Which Regional Pain Rating Best Predicts Patient-Reported Improvement in Lumbar Radiculopathy?

OBJECTIVE

To determine the best regional pain score cutoff value that corresponds with patient-reported improvement in lumbosacral radiculopathy (LSR).

DESIGN

Retrospective pooled data analysis from 3 randomized, controlled, multicenter trials using similar outcome assessments. All participants were exposed to interventions (epidural injections).

SETTING

Military medical centers (6 U.S.A., 1 Germany) and large tertiary care hospitals (4 urban, 1 Veterans Affairs) between 2008 and 2014.

SUBJECTS: A total of 352 active duty military personnel and civilians ≥ 18 years of age with LSR.

METHODS

Receiver operating characteristics (ROC) with area under the curve (AUC) were calculated for 1-month outcomes for pain (numeric rating scale) using absolute and relative change in regional pain scores (back, leg) to predict clinical improvement (global perceived effect).

RESULTS

Leg pain demonstrated greater predictive ability to identify clinical improvement compared to back pain for both absolute (ROC AUC [95% confidence interval (CI)] 0.855 [0.813, 0.896] vs. 0.753 [0.702, 0.805]; P < 0.001) and relative (AUC [95% CI]; 0.867 [0.826, 0.909] vs. 0.780 [0.729, 0.831]; P = 0.002) reduction in reported pain. Clinical improvement was best identified using a leg pain reduction threshold of ≥ 1.75 points (absolute) and ≥ 23.5% (relative).

CONCLUSIONS

Region-specific pain cutoff ratings predicted clinical improvement for patients with LSR. Cutoff points using newly identified, smaller reductions of 1.75 points and 23.5% more accurately predicted clinical improvement for LSR than conventionally used cutoffs (2 points and 30%). LSR patients report meaningful clinical improvement with smaller reductions in pain compared to other chronic pain diagnoses, suggesting LSR patients may have different expectations.