Abstracts

Abstract

Occupational Asthma in Greenhouse Flower and Ornamental Plant Growers; Monso E, Magarolas R, Badorrey I, et al. American Journal of Respiratory and Critical Care Medicine 2002; 165:954–960.

Background. Crop farming has been associated as a risk factor for asthma because agricultural employees are exposed to respiratory irritants and sensitizers, including environmental allergens. These include the allergens pollens and molds, as well as irritants such as endotoxin and pesticides. Cultivation of greenhouse flowers and ornamental plants has emerged as a significant risk characteristic for asthma in the European Farmer Study focusing on problems of airway obstruction and agricultural employees.

Objective. The objective of this study was to determine the problems of occupational asthma and sensitization to occupational allergens in greenhouse flower or ornamental plant growers.

The study population was a random sample of 40 growers who cultivated these crops and had been participants in the European Farmer Study.

Study Design. The study design was a cross-sectional study that encompassed:

1. Field measurements of the greenhouse characteristics including area, temperature, relative humidity, air velocity, CO₂ concentration, and exposure to total dust endotoxin and microorganisms using a personal sampling.

2. Respiratory symptoms that were elicited by a questionnaire and lung function.

3. Occupational asthma that was evaluated by a bronchial provocation.

4. Sensitization to workplace flowers or molds, which was determined by prick skin tests.

Results. Bronchial provocation confirmed occupational asthma in three workers. All of them had been sensitized to workplace flowers or molds. There were no discovered cases of occupational asthma among nonsensitized growers. Poor ventilation was demonstrated to be a marginal risk factor for wheezing, and sensitization to flowers and molds was found in 34%, but was not related to greenhouse characteristics.

Conclusions. The conclusion of the authors is that one-quarter of greenhouse flower and workers sensitized to workplace flowers or molds had occupational airway disease (i.e., asthma).

Reviewer's Comments. It is of interest that cultivation of flowers or ornamental plants inside greenhouses may precipitate occupational asthma in 8% of growers, presumably through sensitization to the flower allergens or workplace molds. The concentration of indoor contaminants, however, is not a major determinant of these workplace allergens, and skin testing clearly identifies sensitization of these allergens in one-third of the growers of these plants. Interestingly, low levels of dust and endotoxin did not appear to be risk factors, although poor ventilation emerged as a marginally significant factor.

Christopher Randolph, M.D. Waterbury, CT

Loss of Response to Treatment with Leukotriene Receptor Antagonists but not Inhaled Corticosteroids in Patients over 50 Years of Age; Creticos P, Knobil K, Edwards LD, et al. Annals of Allergy and Asthma Immunology 2002; 88:401–409.

Background. With the knowledge of the genome now available and interest in pharmacogenetics reaching a peak, studies evaluating the relative efficacy of available therapeutic options in different populations are critical. This study evaluates younger versus older patients (older than 50) with persistent asthma in terms of their relative response to leukotriene antagonist zafirlukast.

Objective. The objective of the study was to assess the relative efficacy of fluticasone propionate (FP) and zafirlukast (Z) in younger (12–49 years of age) versus older (50 years and older) patients with asthma.

Clinical Design. The clinical design was a retrospective evaluation of five randomized double-blind, double dummy studies 4–12 weeks in duration, of approximately 1740 patients younger than 50 years of age, and 243 patients age 50 years or older. The therapeutic interventions involved were inhaled fluticasone propionate (FP) 88 mcg, and oral zafirlukast (Z) 20 mg, or placebo twice daily.

Clinical Findings. Fluticasone therapy provided greater improvement than zafirlukast in all efficacy parameters, except for nighttime awakenings, regardless of age. These included improvement in FEV₁, patient daily morning and evening peak flow, and asthma symptom scores. The most remarkable finding was that fluticasone therapy in patients older than 50 years of age resulted in significantly improved pulmonary function compared with zafirlukast. FEV₁ improvement with fluticasone was +.19 L versus –.34 L for placebo and –.06 L for zafirlukast. Similarly, AM peak expiratory flow rate improved by +25 L/min for fluticasone, placebo –24 L/min and zafirlukast +5 L/min. Furthermore, in comparison with zafirlukast, therapy with fluticasone result in significantly greater increments in the percentage of symptom free days, rescue-free days, and greater reductions in Albuterol use.

Conclusions. The therapy with fluticasone in patients of all age groups demonstrates significantly greater improvement in pulmonary function and overall asthma control than with zafirlukast. In individuals, however, older than 50 years of age, treatment with zafirlukast resulted in even less improvement.

These data suggest that although fluticasone propionate effectively manages inflammation in patients older than 50 years of age, zafirlukast may actually conceal or mask inflammation and not provide adequate level of bronchodilatory or anti-inflammatory activity necessary for effective asthma management in older patients.

Reviewer's Comment. These results, limited by their retrospective nature and the variability of five different investigative groups, are strongly supported by the large number of patients in the five clinical trials. These results suggest that the effectiveness of zafirlukast declines with age, possibly because the leukotriene pathway is not as significant in the inflammatory process in these patients.

Christopher Randolph, M.D.

Waterbury, CT