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

Trial description: RationaleCanada 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 direct and indirect costs associated with asthma are expected to rank among the highest for chronic diseases due to the high prevalence in conjunction with the significant healthcare utilization associated with the disease and the considerable restrictions asthma imposes on the physical, emotional, social, and professional lives of sufferers. 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. Moreover, no study has compared the annual cost between asthmatic patients who are uncontrolled and “well-controlled”. Although population-level direct costs have been previously reported through the use of administrative healthcare databases in various provinces, these databases do not contain clinical information and are limited to subjects who have a public drug insurance plan.ObjectivesThe overall objective of this study is to describe the healthcare management patterns of asthmatic patients and to estimate the direct costs of asthma care in Quebec, Canada.Study DesignTwo year retrospective data in the BD-Asthma database between February 2010–February 2012 will be extracted to select the subjects for the proposed study. From the point of enrolment, subjects will be followed for 2 years to obtain direct costs. A two-step approach will be used to estimate direct costs. The first step is to estimate the quantity of health inputs used and the second step is to estimate the unit costs of the inputs used. The costs are then estimated by multiplying unit costs by the quantities. To ensure that relevant drug and healthcare resource utilization data are included in our estimate, the BD-Asthma database would be linked with the RAMQ, MED-ECHO and REMED databases.Study Population and Sampling MethodsSource Population The source population is defined as individuals with asthma enrolled in BD-Asthma. Study Population The study population is defined as patients with asthma diagnosed by a respirologist and followed at the outpatient asthma clinic of the HSCM or CHUS and enrolled in BD-asthma between February 2010 and February 2012. Furthermore, the study population is defined with the following inclusion and exclusion criteria.Inclusion Criteria• 18 years of age or older• Patients who signed consent for research with BD-Asthma and allowed linkage with the RAMQ, MED-ECHO, and reMed databases when applicable.• Patients identifiable in the RAMQ and MED-ECHO databases for at least twelve months prior and twelve months following the date of enrolment in BD-Asthma Exclusion Criteria• Subjects with the following characteristics are excluded from the study population: Patients with a diagnosis of COPD recorded in BD-Asthma at the time of enrolment.Data SourceThis is a retrospective cohort study conducted with BD-asthma and the administrative databases of the Régie de l’Assurance Maladie du Québec (RAMQ) and MedEcho reMed will also be used for privately insured subjects.Data Analysis MethodsUsing the RAMQ database, we will assess the number of ambulatory medical visits for asthma and those for other causes in the year prior and the year following enrolment in BD-Asthma for each patient. Using the MED-ECHO databases we will assess the number of hospitalizations and the duration of each hospitalisation for asthma and for other causes in the year prior and the year following enrolment in BD-Asthma for each patient. Using the RAMQ databases we will assess the number of ER visits for asthma and for other causes in the year prior and the year following enrolment in BD-Asthma for each patient. Using the RAMQ and the reMed databases, we will describe the use of asthma medications in the 2-year observation period. Poisson regression models will be used to identify the patients’ characteristics associated with the use of health care services for asthma.Sample Size and PowerThe source population is formed of 654 patients enrolled in BD-Asthma. Based on the inclusion and exclusion criteria we expect to have about 400 patients included in the cohort.LimitationsThe level of asthma severity and control will be measured only at enrolment in BD-Asthma. Costs related to licensed health practitioners other than physicians such as private-duty nurses and cost related to supportive care will not be considered in the cost analysis. Samples of medication given by physicians will also not be considered in the cost analysis. The cohort will be over represented by patients with moderate and severe asthma and will not represent a general population of asthmatic subjects.