Race, Social Status, and Depressive Symptoms: A Moderated Mediation Analysis of Chronic Low Back Pain Interference and Severity.

BACKGROUND: Chronic low back pain (cLBP) is the leading cause of disability, with a significant societal cost. It disproportionately affects non-Hispanic blacks and individuals of lower socioeconomic status. The biopsychosocial framework has been used to study and manage cLBP, yet disparities persist. OBJECTIVE: The objective of this study was to assess whether self-identified race moderated the relationship between perceived social status and cLBP outcomes (pain interference and pain severity) and investigate whether race moderated the indirect relationship between perceived social status and pain outcomes via depressive symptoms. METHODS: Fifty-seven blacks and 48 whites with cLBP were recruited as part of a large ongoing study. Depressive symptoms, objective and subjective measures of socioeconomic status, and pain outcomes were measured. Hayes' moderated mediation model was used to estimate conditional direct and indirect relationship between these variables. RESULT: On average black participants reported significantly more pain interference (4.12 [SD=2.65] vs. 2.95 [SD=2.13]) and severity (5.57 [SD=2.27] vs. 3.99 [SD=1.99]) than white participants, (P<0.05). Race moderated the association between perceived social status and pain interference: higher social status decreases pain interference for white participants, but that trend was not observed in black participants. Moreover, race moderated association of perceived social status with depressive symptoms (P<0.001); which mediates the effects of perceived social status on pain outcomes. CONCLUSION: Higher perceived social status is associated with less severe depressive symptoms, which in turn is associated with less pain severity and less pain interference for whites but not for blacks with cLBP.

Perceived Injustice Helps Explain the Association Between Chronic Pain Stigma and Movement-Evoked Pain in Adults with Nonspecific Chronic Low Back Pain.

OBJECTIVE: For most patients with chronic low back pain (cLBP), the cause is "nonspecific," meaning there is no clear association between pain and identifiable pathology of the spine or associated tissues. Laypersons and providers alike are less inclined to help, feel less sympathy, dislike patients more, suspect deception, and attribute lower pain severity to patients whose pain does not have an objective basis in tissue pathology. Because of these stigmatizing responses from others, patients with cLBP may feel that their pain is particularly unjust and unfair. These pain-related injustice perceptions may subsequently contribute to greater cLBP severity. The purpose of this study was to examine whether perceived injustice helps explain the relationship between chronic pain stigma and movement-evoked pain severity among individuals with cLBP. METHODS: Participants included 105 patients with cLBP who completed questionnaires assessing chronic pain stigma and pain-related injustice perception, as well as a short physical performance battery for the assessment of movement-evoked pain and physical function. RESULTS: Findings revealed that perceived injustice significantly mediated the association between chronic pain stigma and cLBP severity (indirect effect = 6.64, 95% confidence interval [CI] = 2.041 to 14.913) and physical function (indirect effect = -0.401, 95% CI = -1.029 to -0.052). Greater chronic pain stigma was associated with greater perceived injustice (P = 0.001), which in turn was associated with greater movement-evoked pain severity (P = 0.003). CONCLUSIONS: These results suggest that perceived injustice may be a means through which chronic pain stigma impacts nonspecific cLBP severity and physical function.