Responsiveness of the modified lower extremity functional scale in patients with low back pain and sciatica A comparison with pain intensity and the modified Roland-Morris Disability Scale

We tested the responsiveness of the modified Lower Extremity Functional Scale (LEFS) for patients with low back pain (LBP) and sciatica and made a comparison with the modified Roland-Morris Disability Scale for sciatica (RMS-L) and self-reported pain intensity measured by visual analogue scale (VAS). One hundred and forty-eight participants were recruited from 2 university hospitals. The evaluation included demographic data, LBP history, and the modified LEFS, RMS-L, and VAS, with a follow-up one month later. Several responsiveness statistics were calculated. The study followed 132 participants, approximately 25% reported improvement. Guyatt responsiveness index (GRI) was 0.8 or higher for 3 measures, while standardized response means were 0.8 or higher for the RMS-L and VAS, but only 0.6 for the modified LEFS among improved group. According to ROC analysis, the modified LEFS had an area under curve (AUC) similar to that of the modified RMS-L, but significantly smaller than that of the VAS. The responsiveness of the modified LEFS was moderate but not superior to the VAS or RMS-L. Although, the modified LEFS could not replace the RMS-L or VAS, it could still be used as a complementary measure since these three measurements covered different body function, activity and participation domains.