Figure 2:

Adjusted incidence rate ratios (aIRR) for the association between chronotropic index obtained from 6-minute walk test (CI-6MWT) and rate of (a) any acute respiratory events and (b) severe acute respiratory events (requiring emergency department visit or hospitalization). Results are presented for all participants (Total), and by spirometry subgroup. Incidence ratio ratios are adjusted for age, sex, race, body mass index (BMI), FEV₁ percent predicted, current vs former smoking status, and 6-minute walk test distance. aIRRs represent the change in rate for each 0.1 unit change in CI-6MWT.

COPD, chronic obstructive pulmonary disease; PRISm, preserved ratio, impaired spirometry.