COPD Mortality: Prognostic Value of Physical Capacity and Physical Activity

Patients with chronic obstructive pulmonary disease (COPD) who have a preserved physical capacity seem to have a significantly lower 6-year risk for mortality compared with those who have a decreased physical capacity, regardless of their level of physical activity. These were among the findings of a retrospective study, recently published in Chest, which was conducted at 3 hospitals in The Netherlands.

Recognizing that physical capacity (“can do”) and physical activity (“do do”) are prognostic indicators in COPD that can be used to subdivide patients into 4 exclusive subgroups (ie, the “can do, do do” quadrants), the researchers sought to explore the

6-year all-cause mortality risk in the “can do, do do” quadrants among patients with COPD. All patients underwent a comprehensive evaluation at their first-ever outpatient consultation. Data from patients with a pulmonologist-confirmed diagnosis of COPD were used. All patients completed a comprehensive standardized health status assessment as part of their usual COPD care at Amphia Hospital (Breda, The Netherlands); Bernhoven Hospital (Uden, The Netherlands); or Radboud University Medical Centre (Nijmegen, The Netherlands) between April 2012 and January 2019.

Patients’ physical capacity was evaluated with use of the 6-minute walk distance (6MWD); physical activity was assessed via use of an accelerometer (measuring steps per day). The Municipal Personal Records Database was used to obtain all-cause mortality data. Threshold values for physical capacity and physical activity were established with the use of receiver operating characteristic curves, in order to predict 6-year all-cause mortality rates. The derived threshold values were utilized to divide the male and female patients into the 4 “can do, do do” quadrants.

The analysis included data from 829 patients (54% men; average age 64±9 years). Patients had mild to very severe COPD, with an impaired physical capacity (6MWD, 68±16% predicted) and a low physical activity level (5556±3339 steps per day). The best discriminatory values for 6-year mortality were 404 meters (physical capacity) and 4125 steps per day (physical activity) for men, and 394 meters and 4005 steps per day for women. Over a median follow-up of 55 months, 15.6% (129 of 829) of the patients died.

After adjustment for age, FEV₁, Medical Research Council (MRC) dyspnea score, and BMI, male patients in the “can do, don’t do” and the “can do, do do” quadrants exhibited a significantly lower risk for mortality compared with male patients in the “can’t do, do do” quadrant (hazard ratio [HR], 0.36; 95% CI, 0.14-0.93 vs HR, 0.24; 95% CI, 0.09-0.61, respectively) and those in the “can’t do, don’t do” quadrant (HR, 0.39; 95% CI, 0.18-0.86 vs HR, 0.26; 95% CI, 0.11-0.58, respectively). No significant difference was reported between male patients in the “can’t do, do do” quadrant and those in the “can’t do, don’t do” quadrant (HR, 1.08; 95% CI, 0.50-2.36; P =.844) or between male patients in the “can do, don’t do” quadrant and those in the “can do, do do” quadrant (HR, 1.51; 95% CI, 0.61-3.75; P =.375).

In a similar fashion, after adjustment for age, FEV₁, MRC dyspnea score, and BMI, female patients in the “can do, don’t do” and the “can do, do do” quadrants exhibited a significantly lower risk for mortality compared with female patients in the “can’t do, do do” quadrant (hazard ratio [HR], 0.37; 95% CI, 0.38-0.99 vs HR, 0.29; 95% CI, 0.10-0.87, respectively) and those in the “can’t do, don’t do” quadrant (HR, 0.19; 95% CI, 0.04-0.84  vs HR, 0.15; 95% CI, 0.06-0.40, respectively). No significant difference was reported between female patients in the “can’t do, do do” quadrant and those in the “can’t do, don’t do” quadrant (HR, 0.52; 95% CI, 0.22-1.24; P =.141) or between female patients in the “can do, don’t do” quadrant and those in the “can do, do do” quadrant (HR, 1.27; 95% CI, 0.26-6.30; P =.771).

The investigators concluded that 6-year all-cause mortality rates were significantly lower among patients with COPD who attended their first-ever outpatient consultation with a preserved physical capacity compared with those with a reduced physical capacity, regardless of an individual’s level of physical activity.

Reference  

Vaes AW, Spruit MA, Koolen EH, et al. “Can do, do do” quadrants and 6-year all-cause mortality in patients with COPD. Chest. Published online January 10, 2022. doi:10.1016/j.chest.2021.12.657