Background

Psoriatic arthritis (PsA) is a chronic inflammatory rheumatic disease, estimated to affect approximately one third of individuals with psoriasis. Evidence exists to suggest that individuals with psoriatic disease are less physically active when compared to the general population. However, to date, most evidence has relied on self-reported measures of physical activity, which are crude and prone to recall bias. Wearable devices, such as accelerometers, can continuously and more objectively measure physical activity.

Objective

We aimed to report the association between psoriatic disease (PsD) and accelerometer measured daily step count and explore the mediating role of comorbidities and relevant
medications on daily steps in PsD.

Methods

This study analysed seven days of wrist-worn accelerometer data collected between 2013-2016 from UK Biobank participants (aged 43-78). Primary care and hospital records were used to identify participants with prevalent psoriasis or PsA at time of accelerometer wear. Median daily step count was computed using a validated hybrid self-supervised machine learning step detection algorithm. Multivariable linear regression modelling was performed to assess the association between daily step count and clinical groups, controlling for demographic and behavioural confounders. Separate mediation analyses exploring the association between body
mass index (BMI by categories: <25, 25-29.9, ≥30 kg/m2), any coded condition on Charlson Comorbidity Index, and comorbid depression on daily steps were conducted. Binary indicator variables for prescription of i) acute opioid within 3 months of accelerometer wear, ii) long term opioids, iii) and any systemic corticosteroids within 18 months of accelerometer wear were generated. Subgroup analyses exploring the association between coded medication and daily steps in PsD were conducted.

Results

Amongst 94,436 participants with valid accelerometer data, we identified 2,625 participants with psoriasis only and 337 participants with PsA. In multivariable models, a diagnosis of PsA was associated with participants taking 540 fewer daily steps [95% CI: 137, 942](p=0.009) than non-psoriatic controls (Figure 1A). Participants with psoriasis took 194 fewer daily steps [95% CI: 48, 340](p=0.009) than non-psoriatic controls. This association was attenuated on mediation analyses adding BMI, comorbidity burden or depression to the primary model. On subgroup analyses exploring the association between medication use and daily step count in psoriatic disease, both acute and long-term opioid prescribing and use of systemic corticosteroids were associated with reduction in daily step counts (Figure 1B-D, respectively).

Conclusions

This study suggests that participants with either psoriasis or PsA took fewer daily steps than non-psoriatic controls, with this reduction mediated through higher BMI, comorbidity burden and comorbid depression. Individuals with psoriatic disease prescribed any opioid or systemic steroids had significantly reduced physical activity. This study provides insight into subgroups of patients with psoriatic disease who may benefit from targeted physical activity interventions.