[Show abstract][Hide abstract] ABSTRACT: Serial measurements of peak expiratory flow (PEF) are recommended in the evidence-based review list as the first stage in objective confirmation of occupational asthma. Different centres have reported widely different success in obtaining records of sufficient data quantity for diagnosis. We investigated different methods of instruction and determined the return rate and quality of the resulting record for the diagnosis of occupational asthma.
Consecutive new referrals were recruited from a specialized occupational lung disease clinic and requested to carry out serial PEFs for the assessment of suspected occupational asthma. Requests to carry out the records were either from written postal instructions or personal instruction from a PEF specialist. Record quality received from other clinicians was also analysed separating those using dedicated occupational forms, and those submitting on graph type forms.
The postal return rate was 56% and the personal rate 85%. The number of records fulfilling all the data quality criteria were similar in the postal and personal groups (55 and 59%, respectively). Pre-existing records from other clinics plotted from graph charts (fulfilling all criteria) were only adequate in 23%, compared with 61% adequate for pre-existing records plotted from occupational forms. Failure of the record to contain consecutive work periods of > or =3 workdays was the most common failure.
The return rate of PEFs for diagnosing occupational asthma is better when patients have been given specific instructions from a PEF specialist and the data quantity better when recorded on a dedicated form.
Full-text · Article · Sep 2005 · Occupational Medicine
[Show abstract][Hide abstract] ABSTRACT: Colophony (rosin) is a natural product obtained from coniferous trees. It is used in a diverse range of products such as adhesives, ink, paints and soldering fluxes. Some workers exposed to colophony during soldering can develop occupational asthma; at present, no specific IgE test is available to assess sensitization to colophony.
Serum samples were obtained from exposed symptomatic individuals (n = 7), some with a likely diagnosis of occupational asthma, exposed asymptomatic individuals (n = 10) and unexposed individuals (n = 11). Serum was tested for specific IgE antibodies against a protein extract produced following in vitro challenge of mono-mac-6 cells with colophony extract.
Serum from exposed symptomatic individuals showed increased binding of specific IgE antibodies to a range of colophony-cell protein conjugates [29% (2/7) of samples tested when cut-off > 0.1 or 86% (6/7) of samples tested when cut-off > 0%] compared with both the exposed asymptomatic [0% when cut-off > 0.1, or 20% when cut-off > 0% (2/10)] and the non-exposed control populations [0% when cut-off > 0.1, or 27% when cut-off > 0% (3/11)].
This novel approach for the production of conjugates to assess sensitization to colophony was able to detect specific IgE in colophony-exposed workers with a likely diagnosis of occupational asthma.
Full-text · Article · May 2005 · Occupational Medicine
[Show abstract][Hide abstract] ABSTRACT: Serial peak expiratory flow records are recommended in the first-line investigation of suspected occupational asthma. The effects of sequentially reducing the numbers of working weeks, consecutive days at work and readings taken per day on diagnostic sensitivity and specificity were investigated, using good quality peak expiratory flow records from 81 workers with independently confirmed occupational asthma and 60 asthmatics without occupational exposure. Sensitivity was 81.8% for records of 4 weeks' duration and 70% for those of 2 weeks' duration (specificity 93.8 and 82.4% respectively). The sensitivity fell to 56.7% if there were only 2 consecutive workdays in each work period. Although best at 8 readings x day(-1), sensitivity and specificity were acceptable with four daily readings (82.4 and 87%). The effect of defining a record as being of adequate quality if it was of > or = 2.5 weeks' duration, with > or = 4 readings x day(-1) and > or = 3 consecutive workdays in each work period, was tested in records not used in the initial data reduction process. The sensitivity and specificity respectively of adequate records were 78.1 and 91.8 versus 63.6 and 83.3% for inadequate records. Peak expiratory flow records for the diagnosis of occupational asthma should be interpreted with caution if they do not satisfy the suggested minimum data quantity criteria.
Full-text · Article · May 2004 · European Respiratory Journal
[Show abstract][Hide abstract] ABSTRACT: Despite having a work related deterioration in peak expiratory flow (PEF), many workers with occupational asthma show a low degree of within day diurnal variability atypical of non-occupational asthma. It was hypothesised that these workers would have a neutrophilic rather than an eosinophilic airway inflammatory response.
Thirty eight consecutive workers with occupational asthma induced by low molecular weight agents underwent sputum induction and assessment of airway physiology while still exposed at work.
Only 14 (36.8%) of the 38 workers had sputum eosinophilia (>2.2%). Both eosinophilic and non-eosinophilic groups had sputum neutrophilia (mean (SD) 59.5 (19.6)% and 55.1 (18.8)%, respectively). The diurnal variation and magnitude of fall in PEF during work periods was not significantly different between workers with and without sputum eosinophilia. Those with eosinophilia had a lower forced expiratory volume in 1 second (FEV1; 61.4% v 83% predicted, mean difference 21.6, 95% confidence interval (CI) 9.2 to 34.1, p=0.001) and greater methacholine reactivity (geometric mean PD20 253 microg v 1401 microg, p=0.007). They also had greater bronchodilator reversibility (397 ml v 161 ml, mean difference 236, 95% CI of difference 84 to 389, p=0.003) which was unrelated to differences in baseline FEV(1). The presence of sputum eosinophilia did not relate to the causative agent, duration of exposure, atopy, or lack of treatment.
Asthma caused by low molecular weight agents can be separated into eosinophilic and non-eosinophilic pathophysiological variants with the latter predominating. Both groups had evidence of sputum neutrophilia. Sputum eosinophilia was associated with more severe disease and greater bronchodilator reversibility but no difference in PEF response to work exposure.