Is Pain Relief Enough? Early Response Discordance After Lumbar Decompressive Surgery: A Prospective Cohort Study

Background Different patient-reported outcome measures (PROMs) may classify the same patient differently as a treatment responder after lumbar decompressive surgery. We aimed to quantify inter-instrument agreement on minimal clinically important difference (MCID)-based responder status at one month postoperatively, characterize multi-dimensional response discordance, and identify residual health dimensions independently driving patient dissatisfaction. Methods In this prospective observational cohort study, 158 consecutive adults undergoing lumbar decompressive surgery for disc herniation (n = 77) or spinal stenosis (n = 81) at a single neurosurgical center were enrolled. Of these, 134 (84.8%) completed paired baseline and one-month assessments using the Visual Analogue Scale for leg pain (VAS), Oswestry Disability Index (ODI), and EQ-5D-5L utility index. MCID thresholds were derived from external sources (VAS ≥1.5 points, ODI ≥10 points, EQ-5D-5L ≥0.10). Inter-instrument agreement was quantified using Cohen's kappa (κ). Patient dissatisfaction was defined by the Spine Surgery Satisfaction Questionnaire (SSSQ > 12). Independent predictors of dissatisfaction were identified by multivariable linear regression with bootstrapped confidence intervals. Results All instruments showed significant improvement at one month (all p < 0.001). MCID-based responder rates differed markedly: VAS 82.1%, EQ-5D-5L 83.6%, and ODI 54.5%. Inter-instrument agreement was slight to fair (κ = 0.19–0.29); Only 47.0% of patients achieved MCID across all three instruments simultaneously, while 94.0% achieved it on at least one — producing a 47-percentage-point disagreement zone (Figure 2). Pain and/or quality-of-life improvement without corresponding functional improvement (Type A discordance) affected 39.6% of patients. Twenty-three percent of patients were dissatisfied at one month. In multivariable regression (R² = 0.34), residual mobility limitation (β = 0.77; p = 0.006) and depression/anxiety (β = 0.81; p = 0.005) were independent predictors of dissatisfaction; residual pain was not significant. Conclusions Instrument selection alone changes responder classification rates by nearly 30 percentage points at one month after lumbar decompressive surgery. Dissatisfaction is driven by residual functional limitation and psychological distress, not residual pain. Multi-dimensional PROM assessment with diagnosis-informed instrument selection should be standard practice at the early postoperative visit to identify patients requiring targeted rehabilitation and psychological support. Trial registration Not applicable