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Session: Wearable
Session starts: Friday 27 January, 11:30
Presentation starts: 11:30
Room: Room 531

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Xiaoping Zheng (university of groningen)
Michiel Reneman (university of groningen )
Bert Otten (university of groningen )
Claudine Lamoth (university of groningen)

Abstract:
Introduction: Chronic low back pain (CLBP) is the leading global cause of disability. Central sensitization (CS) is present in a subsample of patients with CLBP. Optimal physical activity (PA) is often recommended in the management of CLBP because it can reduce the risk of disability. However, the evidence of the relationship between PA intensity levels and CLBP is inconsistent, and the knowledge about the association with CS is limited. This study aimed to investigate PA patterns in patients with CLBP and low or high CS using an unsupervised machine learning approach. Methods: Forty-two patients were included (23 CLBP-, a CS Inventory score lower than 40; 19 CLBP+, 40-100). Patients wore a 3D accelerometer for about one week. For each patient, 4 days of data were used for analyses. Accelerometer data were corrected for gravity and the vector magnitude was calculated. For each group, a Hidden semi Markov Model (HSMM) was made to measure the temporal organization and transition of hidden states (PA intensity levels), based on accelerometer vector magnitude. Differences between CLBP- and CLBP+ in duration and occupation of hidden states were assessed with independent t-tests. The transition probability was assessed by Binomial-proportion test. The compositions of corresponding hidden states were assessed with Jensen–Shannon divergence (JSD). Results: The corresponding 5 hidden states of CLBP- and CLBP+ were similar, indicated by JSD. These states were defined as: rest (e.g., sleeping), sedentary (e.g., desk work), light activity (e.g., standing), light locomotion (e.g., slow walking), and moderate-vigorous activities (e.g., fast walking). Significant differences between 2 groups showed that CLBP+ exhibited higher duration and transition probability of active state (light activity, light locomotion, and moderate-vigorous states) and higher duration of inactive state (rest and sedentary states). Discussion: The significant differences in temporal organization and transition of PA levels may suggest that CLBP- and CLBP+ had different PA patterns. CLBP+ group exhibited a prolonged period of activity engagement (overactive) and then had a long period of rest. This PA pattern may suggest that CLBP+ had the distress-endures response pattern.