BACKGROUND

Asthma has been found to be among the most common conditions in the working age population and is among the most common causes of work limitation, but we could find no longitudinal studies of employment among persons with this condition.

METHODS

A panel of 601 persons with a diagnosis of asthma from random samples of northern California pulmonologists and allergy-immunologists were interviewed as many as three times at 18-month intervals by a trained survey worker to report on the severity of disease, demographic characteristics, and the extent of their employment. Their employment was then compared to that of a matched sample from the U.S. Bureau of the Census Current Population Survey.

RESULTS

Ninety-two percent of the persons with asthma had worked at some point prior to study enrollment. Among persons with onset during adulthood, only 29% of those who were not employed at disease onset were working at study enrollment, compared to 68% among those who were employed. Among the 420 persons interviewed three times, 75, 81, and 75%, respectively, were employed as of the three interviews. Among these 420, 66% were continuously employed and 15% were continuously not employed. The principal determinants of continuity of employment were demographic and employment characteristics, not medical ones. The employment rate and hours of work per week and per year of the persons with asthma were similar to the matched sample.

CONCLUSIONS

Asthma has not substantially impeded the employment of the persons with asthma we studied, with the exception that those who were not employed at disease onset continued to have low employment rates.

BACKGROUND

In general practice settings, the proportion of adult asthma attributable to occupational factors is not known.

OBJECTIVE

The goal of this study was to estimate the proportion of adult asthma cases that can be attributed to occupational factors initiating new disease onset and exacerbating preexisting disease.

METHODS

We performed a cross-sectional analysis of interview data for 150 adults with asthma recruited from a random sample of family practice specialists. We ascertained the asthma and work histories of the subjects and estimated the proportion with likely work-initiated asthma and work-related asthma recrudescence.

RESULTS

Seventy-four subjects (49%) reported adult-onset asthma while employed; an additional 25 (17%) reported recrudescence of previously quiescent childhood-onset asthma during employment. Of those with new-onset asthma while employed, 15 (10% of the study group; 95% confidence interval, 5 to 15%) were employed in occupations at increased risk of occupational asthma initiation on the basis of an independent job scoring matrix. Of those with asthma recrudescence in adulthood, seven (5% of the study group; 95% confidence interval, 2 to 8%) were employed in occupations at increased risk of exposures aggravating asthma.

CONCLUSIONS

Among adults with asthma treated in general practice settings, > 1 in 10 patients has a work history strongly suggestive of a potential relationship between exposure and disease.

We performed analyses to examine the structure, validity, and responsiveness to change of the Marks Asthma Quality of Life Questionnaire (AQLQ), originally validated in Australia in a self-administered format, among 539 U.S. subjects with asthma. Subjects were interviewed twice by telephone over an 18-month period. Based on factor analyses, the subscale structure of the AQLQ was modified slightly to eliminate item overlap among subscale scores. Cross-sectionally, total AQLQ scores were significantly correlated in expected directions with baseline asthma severity scores (r = 0.58), SF-36 physical (r = -0.66) and mental (r = -0.40) health status scores, and pulmonary function (FEV1% predicted, r = -0.14). Longitudinally, changes in AQLQ total and subscale scores were significantly (P<0.01) associated with changes in asthma severity and both physical and mental status. The AQLQ, administered by telephone, appears to be useful for assessing changes in the impact of adult asthma.

BACKGROUND

Bronchiolitis obliterans occurs in 30% to 80% of lung-transplant recipients and is a direct cause of death in more than 40% of patients with this complication. This study assessed the potential utility of measuring fibroblast-proliferative activity in bronchoalveolar lavage fluid from lung-transplant recipients to better understand the pathogenesis of this process.

METHODS

The capacity of bronchoalveolar lavage fluid obtained from transplant recipients, during routine surveillance bronchoscopy, to stimulate the proliferation of human lung fibroblasts in vitro was assessed retrospectively and compared to that of control subjects. For each recipient, a correlation was made between the fibroblast-proliferative activity in serial lavage samples over time and the other modalities employed for detecting post-transplant complications including spirometry, transbronchial lung biopsy, and high-resolution computed tomography.

RESULTS

There was a significant difference in fibroblast-proliferative activity between volunteer and transplant recipient groups (p = 0.002). Further, for each transplant recipient, the decline in the forced expired flow rate between 25% and 75% of expired volume (FEF(25%-75%)) was correlated with the mean fibroblast-proliferative activity during the period of this study (r = 0.83; p = 0.04).

CONCLUSIONS

A sustained increase in fibroblast-proliferative activity in lavage supernatant precedes both histologic and physiologic evidence of bronchiolitis obliterans. Relative to an increase in fibroblast-proliferative activity or abnormalities in FEF25%-75%, a decrease in forced expiratory volume in 1 second is a late finding.

PURPOSE

Many occupational factors can cause asthma or reactivate preexisting disease. We carried out a critical review and synthesis of the available literature to estimate the proportion of adult asthma that is attributable to workplace factors.

METHODS

We reviewed published citations from 1966 through May 1999 as well as recent abstracts of studies providing risk estimates for asthma among various occupations. We extracted published attributable risk estimates, derived others from published data, and extrapolated estimates from the incidence rates of occupational asthma. We used a semiquantitative score to rank studies based on their characteristics.

RESULTS

We obtained 43 attributable risk estimates from 19 different countries: 23 were published estimates, 8 were derived from published data, and 12 were extrapolated from incidence data. The median value for the attributable risk of occupationally associated asthma was 9%(25th to 75th interquartile range: 5% to 19%). The derived estimates (median attributable risk = 25%) were significantly greater than published values (median = 9%, P = 0.002), whereas the extrapolated estimates were significantly lower (median = 5%, P = 0.04). The 12 highest scored studies based on their characteristics yielded a median risk estimate of 15%.

CONCLUSION

Occupational factors are associated with about 1 in 10 cases of adult asthma, including new onset disease and reactivation of preexisting asthma.

Work disability due to respiratory disease, especially asthma, is common and costly among working age adults. The goal of this analysis was to characterize the risk factors for such disability. We analyzed data from the Swedish part of the European Community Respiratory Health Survey (ECRHS), a random population-based sample of adults age 20 to 44, enriched with symptomatic subjects at increased likelihood of having asthma. We analyzed structured interview data available for 2,065 subjects and further analyzed methacholine challenge and skin prick test data for 1,562 of these. We defined respiratory work disability as reported job change or work loss due to breathing affected by a job. We used binary generalized linear modeling with a log link to estimate disability risk. Eighty-four subjects (4%) reported such work disability. This increased to 13% among those with asthma (45 of 350 subjects). Adjusting for covariates, occupations at high risk for asthma were associated with disability (prevalence ratio [PR] 1.8; 95% confidence interval [CI] 1.1 to 3.0), as was self-reported regular exposure to environmental tobacco smoke (ETS) at work (PR 1.8; 95% CI 1.1 to 3.1) and self- reported job exposure to vapors, gases, dust, or fumes (VGDF) (PR 4.3; 95% CI 2.2 to 8.6). Workplace ETS exposure was also associated with methacholine challenge-positive asthma reported to be symptomatic at work among male subjects (PR 4. 2; 95% CI 1.8 to 9.8), whereas high asthma-risk occupations were associated with this outcome among female subjects (PR 2.7; 95% CI 1. 05 to 7.1). Respiratory work disability, defined as breathing-related job change due to work loss, was associated with workplace exposures themselves, even after taking into account other covariates. Better control of workplace exposures, including workplace ETS, may reduce work disability caused by respiratory conditions, especially adult asthma.

Occupational asthma (OA) can be defined as variable airways narrowing causally related to exposure in the working environment to airborne dusts, gases, vapours or fumes. There are many agents in the work-place that can induce asthma or cause substantial deterioration in pre-existing asthma. It has been estimated that 5-15% of adult-onset asthma can be attributed to occupational exposures. Hence adult patients, especially those with new-onset asthma, must be investigated with regard to occupational risk factors for disease. The prognosis for OA is improved if the causal exposure is controlled either by controlling the exposure at the workplace or by moving the patient out of the workplace.