Comparative responsiveness of four visual analogue scales in microdiscectomy for lumbar disc herniation

There is a paucity of studies reporting responsiveness of visual analogue scale (VAS) measures in patients treated by discectomy for symptomatic lumbar disc herniation. The aim of this study was to evaluate the responsiveness of different types of VAS.

VAS score was measured separately for constant leg pain (VAS-LP-constant), severe episode of leg pain (VAS-LP-severe), constant backache (VAS-BP-constant) and severe episode of backache (VAS-BP-severe) in a cohort of patients undergoing discectomy surgery for sciatica. VAS was evaluated preoperatively and postoperatively at final follow-up. Responsiveness was determined using standardised response mean (SRM), effect size (ES) and the area under the curve (AUC) analysis using receiver operating characteristic curves. For AUC analysis, the success of discectomy from the patient's perspective was chosen as the external anchor.

Ninety-eight patients were included in this prospective study. Outcome was assessed at a mean follow-up of 12 weeks postoperatively. The SRM of VAS-LP-severe, VAS-LP-constant, VAS-BP-severe and VAS-BP-constant was 2.16, 2.16, 0.87 and 0.53, respectively. The ES of VAS-LP-severe, VAS-LP-constant, VAS-BP-severe and VAS-BP-constant was 3.53, 2.70, 0.89 and 0.53, respectively. The AUC of VAS-LP-severe, VAS-LP-constant, VAS-BP-severe and VAS-BP-constant was 0.88, 0.75, 0.74 and 0.59, respectively.

We recommend the use of VAS-LP-Severe as the most responsive VAS measure when evaluating the results of discectomy surgery for sciatica.