Validation and Assessment of the COPD Treatment Ratio as a Predictor of Severe Exacerbations.

Abstract

Population-based risk assessments are needed to identify individuals who may benefit from chronic obstructive pulmonary disease (COPD) management programs for preventing exacerbations. This study compared the validated COPD treatment ratio (CTR) versus other COPD exacerbation predictors: prior exacerbation and rescue and maintenance medication use. A retrospective observational study using medical and pharmacy claims data among Medicare Advantage with Part D beneficiaries with COPD (January 2011-August 2016). Unadjusted and adjusted logistic regression models tested the predictive performance (C-statistic) of potential exacerbation predictors for future severe exacerbations. The unadjusted association between exacerbation predictors and severe exacerbation was examined in 60,776 patients: baseline severe exacerbation had the highest C-statistic (0.668), then number of rescue units dispensed (0.651), CTR (0.619), and number of controller units dispensed (0.562). During the at-risk period, baseline CTR was inversely associated with severe exacerbation (odds ratio, <1.0); other predictors were positively associated with a severe exacerbation (odds ratio, >1.0). Adjusting for age, geographic region, chronic oxygen, and nebulizer use, the severe exacerbation odds were 0.90 (95% confidence interval [CI], 0.89-0.91) lower per 0.10 change in CTR (C-statistic, 0.710). The C-statistic was 0.734 when baseline exacerbation was added to the model. The CTR is an effective tool for identifying patients diagnosed with COPD who are at increased risk of severe exacerbation. Although CTR does not predict future exacerbation as well as prior severe exacerbation history, it has the advantage of being applicable in predicting future exacerbations in patients without an exacerbation history, or in databases limited to pharmacy claims only. In addition, the significant reduction in risk has been observed with incremental increases in the ratio: the ratio can be monitored to assess COPD health improvements over time.