Physical activity (PA) is reduced in people with interstitial lung disease (ILD) namely their number of steps per day (SPD). Little is, however, known about what may influence SPD, in this population. We aimed to identify the determinants of SPD in people with ILD.

A retrospective cross-sectional study was conducted where sociodemographic data, ILD-subtype (fibrotic Hypersensitivity Pneumonitis [fHP], Idiopathic Pulmonary Fibrosis [IPF], Connective Tissue Disease-related ILD [CTD-ILD] and other) and functional-based measures (balance-Brief-Balance Evaluation Systems Test [Brief-BESTest] and functional capacity-1-minute sit-to-stand test, % predicted [1-minSTS%p]) were collected. Lung function (FVC, % predicted [FVC%p]; DLCO, % predicted [DLCO%p]) was obtained from medical records. SPD were assessed using an Actigraph® GT3X+. Participants wore the device on the waist for 7 days and were included if they had at least 4 days with 8h (7am to 10pm). A stepwise multiple regression was performed to identify independent contributors to the variance in the SPD.

58 volunteers (48% male; 67 [61-75] years old; 82[66-94] FVC%p; 56[39-67] DLCO%p; 43% diagnosed with IPF) were included. Brief-BESTest (B=187; p=0.01; partial R2=0.17; IC95% 49 to 324) and IPF diagnosis (B=-1927; p=0.04; partial R2=0.10; IC95% -3792 to-62) were identified as significant contributors to the variance of SPD.

Higher scores on Brief-BESTest were associated with higher SPD, while having an IPF diagnosis showed a decrease in SPD. These findings validate the importance of assessing balance and targeting diagnosis when developing personalized interventions to increase SPD in people with ILD.