.4>EOS>=0.3 and EOS>=0.4x109/L, respectively, was 26ml (0.03pp), 29ml (0.10pp) and 34ml (0.27pp) (p<0.001). In adjusted analyses, EOS>=0.3 was significantly associated with FEV1 decline, both in terms of ml (4ml excess annual decline vs EOS<0.3) and pp. The association between EOS and FEV1 decline in pp, but not ml, remained when additionally adjusted for ICS use. The association with NEUT>=5.0x109/L was less clear.On group level, adult asthmatics with higher levels of eosinophils in blood have a history of excess FEV1 decline compared to asthmatics with lower levels of eosinophil inflammation, independent of other factors such as ICS use.
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| 3. |
- Backman, Helena, et al.
(författare)
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FEV1 decline in relation to blood eosinophils and neutrophils in a population-based asthma cohort
- 2020
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Ingår i: World Allergy Organization Journal. - : Elsevier. - 1939-4551. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- Background: The relationship between lung function decline and eosinophils and neutrophils has important therapeutic implications among asthmatics, but it has rarely been studied in large cohort studies.Objective: The aim is to study the relationship between blood eosinophils and neutrophils and FEV1 decline in a long-term follow-up of a population-based adult asthma cohort.Methods: In 2012-2014, an adult asthma cohort was invited to a follow-up including spirometry, blood sampling, and structured interviews, and n = 892 participated (55% women, mean age 59 y, 32-92 y). Blood eosinophils, neutrophils and FEV 1 decline were analyzed both as continuous variables and divided into categories with different cut-offs. Regression models adjusted for smoking, exposure to vapors, gas, dust, or fumes (VGDF), use of inhaled and oral corticosteroids, and other possible confounders were utilized to analyze the relationship between eosinophils and neutrophils at follow-up and FEV1 decline.Results: The mean follow-up time was 18 years, and the mean FEV 1 decline was 27 ml/year. The annual FEV1 decline was related to higher levels of both blood eosinophils and neutrophils at follow-up, but only the association with eosinophils remained when adjusted for confounders. Further, the association between FEV1 decline and eosinophils was stronger among those using ICS. With EOS <0.3 × 109/L as reference, a more rapid decline in FEV1 was independently related to EOS ≥0.4 × 109/L in adjusted analyses.Conclusions and clinical relevance: Besides emphasizing the importance of smoking cessation and reduction of other harmful exposures, our real-world results indicate that there is an independent relationship between blood eosinophils and FEV1 decline among adults with asthma.
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| 4. |
- Backman, Helena, et al.
(författare)
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Severe asthma : A population study perspective
- 2019
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Ingår i: Clinical and Experimental Allergy. - : John Wiley & Sons. - 0954-7894 .- 1365-2222. ; 49:6, s. 819-828
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundSevere asthma is a considerable challenge for patients, health care professionals and society. Few studies have estimated the prevalence of severe asthma according to modern definitions of which none based on a population study.ObjectiveTo describe characteristics and estimate the prevalence of severe asthma in a large adult population‐based asthma cohort followed for 10‐28 years.MethodsN=1006 subjects with asthma participated in a follow‐up during 2012‐14, when 830 (mean age 59y, 56% women) still had current asthma. Severe asthma was defined according to three internationally well‐known criteria: the ATS workshop definition from 2000 used in the US Severe Asthma Research Program (SARP), the 2014 ATS/ERS Task force definition and the GINA 2017. All subjects with severe asthma according to any of these criteria were undergoing respiratory specialist care, and were also contacted by telephone to verify treatment adherence.ResultsThe prevalence of severe asthma according to the three definitions was 3.6% (US SARP), 4.8% (ERS/ATS Taskforce), and 6.1% (GINA) among subjects with current asthma. Although all were using high ICS doses and other maintenance treatment, >40% had uncontrolled asthma according to the asthma control test. Severe asthma was related to age >50 years, nasal polyposis, impaired lung function, sensitization to aspergillus, and tended to be more common in women. Further, neutrophils in blood significantly discriminated severe asthma from other asthma.Conclusions and clinical relevanceSevere asthma differed significantly from other asthma in terms of demographic, clinical and inflammatory characteristics, results suggesting possibilities for improved treatment regimens of severe asthma. The prevalence of severe asthma in this asthma cohort was 4‐6%, corresponding to approximately 0.5% of the general population.
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| 5. |
- Backman, Helena, et al.
(författare)
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Severe asthma among adults : Prevalence and clinical characteristics
- 2018
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Ingår i: European Respiratory Journal. - : European Respiratory Society. - 0903-1936 .- 1399-3003. ; 52
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Severe asthma is a considerable challenge for patients, health care professionals and society. Few studies have estimated the prevalence of severe asthma according to modern definitions of which none based on a population study.Methods: We estimated the prevalence and studied characteristics of severe asthma in a large adult population-based asthma cohort followed for 10-28 years in northern Sweden: 1006 subjects participated in a follow-up during 2012-14, when 830 (82.5%) still had current asthma (mean age 59y, 32-92y, 56% women). Severe asthma was defined according to three internationally well-known criteria: the US SARP, ATS/ERS and GINA. All subjects with severe asthma were undergoing respiratory specialist care, and were also contacted by telephone to verify adherence to treatment.Results: The prevalence of severe asthma according to the three definitions was 3.6% (US SARP), 4.8% (ERS/ATS), and 6.1% (GINA) among subjects with current asthma. Although all were using high ICS doses and other maintenance treatment, >40% had uncontrolled asthma and <10% had controlled asthma according to the ACT. Severe asthma was related to age >50 years, nasal polyposis, decreased FEV1, not fully reversible airway obstruction, sensitization to aspergillus, elevated neutrophils and partly to eosinophils, and tended to be more common in women.Conclusion: The prevalence of severe asthma in this asthma cohort was 4-6%, corresponding to approximately 0.5% of the population in northern Sweden. A substantial proportion of those with severe asthma had uncontrolled disease, and severe asthma differed significantly from other asthma in terms of both clinical and inflammatory characteristics.
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| 6. |
- Eklund, Linda, 1982-
(författare)
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Cold air, physical activity, and the airways : epidemiological and experimental studies
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Cold exposure is associated with increased morbidity and mortality. Elite cross-country skiers are regularly exposed to cold, dry air and have a high prevalence of asthma compared to the Swedish population. However, evidence is limited regarding how a combination of sub-zero temperatures and physical activity affects the airways of healthy individuals.Aims: The aims of this thesis were to study the prevalence of self-reported asthma, age at asthma onset, and predictors of asthma in Swedish endurance athletes, with a focus on cross-country skiers. This thesis also aimed to assess the effects of subzero temperature and physical activity on healthy human airways.Methods: Study 1 (papers I-II) consisted of an annual postal questionnaire investigating asthma prevalence and predictors of asthma that was sent to invited athletes in 2011–2015. Invited athletes were Swedish elite cross-country skiers, biathletes, ski orienteers, and orienteers from Swedish National Elite Sport Schools, national teams, and Swedish Ski Universities, or top orienteers according to national ranking. Former Swedish Olympic skiers and an adolescent reference group were invited in 2013. Paper I included cross-sectional data from 2011 for adolescents/adults and from 2013 for former skiers (n=491). Paper II included adolescent elite skiers (n=253) from the Swedish National Elite Sport Schools invited during 2011-2013, as well as a reference group (n=500) aged 16-20 years that was matched for school municipalities and invited in 2013. Study 2 (papers III-IV) comprised whole-body experimental exposure of healthy adults to sub-zero temperatures and exercise in an environmental chamber. Lung function and biochemical markers in plasma and urine were measured before and after exposure. Symptoms were investigated before, during, and after exposure. In both trials, study subjects were exposed for 50 min on two separate occasions in randomized order. Paper III comprised 31 subjects and moderate-intensity exercise (30 min running at 62-78% of VO2max), at 10°C vs. -10°C. Paper IV included 29 subjects and hard-intensity exercise (30 min of running at 85% of VO2max) vs. rest, both at a temperature of -15°C.Results: In paper I, the overall response rate was 82%. Athletes reporting asthma in the different age categories were: 29% of skiers (38% of the female skiers) and 17% of orienteers (p=0.071) among 15 to 19-year-olds; 35% of skiers and 16% of orienteers (p=0.029) among 20 to 34-year-olds; and 22% of the skiers aged 40–94 years. Asthma onset occurred in adolescence among the active athletes. Increasing age, female sex, allergy, family history of allergy/asthma, and being a skier were predictors of self-reported physician-diagnosed asthma. In paper II, the response rate was 96% for skiers and 48% for the reference group. Skiers reported a higher prevalence of self-reported physician-diagnosed asthma than the reference population (27% vs. 19%, p=0.046). Physician-diagnosed asthma was more frequently reported by female skiers than male skiers (34% vs. 20%, p=0.021). Median age at asthma onset was higher among skiers than in the reference population (12.0 vs. 8.0 years; p<0.001). Female sex, family history of asthma, nasal allergy, and being a skier were risk factors associated with self-reported physician-diagnosed asthma. In paper III, exercise at -10°C decreased FEV1 (p=0.002) and FEV1/FVC (p<0.001) and increased resistance at 20 Hz (p=0.016) to similar magnitudes as exercise at 10°C. Exercise at 10°C increased reactance (p=0.005), which differed (p=0.042) from a less pronounced response after exercise at -10°C. Plasma CC16 increased similarly after both exposures, without significant differences. More intense symptoms from the upper airways were reported after exercise at -10°C than at 10°C. Symptoms from the lower airways were few and mild. In paper IV, FEV1 decreased from baseline after both rest (p<0.001) and exercise (p=0.012) at -15°C, with no differences between exposures. Compared to rest, exercise at -15°C induced greater increases in reactance (p=0.023), plasma CC16 (p<0.001), and plasma IL-8 (p<0.001). Exercise gave rise to more intense symptoms from the lower airways, whereas rest induced more general symptoms.Conclusions: In the 1990s, a high prevalence of physician-diagnosed asthma was reported among Swedish elite cross-country skiers, and our studies show that this has not changed. Asthma onset commonly occurs in early adolescence among skiers, in the beginning of their career. Being an elite skier is an independent risk factor associated with asthma. Targeted preventive measures should be introduced at an early age to avoid the development of asthma in endurance athletes. Healthy individuals performing short-duration moderate- and hard-intensity exercise in sub-zero temperatures responded with lung function changes and an increased airway permeability. These findings warrant further research on airway responses to sub-zero temperatures in vulnerable individuals such as elite endurance athletes.
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