DENVER – The ratio of controller to total asthma medication fills predicts the risk of exacerbations in pediatric patients with persistent asthma, results from a large study demonstrated.
"The occurrence of asthma exacerbations requiring medical attention is a key health outcome, and may be an indicator of the quality of asthma care," Dr. Louis Vernacchio reported at the annual meeting of the Pediatric Academic Societies. "Exacerbations that are cared for in the office setting may be more common than hospital admissions or ED visits, but there is currently no standard methodology for defining exacerbations cared for in the office setting. It would be nice to develop process measures that relate to asthma outcomes, particularly to exacerbations," he said.
Dr. Louis Vernacchio
Dr. Vernacchio, of the Pediatric Physicians’ Organization at Children’s (PPOC) and the general pediatrics division at Children’s Hospital Boston, and his associate, Jennifer M. Muto, set out to assess the accuracy of claims-based definitions of asthma exacerbations cared for in the office setting and to evaluate potential risk factors for asthma exacerbations that could serve as process measures for quality improvement. They analyzed medical claims from a large not-for-profit insurer for patients of the PPOC, a large independent practice association affiliated with Children’s Hospital Boston. The study population included 19,469 patients aged 5-17 years who were continuously enrolled in 2008 and 19,779 patients aged 5-17 years who were continuously enrolled in 2009. Of these, 530 (2.7%) met Healthcare Effectiveness Data and Information Set (HEDIS) criteria for persistent asthma in 2008 and 507 (2.6%) did so in 2009.
Proposed definitions of asthma exacerbations cared for in an office setting included office visits for asthma with oral steroid prescription filled the day of or the day after a visit (definition 1); office visits for asthma with oral steroid prescription filled the day of or the day after a visit or with nebulizer treatment given in the office (definition 2); office visits for asthma with oral steroid prescription filled the day of or the day after a visit or with oral steroid prescription filled the day of or the day after a visit or with nebulizer treatment given in the office, or coded as "with status asthmaticus" or "with acute exacerbation" (definition 3).
The researchers compared each of those three definitions to a chart review, which was considered the gold standard. Two clinicians independently reviewed 144 asthma visits and evaluated three elements in each chart: history of present illness, physical examination, and assessment. "If they found evidence of exacerbation in two of those three areas, we counted the visit as an exacerbation visit," Dr. Vernacchio said.
Receiver operating characteristic curve analysis revealed that definition 1 had a sensitivity of 24.7% and a specificity of 90.5%, definition 2 had a sensitivity of 56.8% and a specificity of 76.2%, and definition 3 had a sensitivity of 95.1% and a specificity of 68.3%. "The overall area under the curve is best with the third definition, but there’s a tradeoff in sensitivity and specificity," he said.
Logistic regression analysis of associations with exacerbations revealed that the ratio of controller to total asthma prescription fills was the process measure that correlated most closely to the risk of asthma exacerbations, with risk ratios near 2.0 for those in the third and fourth quartiles of controller to total asthma prescription fills ratio (corresponding to ratios of 0.5-0.8 and less than 0.5, respectively).
"This ratio can serve as the basis for quality improvement projects in pediatric asthma," Dr. Vernacchio said. He noted that the proposed 2012 HEDIS measure uses a cutoff value of 0.5, "which is well below what appears optimal in our data."
Dr. Vernacchio said that he had no relevant financial conflicts to disclose.