Socioeconomic status and inhaled corticosteroid use in childhood asthma, impact on hospitalization

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Kozyrskyj, Anita L.
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'Introduction'. Low income children are at greater risk for asthma hospitalization, which can be prevented with the utilization of inhaled corticosteroids drugs. Therefore, a population-based study of children was undertaken to determine: (1) the influence of socioeconomic status and pharmaceutical policy on inhaled corticosteroid utilization, and (2) the contribution of inhaled corticosteroid utilization to the association between socioeconomic status and asthma hospitalization. 'Methods'. Using population-based health care administrative data, 16,862 children, aged 5-15 years, were selected by this case definition for asthma: (1) health care for asthma/bronchitis diagnoses, or (2) one+ prescriptions for prophylaxis drugs, or two+ prescriptions for bronchodilators during January 1, 1995-March 31, 1998, AND having one+ asthma drug prescriptions during January 1, 1995-March 31, 1996. A drug treatment-based asthma severity measure was developed and applied to prescription data. Following validity assessments of the case definition and asthma severity measure, the proportionate use of inhaled corticosteroids was ascertained in relation to household income. Inhaled corticosteroid use was also assessed before and after a newly introduced, income-based drug reimbursement policy. The risk of asthma hospitalization by household income was determined, with adjustment for inhaled corticosteroid drug utilization. 'Results'. Forty-five percent of children with asthma had at least one prescription for an inhaled corticosteroid over the time period January 1,1995 to March 31, 1996; inhaled corticosteroid utilization declined as neighbourhood income decreased. The adjusted relative risk for a new inhaled corticosteroid prescription was 0.9 among children living in low income or income assistance households, versus higher income children. Low income children with severe asthma received the fewest number of inhaled corticosteroid doses of all children, and this remained unchanged post income-based policy. Continuous utilization of inhaled corticosteroids was associated with lower risk of asthma hospitalization (severity-adjusted RR = 0.37, 95% CI:0.29-0.48). An increased risk of asthma hospitalization observed in income assistance and low income children, was eliminated following adjustment for continuity of inhaled corticosteroids; and other factors. 'Conclusion'. Low income children with asthma were less likely to utilize inhaled corticosteroid drugs, which increases their risk of asthma hospitalization. An income-based pharmaceutical policy did not improve utilization of these drugs.