Spirometric criteria for asthma: adding further evidence to the debate

Prevalence, Diagnostic Utility and Associated Characteristics of Bronchodilator Responsiveness

Rationale: The prevalence and diagnostic utility of bronchodilator responsiveness (BDR) in a real-life setting is unclear. Objective: To explore this uncertainty in patients aged ⩾12 years with physician-assigned diagnoses of asthma, asthma and chronic obstructive pulmonary disease (COPD), or COPD in NOVELTY, a prospective cohort study in primary and secondary care in 18 countries. Methods: The proportion of patients with a positive BDR test in each diagnostic category was calculated using 2005 (ΔFEV1 or ΔFVC ⩾12% and ⩾200 ml) and 2021 (ΔFEV1 or ΔFVC >10% predicted) European Respiratory Society/American Thoracic Society criteria. Measurements and Main Results: We studied 3,519 patients with a physician-assigned diagnosis of asthma, 833 with a diagnosis of asthma + COPD, and 2,436 with a diagnosis of COPD. The prevalence of BDR was 19.7% (asthma), 29.6% (asthma + COPD), and 24.7% (COPD) using 2005 criteria and 18.1%, 23.3%, and 18.0%, respectively, using 2021 criteria. Using 2021 criteria in patients diagnosed with asthma, BDR was associated with higher fractional exhaled nitric oxide; lower lung function; higher symptom burden; more frequent hospital admissions; and greater use of triple therapy, oral corticosteroids, or biologics. In patients diagnosed with COPD, BDR (2021) was associated with lower lung function and higher symptom burden. Conclusions: BDR prevalence in patients with chronic airway diseases receiving treatment ranges from 18% to 30%, being modestly lower with the 2021 than with the 2005 European Respiratory Society/American Thoracic Society criteria, and it is associated with lower lung function and greater symptom burden. These observations question the validity of BDR as a key diagnostic tool for asthma managed in clinical practice or as a standard inclusion criterion for clinical trials of asthma and instead suggest that BDR be considered a treatable trait for chronic airway disease.

Value of Fractional Exhaled Nitric Oxide in Diagnosing Mild Asthma Responsive to Inhaled Corticosteroids

BACKGROUND

Mild asthma is often characterized by normal spirometric values and a negative bronchodilation test (BDT), which makes accurate diagnosis challenging. The aim of our study was to evaluate the diagnostic accuracy of fractional exhaled nitric oxide (FeNO) in mild asthma.

METHODS

In adults with symptoms suggestive of asthma and normal spirometry values, BDT, FeNO, BPT and skin prick testing were performed. Patients with positive BPT started inhaled corticosteroid (ICS) therapy. Those with positive response to ICS were considered asthmatics.

RESULTS

There were 142 asthmatics and 140 non-asthmatics. No significant difference was found in BDT between the groups, p = 0.233. Median FeNO levels were significantly higher in the asthma group (49.5 ppb) than in the non-asthma group (23 ppb), p < 0.001. BPT was positive in 145 (51.42%) and negative in 137 (48.58%) patients. Positive response to ICS treatment was recorded in 142/145 (97.9%) patients. In diagnosing asthma, FeNO ≥ 25 ppb had a sensitivity of 75.4% and specificity of 47.9%.

CONCLUSIONS

FeNO has insufficient sensitivity and specificity in mild asthma and the application of BPT is often necessary to establish an accurate diagnosis.

Clinical value of bronchodilator response for diagnosing asthma in steroid-naïve adults

Spirometry and testing for bronchodilator response have been recommended to detect asthma, and a bronchodilator response (BDR) of ≥12% and ≥200 mL has been suggested to confirm asthma. However, the clinical value of bronchodilation tests in newly diagnosed steroid-naïve adult patients with asthma remains unknown. We evaluated the sensitivity of BDR in forced expiratory volume in 1 s (FEV₁) as a diagnostic test for asthma in a real-life cohort of participants in the Seinäjoki Adult Asthma Study. In the diagnostic phase, 369 spirometry tests with bronchodilation were performed for 219 steroid-naïve patients. The fulfilment of each test threshold was assessed. According to the algorithm of the National Institute for Health and Care Excellence, we divided the patients into obstructive (FEV₁/forced vital capacity (FVC) <0.70) and non-obstructive (FEV₁/FVC ≥0.70) groups. Of the overall cohort, 35.6% fulfilled ΔFEV₁ ≥12% and ≥200 mL for the initial FEV₁, 18.3% fulfilled ΔFEV₁ ≥15% and ≥400 mL for the initial FEV₁, and 36.1% fulfilled ΔFEV₁ ≥9% of predicted FEV₁ at least once. One-third (31%) of these steroid-naïve patients was obstructive (pre-bronchodilator FEV₁/FVC <0.7). Of the obstructive patients, 55.9%, 26.5% and 48.5%, respectively, met the same thresholds. In multivariate logistic regression analysis, different thresholds recognised different kinds of asthma patients. In steroid-naïve adult patients, the current BDR threshold (ΔFEV₁ ≥12% and ≥200 mL) has low diagnostic sensitivity (36%) for asthma. In obstructive patients, sensitivity is somewhat higher (56%) but far from optimal. If the first spirometry test with bronchodilation is not diagnostic but asthma is suspected, spirometry should be repeated, and other lung function tests should be used to confirm the diagnosis.

Residual Volume Responsiveness Testing May Improve the Detection of Reversible Airway Obstruction in Asthma

BACKGROUND

Residual volume responsiveness to bronchodilator administration has been observed in subjects with chronic obstructive pulmonary disease. However, the prevalence of residual volume (RV) responsiveness has not been formally studied in asthma.

OBJECTIVE

To identify the prevalence and magnitude of RV responsiveness in asthma.

METHODS

Physician-diagnosed adult subjects with asthma on treatment for >12 months were prospectively recruited to perform spirometry and measurement of lung volumes using body plethysmography before and after administration of 360 μg of albuterol.

RESULTS

Among 120 subjects, 76% were women. The ethnic composition was 64% Caucasian, 32% Hispanic, and 13% African American. The mean age was 52 ± 15 years. The mean duration of asthma was 16 ± 15 years. The mean RV% responsiveness was -7.74 ± 14. Whereas patients with the lowest baseline forced expiratory volume in 1 second (FEV1) value showed the highest mean responsiveness (P = .001), the baseline RV value had minimal influence on RV responsiveness. Using -7.74% to define significant RV responsiveness, and ≥12% and ≥200 mL to define significant FEV1 responsiveness, more subjects showed isolated RV responsiveness (37%) compared with 6% with isolated FEV1 responsiveness and 14% with both FEV1 and RV responsiveness (P = .04). There was a minimal correlation between FEV1 responsiveness and RV responsiveness (r = 0.17, P = .06). The RV responsiveness was significantly associated with the wheeze score (P = .006) and dyspnea score (P = .029).

CONCLUSION

The addition of RV responsiveness testing to spirometry based responsiveness testing can improve the identification of reversible airway obstruction in asthma. RV responsiveness may be useful in monitoring symptoms associated with air trapping in asthma.

Bronchodilator reversibility as a diagnostic test for adult asthma: findings from the population-based Tasmanian Longitudinal Health Study

Bronchodilator reversibility (BDR) is often used as a diagnostic test for adult asthma. However, there has been limited assessment of its diagnostic utility. We aimed to determine the discriminatory accuracy of common BDR cut-offs in the context of current asthma and asthma–COPD overlap (ACO) in a middle-aged community sample.

The Tasmanian Longitudinal Health Study is a population-based cohort first studied in 1968 (n=8583). In 2012, participants completed respiratory questionnaires and spirometry (n=3609; mean age 53 years). Receiver operating characteristic (ROC) curves were fitted for current asthma and ACO using continuous BDR measurements. Diagnostic parameters were calculated for different categorical cut-offs.

Area under the ROC curve (AUC) was highest when BDR was expressed as change in forced expiratory volume in 1 s (FEV₁) as a percentage of initial FEV₁, as compared with predicted FEV₁. The corresponding AUC was 59% (95% CI 54–64%) for current asthma and 87% (95% CI 81–93%) for ACO. Of the categorical cut-offs examined, the European Respiratory Society/American Thoracic Society threshold (≥12% from baseline and ≥200 mL) was assessed as providing the best balance between positive and negative likelihood ratios (LR+ and LR−, respectively), with corresponding sensitivities and specificities of 9% and 97%, respectively, for current asthma (LR+ 3.26, LR− 0.93), and 47% and 97%, respectively, for ACO (LR+ 16.05, LR− 0.55).

With a threshold of ≥12% and ≥200 mL from baseline, a positive BDR test provided a clinically meaningful change in the post-test probability of disease, whereas a negative test did not. BDR was more useful as a diagnostic test in those with co-existent post-bronchodilator airflow obstruction (ACO).

Using the commonly adopted threshold, a positive BDR test provides a meaningful change in post-test probability of adult asthma, whereas a negative test does not. Discriminatory accuracy is much greater in those with coexistent post-BD airflow obstruction.https://bit.ly/3gPvlm8

Relationship between age and bronchodilator response at diagnosis in adult-onset asthma

BACKGROUND

Possible variation in bronchodilator response (BDR) according to age at the diagnosis of adult-onset asthma is unknown. Our aim was to assess if BDR in FEV1 is related to age at diagnosis of adult-onset asthma and how many subjects fulfill the 400 mL criterion of BDR, the suggested cut-off for asthma-like reversibility in asthma-COPD overlap (ACO).

METHODS

A total of 1030 patients with adult-onset asthma were included; 245 from SAAS (Seinäjoki Adult Asthma Study, Finland) and 785 from COREA (Cohort for Reality and Evolution of Adult Asthma in Korea) cohorts. BDR in FEV1 at the diagnosis of asthma was assessed. Patients were divided into groups based on age at asthma diagnosis: < 40, 40-59.9, and ≥ 60 years. The cohorts were analyzed separately.

RESULTS

BDR % in FEV1 did not differ between the groups of different age at asthma diagnosis and no correlation between BDR and age was found. Of patients aged ≥40 years, only 18% (SAAS-cohort) and 5% (COREA-cohort) reached the 400 mL BDR in FEV1. After exclusion of possible ACO patients, the results remained similar.

CONCLUSION

By using two large cohorts of steroid-naive patients with asthma, we have shown that BDR at diagnosis of asthma is constant over large age span range, and the limit of 400 mL in BDR in FEV1 is rarely reached.

TRIAL REGISTRATION

Seinäjoki Adult Asthma Study is registered at ClinicalTrials.gov with identifier number NCT02733016 .

Early life acetaminophen exposure, glutathione S-transferase genes, and development of adolescent asthma in a high-risk birth cohort

BACKGROUND

Although the impact of early life acetaminophen on asthma risk is still not clear, potential interactions with glutathione S-transferase (GST) genes due to reduced antioxidant function in particular polymorphisms, and possible impact on lung function, have never been investigated in adolescents.

OBJECTIVE

We aimed to investigate associations between early life acetaminophen use and adolescent asthma and lung function and to assess potential interactions by GST polymorphisms.

METHODS

Acetaminophen use was recorded 18 times up to age 2 years (n = 575 [92.7%]). Participants were genotyped for GST polymorphisms (GSTM1/T1/P1) (n = 429 [69.2%]). Asthma and lung function were measured at 12 (n = 365 [58.9%]) and 18 years (n = 413 [66.6%]). Regression models assessed associations and interactions.

RESULTS

Doubling of days of acetaminophen use was associated with reduced prebronchodilator FEV₁/forced vital capacity (β coefficient, -0.10; 95% CI, -0.19 to -0.01) and midexpiratory flow (-0.09; 95% CI, -0.18 to 0) at 18 years, but this association was not found when restricted for nonrespiratory reasons, suggesting confounding by indication. However, in children with GSTM1 null and GSTT1 present, increasing acetaminophen use for nonrespiratory reasons was associated with reduced FEV₁ and midexpiratory flow at 18 years (interaction between GSTM1/T1 and acetaminophen P < .05). Increased acetaminophen use was associated with asthma at 18 years for children with GSTP1 Ile/Ile (odds ratio, 1.66; 95% CI, 1.07 to 2.57), but not other GSTP1 genotypes.

CONCLUSIONS

These novel findings need to be investigated for consistency in other studies but suggest that children carrying risk genotypes may be susceptible to respiratory consequences from acetaminophen use.

Interaction of Glutathione S-Transferase M1, T1, and P1 Genes With Early Life Tobacco Smoke Exposure on Lung Function in Adolescents

BACKGROUND

Glutathione S-transferase (GST) genes are involved in the management of oxidative stress in the lungs. We aimed to determine whether they modify the associations between early life smoke exposure and adverse lung health outcomes.

METHODS

The Melbourne Atopy Cohort study (a high-risk birth cohort) enrolled 620 children and followed them prospectively from birth. We recorded perinatal tobacco smoke exposure, asthma, and lung function at 12 (59%) and 18 years (66%) and genotyped for GSTM1, GSTT1, and GSTP1 (69%).

RESULTS

GST genotypes were found to interact with tobacco smoke exposure on lung function outcomes (P interaction ≤ .05). Only among children with GSTT1 null genotypes was exposure to mother's, father's, or parental tobacco smoke in early life associated with an increased risk of reductions in prebronchodilator (BD) FEV₁ and FVC at both 12 and 18 years. These associations were not seen in children with GSTT1 present. Similarly, only among children with GSTM1 null genotypes was exposure to father's or parental smoking associated with reductions in pre- and post-BD FEV₁ and FVC at 18 years. Only among children with Ile/Ile genotypes of GSTP1 was exposure to mother's smoking associated with increased risk of reduced FEV₁ at 18 years, but this was not the case among children with Val/Val or Ile/Val genotypes.

CONCLUSIONS

Our study provides evidence of interaction between early tobacco smoke exposure and GST genotypes on lung function. Carriers of GST null mutations and GSTP1 Ile/Ile alleles may be more susceptible when exposed to tobacco smoke in early life. These findings support stronger recommendations to protect all infants from tobacco smoke exposure.

TRIAL REGISTRY

Australian and New Zealand Clinical Trials Registry; No.: ACTRN12609000734268; URL: http://www.anzctr.org.au/.

Bronchodilation Test with Inhaled Salbutamol Versus Bronchial Methacholine Challenge to Make an Asthma Diagnosis: Do They Provide the Same Information?

BACKGROUND

Methacholine bronchial challenge and bronchodilation to salbutamol are key tests in clinical practice to make asthma diagnosis.

OBJECTIVE

To assess the concordance between the 2 tests and to see whether they actually identify the same population of asthmatics.

METHOD

We conducted a retrospective study using our asthma clinic database to see how methacholine bronchial challenge compared to bronchodilation to salbutamol in untreated patients with recurrent or chronic symptoms suspicious of asthma. We identified 194 untreated patients with baseline forced expiratory volume in 1 second (FEV₁) ≥70% predicted who had both a bronchodilation test with salbutamol and a methacholine bronchial challenge 7 to 14 days apart. A positive bronchial challenge was a provocative concentration of methacholine causing a 20% fall in FEV₁ ≤16 mg/mL, whereas a positive bronchodilation test was a reversibility to 400 μg inhaled salbutamol ≥12% from baseline and 200 mL.

RESULTS

Overall, asthma diagnosis was confirmed in 91% of cases leaving 9% of subjects with double negative tests. Isolated positive methacholine challenge was found in 71% of subjects, double positive tests in 17%, whereas isolated significant bronchodilation to salbutamol was rare (3%). There was no correlation between provocative concentration of methacholine causing a fall in FEV₁ of 20% (PC20M) and the magnitude of salbutamol reversibility (P = .10). Baseline FEV₁/forced vital capacity ratio inversely correlated with reversibility to salbutamol (P < .001) but not with PC20M (P = .1). No difference was found between the groups regarding demographic and immunoinflammatory features, including the proportion of eosinophilic asthma.

CONCLUSION

We conclude that methacholine challenge outperforms reversibility to salbutamol to diagnose asthma without selecting patients with distinct inflammatory profile. Baseline airway obstruction predicts magnitude of reversibility but not hyperresponsiveness.

Sociodemographic, lifestyle and metabolic predictors of all-cause mortality in a cohort of community-dwelling population: an 18-year follow-up of the North West Adelaide Health Study

INTRODUCTION

Studies examining potential factors of all-cause mortality comprehensively at community level are rare. Using long-term community-based follow-up study, we examined the association of sociodemographic and behavioural characteristics, metabolic and chronic conditions, and medication and health service utilisation with all-cause mortality.

METHODS

We followed 4056 participants, aged 18-90 years, for 18 years in the North West Adelaide Health Study (NWAHS). Mortality data were obtained from South Australian (SA) public hospitals and registries including SA births, deaths and marriages, the National Death Index and the NWAHS follow-up. Predictors of all-cause mortality were explored using Cox proportional hazard model, adjusting for potential confounders. We performed subgroup analyses by sex and age.

RESULTS

Mean (SD) age at baseline was 50.4 (16.4) years. Less than half (47.8%) of the participants were men. A total of 64 689.7 person-years from 4033 participants with 18.7 years of follow-up were generated. The median follow-up time was 17.7 years; 614 deaths were recorded. The overall crude death rate was 9.6 (95% CI 8.9 to 10.4) per 1000 person-years. After adjusting for potential confounders, a reduced risk of mortality was significantly associated with being separated or divorced, being in the highest Socioeconomic Indexes for Areas quintile, engaging in moderate exercise, being overweight (body mass index: 25.0-29.9 kg/m²) and per 10% increase in per cent predicted forced expiratory volume in 1 s. We found that the most important predictors of all-cause mortality were sociodemographic and behavioural characteristics. Sociodemographic factors were more important predictors of all-cause mortality in young age bracket compared with older people.

CONCLUSIONS

Socioeconomic factors were found to be the most important predictors of all-cause mortality. The study highlights the need to address the social inequalities and strengthen behavioural interventions for different subgroups of population to prevent premature deaths.

Immediate bronchodilator response in FEV1 as a diagnostic criterion for adult asthma

Asthma is characterised by variable and reversible expiratory airflow limitations. Thus, it is logical to use the change in forced expiratory volume in 1 s (FEV₁) in response to a bronchodilator (ΔFEV₁BDR) as a diagnostic tool; increases of ≥12% and ≥200 mL from the baseline FEV₁ are commonly used values. We aimed to evaluate the historical development of diagnostic cut-off levels for the ΔFEV₁BDR for adults and the evidence behind these recommendations.We searched for studies from the reference lists of all the main statements, reports and guidelines concerning the interpretation of spirometry and diagnostics for asthma and conducted a literature search.A limited amount of evidence regarding the ΔFEV₁BDR in healthy populations was found, and even fewer patient studies were found. In healthy persons, the upper 95th percentile for the absolute ΔFEV₁BDR ranges between 240 mL and 320 mL, the relative ΔFEV₁BDR calculated from the initial FEV₁ ranges from 5.9% to 13.3% and the ΔFEV₁BDR calculated from the predicted FEV₁ ranges from 8.7% to 11.6%. However, the absolute and percentage ΔFEV₁BDR values calculated from the initial FEV₁ are dependent on age, sex, height and the degree of airway obstruction. Thus, the use of the ΔFEV₁BDR calculated from the predicted FEV₁ might be more appropriate.Not enough data exist to assess the sensitivity of any of the cut-off levels for the ΔFEV₁BDR to differentiate asthma patients from healthy subjects. Further studies in newly diagnosed asthma patients are needed.

Diagnostic Accuracy of Bronchodilator Response for Asthma in a Population of South China

INTRODUCTION

A significant bronchodilator response is commonly defined as a 12% or greater and 200 ml or greater change in FEV₁ from baseline according to the 2005 American Thoracic Society (ATS)/European Respiratory Society (ERS) criterion. A number of studies have shown that the ATS/ERS criterion has limitations in asthma diagnosis, and some experts have argued for correcting the criteria. The aim of this study is to investigate the diagnostic value of acute bronchodilator response for asthma in a Southern Chinese population.

METHODS

We prospectively evaluated 805 patients with obstructive lung disease (309 for asthma, 496 for non-asthma). Spirometry was performed according to the ATS/ERS guidelines. Data were analyzed by SPSS 18.0. The receiver-operating characteristic (ROC) curve was drawn to assess the diagnostic accuracy of the ATS/ERS criterion based on FEV₁. Linear regression was used to analyze the factors of FEV₁ change.

RESULTS

The sensitivity and specificity of the acute bronchodilator test when judged by the ATS/ERS criteria (200 ml or higher and 12% improvement) were 68.6% and 78.2%, respectively. For the ATS/ERS criteria, the Youden Index, which comprehensively reflects the authenticity of a diagnostic test, was 46.8%. The absolute change of FEV₁ positively correlated with baseline FEV₁ and weight and negatively with age, while the percentage change of FEV₁ was negatively correlated with baseline FEV₁, age and height and positively with weight. Compared with the different diagnostic values, when ∆FEV₁ was 195 ml and ∆FEV_1i% was 14%, the Youden Index was the largest (48.2%) and the diagnostic capability of the test the biggest.

CONCLUSIONS

The ATS/ERS criterion for acute bronchodilator response might not be completely suitable for asthma in the Chinese population.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (Registry ID: ChiCTR-DDT-14004976).

FUNDING

This work was supported by the National Natural Science Foundation of China (grant nos. 81670027, 81270080).

Early smoke exposure is associated with asthma and lung function deficits in adolescents

OBJECTIVE

Early life tobacco smoke exposure may influence asthma, lung function and lung function growth into adolescence. We aimed to determine the associations between perinatal smoke exposure and asthma and lung function up to 18 years of age.

METHODS

We prospectively recorded perinatal parental smoking and measured respiratory outcomes at 12 and 18 years in the Melbourne Atopy Cohort Study (MACS), a longitudinal birth cohort. Multiple logistic regression was used to analyse the associations between perinatal smoke exposure and asthma at 12 (n = 370) and 18 years (n = 411). Multiple linear regression was used to investigate the relationship between perinatal smoking and: lung function (12 and 18 years) and lung function growth (between 12 and 18 years).

RESULTS

At 18 years, girls exposed to parental smoking during the perinatal period had increased odds of asthma (OR: 3.45, 95%CI: 1.36, 8.77), reduced pre-bronchodilator Forced expiratory volume in one-second (FEV₁) (-272 ml/s; -438, -107); FEV₁/ forced vital capacity (FVC) (-0.038; -0.065, -0.010); mid expiratory flow (MEF_25-75) (-430 ml/s; -798, -61), and reduced post-bronchodilator FEV₁/FVC (-0.028, -0.053, -0.004). No associations were found for boys (pre-bronchodilator FEV₁ 26ml/s; -202, 255; FEV₁/FVC 0.018; -0.013, 0.049).

CONCLUSIONS

Perinatal smoke may affect risk of asthma, reduce lung function and lung function growth in adolescence. Girls appear to be more susceptible than boys.

Infections in "noninfectious" lung diseases

Many chronic pulmonary diseases, including those that are not primarily infectious in etiology, have some aspects of their pathogenesis that are influenced by infectious organisms. Microorganisms may contribute to chronic lung diseases, either directly (i.e., overt infection) or indirectly, via the amplification of inflammatory pathways that are critical to host defense. As techniques for detecting and characterizing microorganisms have advanced, investigations of both infecting and colonizing organisms have yielded new insights into mechanisms of pulmonary disease. In addition, changes in patterns of infection and microbial resistance have important implications for treatment. Examples of these infectious-pulmonary associations, including Haemophilus influenzae infection and chronic obstructive pulmonary disease, nontuberculous mycobacteria and bronchiectasis, and human immunodeficiency virus and obstructive lung disease, are reviewed.

Does guideline knowledge affect treatment compliance among emergency doctors?

BACKGROUND

The insufficient adoption of internationally accepted clinical guidelines may lead to less than adequate patient care of patients with asthma.

OBJECTIVE

To evaluate the knowledge and treatment compliance with Global Initiative of Asthma (GINA, 2011) asthma treatment guidelines among emergency physicians (EPs) at a referral hospital in northern Malaysia.

METHODS

A cross-sectional study was designed in the territory-level referral hospital in northern Malaysia. Twenty-seven EPs were asked to complete an asthma guideline questionnaire to assess their knowledge regarding GINA 2011 asthma treatment guidelines. A total of 810 patients were enrolled, and 30 patients were selected per physician. The authors evaluated the physicians' compliance with GINA 2011 asthma treatment guidelines.

RESULTS

Of 27 EPs, 20 (74.1%) had adequate knowledge of GINA 2011 asthma treatment guidelines. A total of 615 (75.9%) patients received guideline-recommended emergency treatment. Shortness of breath (n = 436, 53.8%) was the most frequently reported chief complaint. Furthermore, there was a significant but weak association between knowledge of the guideline and treatment compliance among emergency doctors (P = 0.003, φ = 0.110). Moreover, there was no significant change in therapy for patients with comorbid conditions. The mean age of respondents was 27.3 years.

CONCLUSIONS

Overall, a fair level of guideline knowledge and treatment compliance was noted among EPs. Doctors with adequate guideline knowledge were more likely to comply with GINA 2011 asthma treatment guidelines.

Understanding the evolution of multimorbidity: evidences from the North West Adelaide Health Longitudinal Study (NWAHS)

OBJECTIVE

The aim of this study is to describe the evolution of multimorbidity.

STUDY DESIGN AND SETTING

Data from 1854 South Australians who participated in the North West Adelaide longitudinal Health Study (NWAHS) was collected between baseline (2000-2002) and follow-up (2008-2010). Status for eight chronic diseases (CDs) was determined by biomedical measurement or self-report. Chronic disease (CD) mean age of occurrence and order of appearance was investigated.

RESULTS

The prevalence of multimorbidity increased from 32% to 64% during the 7.8±1.1 years of follow-up. The estimated mean age of onset of a new CD was significantly older for hypertension, cardiovascular disease (CVD) and chronic obstructive pulmonary disease (COPD) and younger for hypercholesterolemia, asthma and other mental problem. Hypercholesterolemia was more likely to develop as a first than as a subsequent CD (39%vs.16%, p<0.0001) while CVD (1%vs.5%, p<0.0001), diabetes (5%vs.11%, p<0.001) and COPD (6%vs.16%, p<0.0001) were less likely. The presence of mood disorders at baseline was associated with an increased risk of developing other mental disorders (36%vs.12%, p<0.0001), diabetes (18%vs.9%, p<0.01) and asthma (30%vs.21%, p<0.05).

CONCLUSION

Longitudinal data could be used to study the evolution of multimorbidity and could provide information on CDs mean age of occurrence, order of appearance and impact on the development of future CDs.

Asthma is associated with cardiovascular disease in a representative population sample

SUMMARY

RATIONALE

People with asthma may have an increased risk of cardiovascular disease (CVD) and metabolic disorders due to the direct involvement of common inflammatory mediators in the pathogenesis of CVD and insulin resistance. The aim of this study was to determine whether asthma was associated with an increased prevalence of CVD/stroke, and diabetes in a cross-sectional population study and whether the relationship was modified by obesity.

METHODS

The North West Adelaide Health Study (NWAHS) (n = 4060, age ≥18 years) clinical assessment included spirometry, anthropometry, blood pressure, fasting lipids, glucose and HbA1c. Questionnaires assessed doctor diagnosed asthma, diabetes, CVD (myocardial infarction, angina)/stroke, smoking status, and demographics. Asthma was identified by self-report or significant bronchodilator reversibility of lung function.

RESULTS

After adjustment for known risk factors and confounders, asthma was not associated with diabetes (odds ratio (OR) = 1.06, 95% confidence interval (CI): 0.45-2.49, p = .91) yet remained positively associated with CVD/stroke (OR = 1.82, 95% CI: 1.20-2.73, p < 0.01) independent of the level of BMI (p for interaction between asthma and BMI = .22), smoking and lung function. Asthma was not positively associated with CVD risk factors or the metabolic syndrome.

CONCLUSIONS

In a representative population sample, asthma was associated with CVD/stroke after adjustment for traditional risk factors and lung function. Asthma may lead to CVD events via pathways unrelated to traditional risk factors and this requires further investigation. No significant effect modification by BMI was observed in relation to CVD, or diabetes.

Human immunodeficiency virus-associated obstructive lung diseases

In the era of effective antiretroviral therapy (ART), epidemiologic studies have found that persons infected with human immunodeficiency virus (HIV) have a higher prevalence and incidence of chronic obstructive pulmonary disease than HIV-uninfected persons. In comparison with HIV-uninfected persons and those with well-controlled HIV disease, HIV-infected persons with poor viral control or lower CD4 cell count have more airflow obstruction, a greater decline in lung function, and possibly more severe diffusing impairment. This article reviews the evidence linking HIV infection to obstructive lung disease, and discusses management issues related to the treatment of obstructive lung disease in HIV-infected patients.

Pathogenesis of HIV and the lung

Antiretroviral therapy has improved longevity for HIV-infected persons, but long-term HIV infection is now complicated by increased rates of chronic medical conditions including pulmonary disorders. Chronic obstructive pulmonary disease, lung cancer, asthma, and pulmonary hypertension are becoming common comorbidities of HIV infection, and these diseases may develop as a result of HIV-related risk factors, such as antiretroviral drug toxicities, colonization by infectious organisms, HIV viremia, immune activation, or immune dysfunction. It also appears that the ability to control HIV infection does not completely eliminate the risk for infectious complications, such as bacterial pneumonia and tuberculosis. The effect of HIV infection on lung-specific immune responses is being elucidated to help develop better prevention and treatment strategies in HIV-infected persons.

Reassessing the evidence hierarchy in asthma: evaluating comparative effectiveness

Classical randomized controlled trials are the gold standard in medical evidence because of their high internal validity. However, their necessarily strict design can limit their external validity and the ability to extrapolate these data to real world patients. Therefore, alternatively designed studies may play a complementary role in evaluating the comparative effectiveness of therapies in nonidealized patients in more naturalistic, real world settings. Observational studies have high external validity and can evaluate real world outcomes. Their strength lies in hypothesis generation and testing and in identifying areas in which further clinical trials may be required. Pragmatic trials are designed to maximize applicability of trial results to usual care settings by relying on clinically important outcomes and enrolling a wide range of participants. A combination of these approaches is preferable and necessary.

Multimorbidity - not just an older person's issue. Results from an Australian biomedical study

BACKGROUND

Multimorbidity, the simultaneous occurrence of two or more chronic conditions, is usually associated with older persons. This research assessed multimorbidity across a range of ages so that planners are informed and appropriate prevention programs, management strategies and health service/health care planning can be implemented.

METHODS

Multimorbidity was assessed across three age groups from data collected in a major biomedical cohort study (North West Adelaide Health Study). Using randomly selected adults, diabetes, asthma, and chronic obstructive pulmonary disease were determined clinically and cardio-vascular disease, osteoporosis, arthritis and mental health by self-report (ever been told by a doctor). A range of demographic, social, risk and protective factors including high blood pressure and high cholesterol (assessed bio-medically), health service use, quality of life and medication use (linked to government records) were included in the multivariate modelling.

RESULTS

Overall 4.4% of the 20-39 year age group, 15.0% of the 40-59 age group and 39.2% of those aged 60 years of age or older had multimorbidity (17.1% of the total). Of those with multimorbidity, 42.1% were aged less than 60 years of age. A variety of variables were included in the final logistic regression models for the three age groups including family structure, marital status, education attainment, country of birth, smoking status, obesity measurements, medication use, health service utilisation and overall health status.

CONCLUSIONS

Multimorbidity is not just associated with older persons and flexible care management support systems, appropriate guidelines and care-coordination programs are required across a broader age range. Issues such as health literacy and polypharamacy are also important considerations. Future research is required into assessing multimorbidity across the life course, prevention of complications and assessment of appropriate self-care strategies.

Oral complementary medicine and alternative practitioner use varies across chronic conditions and attitudes to risk

OBJECTIVES

To determine whether chronic conditions and patient factors, such as risk perception and decision-making preferences, are associated with complementary medicine and alternative practitioner use in a representative longitudinal population cohort.

PARTICIPANTS AND SETTING

Analysis of data from Stage 2 of the North West Adelaide Health Study of 3161 adults who attended a study clinic visit in 2004-2006. The main outcome measures were the medications brought by participants to the study clinic visit, chronic health conditions, attitudes to risk, levels of satisfaction with conventional medicine, and preferred decision-making style.

RESULTS

At least one oral complementary medicine was used by 27.9% of participants, and 7.3% were visiting alternative practitioners (naturopath, osteopath). Oral complementary medicine use was significantly associated with arthritis, osteoporosis, and mental health conditions, but not with other chronic conditions. Any pattern of complementary medicine use was generally significantly associated with female gender, age at least 45 years, patient-driven decision-making preferences (odds ratio [OR] 1.38, 95% confidence interval [CI]: 1.08-1.77), and frequent general practitioner visits (>five per year; OR 3.62, 95% CI: 2.13-6.17). Alternative practitioner visitors were younger, with higher levels of education (diploma/trade [OR 1.88, 95% CI: 1.28-2.76], bachelor's degree [OR 1.77, 95% CI: 1.11-2.82], income >$80,000 (OR 2.28, 95% CI: 1.26-4.11), female gender (OR 3.15, 95% CI: 2.19-4.52), joint pain not diagnosed as arthritis (OR 1.68, 95% CI: 1.17-2.41), moderate to severe depressive symptoms (OR 2.15, 95% CI: 1.04-4.46), and risk-taking behavior (3.26, 1.80-5.92), or low-to-moderate risk aversion (OR 2.08, 95% CI: 1.26-4.11).

CONCLUSION

Although there is widespread use of complementary medicines in the Australian community, there are differing patterns of use between those using oral complementary medicines and those using alternative practitioners.

Associations of physical and mental health problems with chronic cough in a representative population cohort

BACKGROUND

Although chronic cough is a common problem in clinical practice, data on the prevalence and characteristics of cough in the general population are scarce. Our aim was to determine the prevalence of chronic cough that is not associated with diagnosed respiratory conditions and examine the impact on health status and psychological health, in a representative adult population cohort

METHODS

North West Adelaide Health Study (n stage 1 = 4060, stage 2 = 3160) is a representative population adult cohort. Clinical assessment included spirometry, anthropometry and skin tests. Questionnaires assessed demographics, lifestyle risk factors, quality of life, mental health and respiratory symptoms, doctor diagnosed conditions and medication use.

RESULTS

Of the 3355 people without identified lung disease at baseline, 18.2% reported chronic cough. In multiple logistic regression models, at follow-up, dry chronic cough without sputum production was significantly more common in males (OR 1.5, 95% CI 1.1, 1.9), current smokers (OR 4.9, 95% CI 3.4, 7.2), obesity (OR 1.9, 95% CI 1.3, 2.9), use of ACE inhibitors (OR 1.8, 95% CI 1.1, 2.9), severe mental health disturbance (OR 2.1, 95% CI 1.4, 3.1) and older age (40-59 years OR 1.7 95% CI 1.2, 2.4; > or = 60 years OR 2.1 95% CI 1.3, 3.5). Among non-smokers only, all cough was significantly more common in men, those with severe mental health disturbance and obesity.

CONCLUSIONS

Chronic cough is a major cause of morbidity. Attention to cough is indicated in patients with obesity, psychological symptoms or smokers. Inquiring about cough in those with mental health problems may identify reversible morbidity.

Asthma in the elderly

Bronchial asthma is a common problem with enormous medical and economics impacts. It is an inflammatory disease of the airways associated with intermittent episodes of bronchospasm. Asthma is not uncommon in the elderly patients. Prevalence of asthma is similar in older and younger adults. Asthma in the elderly patient is underdiagnosed because of false perceptions by both patient and physician. The high incidence of comorbid conditions in the elderly patient makes the diagnosis and management more difficult. Correct diagnosis is demonstrated with spirometry. The goals of asthma treatment are to achieve and maintain control of symptoms and to prevent development of irreversible airflow limitation. Asthma drugs are preferably inhaled because this route minimizes systemic absorption and, thus, improves the ratio of the therapeutic benefit to the potential side-effects in elderly patients.

Gender differences in asthma prevalence: variations with socioeconomic disadvantage

BACKGROUND AND OBJECTIVE

Socioeconomic inequalities in health have been shown to vary for different diseases and by gender. This study aimed to examine gender differences in associations between asthma and socioeconomic disadvantage.

METHODS

Socioeconomic variables were assessed among men and women in the North West Adelaide Health Study, a representative population cohort (n = 4060) aged 18 years and over in metropolitan South Australia. Asthma was determined from spirometry and self-reported doctor diagnosis.

RESULTS

The prevalence of asthma was 12.0% (95% CI: 11.1-13.1), and was significantly higher among women (13.5%) than men (10.5%). For participants aged 18-64 years a higher prevalence of asthma was associated with an education level of secondary school or lower, or not being in the paid labour force among men, and with a gross annual household income of $20,000 or less among women. Among socioeconomically advantaged groups, the prevalence of asthma was significantly higher among women than men.

CONCLUSIONS

Socioeconomic disadvantage was associated with higher asthma prevalence, although this varied by gender depending on the indicator of socioeconomic position used. Men with low education or those not employed in the paid labour force had higher asthma prevalence than more socioeconomically advantaged men. Women with low income had higher asthma prevalence than those with higher income. Among all socioeconomically advantaged groups, and also the low-income group, women experienced a higher prevalence of asthma than men.

Cardiovascular disease risk associated with asthma and respiratory morbidity might be mediated by short-acting beta2-agonists

BACKGROUND

Studies examining the asthma-related risks of cardiovascular disease (CVD) events have generally used selected samples or did not control for the effects of beta(2)-agonist use, itself associated with CVD events.

OBJECTIVES

We assessed the relationship between incident CVD/stroke and asthma and the effect of atopy while controlling for beta(2)-agonist use in a representative adult population cohort free of CVD at baseline.

METHODS

The North West Adelaide Health Study (stage 1, n = 3812; stage 2, n = 3113) assessed spirometry, anthropometry, atopy, blood pressure, and lipid levels. Questionnaires assessed doctor-diagnosed asthma and CVD (myocardial infarction and angina)/stroke, smoking status, and demographics. Asthma was defined by self-report or FEV(1) reversibility. Current short- and long-acting beta(2)-agonist use was identified at follow-up.

RESULTS

Results are expressed as odds ratios (ORs) and 95% CIs. By using multivariable logistic regression, after adjustment for risk factors, in female subjects incident CVD/stroke events were associated with asthma (OR, 3.24; 95% CI, 1.55-6.78), with no effect modification by atopy (P for interaction = .61), and with as-required short-acting beta(2)-agonist use (OR, 2.66; 95% CI, 1.06-6.61). In male subjects events were associated with daily cough/sputum (OR, 1.92; 95% CI, 1.05-3.50) and FEV(1) of less than 80% of predicted value but an FEV(1)/forced vital capacity ratio of greater than 0.70 (OR, 2.15; 95% CI, 0.91-5.09; P = .08). Although few CVD/stroke events occurred in male subjects with asthma, a significant interaction with atopic status was found (P = .05).

CONCLUSIONS

Studies are required to elucidate how asthma exposes older women to excess macrovascular risk and prospectively determine the short-acting beta(2)-agonist-related risk in persons without existing CVD. CVD risk in relation to atopic status of asthma also requires further investigation.

Bronchodilator response to adrenergic beta2-agonists: relationship to symptoms in an adult community

BACKGROUND

Wheeze and chest tightness has traditionally been associated with enhanced bronchial responsiveness. However, no community studies are available on the associations between bronchodilator response and respiratory symptoms among adults.

AIM

To examine how respiratory symptoms predict bronchodilator response.

METHODS

An age and gender stratified random sample of all adults aged 47-48 and 71-73 years in Bergen, Norway, were invited. The 3506 participants (69%) filled in questionnaires including nine symptoms and performed bronchodilator reversibility tests. Subjects without current anti-asthmatic medication performing acceptable reversibility tests were included in the analyses (n=3088).

RESULTS

A reversibility with FEV(1) increase 12% and 200 ml was obtained in 2% of middle-aged and 4% of elderly subjects (p=0.001). In multiple linear regression analysis bronchodilatation was positively associated with wheezing without cold (FEV(1) increase of 1.5%, 95% CI: (0.9, 2.2)% in all participants and 31 ml, 95% CI: (1, 61)ml in men only) and dyspnoea climbing two flights of stairs (0.9%, 95% CI: (0.5,1.4)% and 12 ml, 95% CI: (1,23)ml). Chronic cough predicted the response negatively (-0.7%, 95% CI: (-1.3,-0.1)% and -17 ml, 95% CI: (-32,-2)ml). In multiple logistic regression analysis morning cough predicted an FEV(1) increase 12% and 200 ml (OR: 1.8, 95% CI: (1.1,2.8)).

CONCLUSIONS

A small fraction of adults in a general population has bronchodilatation after salbutamol inhalation. "Wheezing without cold", "dyspnoea climbing two flights of stairs", and "morning cough" predict an increased bronchodilator response among subjects without current anti-asthmatic medications.

External validity of randomised controlled trials in asthma: to whom do the results of the trials apply?

BACKGROUND

Asthma is a heterogeneous disease with a wide range of clinical phenotypes, not all of which may be encompassed in the subjects included in randomised controlled trials (RCTs). This makes it difficult for clinicians to know to what extent the evidence derived from RCTs applies to a given patient.

AIM

To calculate the proportion of individuals with asthma who would have been eligible for the major asthma RCTs from the data of a random community survey of respiratory health.

METHODS

A postal survey was sent to 3500 randomly selected individuals aged 25-75 years. Respondents were invited to complete a detailed respiratory questionnaire and pulmonary function testing. Participants with current asthma were assessed against the eligibility criteria of the 17 major asthma RCTs cited in the Global Initiative for Asthma (GINA) guidelines.

FINDINGS

A total of 749 participants completed the full survey, of whom 179 had current asthma. A median 4% of participants with current asthma (range 0-36%) met the eligibility criteria for the included RCTs. A median 6% (range 0-43%) of participants with current asthma on treatment met the eligibility criteria.

INTERPRETATION

This study shows that the major asthma RCTs on which the GINA guidelines are based may have limited external validity as they have been performed on highly selected patient populations. Most of the participants with current asthma on treatment in the community would not have been eligible for these RCTs.

Advances in adult and pediatric asthma

This year we present updates on the management and therapeutics of asthma and research on the relationship of airway remodeling to clinically irreversible disease and continue a discussion about the origins of asthma. Significant advances are occurring in our understanding of the natural history of asthma, including the application of biomarkers and genetics. These tools should assist the clinician in defining patients at risk for significant morbidity related to asthma. Incorporating this knowledge will help prompt the development of more effective management techniques and new medications. Meanwhile, more effective health care strategies must be developed to reduce the reported disparities in asthma care noted in our patient populations.