Factors Associated with Pain Sensitivity and its Impact on Long-Term Outcomes in Patients with Chronic Pain: A Retrospective Cohort Study

Purpose Low back pain is estimated to affect 632 million people globally and treatment of back and neck pain in the United States costs upwards of $100 billion annually. Major clinical practice guidelines have been established for chronic pain in general, and for chronic low back pain (CLBP) in particular, with non-pharmacological and non-opioid therapies as first-line treatments. Nevertheless, these guidelines do not address how pain sensitivity may influence treatment. Pain sensitivity may be defined as the perception of pain in different situations, which varies from person to person. This study aims to determine if pain sensitivity is associated with long-term outcomes relating to low back pain intensity, back-related disability, and health-related quality of life in patients with CLBP. Methods Participants with CLBP were recruited from the Pain Registry for Epidemiological, Clinical, and Interventional Studies and Innovation (PRECISION Pain Research Registry) from April 2016 through December 2021. Pain sensitivity was measured for each participant using the Pain Sensitivity Questionnaire (PSQ), wherein scores range from 0 (least pain sensitivity) to 10 (greatest pain sensitivity). Participants were subsequently classified as having low (PSQ score ≤4) or high (PSQ score >4) pain sensitivity based on a median split. The primary outcomes were measured at quarterly encounters over 12 months, and included low back pain intensity measured with a numerical rating scale, back-related disability measured with the Roland-Morris Disability Questionnaire, and health-related quality of life measured with the SPADE cluster (sleep disturbance, pain interference, anxiety, depression, and low energy/fatigue) derived from the Patient-Reported Outcomes Measurement Information System. Multiple logistic regression was initially used to predict participant characteristics associated with high pain sensitivity. Longitudinal outcomes over 12 months were then compared according to pain sensitivity level using repeated measures analysis of variance, while simultaneously controlling for potential confounders using propensity scores. Results The strongest predictors of high pain sensitivity were being Black (OR, 6.43; 95% CI, 4.01-10.32; P< 0.001) and having high pain catastrophizing (OR, 3.11; 95% CI, 2.09-4.62; P< 0.001). High pain sensitivity was associated with greater overall levels of low back pain intensity (P< 0.001), back-related disability (P< 0.001), and health-related quality-of-life deficits (P< 0.001). However, after controlling for confounding variables, only the findings for pain intensity remained significant (P< 0.001). Conclusions High pain sensitivity is associated with greater low back pain intensity (but not with back-related disability or health-related quality of life) after controlling for confounding variables. Being Black and having high levels of pain catastrophizing were highly significant predictors of high pain sensitivity. The latter finding has important implications for rehabilitation of patients with chronic pain, as it highlights the importance of interventions that address patient pain catastrophizing, pain sensitivity, and ultimately adverse health outcomes. Physicians should be aware of how they can improve long-term chronic pain outcomes by addressing the patient's mental state relating to pain, as well as using other more conventional approaches to pain management.