Similar negative effects of fatigue on physical activity in persons with rheumatoid arthritis and healthy controls: results of a cross-sectional patient-control study.

OBJECTIVES

The objective of this study was to investigate objectively measured physical activity (PA) patterns and the association between PA and self-reported fatigue in persons with rheumatoid arthritis (pwRA), as compared with healthy controls (HCs).

METHODS

In this cross-sectional study, 23 pwRA (Disease Activity Score 28 > 2.6, 52 ± 13 years, 20 females) and 18 HCs (52 ± 10 years, 14 females) wore an ActiGraph wGT3X-BT tri-axial accelerometer (ActiGraph LLC) on 1 ankle for at least 4 days. Accelerometer-based outcomes were vector magnitude counts/min (VMCPM), step count, and the amount of time that PA was performed at moderate-to-vigorous intensity (MVPA). Accelerometer data were categorised by day (weekday vs weekend) and time of the day (daytime vs evening) to investigate PA patterns. Physical and cognitive fatigue were assessed with questionnaires (Fatigue Severity Scale and Modified Fatigue Impact Scale). Associations between fatigue, presence of RA, and PA were examined using multilevel generalised estimating equations models, with patient and day-timing as levels. Interactions between the presence of RA and fatigue were tested.

RESULTS

The VMCPM, step count, and MVPA were lower in pwRA than in HC across various daytime periods (overall: 1233.4 ± 509.4 cpm/h in pwRA vs 1701.2 ± 492.8 in HC, 586.9 ± 225.8 vs 723.8 ± 224.1 steps/h, and 1.6 ± 1.4 vs 2.7 ± 1.5 min/h, respectively). Multivariably, lower VMCPM was seen in pwRA (β = -330.63; 95% CI = -650.45 to -10.81), with higher fatigue (β = -43.89; 95% CI = -135.26 to 47.48), and with higher body mass index (β = -27.18; 95% C I = -50.73 to -3.62). The effect of fatigue or daytime on PA was not modified by the presence of RA.

CONCLUSIONS

Persons with RA performed less PA than HC. Fatigue had a similarly negative effect on PA in pwRA and HC.