Pro-inflammatory dietary patterns are associated with increased pain and functional disability in sciatica: a hospital-based cross-sectional study

Background Sciatica is a common neuropathic pain condition associated with substantial functional disability. Emerging evidence suggests that diet-induced inflammation may play a role in chronic pain development. However, the association between dietary inflammatory potential and clinical outcomes in sciatica remains unclear. Methods In this cross-sectional study, we enrolled 598 patients diagnosed with sciatica from two hospitals in Sichuan Province, China. The Dietary Inflammatory Index (DII) was calculated from food frequency questionnaires. Pain intensity and functional disability were assessed using the Visual Analog Scale (VAS) and Oswestry Disability Index (ODI), respectively. Serum C-reactive protein (CRP) was measured as an inflammatory biomarker. Correlation analysis, multivariable linear regression, mediation analysis, and restricted cubic spline models were applied. Results In adjusted models ( n = 598; mean age 55.6 years, 47.5% male), higher DII scores were strongly associated with greater pain and disability. Each 1-unit increase in DII corresponded to a 0.48-point increase in VAS ( β = 0.48, 95% CI: 0.42–0.53, partial R 2 ≈ 0.31) and a 4.75-point increase in ODI ( β = 4.75, 95% CI: 4.16–5.34, partial R 2 ≈ 0.30; all p < 0.001). The magnitude of the association with VAS exceeded the commonly reported minimal clinically important difference (≈1.5 points) for leg pain, suggesting clinical relevance. DII was not significantly associated with CRP, and CRP did not mediate the DII–pain relationship. Nonlinear dose–response patterns were observed for both VAS and ODI. Conclusion Pro-inflammatory dietary patterns, as reflected by higher DII scores, are independently associated with greater pain and disability in patients with sciatica, not mediated by CRP but likely involving broader inflammation-related pathways. These findings highlight the potential role of anti-inflammatory nutritional strategies in the integrative management of sciatica.