How have we been managing chronic obstructive pulmonary disease in Australia?

AIM: Although chronic obstructive pulmonary disease (COPD) is a main cause of disability, hospital admissions and premature deaths in Australia, little is known about the community management of COPD in relation to recently published guidelines. The aim of the article was to report on COPD management in a community based cohort. METHODS: A random sample of adults aged between 45 and 70 years drawn from the electoral roll participated in the study. They completed a detailed respiratory questionnaire, spirometry, methacholine challenge and measurement of transfer factor. COPD was defined according to the Global initiative for Chronic Obstructive Lung Disease (GOLD) criteria. Current asthma was defined as wheeze during the last 12 months together with bronchial hyperreactivity. Subjects were classified as either COPD-only, asthma-only or both asthma and COPD. RESULTS: Of 1224 subjects completing spirometry, 39 (3.5%) met the GOLD criteria for stage 2 or 3 COPD, asthma-only was found in 99 (8.9%) subjects and 40 (3.6%) subjects had both asthma and COPD. The COPD-only group was significantly older than the other two groups. More than 40% of subjects with COPD did not have a diagnosis of COPD from their doctors. Only 48.7% of subjects with COPD had ever been prescribed medication for their breathing. More than two-thirds of all subjects had seen a doctor for breathing problems, but very few had seen a general practitioner in the last 12 months and even fewer had respiratory function tests. CONCLUSIONS: Most subjects with COPD are being undertreated. Diagnosis, monitoring and referral systems should be improved. Preventive activities such as influenza vaccination and smoking cessation should be intensified.

Changes in indoor allergen and fungal levels predict changes in asthma activity among young adults.

BACKGROUND: Exposures to allergens are thought to be important risk factors for asthma. We conducted a longitudinal study of indoor allergen and fungal levels in Melbourne homes between 1996 and 1998 to examine the effect of changes in allergen exposure upon asthma and associated outcomes. METHODS: Participants were visited at home in 1996 (n=485) and 1998 (n=360), when dust and air samples were collected from their bedrooms and assayed for Der p 1, Fel d 1, ergosterol and fungal propagules. Subjects then attended the lung function laboratory to complete a questionnaire, spirometry, methacholine challenge and skin prick testing. The associations between the change in allergen levels and change in clinical outcomes were examined using multiple logistic and linear regression. RESULTS: Participants whose Cladosporium fungal exposure doubled had 52% greater odds of having had an attack of asthma in the last 12 months. A doubling of fungal exposure was also associated with 53% greater odds of developing atopy. A doubling of Fel d 1 floor levels was associated with 73% increased odds of doctor-diagnosed asthma. A doubling of Der p 1 levels in bed dust was associated with a 64% greater odds of persistent bronchial hyper-reactivity. CONCLUSIONS: These findings provide evidence that changes in indoor levels of fungi and house dust mites can affect the risk of development and persistence of asthma and atopy in adults. Further studies are required to establish any benefit of sustained reductions in indoor allergen exposures, and to determine whether these effects are truly 'allergic' or because of immune stimulation in the airway through other less specific mechanisms.

Fatty acid levels and risk of asthma in young adults.

BACKGROUND: There is current interest in the possible protective effect of long chain (n-3) fatty acids from fish in chronic lung diseases such as asthma. The aim of this community based cross sectional study was to determine whether plasma long chain (n-3) fatty acids, as a measure of dietary intake, differed between 1601 young adults with and without asthma. METHODS: Subjects of mean (SD) age 34.6 (7.1) years completed a detailed respiratory questionnaire, food frequency questionnaire, skin prick testing, and lung function tests including methacholine challenge test for bronchial hyperreactivity (BHR) and had venous blood taken for analysis of plasma fatty acids. Plasma fatty acid levels (%) were analysed using multiple logistic regression with alternative definitions of asthma and atopy as the outcomes. RESULTS: Atopy was not associated with any plasma fatty acid. The n-3 polyunsaturated fatty acids and n-6:n-3 ratio were not consistently associated with asthma or atopy. The n-6 polyunsaturated fatty acid dihomo gamma-linolenic acid (DHGLA) was positively associated with current asthma (OR=1.30, 95% CI 1.06 to 1.60), asthma (OR=1.34, 95% CI 1.13 to 1.60), and doctor diagnosed asthma (OR=1.25, 95% CI 1.06 to 1.48). CONCLUSION: Plasma n-3 fatty acids are not associated with a reduced risk of asthma or atopy among young adults. The association of DHGLA with asthma warrants further research to determine a cause-effect relationship.

Residential characteristics predict changes in Der p 1, Fel d 1 and ergosterol but not fungi over time.

BACKGROUND: Allergen and fungal exposures are important risk factors for asthma. We conducted a longitudinal analysis of allergen levels in Melbourne homes between 1996 and 1998 to examine the effects of changing residential characteristics on allergen and fungal levels. We also examined the changes in levels of indoor allergens. METHODS: The subjects were participants in the European Community Respiratory Health Survey (ECRHS) in Melbourne. In 1996, 485 subjects participated in a follow-up study, which involved both home and laboratory visits. Dust and air samples were collected from participants' bedrooms and a validated residential questionnaire was administered. In 1998, 360 participants underwent further follow-up. House dust mite (Der p 1) and cat allergens (Fel d 1) and ergosterol were measured in dust. RESULTS: We observed moderate within home correlations between 1996 and 1998 in floor Der p 1 (intraclass correlation ICC=0.48), bed Der p 1 (ICC=0.61), Fel d 1 (kappa=0.53) and ergosterol (ICC=0.28) levels. We found that the floor Der p 1 levels decreased from 1996 to 1998 in the homes of participants who moved to an attached home, moved their bedrooms to the first floor, removed fitted carpet or central heating. Replacing or vacuuming the mattress more than twice per year reduced levels of Der p 1 in the bed. Ergosterol levels were reduced by removing visible mould and fitted carpet. CONCLUSIONS: These findings provide evidence to support current advice with regard to allergen avoidance in patients with dust mite and fungal allergies.

Reported food intolerance and respiratory symptoms in young adults.

The aim of the study was to assess the ability of the European Community Respiratory Health Survey (ECRHS) questionnaire to provide data on the prevalence, type and reported symptoms associated with food intolerance from a group of young adults in Melbourne. Six hundred and sixty nine randomly selected subjects completed the questionnaire with 553 attending the laboratory for skin-prick tests, anthropometry, and ventilatory function tests. A further 207 symptomatic participants completed the questionnaire, with 204 of them attending the laboratory. Seventeen per cent of all respondents reported food intolerance or food allergy. A wide variety of food items was cited as being responsible for food-related illnesses. Those with current asthma did not report food-related illness more frequently than those without asthma. Respondents who reported respiratory symptoms following food ingestion were more likely to be atopic, to have used inhaled respiratory medications in the previous 12 months, reported less exposure to regular passive smoking over the past 12 months and weighed more. These associations between respiratory symptoms and food intolerance require further prospective investigation and verification. The importance of using appropriate dietary methodology in future studies for determining diet-disease relationships was highlighted by this study.

Do wheezy infants recovering from bronchiolitis respond to inhaled salbutamol?

Wheezy infants, less than 6 months of age, were given either inhaled salbutamol or saline in a double-blind study. A significant change in maximal flow at functional residual capacity (VmaxFRC) was defined as being greater than twice the coefficient of variation of the baseline measurements. There was no difference in the infants' response to saline or salbutamol. Wheezy infants, less than 6 months of age, do not have an increase in VmaxFRC following a single dose of inhaled salbutamol.

Should TGV be measured from end-inspiratory occlusions rather than end-expiratory occlusions in wheezy infants?

It has been suggested that thoracic gas volume (TGV) measured in infants in a plethysmograph most accurately represents true lung volume when calculated from end-inspiratory airway occlusions. The rationale proposed is that pressure measured at the mouth underestimates alveolar pressure more at end-expiration than at end-inspiration, presumably due to small airway closure, and this results in greater overestimation of TGV. To investigate this possibility we calculated TGV in 40 wheezy infants from occlusions at both end-inspiration (TGVei) and end-expiration (TGVee) using a 60 L whole body plethysmograph. TGV was corrected for equipment dead space and tidal volume. When a significant change in TGV was defined as lying outside the 95% confidence interval of the TGVee measurements, 8 of the 40 infants tested had significantly higher TGV values measured from occlusions made at end-expiration, while two infants had significantly lower TGV values measured from occlusions made at end-expiration. This trend was not more common in infants with "concave" flow-volume curves. Although it is technically easier to make occlusions at end-expiration, occluding at end-inspiration may minimize errors of TGV measures in a few individuals due to small airway closure at low lung volumes.

Effect of forced expiration on thoracic gas volume in wheezy infants.

Partial expiratory flow-volume curves are commonly used in infant pulmonary function testing. The flow measurements are volume dependent and thoracic gas volume (TGV) is often measured in conjunction with forced expiratory maneuvers. Since it is not possible to make continuous, simultaneous measurements of TGV during forced expiration, it is assumed that lung volume returns to its original value after forced expiration. To test this assumption we measured TGV using a whole body plethysmograph in 14 wheezy infants before and after a series of forced expirations produced with an inflatable jacket. Forced expiration did not cause a significant change in group mean TGV measurements. Examination of individual data did not show any systematic difference between TGV measured before and after forced expiration. These results suggest that repeated forced expirations do not alter TGV within the time scale of usual pulmonary function testing protocols.

Influence of the "squeeze jacket" on lung function in young infants.

The possible influence of the "squeeze jacket" on measurements of lung function in young infants was examined in 29 infants. In 19 infants, a comparison was made between jacket off and jacket on with the arms held inside the jacket. With the jacket on (arms inside), we found a significant reduction in thoracic gas volume (TGV). Passive compliance of the respiratory system (Crs) was also significantly decreased, while the resistance of the respiratory system (Rrs) was significantly increased. An additional 10 infants were studied comparing jacket off with jacket on (arms outside) and jacket on (arms inside). TGV was significantly less with the jacket on (arms inside) compared to jacket off and jacket on (arms outside), while Rrs and mouth pressure at end-inspiratory occlusion (Pm) were significantly increased. There was no difference between jacket off and jacket on (arms outside). These observations suggest that the squeeze jacket with the arms held at the infant's side inside the jacket exerts a restricting effect on chest and abdominal wall movement and leads to errors in the measurements. To avoid these potential errors, measurements should be made without the jacket on or with the arms held outside the jacket.