Screening questionnaires for bakers' asthma - are they worth the effort?

The use of a respiratory screening questionnaire is recommended annually to screen bakery workers in the UK. We compared questionnaire screening with other methods of detecting workers with asthmatic symptoms and then assessed the significance of these symptoms with careful investigation and follow-up. Reasons for questionnaire failures were then explored. A questionnaire was issued to 362 flour-exposed workers in a large bakery. All positive respondents to respiratory symptom questions were interviewed by an occupational nurse. Workers with occupationally related symptoms at this interview were referred to the chest clinic. In addition, workers with negative quesiionnaires were screened using attendance records, sick notes and direct workplace observations. Workers with frequent absence from work or sick notes with respiratory diagnoses were interviewed in the same manner as those answering the questionnaire positively and then referred to clinic. At clinic, a diagnosis was made for each worker on the basis of clinical assessment, spirometry, serial peak expiratory flow rate (PEFR) analysis and radioallergosorbent testing (RAST) testing for specific IgE. Using the clinic diagnoses, the referral routes were audited to assess the rates of case detection of asthma and occupational asthma. The respiratory screening questionnaire identified 68 workers with respiratory symptoms. Of these, 21 proceeded to full assessment. A diagnosis of asthma was made in five cases, one of which was bakers' asthma. In addition, 11 workers not reporting any symptoms by questionnaire were referred to clinic and five were diagnosed as having asthma. Screening questionnaires may lead to an underestimate of the prevalence of asthmatic symptoms and as such should not be used alone in workplace screening.