pulmonary disorders
Work Related Asthma
Diagnosis of Work Related Asthma
Clarify the diagnosis of Asthma (including Identify work exposures that are associated with asthma Clarify the temporal relationships between asthma and work Work-related asthma should be considered in all adults with new-onset or worsening asthma. Improvement in asthma symptoms when the patient is away from work (eg, on weekends or holidays) should raise suspicion of work-related asthma. Worsening symptoms or greater use of asthma medications related to work should also prompt further investigation. As the diagnosis of work-related asthma can impact employment, it is important to document the diagnosis of asthma, known or suspected causative agents, and the rationale for work-relatedness. Clinicians should note typical symptoms of asthma and clinical improvement in response to inhaled bronchodilators and corticosteroids. Spirometry may be helpful in establishing a diagnosis of asthma if it shows variable airflow obstruction, which is most commonly demonstrated by improvement in forced expiratory volume in 1 second (FEV1) after taking an inhaled bronchodilator. Improvement in spirometry results after asthma treatment or after removal from triggering exposures and elevation in exhaled nitric oxide also support a diagnosis of asthma. Asthma is characterized by variable airflow obstruction, so many patients with asthma have normal spirometry results when they are not symptomatic or when they are being treated. Normal spirometry and a lack of response to inhaled bronchodilators do not rule out the diagnosis of asthma, especially when the patient is taking asthma medication or is not symptomatic. A patient with work-related respiratory symptoms in whom asthma is not documented may have another work-related condition such as Vocal Cord Dysfunction , upper respiratory tract irritation, Following clarification of the asthma diagnosis, the clinician should document the timing, onset, and progression of asthma in relationship to work and also non-workplace exposures to asthma triggers. A thorough occupational history, including job title, industry, job tasks, and description of the work environment and materials used should be obtained. Asthma becomes more generalized over time, thus in trying to identify the causative factor(s), in addition to evaluating the patient's current symptoms, the clinician should focus on when the patient’s asthma began and/or worsened, especially if the patient is no longer at the workplace in question. Safety data sheets, mandatory at all work sites in the United States, can be used to identify irritants and allergens that can cause asthma. However, the absence of a known irritant on the safety data sheet does not exclude the diagnosis of work-related asthma. For the few asthma-causing agents for which commercially available allergy testing is available, such as for certain animals and grains, allergy testing can help identify a causative agent, although false negatives and positives are possible. Once work and non-work exposures have been characterized, it is important to assess and document the relationship of the patient’s symptoms to work. Serial peak flow measurements taken while the patient is at and also while away from work, changes in inhaler use at and away from work, and allergy testing can provide greater diagnostic certainty. It is more challenging to diagnose work-related asthma once the patient is away from the causative workplace. Thus, unless the patient is having severe symptoms, it is generally preferable not to remove a patient from work while evaluating a possible diagnosis of work-related asthma. The diagnosis of work-exacerbated asthma is based on history of pre-existing asthma (symptoms, medical history, medication usage, variable airflow obstruction) and the presence of conditions at work that can exacerbate asthma, which includes common irritants, allergens, extremes of temperature and humidity, and physical exertion in conjunction with increase in asthma symptoms and/or inhaler use. Worsening asthma related to work can be documented by noting worsening symptoms, increased frequency of physician visits for asthma symptoms, increased use of asthma medications, or rarely, worsening lung function (peak flows, spirometry) related to work. Recurrence of asthma that had resolved may be new-onset work-related asthma. 