Prevalence of Work-Related Asthma in Primary Health Care: Study Rationale and Design

Occupational Asthma (OA) is the most frequent origin of occupational respiratory diseases in industrialized countries and accounts for between 5% and 25% of asthmatic patients. The correct and early diagnosis of OA is of great preventive and socio-economic importance. However, few studies exist on OA's prevalence in Catalonia and in Spain and those affected are mainly treated by the public health services and not by the occupational health services, which are private.

To determine the prevalence of OA in patients diagnosed with asthma in the Primary Healthcare system and to evaluate the socio-economic impact of OA in the Primary Healthcare system.

We will carry out an observational, transversal and multi-center study in the Primary Healthcare Service in the Barcelona region (Catalonia, Spain), with 385 asthmatic workers aged between 16 and 64 who are currently working or have been working in the past. We will confirm the asthma diagnosis in each patient, and those meeting the inclusion criteria will be asked to answer a questionnaire that aims to link asthma to the patient's past employment history. The resulting diagnosis will be of either occupational asthma, work-aggravated asthma or common asthma. We will also collect socio-demographic information about the patients, about their smoking status, their exposure outside of the workplace, their work situation at the onset of the symptoms, their employment history, their symptoms of asthma, their present and past medical asthma treatment, and, in order to estimate the economic impact in the Primary Healthcare system, where they have been attended to and treated. Prevalence will link OA or work-aggravated asthma to the total of patients participating in the study with a asthma diagnosis.

The results will show the prevalence of OA and work-aggravated asthma, and shall provide valuable information to set out and apply the necessary personal and technical measures, either in the public or in the occupational health services. No studies evaluating the costs generated by the OA in the Primary Healthcare system have been carried out.