Indirect Cost of Illness Study of Moderate and Severe Asthma in Quebec

Rationale Asthma is a chronic inflammatory disorder of the airways affecting persons of all ages and is recognized as one of the most common chronic diseases. Canada has one of the highest asthma prevalence rates in the world (8.5%, aged 12 and over) and it is a major cause of hospitalization. The cost of asthma varies dramatically across disease severity, and it is expected that these costs are greater when the condition is sub-optimally managed and controlled. Although a number of publications have been reported on the economic burden of asthma, there is a lack of information on the cost of asthma based on disease severity and level of disease control in Canada. The proposed study aims to i) estimate the annual indirect cost of asthma and ii) the impact of asthma on absenteeism, presenteeism and work productivity in Canada. This information is essential to further quantify the burden of asthma on patients and the healthcare system in the Canadian setting. Overall Objectives The overall objective of this study is to describe the impact of asthma on patients with moderate to severe asthma and to estimate the indirect costs of asthma care in asthmatic patients followed in tertiary clinics specialized in the field of asthma in Quebec, Canada. Study Design A prospective cohort study will be conducted to measure the indirect economical burden of asthma on patients. Patients will be selected and recruited from the BD-Asthma registry and followed prospectively for 1 year. Recruited patients will be asked to complete questionnaires at regular intervals for 1 year to measure indirect cost of disease, using the Valuation of lost productivity (VOLP) questionnaire. Data Collected For each patient, the following data will be collected * Patient demographics * Age * Sex * Income * Level of education * Smoking * Disease management and Treatment utilization in the year prior to recruitment * Physician visits and follow up * Hospitalizations (number and total days) * Emergency room visits * Disease characteristics * Asthma history * Year of first diagnosis of asthma severity * Asthma Control Questionnaire score * Lung function measures Data Analysis Methods For each participant, the percentage of time missed from work over a year will be calculated. We will use the human capital approach to calculate the costs of asthma due to lost productivity, incorporating both absenteeism and presenteeism in the calculation of the productivity loss. We will calculate the number of work days in which the person was unable to attend the workplace, and the number of days and percentage of time lost during the days the person's work was affected by their asthma. The fraction of time lost from work in the past year will be multiplied by the average income in Quebec. Finally, this value will be multiplied by the coefficient generated by the VOLP, which reflects the relative value of the productivity loss. In addition, we will calculate the VOLP multiplier for each participant which, combined with the percentage of time missed from work, will create a measure of productivity loss adjusted for the relative importance and replace-ability of the participant's profession. Sample Size and Power One hundred subjects will be randomly selected from the BD-Asthma registry. Limitations The study population may not be representative of the general asthma population, as moderate to severe asthma will be over represented in these tertiary centers.