How to determine an impaired health status in COPD: Results from a population-based study

Chronic obstructive pulmonary disease (COPD) is associated with a significantly impaired health status and lost work productivity across all degrees of airflow limitation. The current study investigated whether an impaired health status is better represented by the recommended COPD Assessment Test (CAT) cut-point of 10 points, or the 95th percentile of the CAT score in a non-COPD population. Additionally, the impact of COPD on health status in a Dutch population, after stratification for work status, was measured.

Demographics, clinical characteristics, post-bronchodilator spirometry, and CAT were assessed in subjects from the Longitudinal Aging Study Amsterdam (LASA), a large Dutch population-based study. Normative values for the CAT score were described by percentiles using the mean, standard deviation, median and range.

In total, 810 COPD and non-COPD subjects (50.4% male, mean age 60.5 ±; 2.9 years) were analysed. Significant differences were observed in CAT scores between non-COPD and COPD subjects (6.7 ±; 5.2 vs. 9.5 ±; 5.9, p < 0.001 respectively). The proportion of COPD subjects with an impaired health status differed between applying the CAT ≥ 10 cut-point (50.0%) and applying the 95th percentile of CAT in non-COPD subjects (> 18 cut-point; 7.6%). Higher CAT scores were seen in working COPD patients compared with working non-COPD subjects (9.3 ±; 5.2 vs. 6.0 ±; 4.6, p < 0.001).

We suggest a CAT cut-point of > 18 points to indicate an impaired health status in COPD. This would imply an adaptation of the current GOLD classification of the disease.