Pain and Sleep Biomarkers in Participants Undergoing Orthopedic Surgeries

The bidirectional relationship between chronic pain and poor sleep are well reported. Disrupted sleep and chronic pain, either alone or in conjunction, are often associated with poor post-surgical outcomes. However, the relationship between peripheral blood biomarkers and chronic pain and sleep disturbances after orthopedic surgery has not been extensively studied. The goal of this observational prospective study was to conduct an analysis on the relationship of blood cytokines and chemokines with chronic pain and sleep outcomes among US service members undergoing orthopedic surgery. Active-duty service members (N = 114) who underwent orthopedic extremity or spinal surgery were recruited, of whom 69 completed pre-surgery and 64 completed 6-week post-surgery surveys and blood draws. Blood cytokine and chemokine analyses were performed using multiplex immunoassays. Non-parametric correlations with blood cytokine and chemokine showed significant associations with both pre- and post-surgical pain scores whereas no significant correlations were observed with sleep disturbance scores. Increased pain intensity 6 weeks after surgery was positively associated with increased hepatocyte growth factor (ρ_s = 0.11; p < 0.05) and negatively correlated with interleukin-2r (ρ_s= -0.42; p < 0.001). This study found that inflammatory biomarkers are associated with pre- and post-surgical pain but not sleep disturbances.