Prognosis of occupational asthma

Seafood workers and respiratory disease: an update

PURPOSE OF REVIEW

This review focuses on seafood workers engaged in harvesting, processing and food preparation. These groups are increasingly at risk of developing occupational allergy and respiratory disease as a result of seafood handling and processing activities. This review provides an update of a previous review conducted a decade ago.

RECENT FINDINGS

Exposure characterization studies have demonstrated that aerosolization of seafood (muscle, visceral organs, skin/mucin) during canning and fishmeal operations result in highly variable levels of airborne particulate (0.001-11.293 mg/m3) and allergens (0.001-75.748 ug/m3). Occupational asthma is more commonly associated with shellfish (4-36%) than with bony fish (2-8%). Other seafood-associated biological (Anisakis) and chemical agents (protease enzymes, toxins and preservatives) have also been implicated. Atopy, smoking and level of exposure to allergens are significant risk factors for sensitization and the development of occupational asthma. Molecular studies of the allergens suggest that aside from tropomyosin and parvalbumin, other as yet uncharacterized allergens are important.

SUMMARY

Future research needs to focus on detailed characterization of allergens in order to standardize exposure assessment techniques, which are key to assessing the impact of interventions. The clinical relevance of agents such as serine proteases and endotoxins in causing asthma through nonallergic mechanisms needs further epidemiological investigation.

Use of objective testing in the diagnosis of work-related asthma by physician specialty

BACKGROUND

Although early and accurate diagnosis of work-related asthma is critical to avoid unnecessary medical, legal, social, and economic consequences, little is currently known about the diagnostic practices of physicians treating workers with work-related asthma.

OBJECTIVE

To characterize the use of objective diagnostic testing for work-related asthma by physician specialty.

METHODS

A cross-sectional, descriptive, comparative evaluation was conducted of 301 workers' compensation claimants with work-related asthma.

RESULTS

A few claimants (36.9%) were treated by specialists in work-related asthma (allergists, pulmonologists, or occupational medicine physicians) either initially or through the course of their claim. Workers with occupational asthma were more likely to have seen a specialist than those with work-aggravated asthma (47.9% vs 23.0%; P < .001). Less than half of the claimants with work-related asthma (43.2%) had received an objective evaluation of pulmonary function, through either pulmonary function testing or testing for reversible airflow limitation, for the evaluation of their work-related asthma. Claimants treated by specialists were significantly more likely to have received diagnostic testing during evaluation of their disease than those treated solely by generalists (82.9% vs 20.0%; P < .001).

CONCLUSIONS

The results of this study point to the lack of appropriate diagnostic care received by workers with work-related asthma. Physicians who may have questions about diagnostic procedures should consider referral to a specialist. The development of referral networks for work-related asthma may be warranted and should be explored.

Occupational asthma: an assessment of diagnostic agreement between physicians

OBJECTIVES

To investigate the levels of agreement between expert respiratory physicians when making a diagnosis of occupational asthma.

METHODS

19 cases of possible occupational asthma were identified as part of a larger national observational cohort. A case summary for each case was then circulated to 12 physicians, asking for a percentage likelihood, from the supplied information, that this case represented occupational asthma. The resulting probabilities were then compared between physicians using Spearman's rank correlation and Cohen's kappa coefficients.

RESULTS

Agreement between the 12 physicians for all 19 cases was generally good as assessed by Spearman's rank correlation. For all 66 physician-physician interactions, 45 were found to correlate significantly at the 5% level. The agreement assessed by kappa analysis was more variable, with a median kappa value of 0.26, (range -0.2 to +0.76), although 7 of the physicians agreed significantly (p<0.05) with >or=5 of their colleagues. Only in one case did the responses for probability of occupational asthma all exceed the "on balance" 50% threshold, although 12 of the 19 cases had an interquartile range of probabilities not including 50%, implying "on balance" agreement. The median probability values for each physician (all assessing the identical 19 cases) varied from 20% to 70%. Factors associated with a high probability rating were the presence of a positive serial peak expiratory flow Occupation Asthma SYStem (OASYS)-2 chart, and both the presence of bronchial hyper-reactivity and significant change in reactivity between periods of work and rest.

CONCLUSIONS

Despite the importance of the diagnosis of occupational asthma and reasonable physician agreement, certain variations in diagnostic assessment were seen between UK expert centres when assessing paper cases of possible occupational asthma. Although this may in part reflect the absence of a normal clinical consultation, a more unified national approach to these patients is required.

Occupational exposures as triggers of asthma

The prevalence of occupational asthma is rising, possibly due to the introduction of different chemicals and substances in the workplace. Etiologic agents include organic and inorganic compounds that are encountered in a variety of industries. Early diagnosis, adequate management of inflammation, and prevention of further exposure are essential to occupational asthma management. Reducing complications and disability while providing work rehabilitation should be the ultimate goal of the health care provider. This article discusses these issues and gives guidance to the clinician treating patients with possible occupational asthma.

8. Occupational asthma and allergies

A diversity of airborne dusts, gases, fumes, and vapors can cause dose-related symptoms in individuals exposed in the workplace. More than 250 chemicals have been incriminated as a cause of occupational asthma (OA). The prevalence of OA ranges from 2% to 6% of the asthmatic population. Predisposing factors facilitating the development of OA include the work environment, climatic conditions, genetic proclivities, tobacco and recreational drug use, respiratory infection, and bronchial hyperresponsiveness. Pathogenetically, new-onset OA may be immunologic or nonimmunologic in origin. The immunologic variants are usually caused by high molecular-weight allergens such as grain dust and animal or fish protein. Symptoms ensue after a latent period of months to years. Nonimmunologic OA can be precipitated by a brief, high-level exposure to a potent irritant. Symptoms occur immediately or within a few hours of the exposure. In either instance, once the diagnosis is established, the worker should be removed from the workplace. If the diagnosis is made in a timely fashion, most workers experience improvement. Prevention is the best therapeutic intervention.

Occupational asthma

Occupational asthma is a common yet all too frequently unnoticed form of adult asthma. Many agents can trigger disease by a variety of mechanisms, some of which are unknown. Awareness of high-risk occupations and knowledge that adults with persistent asthma may have an occupational trigger are vital in early identification and treatment of this population of patients where the stakes are high. Although the sensitivity and specificity of various tests are low, a multidimensional approach, which includes the cooperation of primary care physician, allergist-immunologist, pulmonologist, industrial hygienist, occupational medicine specialist, and industry (union and management), can lead to a successful outcome in a timely manner.