Latex-induced occupational asthma: time trend in incidence and relationship with hospital glove policies.

BACKGROUND: Natural rubber latex (NRL) has become as a major cause of occupational asthma (OA) in workers using NRL gloves. Few population-based studies have assessed the impact of changes in the patterns of glove usage on the incidence of NRL-induced OA. OBJECTIVE: To characterize the time trends in incident cases of NRL-induced OA in Belgium and examine whether incidence rates were related to the types of gloves used in hospitals. METHODS: Incident cases of NRL-induced OA were identified through a retrospective review of all claims submitted to the Workers' Compensation Board up to December 2004. Based on the results of diagnostic procedures, the diagnosis of NRL-induced OA was categorized as definite, probable, unlikely, or indeterminate. The patterns of glove usage were characterized through a questionnaire survey of Belgian hospitals. RESULTS: A total of 298 claims for NRL-induced OA were identified, including 127 subjects with definite OA and 68 with probable OA. Categorized by the year of asthma onset, the incident cases of definite and probable NRL-induced OA markedly decreased from 1999 onwards. The use of powdered NRL gloves fell from 80.9% in 1989 to 17.9% in 2004. Powdered NRL gloves were predominantly substituted with NRL-free gloves, especially in the case of non-sterile procedures. CONCLUSION: These national compensation-based data confirm that a persistent decline in the incidence of NRL-induced OA has occurred since late 1990s. This downward trend has temporally been associated with a decreasing usage of powdered NRL, further supporting a beneficial role of changes in glove policies.

[Epidemiology and etiologic agents of occupational asthma]. / Epidémiologie et étiologies de l'asthme professionnel.

INTRODUCTION: Occupational asthma is, by definition, a disease that can be prevented through appropriate protective strategies. Epidemiological information is required to guide these interventions, and we here examine epidemiological data on the burden, causes, and risk factors for this condition. STATE OF THE ART: Population-based surveys indicate that approximately 15% of adult asthma is attributable to the workplace environment. The most common occupational agents implicated include flour, isocyanates, latex, and persulphate salts. The occupations in which occupational asthma has been most commonly reported are bakers, spray painters, health-care workers, hairdressers, and cleaners. The level of exposure to sensitizing agents seems to be the most relevant risk factor. Atopy is a significant risk factor only for the development of sensitization to high molecular weight agents. The role of other individual determinants, such as genetic factors, has been less consistently established. Occupational asthma is associated with a substantial adverse impact on the employment and financial status of affected workers. PERSPECTIVES: Methodological improvements are required in order to distinguish more accurately between occupational and work-exacerbated asthma. Further investigations of the effectiveness of primary and secondary preventive interventions are also needed.

[The epidemiology of occupational asthma in Belgium]. / Epidémiologie de l'asthme professionnel en Belgique.

INTRODUCTION: A national surveillance programme of occupational asthma was set up to estimate the incidence and identify the causes of this disorder in Belgium. MATERIALS AND METHODS: The programme was based on the voluntary notification of new cases of occupational asthma by chest specialists and occupational physicians during the period 2000-2002. RESULTS: 92% of the reported cases included occupational asthma of an immunological type and 8% bronchial irritability. According to the opinion of the reporting physicians the diagnosis was considered certain in 39%, probable in 29% and possible in 32% of cases. On the basis of these notifications the mean annual incidence of occupational asthma is estimated as 23.5 cases per million workers (95% confidence interval 19.2-28.8). The most frequently incriminated substances were isocyanates (16%), cereals (12%) and latex (10%). At the time of diagnosis 38% of patients had not applied for compensation. CONCLUSION: The results of this programme of notification of occupational asthma agree with the data available from other countries and provide information complementary to the medico-legal statistics.

Comparison of FEV1 and specific airway conductance in assessing airway response to occupational agents.

BACKGROUND: There is theoretical evidence that specific airway conductance (SGaw) could be more reliable than forced expiratory volume in 1 s (FEV1) for assessing changes in airway calibre. We investigated the changes in FEV1 and SGaw when assessing bronchial responses to occupational agents. METHODS: SGaw and FEV1 were measured during inhalation challenges with various occupational agents in 174 consecutive subjects investigated for possible occupational asthma. RESULTS: A decline in SGaw of 50% or greater was documented in 77 of 90 subjects (86%) who showed a >/=20% fall in FEV1 and in 11 of 84 subjects (13%) who failed to demonstrate such a fall in FEV1. Among subjects who developed a >/=20% fall in FEV1, those who failed to develop a >/=50% decline in SGaw had a lower baseline SGaw than those who did. Among the group without a >/=20% fall in FEV1, a >/=50% decrease in SGaw was associated with either an 'intermediate' fall in FEV1 (between 15 and 17% from baseline value) (n = 4), a significant postchallenge increase in nonspecific bronchial hyper-responsiveness to histamine (n = 2), or both features (n = 3). CONCLUSIONS: A decline in SGaw of 50% or greater may provide useful complementary evidence of a bronchial response during challenges that produce equivocal results in FEV1.

Fever and neutrophilic alveolitis caused by a vanadium based catalyst.

AIMS: To investigate a worker who experienced systemic and respiratory symptoms when exposed to a vanadium containing powder used as a catalyst in the production of maleic anhydride. METHODS: The investigation included inhalation challenge with the suspected compound combined with monitoring of lung function tests and post-challenge bronchoalveolar lavage. RESULTS: Exposure to the vanadium containing catalyst for 120 minutes resulted in a sustained decline in forced vital capacity and forced expiratory volume in one second, while the transfer factor for carbon monoxide did not change significantly. The subject developed fever and peripheral blood neutrophilia. Bronchoalveolar lavage performed 48 hours after the end of challenge exposure showed a marked increase in neutrophils (60% of total cell count). CONCLUSIONS: Exposure to vanadium can cause a metal fume fever-like syndrome associated with neutrophilic alveolitis.

[Diagnostic approach occupational asthma]. / Approches diagnostiques de l'asthme professionnel.

Occupational asthma is associated with significant medical and socioeconomic consequences. Therefore, the diagnosis should be based on objective and accurate evidence. Available diagnostic procedures include the clinical history, measurement of non-specific bronchial hyperresponsiveness, monitoring of expiratory peak flows at work, and specific inhalation challenges in the laboratory. Advantages and limitations of these tests are discussed in order to propose a pragmatic diagnostic approach where specific inhalation challenges play a central role.

Socioeconomic outcome of subjects experiencing asthma symptoms at work.

The aim of this study was to investigate the socioeconomic outcomes of subjects who experienced work-related asthma symptoms in the absence of demonstrable occupational asthma (OA) and to compare these outcomes with those found in subjects with documented OA. Subjects (n=157) who were being investigated for work-related asthma, were surveyed. Of these 86 had OA, ascertained by a positive specific inhalation challenge (SIC), and 71 subjects had a negative SIC response. After a median interval of 43 months (range 12-85 months), the subjects were interviewed to collect information on employment status, income changes, and asthma-related work disability. Rates of work disruption and income loss at follow-up were similar in subjects with negative SIC (46% and 59%, respectively) and in those with OA (38% and 62%). The median loss as a percentage of initial income was 23% in subjects with negative SIC and 22% in subjects with OA. Asthma-related work disability, defined as any job change or work loss due to asthma, was slightly more common in subjects with OA (72%) than in those with negative SIC (54%). This study shows that, even in the absence of demonstrable occupational asthma, work-related asthma symptoms are associated with considerable socioeconomic consequences.

Occupational asthma in symptomatic workers exposed to natural rubber latex: evaluation of diagnostic procedures.

BACKGROUND: Natural rubber latex (NRL) has been increasingly identified as a cause of occupational asthma (OA). OBJECTIVE: We sought to examine the accuracy of the clinical history, immunologic tests, and assessment of nonspecific bronchial hyperresponsiveness in diagnosing OA caused by latex compared with that of the specific inhalation challenge (SIC). METHODS: Forty-five consecutive patients referred for investigation of possible OA caused by latex underwent a diagnostic protocol, including an open medical questionnaire, skin prick testing against latex, measurement of bronchial responsiveness to histamine, and inhalation challenge with latex gloves. Recorded clinical history was judged retrospectively by 4 physicians who were blinded for the results of other objective tests. RESULTS: The clinical history, skin prick testing against NRL, and assessment of nonspecific bronchial hyperresponsiveness showed a high sensitivity (87%, 100%, and 90%, respectively) but a low specificity (14%, 21%, and 7%, respectively) when compared with the results of the SIC. Logistic regression analysis showed that combining the results of skin prick tests against latex with the clinical history enhanced the negative predictive value from 50% to 71%, whereas the positive predictive value remained virtually unchanged (75% vs 76%). CONCLUSION: The clinical history and immunologic tests were the most useful procedures in diagnosing NRL-induced asthma, although combining the 2 procedures remained less accurate than SIC. Further examination of the predictive values of available tests is warranted to recommend diagnostic strategies that are specific to the various agents causing OA.