Long-term health and employment outcomes of occupational asthma and their determinants

Work-related asthma consequences on socioeconomic, asthma control, quality of life, and psychological status compared with non-work-related asthma: A cross-sectional study in an upper-middle-income country

BACKGROUND

Work-related asthma (WRA) is the most prevalent occupational respiratory disease, and it has negative effects on socioeconomic standing, asthma control, quality of life, and mental health status. Most of the studies on WRA consequences are from high-income countries; there is a lack of information on these effects in Latin America and in middle-income countries.

METHODS

This study compared socioeconomic, asthma control, quality of life, and psychological outcomes among individuals diagnosed with WRA and non-work-related asthma (NWRA) in a middle-income country. Patients with asthma, related and not related to work, were interviewed using a structured questionnaire to assess their occupational history and socioeconomic conditions, and with questionnaires to assess asthma control (Asthma Control Test and Asthma Control Questionnaire-6), quality of life (Juniper's Asthma Quality of Life Questionnaire), and presence of anxiety and depression symptoms (Hospital Anxiety and Depression Scale). Each patient's medical record was reviewed for exams and use of medication, and comparisons were made between individuals with WRA and NWRA.

RESULTS

The study included 132 patients with WRA and 130 with NWRA. Individuals with WRA had worse socioeconomic outcomes, worse asthma control, more quality-of-life impairment, and a higher prevalence of anxiety and depression than individuals with NWRA. Among individuals with WRA, those who had been removed from occupational exposure had a worse socioeconomic impact.

CONCLUSIONS

Consequences on socioeconomic, asthma control, quality of life, and psychological status are worse for WRA individuals when compared with NWRA.

Clinical Characteristics of Irritant-Induced Occupational Asthma

BACKGROUND

Work is a substantial contributing factor of adult-onset asthma. A subtype of occupational asthma (OA) is caused by irritant agents, but knowledge of the clinical outcomes of irritant-induced asthma (IIA) is incomplete.

OBJECTIVES

To evaluate whether the clinical picture of IIA differs from that of sensitizer-induced OA.

METHODS

This retrospective study analyzed acute and subacute IIA patients diagnosed in an occupational medicine clinic during 2004 to 2018. Sixty-nine patients fulfilled the inclusion criteria, and their characteristics were analyzed at the time of the diagnosis and 6 months later. The results were compared with those of 2 subgroups of sensitizer-induced OA: 69 high-molecular-weight (HMW) and 89 low-molecular-weight (LMW) agent-induced OA patients.

RESULTS

Six months after the diagnosis, 30% of the patients with IIA needed daily short-acting β-agonists (SABA), 68% were treated with Global Initiative for Asthma, 2020 report (GINA) step 4-5 medication, and 24% of the patients had asthma exacerbation after the first appointment. IIA depicted inferiority to LMW-induced OA in daily need for SABA (odds ratio [OR]: 3.80, 95% confidence interval [CI]: 1.38-10.46), treatment with GINA step 4-5 medication (OR: 2.22, 95% CI: 1.08-4.57), and exacerbation (OR: 3.85, 95% CI: 1.35-11.04). IIA showed poorer results than HMW-induced OA in the latter 2 of these features (OR: 2.49, 95% CI: 1.07-5.79 and OR: 6.29, 95% CI: 1.53-25.83, respectively).

CONCLUSIONS

Six months after the OA diagnosis, a significant proportion of the patients with IIA remain symptomatic and the majority of these patients use asthma medications extensively suggesting uncontrolled asthma. The short-term outcomes of IIA appear poorer than that of sensitizer-induced OA.

Occupational exposures associated with severe exacerbation of asthma

BACKGROUND

The exacerbation of asthma by workplace conditions is common, but little is known about which agents pose a risk.

OBJECTIVE

We used data from an existing survey of adults with asthma to identify occupational exposures associated with severe exacerbation of asthma.

DESIGN

Questionnaires were completed by 557 working adults with asthma. Severe exacerbation of asthma in the past 12 months was defined as asthma-related hospitalization, or reports of both unplanned asthma care and treatment with a short course of oral corticosteroids. Occupational exposures for the same time period were assessed using an asthma-specific job exposure matrix. We modeled severe exacerbation to yield prevalence ratios (PRs) for exposures while controlling for potential confounders.

RESULTS

A total of 164 participants (29%) were positive for severe exacerbation, and 227 (40.8%) were assessed as being exposed to asthma agents at work. Elevated PRs were observed for several specific agents, notably the irritant subcategories of environmental tobacco smoke (PR 1.84, 95%CI 1.34-2.51) among all participants, inorganic dusts (PR 2.53, 95%CI 1.37-4.67) among men, and the low molecular weight subcategory of other highly reactive agents (PR 1.97, 95%CI 1.08-3.60) among women.

CONCLUSION

Among working adults with asthma, severe exacerbation was associated with several occupational agents.

Role of infections in the induction and development of asthma: genetic and inflammatory drivers

Genetic and environmental factors interact to initiate and even maintain the course of asthma. As one of the highly risky environmental factors, infections in predisposed individuals can promote asthma development and exacerbations and/or prolong symptoms. This review will describe our current understanding of the genetic markers of innate immunity in the induction and development of asthma, the diverse roles of infections in modulating allergic inflammation, host susceptibility to infections and subsequent acute exacerbations in an allergic setting, and the therapeutic or preventive implications of existing knowledge. Current challenges and future directions in basic and clinical research of asthma are also discussed.

Predictors for return to work for those with occupational respiratory disease: clinical and structural factors

BACKGROUND

Few occupational researchers have examined "return to work" among patients with work-related respiratory diseases. In addition, prior studies have emphasized individual patient characteristics rather than a more multi-dimensional approach that includes both clinical and structural factors.

METHODS

A retrospective chart review identified patients with occupational respiratory diseases in the Occupational Health Clinical Center, Syracuse, NY between 1991 and 2009. We assessed predictors of work status using an exploratory, sequential mixed methods research design, multinomial (n = 188) and Cox regressions (n = 130).

RESULTS

The findings suggest that patients with an increased number of diagnoses, non-union members, and those who took more than a year before clinical presentation had significantly poorer work status outcomes, after adjusting for age, education level, and relevant diagnoses.

CONCLUSIONS

Efforts to prevent slow return to work after developing occupational respiratory disease should recognize the importance of timely access to occupational health services, disease severity, union membership, and smoking status.

Occupational asthma

Occupational asthma is the most common occupational lung disease. Work-aggravated asthma and occupational asthma are two forms of asthma causally related to the workplace, while reactive airways dysfunction syndrome is a separate entity and a subtype of occupational asthma. The diagnosis of occupational asthma is most often made on clinical grounds. The gold standard test, specific inhalation challenge, is rarely used. Low molecular weight isocyanates are the most common compounds that cause occupational asthma. Workers with occupational asthma secondary to low molecular weight agents may not have elevated specific IgE levels. The mechanisms of occupational asthma associated with these compounds are partially described. Not all patients with occupational asthma will improve after removal from the workplace.

Socioeconomic impact of work-related asthma

Work-related asthma (WRA) accounts for 10-15% of adult asthma. This review will summarize the available information related to the socioeconomic outcomes inherent to WRA. A substantial proportion of subjects suffering from WRA experience prolonged work disruption and subsequent loss of income. Moreover, recent studies have established that WRA is associated with a higher use of healthcare resources and a lower quality of life than asthma unrelated to work. The negative socioeconomic consequences are mostly influenced by professional and demographic factors, including reduced possibilities for relocation to an unexposed job within the same company, lack of effective retraining programs and low level of education. These socioeconomic considerations should be regarded as a central component in the implementation of rational management and prevention policies.

Predictors of early cessation of dairy farming in the French Doubs province: 12-year follow-up

BACKGROUND

A healthy worker effect due to respiratory disability has been noted in the farming population, but other factors may also interfere. Little has been published about factors influencing the early cessation of work in self-employed dairy farmers.

METHODS

Two hundred and nineteen dairy farmers were included from a cohort constituted in eastern France in 1993-1994 with a 12-year follow-up. Spirometric data, personal, and farm characteristics were registered. Cox models with delayed entry in which age was the time-scale were applied to identify the baseline predictive factors of the early cessation of dairy farming.

RESULTS

Working in a modern farm was protective against early cessation of dairy farming (hazard ratio: 0.36 [95% CI: 0.16-0.81]), especially in men. Having asthma was a predictive factor of early cessation, especially in women (hazard ratio: 16.12 [95% CI: 3.28-79.12]).

CONCLUSIONS

The most predictive factors of early cessation of dairy farming were health related in women and farm related in men.

An official american thoracic society statement: work-exacerbated asthma

RATIONALE

Occupational exposures can contribute to the exacerbation as well as the onset of asthma. However, work-exacerbated asthma (WEA) has received less attention than occupational asthma (OA) that is caused by work.

OBJECTIVES

The purpose of this Statement is to summarize current knowledge about the descriptive epidemiology, clinical characteristics, and management and treatment of WEA; propose a case definition for WEA; and discuss needs for prevention and research.

METHODS

Information about WEA was identified primarily by systematic searches of the medical literature. Statements about prevention and research needs were reached by consensus.

MEASUREMENTS AND MAIN RESULTS

WEA is defined as the worsening of asthma due to conditions at work. WEA is common, with a median prevalence of 21.5% among adults with asthma. Different types of agents or conditions at work may exacerbate asthma. WEA cases with persistent work-related symptoms can have clinical characteristics (level of severity, medication needs) and adverse socioeconomic outcomes (unemployment, reduction in income) similar to those of OA cases. Compared with adults with asthma unrelated to work, WEA cases report more days with symptoms, seek more medical care, and have a lower quality of life. WEA should be considered in any patient with asthma that is getting worse or who has work-related symptoms. Management of WEA should focus on reducing work exposures and optimizing standard medical management, with a change in jobs only if these measures are not successful.

CONCLUSIONS

WEA is a common and underrecognized adverse outcome resulting from conditions at work. Additional research is needed to improve the understanding of the risk factors for, and mechanisms and outcomes of, WEA, and to inform and evaluate preventive interventions.

Factors associated with a higher prevalence of work disability among asthmatic patients

OBJECTIVE

To study asthma-related absenteeism in the asthmatic population in Spain and to identify some risk factors for absenteeism.

METHODS

A cross-sectional study was performed on patients who had been diagnosed with asthma in the primary care setting at least 1 year before the start of this study. A questionnaire was designed that included socio-demographic and clinical variables. The time absent from work in the previous year was self-reported by the patients.

RESULTS

More than 25% of the asthmatic population in Spain took sick leave during the previous year. Visits to a general practitioner or to the emergency department are the factors associated with the greatest risk of absenteeism.

CONCLUSIONS

Absenteeism is common within the asthmatic population in Spain. The authors of this study believe that some of the determining factors could be modified by the health-care system.

Diagnosis and management of work-related asthma: American College Of Chest Physicians Consensus Statement

BACKGROUND

A previous American College of Chest Physicians Consensus Statement on asthma in the workplace was published in 1995. The current Consensus Statement updates the previous one based on additional research that has been published since then, including findings relevant to preventive measures and work-exacerbated asthma (WEA).

METHODS

A panel of experts, including allergists, pulmonologists, and occupational medicine physicians, was convened to develop this Consensus Document on the diagnosis and management of work-related asthma (WRA), based in part on a systematic review, that was performed by the University of Alberta/Capital Health Evidence-Based Practice and was supplemented by additional published studies to 2007.

RESULTS

The Consensus Document defined WRA to include occupational asthma (ie, asthma induced by sensitizer or irritant work exposures) and WEA (ie, preexisting or concurrent asthma worsened by work factors). The Consensus Document focuses on the diagnosis and management of WRA (including diagnostic tests, and work and compensation issues), as well as preventive measures. WRA should be considered in all individuals with new-onset or worsening asthma, and a careful occupational history should be obtained. Diagnostic tests such as serial peak flow recordings, methacholine challenge tests, immunologic tests, and specific inhalation challenge tests (if available), can increase diagnostic certainty. Since the prognosis is better with early diagnosis and appropriate intervention, effective preventive measures for other workers with exposure should be addressed.

CONCLUSIONS

The substantial prevalence of WRA supports consideration of the diagnosis in all who present with new-onset or worsening asthma, followed by appropriate investigations and intervention including consideration of other exposed workers.

Primary prevention of occupational asthma: identifying and controlling exposures to asthma-causing agents

BACKGROUND

Primary prevention of occupational asthma requires timely identification and regulation of asthma-causing agents.

METHODS

We examined 39 substances identified as causing allergic occupational asthma in the US to determine the basis for their identification and their regulatory status. We compared them with occupational asthmagens identified and regulated in the UK and Germany.

RESULTS

US regulatory agencies have not established consistent, evidence-based methods to identify and control exposures to substances that cause occupational asthma. Occupational asthmagens are identified primarily by non-regulatory US organizations, and most are not regulated to prevent asthma.

CONCLUSIONS

Implementing an evidence-based identification and regulatory process for occupational asthmagens will help to ensure primary prevention of occupational asthma in the US. This should include: establishing consistent identification criteria; publishing a list of occupational asthmagens; collecting use, exposure, and health effects information on asthma-causing substances; requiring medical surveillance and medical removal protection in addition to exposure limits; and stimulating development of safer alternatives.

Predictors of delayed return to work or job loss with respiratory ill-health: a systematic review

INTRODUCTION

Every year approximately 17,000 people in the UK are off work through sickness for six or more weeks. Only fifty percent of those off for six months return to work.

METHODS

A systematic review was conducted to identify potential risk factors for non-return to work within six to 26 weeks or job loss in adult workers with respiratory ill-health. Twelve databases, citation and author lists and cited references were searched. All abstracts and papers were double read and quality assessed. Main outcome measures were return to work and employment status.

RESULTS

Five studies of variable methodological quality were identified, all focussing on asthma, occupationally induced or not, with two single studies also covering chronic obstructive pulmonary disease or rhinitis. In the single study of a general working population, blue collar workers having either asthma or chronic obstructive pulmonary disease, were from two to six times less likely to return to work quickly compared with office workers. Overall, unemployment was high with becoming unemployed three times higher in those with all forms of asthma compared with rhinitis. Also, in those with occupational asthma, job loss was more likely if working in smaller companies and being less well educated.

CONCLUSIONS

Evidence on predictors for non-return to work or job loss with respiratory ill-health in a general working population is limited. Yet without an understanding of these, interventions to reduce the further step to long term disability cannot be designed and implemented.

Occupational asthma and work-exacerbated asthma: factors associated with time to diagnostic steps

BACKGROUND

Little is known regarding the factors associated with the times for patients' first physician visit, the first physician suspicion of work-related asthma (WRA), and final diagnosis after the onset of WRA symptoms. This study examined individual and work-related factors that are associated with longer times to these diagnostic milestones among groups with occupational asthma (OA) and work-exacerbated asthma (WEA).

METHOD

Suspected WRA cases were identified from an occupational lung disease clinic and claimants to the Ontario Workplace Safety and Insurance Board (100 patients each). Questionnaire administration and chart review were undertaken.

RESULTS

Eighty participants were classified as having sensitizer-induced OA and 87 as having WEA. For the OA group, the risk factors for delay included male sex, being unmarried, low education, and lack of awareness of association of symptoms with work. Other factors included older age, being the sole income earner, and lack of knowledge of the Workplace Hazardous Materials Information System program. For WEA, lower household income, lower education, absence of a health-and-safety program at work, absence of a union, and lack of awareness of OA and of agents at work that could affect asthma significantly increased the time to diagnostic milestones.

CONCLUSIONS

Different factors affect the diagnostic milestones for OA and WEA. Findings suggest a need for educational programs for workers who are at risk of OA and WEA and a need for further primary care physician education on WRA.

Outcome of occupational asthma after cessation of exposure: a systematic review

BACKGROUND

Patients with occupational asthma, and their medical advisers, need valid information about the prognosis of their disease.

METHODS

A systematic review of the published literature on the symptomatic and functional outcomes of occupational asthma was carried out after avoidance of exposure to the causative agent. Through a full search of electronic and bibliographic sources, original studies documenting complete recovery from asthma (n = 39,1681 patients) or improvement in non-specific bronchial hyper-responsiveness (NSBHR; n = 28,695 patients) were identified. The median duration of follow-up was 31 (range 6-240) months for studies of symptomatic recovery and 37 (6-240) months for studies of NSBHR. Most studies were of patients recruited from special clinics.

RESULTS

Reported rates of symptomatic recovery varied from 0% to 100%, with a pooled estimate of 32% (95% CI 26% to 38%). These rates were lower with increasing age (p = 0.019) and among clinic based populations (p = 0.053). Patients with the shortest durations of exposure (< or =76 months) had the highest rate of recovery (36%; 95% CI 25% to 50%), but the effect was not linear. The pooled prevalence of persistent NSBHR at follow-up was 73% (95% CI 66% to 79%). This figure was higher among patients whose disease was due to high-molecular-weight agents (p = 0.006) and, less clearly, those from clinic-based populations (p = 0.561). In between-study comparisons, no clear patterns of improvement relating to total duration of exposure or follow-up were found. From within-study comparisons there was some evidence that a shorter duration of symptoms was associated with a higher rate of symptomatic recovery.

CONCLUSION

The available data on the prognosis of occupational asthma are insufficiently consistent to allow confident advice to be given to patients with the disease. Clinicians and epidemiologists with an interest in this disease should consider a collaborative and carefully standardised study of the prognosis of occupational asthma.

Prevention of occupational asthma--practical implications for occupational physicians

BACKGROUND

Occupational factors have been estimated to contribute to approximately 10% of adult-onset asthma and occupational asthma (OA) is one of the most common occupational lung diseases in industrialized areas. Persistent asthma frequently occurs with significant socio-economic impacts.

METHODS

A literature search was performed using PubMed. The key term searched was occupational asthma combined with prevention.

RESULTS

Primary prevention has been effective for OA related to natural rubber latex, and may have reduced the incidence of diisocyanate-induced asthma. Medical health surveillance has been effective in settings such as the detergent enzyme industry, workers exposed to complex platinum salts and likely for diisocyanate workers in Ontario. Tertiary prevention is still required for workers with OA and can improve prognosis.

CONCLUSIONS

OA is potentially preventable. Sufficient studies have demonstrated the rationale and benefit of primary preventive strategies. Medical health surveillance programs combined with occupational hygiene measures and worker education have been associated with improved outcomes but further studies are needed to understand the optimum frequency and measures for such programs and to identify the separate contribution of the components. Until primary and secondary prevention is better understood and implemented, there will also remain a need for tertiary preventive measures.

The frequency of workplace exacerbation among health maintenance organisation members with asthma

OBJECTIVES

Workplace conditions can potentially contribute to the worsening of asthma, yet it is unclear what percentage of adults with asthma experience workplace exacerbation of symptoms. The objective of this investigation was to determine the prevalence of workplace exacerbation of asthma (WEA).

METHODS

Adults with asthma aged 18-44 were enrolled into the baseline survey of a longitudinal study. Members of a health maintenance organisation were considered candidates for participation if they fulfilled membership, diagnostic, and treatment criteria based on automated review of electronic billing, claims, and pharmacy records. Diagnosis and treatment were confirmed by manual review of medical records. A telephone questionnaire was administered. A work related symptom score was assigned to each participant based on responses to questions about work related asthma symptoms, medication use, and symptom triggers. Blinded to participants' answers to these questions, two researchers independently reviewed the self-reported work histories and assigned exposure ratings. A final exposure score was then calculated. Participants with sufficient evidence for work related symptoms and exposure were classified as having WEA.

RESULTS

Of the 598 participants with complete data, 557 (93%) were working, and 136 (23%) fulfilled the criteria for WEA. Those with WEA were more likely to be male and to report that they had been bothered by asthma symptoms during the past seven days.

CONCLUSIONS

Workplace exacerbation of asthma was common in this study population, occurring in over a fifth of these adults with asthma. Physicians should consider that work can contribute to the exacerbation of symptoms when treating adults with asthma.

Work life of persons with asthma, rhinitis, and COPD: a study using a national, population-based sample

OBJECTIVE

To estimate the duration of work life among persons reporting a physician's diagnosis of COPD, asthma, or rhinitis compared to those with select non-respiratory conditions or none and to delineate the factors associated with continuance of employment.

METHODS

Persons ages 55 to 75 reporting a physician's diagnosis of COPD, asthma, or rhinitis as well as those without any of these conditions were identified by random-digit dialing (RDD) in the continental U.S and administered a structured survey. We used Kaplan-Meier life table analysis to estimate the duration of work life among persons with and without the three conditions and Cox proportional hazard regression to examine the role of demographic and work characteristics in the proportion leaving employment in each time interval.

RESULTS

Persons with COPD, asthma, and rhinitis were no less likely than the remainder of the population to have ever worked, but those with COPD were less likely to be working when interviewed or as of age 65, whichever came first. As of age 55, only 62 percent of persons with COPD continued to work versus 72 and 78 percent of persons with asthma and rhinitis, respectively. Persons with COPD, asthma, and rhinitis all had an elevated risk of leaving work prior to age 65 relative to those without chronic conditions, with and without adjustment for demographic and work characteristics.

CONCLUSION

COPD and to a lesser extent asthma and rhinitis were associated with a substantially shortened work life, an effect not due to demographic and work characteristics.

Surveillance for isocyanate asthma: a model based cost effectiveness analysis

AIMS

Because logistical and financial obstacles impede using large prospective cohort studies, surveillance decisions in occupational settings must often be made without evidence of relative benefits and costs. Using the example of isocyanate induced asthma, the most commonly reported immune mediated occupational asthma, the authors developed a model based approach to evaluate the costs and benefits of surveillance from both an employer and a societal perspective.

METHODS

The authors used a mathematical simulation model of isocyanate asthma to compare annual surveillance to passive case finding. Outcome measures included symptom free days (SFD), quality adjusted life years (QALY), direct costs, productivity losses, and incremental cost effectiveness ratio (CER), measured from the employer and the societal perspectives. Input data were obtained from a variety of published sources.

RESULTS

For 100,000 exposed workers, surveillance resulted in 683 fewer cases of disability over 10 years. Surveillance conferred benefits at an incremental cost of 24,000 dollars/QALY (employer perspective; 13.33 dollars/SFD) and was cost saving from the societal perspective. Results were sensitive to assumptions about sensitisation rate, removal rates, and time to diagnosis, but not to assumptions about therapy costs and disability rates.

CONCLUSIONS

Baseline results placed the CER for surveillance for isocyanate asthma within the acceptable range. Costs from the societal and employer perspective differed substantially with a more attractive CER from the societal perspective, suggesting opportunities for employer/societal cost sharing. The analysis demonstrates the value of a model based approach to evaluate the cost effectiveness of surveillance programmes for isocyanate asthma, and to inform shared decision making among clinicians, patients, employers, and society. Such a modeling approach may be applicable to surveillance programmes for other work related conditions.

Clinical practice guidelines: medical follow-up of patients with asthma--adults and adolescents

The follow-up of patients with asthma should focus on asthma control (disease course over a number of weeks).

Symptom onset in the first 2 years of employment at a wood products plant using diisocyanates: some observations relevant to occupational medical screening

BACKGROUND

Questionnaires are essential tools for medical screening, but their role in monitoring workers at increased risk of occupational asthma (OA) remains indeterminate.

METHODS

Employees who were at a newly established wood products plant without previous exposure to methylene diphenyl diisocyanate (MDI) completed an initial questionnaire and from one to four follow-up questionnaires during a 2-year period. Onset of symptoms in 132 workers was assessed by exposure groups and modeled using generalized estimating equations.

RESULTS

Onset of attacks of dyspnea with wheeze, attacks of dyspnea or cough at rest, and chest tightness were significantly associated with MDI exposure after controlling for age, smoking, and wood dust exposure. Onset of cough on most days was significantly related to smoking and dust. Onset of phlegm production was significantly related to both MDI and dust exposure.

CONCLUSIONS

Onset of certain symptoms is significantly associated with MDI exposure. Early detection of MDI-associated health effects using a short screening questionnaire appears feasible.

A descriptive study of work aggravated asthma

BACKGROUND AND AIMS

Work related asthma (WRA) is one of the most frequently reported occupational lung diseases in a number of industrialised countries. A better understanding of work aggravated asthma (WAA), as well as work related new onset asthma (NOA), is needed to aid in prevention efforts.

METHODS

WAA and NOA in the United States were compared using cases reported to the National Institute for Occupational Safety and Health (NIOSH) from four state Sentinel Event Notification Systems for Occupational Risks (SENSOR) surveillance programmes for 1993-95.

RESULTS

A total of 210 WAA cases and 891 NOA cases were reported. WAA cases reported mineral and inorganic dusts as the most common exposure agent, as opposed to NOA cases, in which diisocyanates were reported most frequently. A similar percentage of WAA and NOA cases still experienced breathing problems at the time of the interview or had visited a hospital or emergency room for work related breathing problems. NOA cases were twice as likely to have applied for workers' compensation compared with WAA cases. However, among those who had applied for worker compensation, approximately three-fourths of both WAA and NOA cases had received awards. The services and manufacturing industrial categories together accounted for the majority of both WAA (62%) and NOA (75%) cases. The risk of WAA, measured by average annual rate, was clearly the highest in the public administration (14.2 cases/10(5)) industrial category, while the risk of NOA was increased in both the manufacturing (3.2 cases/10(5)) and public administration (2.9 cases/10(5)) categories.

CONCLUSIONS

WAA cases reported many of the same adverse consequences as NOA cases. Certain industries were identified as potential targets for prevention efforts based on either the number of cases or the risk of WAA and NOA.

Costs of occupational asthma and of occupational chronic obstructive pulmonary disease

PURPOSE OF REVIEW

The purpose of this review is to summarize the most recent findings on the costs of occupational asthma and chronic obstructive pulmonary disease, illustrating the different approaches for estimates, the results and the social and financial implications.

RECENT FINDINGS

Many published data in the literature show that occupational asthma and chronic obstructive pulmonary disease represent a relevant proportion of the total prevalence of these diseases. Previous findings demonstrated that occupational asthma has adverse economic and employment consequences for the worker, and a significant cost related to the claims. Recent studies using a standard method have specifically estimated the cost of the proportion of cases of asthma and chronic obstructive pulmonary disease attributable to occupational exposure out of the total costs of these diseases, and demonstrated that it is significant. Some recent data indicate a beneficial outcome of occupational asthma and a reduction in the number of the claims from primary and secondary preventive intervention at the workplace.

SUMMARY

In conclusion, occupational asthma and chronic obstructive pulmonary disease are likely to pay a substantial contribution to the total costs of the two disorders. These costs are expected to rise with the increasing prevalence of the diseases. Intervention strategies for effective control and prevention at the workplace should lessen the burden of long-term illness and impact on public health costs.

Work-related reactive airways dysfunction syndrome cases from surveillance in selected US states

The objective was to elaborate the descriptive epidemiology of work-related cases of reactive airways dysfunction syndrome (RADS). Cases of work-related asthma (WRA) were identified in four states in the United States during 1993-1995 as part of the Sentinel Event Notification Systems for Occupational Risks (SENSOR). Information gathered by follow-back interview was used to describe 123 work-related RADS cases and to compare them to 301 other WRA cases whose onset of disease was associated with a known asthma inducer. RADS represented 14% of all new-onset WRA cases identified by the state SENSOR surveillance systems. RADS cases had significant adverse medical and occupational outcomes identified by follow-back interview. In particular, 89% still had breathing problems, 78% had ever sought emergency care and 39% had ever been hospitalized for work-related breathing problems, 54% had applied for worker compensation benefits, and 41% had left the company where they experienced onset of asthma. These values equaled or exceeded the comparable figures for those WRA cases whose onset was attributed to a known inducer. Work-related RADS represents a minority of all WRA cases, but the adverse impact of this condition appears to equal that of other WRA cases.

Persistence of airway responsiveness to occupational agents: what does it matter?

In the majority of workers with occupational asthma, the disease remains active even several years after removal from exposure or diminution of the levels of exposure to the causal agent. Only 25% or so normalize their lung function and their bronchial responsiveness to nonspecific agents. The aim of this review is to present recent findings illustrating the persistence of specific bronchial responsiveness and the associated factors in workers who apparently have recovered from occupational asthma. This subject is also examined from a socioeconomic perspective.

Clinical evaluation, management, and prevention of work-related asthma

Work-related asthma (WRA) is asthma that is attributable to, or is made worse by, environmental exposures in the workplace. WRA has become the most prevalent occupational lung disease in developed countries, is more common than is generally recognized, and can be severe and disabling. Identification of workplace exposures causing and/or aggravating the asthma, and appropriate control or cessation of these exposures can often lead to reduction or even complete elimination of symptoms and disability. This depends on timely recognition and diagnosis of WRA. In this review, the diagnostic evaluation has been organized in a stepwise fashion to make it more practical for primary care physicians as well as physicians specializing in occupational diseases and asthma. WRA merits more widespread attention among clinicians, labor and management health and safety specialists, researchers, health care organizations, public health policy makers, industrial hygienists, and others interested in disease prevention.

The natural history of asthma in adults: the problem of irreversibility

Asthma is common, affecting 5% to 10% of adults; asthma is progressive, leading to irreversible obstruction in 80% of elderly patients; and asthma is complex, often complicated by coexisting lung diseases. This loss of lung function results from 4 independent pathologic conditions: (1) airway remodeling, especially in the small airways, from the lymphocytic-eosinophilic inflammation that characterizes asthma; (2) bronchiectasis; (3) postinfectious pulmonary fibrosis; and (4) emphysema and chronic bronchitis from tobacco smoke. Deterioration in lung function develops faster in nonallergic patients with intrinsic asthma during the period shortly after onset of asthma and in older patients. About 4% of patients die of asthma, and most are elderly. Death most often results from complications of irreversible obstruction or cardiotoxicity of bronchodilator therapy. More research is needed to improve therapy for preventing remodeling of small airways, to confirm the frequency of bronchiectasis and postinfectious fibrosis and to determine their causes, and to develop diagnostic criteria to identify these complications. Meanwhile, clinicians treating adult asthmatic patients need to be aggressive in preventing the damage from cigarette smoke; in immunizing for influenza and pneumococcus infection and identifying and treating respiratory infections, particularly at times of acute exacerbations; in diagnosing and managing bronchiectasis; and in objectively confirming the efficacy of asthma therapy to prevent illness from overtreatment with glucocorticoids and bronchodilators.