Association of daily steps over time with adult asthma incidence

Higher daily step counts is associated with reduced risk of many chronic diseases. Increased physical activity improves asthma outcomes. There are no known prevention strategies for adult incident asthma.

We sought to determine whether objective physical activity affects adult asthma incidence.

Participants in the All of Us Research Program retrospective cohort aged ≥18 years with linked personal activity tracker and electronic health record data met the inclusion criteria. Asthma was defined as two relevant ICD-9/10 codes and prescription of ≥1 medication. Participants with an asthma diagnosis date before or within 6 months of activity-monitor initiation were assigned to the prevalent asthma group; participants diagnosed after 6 months of activity monitoring were assigned to the incident asthma group.

A total of 8,360 participants were included. Median average steps per day were higher among asthma-free participants (7,795; 95% confidence interval [CI], 5,879-9,921, n = 7,700) than participants with prevalent (6,968; 95% CI, 5,036-9,014, n = 450) or incident (6,953; 95% CI, 5,215-8,261, n = 210) asthma (P < .0001). Significant time-by-incident asthma interaction was observed with a greater decline in steps per day over time in the incident asthma cohort (P = .018). An inverse relationship was observed between average steps per day and asthma incidence after adjusting for age, sex, race, body mass index, major depressive disorder, obstructive sleep apnea, and chronic obstructive lung disease (adjusted hazard ratio, 0.93, 95% CI, 0.88-0.98 per 1,000 average daily step increase).

Objectively measured daily steps are lower in adults who develop incident asthma and may represent a modifiable risk factor to reduce asthma incidence. Future studies should objectively monitor physical activity among adults at risk for and with asthma.