Objectively measured steps/day in patients with chronic obstructive pulmonary disease: A systematic review and meta-analysis

Background: Although individual studies have reported on the number of steps/day taken by individuals with COPD, this evidence has not been systematically reviewed or synthesized. Methods: MEDLINE and PsycINFO were searched for studies reporting objectively-measured steps/day and percent predicted forced expiratory volume in one second (FEV1%) in patients with COPD. Meta-analyses were used to estimate steps/day across studies, while meta-regression was used to estimate between-study variance based on clinical and demographic factors (year and location of study, activity monitor brand, number of days wearing the monitor, whether participants were about to enter pulmonary rehabilitation, 6 minute walk distance (6MWD), FEV1%, age, and sex). Results: 38 studies including 2621 participants met inclusion criteria. The pooled mean estimate was 4579 steps/day (95% CI:4310-5208) for individuals with COPD. Only 6MWD, FEV1% and whether or not patients were about to undergo pulmonary rehabilitation explained a significant portion of the variance (p<0.1) in univariate meta-regression. In a multivariate model including the above risk factors, only FEV1% was associated with steps/day after adjustment for other covariates. Conclusions: These results indicate that patients with COPD achieve extremely low levels of physical activity as assessed by steps/day, and that severity of airflow obstruction is associated with activity level.