Association of adjunctive low-level laser therapy with short-term pain and functional outcomes in chronic low back pain: A retrospective comparative study

Introduction: Chronic low back pain (CLBP) is a major cause of pain-related disability, and the incremental value of adjunctive low-level laser therapy (LLLT) within multimodal physiotherapy remains uncertain. This retrospective comparative study evaluated whether adding LLLT to conventional physiotherapy was associated with more favorable short-term pain and functional outcomes in patients with CLBP.Methods: Medical records of 69 patients with CLBP were reviewed. Patients received either conventional physiotherapy alone (control group, n=34) or the same program with adjunctive LLLT (LLLT group, n=35). Both groups completed 15 treatment sessions including infrared therapy, ultrasound, transcutaneous electrical nerve stimulation, and a home exercise program; the LLLT group additionally received 830-nm laser therapy (50 mW, 4 J/cm²). Pain and disability were assessed using the Visual Analog Scale (VAS) and Quebec Back Pain Disability Scale (QBPDS). Because baseline VAS and QBPDS scores differed significantly between groups, primary comparisons used 5,000-resample bootstrapped ANCOVA adjusted for the corresponding baseline values.Results: Baseline VAS and QBPDS scores were significantly lower in the LLLT group (VAS, p=0.001; QBPDS, p<0.001). Both groups improved significantly in VAS and QBPDS scores from baseline to post-treatment (all p<0.001; within-group effect sizes r=0.617–0.624 across groups and outcomes). After baseline adjustment, post-treatment VAS was 1.06 points lower in the LLLT group than in the control group (b=−1.06, 95% BCa CI −1.67 to −0.43; partial η²=0.15). Post-treatment QBPDS was 13.47 points lower in the LLLT group (b=−13.47, 95% BCa CI −20.02 to −5.94; partial η²=0.17).Conclusion: Adjunctive LLLT was associated with lower short-term post-treatment pain intensity and back-related disability after adjustment for baseline differences. These findings suggest a potential additional benefit of LLLT within multimodal physiotherapy but should be interpreted cautiously given the retrospective non-randomized design, baseline group differences, and active treatment in both groups. Prospective randomized studies with longer follow-up are warranted.