OBJECTIVES: To analyze prospectively the effect of adding Pregabalin (PGB) on PRO measurements evolution in the treatment of refractory Low Back Pain under routine medical practice conditions METHODS: Post-hoc analysis of patients above 18 years, with 6-month chronic Low Back pain refractory to, at least, one previous analgesic [previous mean (SD) number of drugs was 2.1 (1.3), 22.7% on one-drug], included in a prospective, naturalistic, 12-weeks two-visit study. This analysis compared patients receiving PGB as an add-on therapy (PGB add-on) versus subjects receiving any other analgesic pattern not including PGB (non-PGB). PRO measurements included evaluation of severity and interference of pain (Brief Pain Inventory), anxiety and depression symptoms (HAD scale), and quality-of-life (SF-12). RESULTS: A total of 683 [49.5% women, 55.0 (12.7) years] patients were analyzed: 82.6% received PGB add-on and 17.4% non-PGB. Twelve weeks therapy with PGB add-on was associated with higher reduction in pain severity than in non-PGB; -3.4 (2.0) pts, 61.6% responders (³50% baseline pain reduction) vs.-2.0 (2.1), 37.3% responders; p<0.0001, respectively. Pain interference was also reduced more with PGB add-on: -3.5 (2.1) pts vs. -2.0 (2.3), respectively; p<0.0001, and showed greater reduction in depression [-4.0 (4.1) pts vs. -2.1 (3.3); p<0.0001] and anxiety [-3.7 (3.6) pts vs. -1.9 (3.0); p<0.0001] symptoms scores, yielding to a significant improvement in patient’s quality of life: mental and physical summary components change were higher in PGB add-on therapy group: +7.3 (10.6) vs. +2.0 (7.4); p<0.0001, and +9.7 (9.6) vs. +5.8 (8.3); p<0.0001, respectively.   CONCLUSIONS: Compared with adding other any drug, the addition of PGB to the treatment pattern of refractory Low Back Pain seems to be associated with higher improvement in PRO measurements, including reduction of pain severity and interference and improvement of quality of life under routine medical practice condition.