Abstract
BACKGROUND: A previous longitudinal study of chronic obstructive pulmonary disease (COPD) Assessment Test (CAT) score changes suggested patients fall into 3 patterns: stable, improving, and worsening. This study assessed the evolution of CAT scores over time and its relationship to exacerbations. METHODS: In total, 84 participants used a telemedicine platform to complete CAT weekly for 52 weeks. Completion rates, annualized change in CAT scores, and learning effects were measured, as well as CAT changes of >4 units during look-back periods of 4 and 8 weeks. In a subgroup of participants with at least a 25% completion rate (adherent group, n=68 [81%]), the relationship between change in CAT score and exacerbations at any time during the study was examined post hoc. RESULTS: Linear regression showed that 50%, 22%, and 28% of the adherent subgroup had CAT scores indicating worsening, stable, and improving health status, respectively. In the adherent subgroup, 70% (n=7/10) of participants who had an exacerbation during the study had worsening CAT scores, versus 47% (n=27/58) without an exacerbation. The hazard ratio association between CAT score increase and moderate exacerbation was 1.13 (95% confidence interval: 1.03-1.24). Most participants experienced at least one CAT score change of >4 units, and 7% showed an initial learning effect with a median of 2 weeks. CONCLUSION: Measuring trends in CAT scores may allow future studies to group patients into 3 defined categories of change over time and quantify CAT change trajectories to assess treatment response and potentially predict medium-term outcomes within individual patients.