Outcomes of Minimally Invasive Decompression Alone Versus Fusion for Predominant Back Pain.

Background: Although a few recent studies showed good outcomes in back pain-predominant patients following decompression alone, none of the studies had a comparative fusion group. Purpose: We sought to compare outcomes of minimally invasive decompression alone versus fusion in patients with predominant back pain. Methods: This retrospective cohort study included patients who underwent minimally invasive decompression alone or fusion and had preoperative back pain > leg pain. Outcome measures were (1) patient-reported outcome measures (PROMs), (2) minimal clinically important difference (MCID) achievement, (3) patient acceptable symptom state (PASS) achievement, and (4) global rating change (GRC). As a subgroup analysis, MCID, PASS, and GRC rates were also compared between the decompression and fusion groups for patients with preoperative back pain < leg pain. Results: Of 510 patients included, there were statistically significant improvements in all PROMs in both groups at <6 and >6 months with no significant difference in the magnitude of improvement. The fusion group showed significantly higher MCID achievement rates for Visual Analog Scale (VAS) back at <6 months (85% vs 70%) and Oswestry Disability Index (ODI) at >6 months (67% vs 51%). Proportion of patients achieving PASS and feeling better after surgery based on response to GRC showed no difference between the groups. The subgroup analysis for decompression versus fusion in patients with preoperative back pain < leg pain showed no differences in MCID, PASS, or GRC rates. Conclusions: This retrospective cohort study found that in patients with predominant back pain, minimally invasive decompression alone had significantly less MCID achievement rates in VAS back at <6 months and ODI at >6 months. However, it did lead to an overall significant improvement in PROMs, similar PASS achievement rates, and similar responses on the GRC scale.