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Logo of oenvmedOccupational and Environmental MedicineVisit this articleSubmit a manuscriptReceive email alertsContact usBMJ
Occup Environ Med. 2007 December; 64(12): e5.
PMCID: PMC2095373

Asthma surveillance

008 Development of a country‐wide health surveillance among bakers: application of a diagnostic model for sensitisation to wheat and amylase allergens

D. Heederik, E. Suarthana, E. Meijer. IRAS University Utrecht

ObjectivesIn The Netherlands the baking and flour producing industries (3000 small bakeries, 80 industrial bakeries and 50 flour manufactures) agreed to reduce the high rate (up to 30%) of occupational related allergic diseases.

MethodsHealth surveillance for early detection of occupational allergic diseases is ongoing. In the preparation phase, a diagnostic model for sensitisation to wheat and fungal α‐amylase allergens was developed and validated. The model was converted into a score chart and two cut‐off points of the sum scores were selected for screening purposes. In the first phase, a questionnaire including the diagnostic predictors from the model was distributed to 8480 bakers. Surveillance simulation was done in 4843 bakers who returned the questionnaire. Bakers with high and medium sum scores will be referred to specialised occupational clinics and occupational physicians, respectively, for advanced medical examination. Bakers with low scores will be enrolled in the next health surveillance.

ResultsApplication of the diagnostic questionnaire model yielded 57.4%, 23.9% and 18.8% bakers in the low, medium and high scores groups. Workers with high scores showed the highest percentage of occupational allergic diseases. The first groups of bakers have been referred to a specialised occupational respiratory disease clinic. A validation study among approximately 900 bakers has been undertaken and diagnoses are available for referred workers.

ConclusionResults from the validation study and the available diagnoses indicate that the simple questionnaire is relatively accurate in distinguishing high risk groups of workers. With proper cut‐off points for referral, the diagnostic model could increase the efficiency of the health surveillance for occupational allergic diseases and lead to relatively accurate decision making.

Key wordsoccupational asthma; surveillance; sensitisation

009 New onset adult asthma (NOAA) in Alberta workers

N. M. Cherry1, J. Beach1, I. Burstyn1, N. Kapur1, S. M. Kennedy2. 1University of Alberta; 2University of British Columbia

ObjectivesTo explore patterns of new onset adult asthma by linking routinely collected data sets and to evaluate the potential for detecting occupational aetiology.

MethodsAll Alberta Workers Compensation Board (WCB) records for 10 years (1995–2004) were scrutinised and those for workers aged 18–65 years with a valid personal health number retained. Residence in Alberta was determined from Alberta Health records and physician visits for asthma (ICD9 493) identified from administrative (billing) records. Analysis of incidence was related to the date of WCB claim (for any reason), with a subject giving rise to a physician claim for asthma in the 12 months prior to the claim but not in the previous 3 years being considered an incident case. The analysis was limited to those living in Alberta throughout the 4 years prior to the claim and without asthma billings in years −4 to −1. Occupation and industry at the time of claim was extracted from WCB records and exposure to 18 asthmagens estimated from a job‐exposure matrix previously validated in a French worker population.

ResultsA total of 1 111 303 unique claims with a legitimate health care number were identified. Of these 742 876 met the residence criterion and were not prevalent cases. The overall incidence of NOAA was 1.69% with an increasing trend (1.55% in 1995–98, 1.62% 1999–2001, 1.89% in 2002–04). Rates for women were higher than those for men in this working population. Some expected associations with incidence were seen (in men, latex exposures and work with textiles, in women, work with reactive chemicals) but no significant increase in risk was seen with other known asthmagens (for example, work with laboratory animals, isocyanates).

ConclusionThe increasing incidence rates of physician diagnosed NOAA were compatible with those reported elsewhere. Linkage with WCB data provided a valuable opportunity to investigate occupational causes, but analysis so far has shown only limited ability to detect harmful exposures.

Key wordsoccupational asthma; surveillance; administrative data sets

010 Asthma in British Columbia: an administrative data approach to determine how much asthma is work related

C. McLeod1, M. Koehoorn2, S. M. Kennedy3, P. A. Demers3, L. Tamburic1. 1Centre for Health Services and Policy Research, University of British Columbia; 2Department of Health Care and Epidemiology, University of British Columbia; 3School of Occupational and Environmental Hygiene, University of British Columbia

ObjectivesTo determine the prevalence and incidence of asthma in British Columbia for working‐age adults for the period of 1991–2001; to derive an estimate of how much asthma may be work related; and to compare these estimates with the amount of occupational asthma compensated by BC's workers' compensation board.

MethodsEstimates of the incidence and prevalence of asthma were derived from health care contacts for asthma diagnoses via the BC Linked Health Database, a population‐based data resource comprising compensation, physician and hospitalisation records on almost all individuals in the province. An evidence‐based population attributable risk (PAR) of 15% was applied to the number of working‐age adults who met the asthma definition (any hospitalisation or compensation claim, or two physician visits within a 365‐day period) to estimate work‐related asthma.

ResultsIn 2000, the 10‐year cumulative prevalence of asthma among the working‐age population of BC was 51 and 68 cases per 1000 among males and females, respectively. Of this population, 37% of females and 34% of males received physician or hospital treatment for their asthma in 2000, an overall rate of 26 per 1000 for active asthma. The prevalence of active asthma increased slightly between 1996 and 2000, most notably among adult females. The incidence of new cases of asthma among the working‐age population was four and three cases per 1000 among males and females, respectively, in 2000. Overall, the incidence of new cases of asthma remained relatively stable in the province. Using a PAR of 15%, approximately 27 000 working‐age British Columbians experienced work‐related asthma in 2001 (nine cases per 1000). Five hundred and thirty occupational asthma claims were accepted by WorkSafeBC between 1991 and 2001—2% of estimated work‐related asthma.

ConclusionThe potential burden of work‐related asthma—whether active cases or cumulative prevalence—measures in the ten of thousands of cases. The estimates offered in this study, while broad, suggest that there is a need to focus prevention and screening efforts on this disease, which impacts one in 16 British Columbians.

Key wordsoccupational asthma; administrative data; workers' compensation

011 Asthma in relation to job exposure among Canada's adult population: comparison of surveillance information from two surveys

N. A. Garzia, M. Koehoorn, P. A. Demers, S. M. Kennedy. University of British Columbia

ObjectivesThis project investigates adult asthma in relation to job risk and compares the results from two surveys with different asthma and work surveillance information.

MethodsThe National Population Health Survey (NPHS) Longitudinal Household Component (n = 17 276 residents, all ages and provinces) was used to identify the first adult population 15–65 years old, employed full‐time in 2002/03. Current asthmatics were adults who reported “yes” to asthma in 2002/03. Using age of onset, current asthmatics were classified into adult‐ or childhood‐onset asthmatics. For most adult‐onset asthmatics, the job held at time of onset was determined. For childhood‐onset asthmatics, current job held (2002/03) was used. Jobs were categorised into high risk (HR) and low risk (LR) groups based on an asthma‐specific job exposure matrix (JEM).The Canadian Community Health Survey (CCHS) 2002/03 was used to identify the second adult population, 15–65 years old and currently employed (n = 101 123 residents from all provinces). Current asthmatics were identified the same as above, but data on age of onset or job held at time of onset were not included in the CCHS. For current asthmatics, jobs held in 2002/03 were classified into HR and LR based on the asthma‐specific JEM.

ResultsIn the NPHS, men with adult‐onset asthma were more likely to be in HR versus LR exposure jobs at time of onset (5.7% vs 2.8%, p<0.0001), but not women (5.7% vs 6.0%). Women with childhood‐onset asthma were more likely to be in current HR versus LR exposure jobs (7.2% vs 3.8%, p<0.0001) than men (4.1% vs 2.9%). In contrast, CCHS analyses showed no significant effect of job risk on asthma prevalence among current asthmatics, for either men (6.7% HR vs 6.2% LR) or women (8.9% HR vs 9.5% LR).

ConclusionNPHS results show a potential risk of adult‐onset asthma among men and work‐exacerbated asthma among women working in HR jobs. CCHS results may have been biased by the healthy worker effect because age of asthma onset was unknown and job exposure at time of onset could not be assigned. Necessary asthma and work surveillance information includes age of onset AND appropriate job information depending on age of onset.

Key wordsasthma; job; surveillance

012 Investigating the diagnosis of occupational asthma (OA) by occupational and respiratory physicians who report to The Health and Occupation Reporting (THOR) network

S. Turner1, R. McNamee2, C. Roberts1, S. Lines1, M. Henson3, L. Bradshaw3, A. Curran2, D. Fishwick2, R. Agius1. 1Centre for Occupational and Environmental Health, University of Manchester; 2Biostatistics, University of Manchester; 3Health and Safety Laboratory, Buxton, UK

ObjectivesTHOR is a voluntary surveillance scheme receiving case reports of occupational ill‐health from UK‐based physicians. Cases are reported if the clinician believes that the condition was caused by occupational factors, however the degree of reliability that THOR reporters assign to a diagnosis of OA has not been studied. This study aimed to investigate the likelihood of assigning a diagnosis of OA by occupational and respiratory physicians reporting to THOR.

MethodsBetween 2002 and 2004, THOR data estimated the incidence of OA as 1393 diagnoses. Just over half of these diagnoses (770/1393, 55.3%) originated from occupational physicians, and 623 (44.7%) from respiratory physicians. In phase one of this study, 19 “possible” case histories of OA (prepared by chest physicians specialising in occupational respiratory disease) were sent to 51 occupational and 53 respiratory physicians actively participating in THOR. Each physician was asked to determine the certainty (0–100%) that (s)/he would assign to an OA diagnosis for four case histories. For phase two, each physician was sent results of investigations for two of the four cases, and asked to determine the certainty that (s)/he would assign to an OA diagnosis for these two cases. Responses were analysed to investigate patterns of reporting within and between these two groups of clinical specialists using a multilevel (mixed) model to account for the repeated measures structure.

ResultsThe return rate for the study was 86% (occupational physicians) and 81% (respiratory physicians). The range of probabilities of OA assigned by physicians was wide, ranging from 0 to 100%. Preliminary analysis to compare OA ratings showed no overall difference between the mean probabilities assigned by occupational and respiratory physicians (a mean difference of −1.7% (95% CI −6.5 to 3.1) p = 0.49). Preliminary analysis to compare results from “case histories” and “case histories plus investigations” showed no difference between the mean probabilities for OA ratings (a mean difference of −5.1% (95% CI −10.9 to 0.8) p = 0.09).

ConclusionPatterns of reporting to THOR may differ within and between clinical specialties, perhaps caused by variations in physicians' case loads/mixes. However, such differences are not necessarily reflected in diagnostic preferences, despite disparities in physicians' training and experience.

Key wordssurveillance; occupational asthma; diagnosis

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