Introduction: Chronic pain represents a global health issue. The WHO conducted an extensive research
study in order to assess the prevalence of persistent pain among primary care patients; among these, 22% were
suffering from chronic pain syndromes. The Brief Pain Inventory (BPI) was created in 1994 in an effort to
characterize pain (severity and interference), its severity and its perception, in order to evaluate its interference
with the patient’s everyday life. The aim of this study was to analyze the association between different
biopsychosocial factors and pain interference (at entry and the difference in pain interference between entry and
discharge) according to the BPI among rehabilitation patients suffering from chronic pain following an
orthopaedic trauma.
Methods: This is a retrospective study and the data were collected from the Clinique Romande de
Réadaptation (CRR) in Sion between April 2012 and June 2017 upon patient admission and upon discharge. A
total of 1902 patients suffering from chronic pain and pain-related impairments following an orthopaedic
trauma were examined. In order to determine the impact that biopsychosocial factors have on pain interference,
a systematic review of pertinent research publications was performed. This research identified 20 potentially
relevant biopsychosocial factors, and in addition to the predefined factors, we included four additional ones.
Statistical association between the BPI interference and biopsychosocial factors were performed using linear
regression and multi-variable models. All potential predictors were first screened individually, then variables
with a probability <0.20 were kept in the multivariable models. The 2 final models (entry and difference
between entry and discharge) were obtained after a backward elimination, as those that minimized the Akaike
Information Criterion (AIC). All statistical analyses were performed with Stata 15.0 (StataCorp, College
Station, TX, USA). The significance level was set to p< 0.05.
Results: The BPI interference at entry was associated with eight biopsychosocial factors: four
biological (pain severity, sleep interference, BMI, and pain localization), two psychological (depressive
symptoms and pain catastrophizing), and two social (professional qualification and social domain restrictions)
factors. The explained variance was 68%. The BPI interference difference between entry and discharge was
associated with ten biopsychosocial factors: four biological (smoking habit, gender, pain severity, and BMI),
three psychological (depression, anxiety, and pain catastrophizing), and three social (resistance to treatment,
qualification and an education of > 9 years). The variance was 32%. Five factors were common to both models.
Conclusion: A statistically significant association between these biopsychosocial factors and BPI pain
interference was assessed. The majority of these factors are amenable to therapeutic actions in pain
management rehabilitation.