Guideline-concordant inhaled medication use in COPD: a systematic review of definitions used in administrative health data.

Background: Assessments of guideline-discordant use of maintenance inhaled therapies for COPD in administrative health data are common but restricted by lack of patient characteristics. We systematically reviewed definitions of guideline-concordant and guideline-discordant maintenance inhaled medication use applied to administrative health data. Methods: We searched MEDLINE and Embase from January 2000 to September 2024 for studies that 1) used administrative health data to identify adults with COPD who were prescribed long-acting bronchodilators (LABDs) or inhaled corticosteroids (ICS) for outpatient treatment; 2) defined maintenance inhaled medication use as guideline-concordant and/or guideline-discordant at the patient level. We developed standardised definitions for claims data aligned with management recommendations and conducted a meta-analysis to assess the proportion of patients with guideline-concordant and guideline-discordant medication use. Results: We screened 4578 records and included 20 studies. There were 22 unique definitions of guideline-concordance or discordance, based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) recommendations. The most common measurements were 1) guideline-discordant ICS use (n=10); 2) guideline-concordant LABDs use (n=8); and 3) guideline-concordant ICS use, focusing on ICS alone (n=4) regardless of LABDs or with LABDs (n=6). Given that acute exacerbations of COPD (AECOPD) was the most commonly used criterion and aligned with recommendations, we developed an AECOPD risk-based definition. Pooled analysis showed 50% guideline-concordant LABDs use and 45% guideline-discordant ICS use across populations. Conclusions: Definitions of guideline-concordant LABDs use and guideline-discordant ICS use in administrative health data are largely congruent with GOLD. AECOPD risk-based definitions provide a generalisable approach for assessing guideline-concordance in administrative data.