RESUMEN
Introduction: Low back pain (LBP) is a prevalent condition, which causes an important economic and clinical impact to individuals during their productive work-life. Electro-anaesthesia methods of choice are Interferential Current (IC) and transcutaneous Electric Nervous Stimulation (TENS). The objetive of this study is to determine the effectiveness of both therapies, as well as variability in the measurement of pain. We also preliminary evaluate the comparative effectiveness of IC and TENS by determining the mean difference of decreased acute back pain in patients treated at Hospital of Trabajador, in Temuco, Chile. Material and Method: 30 LBP patients were studied (0-3 weeks evolution). Intensity of pain before and after the aplication of IC and TENS was assessed usin the Visual Analogue Scale (VAS). IC intervention considered an amploitude.frequency spectrum ranging from 5 Hz to 10 Hz, with vector, while TENS was an asymmetric biphasic stimulus with a phase time of 150 useg, using a frequency of 100 Hz, pulses of 2 Hz. These were applied using four rubber electrodes (60 mm by 40 mm) placed on the lumbar zone for a period of 30 minutes. Results: The study group included 67 por ciento (n = 20) male with an average age of 38.3 years (SD: 9.5 years), 67 por ciento of them were workmen. The reduction of pain mean difference in patients treated with TENS was 1.24 cm (p = 0005), and 2.18 cm (p = 0001) with IC. The difference of both results, adjusted by VAS baseline, age, sex, and occupation of patients was 0.91 cm (p = 0.0261) in favour of IC. Conclusions: The magnitude of treatment effects for TENS was 18.4 por ciento, and 31.5 por ciento for IC in relation to baseline pain. In this study group, there were no clinically relevant differences to control LBP in patients inmediately after application, between IC and TENS. Both demonstrated to be effective.