Movement Behavior in Adults with Sickle Cell Disease Compared to Healthy Adults: Preliminary Results

Background

Sickle cell disease (SCD) is one of the most common monogenic disorders in the world. People with SCD experience pain due to blood flow obstruction and have musculoskeletal and cardiopulmonary complications, which correspond to different chronic conditions. In other chronic diseases, this leads to a reduction in movement behavior. Movement behavior during the day consists of sedentary behavior (sitting and lying), and physical activity (PA) (walking, biking, and running). It has recently been shown that low-to-moderate physical exercises are safe to perform and yield benefits by increasing exercise tolerance and decreasing inflammation in individuals with sickle cell anemia¹. Movement behavior of adults with SCD has not been analyzed so far, although patients with SCD have demonstrated to have a reduced 6 minutes walking test previously². It is hypothesized that adults with SCD are less active and have a more sedentary lifestyle compared to healthy adults. The aim of this study is to identify differences in movement behavior between patients with SCD and healthy adults.

Methods

Movement behavior of patients with a diagnosis of SCD (>16 years) was evaluated prospectively during their regular outpatient check-ups in two tertiary teaching hospitals in the Netherlands. To compare movement behavior of patients with SCD with a healthy population, data of healthy adults with migration background from a former movement behavior study was used. Demographic characteristics of the healthy adults were compared to statistics of the Dutch population with a migration background to check whether the sample was representative. Movement behavior was measured for seven consecutive days with an accelerometer (Activ8), distinguishing between lying/non-wear, sitting, walking, running, and biking. Absolute time spent on activities and PA (combining walking, running, and biking) were compared between patients with SCD and healthy adults with the Mann-Whitney U test. To adjust for multiple testing, season, sex, and age, a linear regression for each activity was performed using a Bonferroni correction, with activity as dependent variable and group as independent variable. To account for differences in wear time (spending 90 minutes or more lying down/non-wear during the day was classified as non-wear), a sensitivity analysis was performed with absolute time spent on activities expressed as percentage of wear time.

Results

Twenty-five patients with SCD (median age (IQR) 30 years (21.5) were analyzed and compared with 57 healthy adults (37 years (20)). Patients with SCD were less physically active per day than healthy adults (SCD median (IQR) 117 (70.8) vs healthy 154 (85.8) minutes respectively). With respect to the type of activity, patients with SCD walked 42 minutes per day (-0,7 hours 99.2% CI [-1.27 to -0.13]) less than healthy adults. Sensitivity analysis showed similar results. After adjusting for actual wear time, patients with SCD walked -4.24% less 99.2%CI [-7.51 to -0.97]) than healthy adults and lied down more (5.74% 99.2%CI [0.65 - 10.82]). No significant differences in other activities were identified (sitting, running, and biking).

Conclusion and key findings

Patients with SCD appear to be less physically active compared to healthy adults, which is mainly reflected by less walking during the day. Less PA during the day in patients with SCD can possibly be explained by SCD-related complications such as poor physical functioning, pain, anemia, and fatigue. These factors can disincentive PA and restrict activity levels during the day. Guidance in changing movement behavior is helpful for patients with SCD. Given the heterogeneity of symptoms in SCD, an individual approach will be necessary. Therefore, a physical therapist could be a key health professional in the multidisciplinary team to help patients with SCD to positively change their movement behavior without significantly increasing the risk of triggering a vaso-occlusive crisis.

van Dijk:Axcella Therapeutics: Research Funding; Agios Pharmaceuticals, Inc.: Research Funding. van Beers:Sobi: Research Funding; Sanofi: Consultancy; Pfizer: Research Funding; RR Mechatronics: Research Funding; Global Blood Therapeutics: Consultancy; Agios Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding. Biemond:BMS: Research Funding; Modus Therapeutics: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees; Chiesi: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; GBT: Research Funding; BMS: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Chiesi: Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees; GBT: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanquin: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding. Nur:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Timmer:Novo Nordisc: Research Funding; SOBI: Consultancy.