Prevalence of psychological comorbidities and their association with injection therapy outcomes in patients with chronic low back pain: a registry-based retrospective cohort study

Background Chronic low back pain (CLBP), with or without radicular pain (RP), is a major cause of disability and reduced quality of life. Psychological comorbidities such as depression, anxiety, and chronic pain disorder are common in this population and may influence pain perception and treatment outcomes. This study aimed to assess the prevalence of psychological disorders in patients with CLBP and RP and to evaluate their association with pain severity and response to lumbar injection therapy. Methods This retrospective cohort study included 963 patients with chronic lumbar pain refractory to conservative treatment and without surgical indications. Psychological conditions were assessed using validated instruments incorporated into the German Pain Questionnaire (DSF), including DIPS, HADS-D, and DASS-21. Pain severity was measured using the Numerical Rating Scale (NRS) before and after injection therapy. Associations between psychological comorbidities and treatment outcomes were analyzed. Results Depression was identified in 37.6% of patients using DIPS, with prevalence estimates of 41 and 31% using HADS and DASS, respectively. Anxiety was present in 28–31% of patients, and stress symptoms in 45%. Chronic pain disorder with somatic and psychological factors (F45.41) was diagnosed in 17.1%. Patients with psychological comorbidities reported higher baseline NRS scores and experienced smaller reductions in pain following treatment. For example, patients with depression had higher baseline back pain scores than those without depression (8.15 vs. 7.24) and higher post-treatment scores (4.37 vs. 3.05, p < 0.01). Similar patterns were observed for anxiety and chronic pain disorder. Conclusion Psychological comorbidities are highly prevalent in patients with CLBP and RP and are associated with greater pain severity and reduced improvement following injection therapy. These findings support the integration of psychological assessment and intervention into multidisciplinary management strategies for CLBP.