Cambio mínimo clínicamente relevante en la calidad de vida de pacientes con lumbalgia inespecífica

Abstract

BACKGROUND CONTEXT: Chronic low back pain represents one of the greatest health problems in industrialized countries. In western countries, 80% of the population suffers from back pain at some time in their lives, and it is one of the leading causes of disability, restricted mobility and decrease in the long-term quality of life. The results of the effectiveness of different interventions in low back pain are usually expressed by p-values based on statistical significance and in mathematical concepts, which do not imply that the patient has received a real improvement with the intervention. In this way, the concept of minimal clinical important change (MCIC) is developed, which is defined as the smallest difference in score within the quality of life questionnaire that is perceived as beneficial to the patient. PURPOSE: To determine the MCIC for the questionnaire SF-12 version 1 in chronic low back pain. METHODS: A randomized clinical trial was conducted by clusters. The clinical trial consisted of three groups: the group “Education” that included a short educational program and usual physiotherapy, the group “Group GDS” that included the same short educational program and group physiotherapy based on the method of physiotherapy GDS, and the group “Individual GDS” which included the short educational program and group and individual physiotherapy based on the method GDS. We used four different methods for the calculation of the MCIC: average change approach, minimum detectable change (MDC), the change difference approach and receiving operating characteristic curve approach (ROC), using as an anchor the external state of health perceived by the patient in each control in relation to the first time that he was served at the physiotherapy unit. RESULTS: In relation to the physical component (PCS) and the mental component (MCS) of the quality of life that are measured by the SF-12 questionnaire version 1: in the physical component (PCS) the group of greater improvement was the group “Group GDS” with an increase of 1.441 points (standard deviation 0.485 ; p-value=0,004) and 0.953 points (standard deviation 0.479 ; p-value=0,047) in relation to the group “Education” and the group “Individual GDS” respectively; in the mental component (MCS) no statistically significant differences were found between any of the three groups. The MCIC obtained using the four methods was: in the method average change: 2.715 for the PCS (Physical Component Summary) and 3.543 for the MCS (Mental Component Summary); in the minimum detectable change (MDC): 0,590 for the PCS 0.590 and 3.774 for the MCS; in the change method difference approach: 3.297 for the PCS and 1.135 for the MCS; and in the method using the ROC curves, the MCIC was discarded by having an area under the curve of 0.6332 for the PCS and 0.551 for the MCS, with little power classificatory practically equal to the random. CONCLUSIONS: The method minimum detectable change (MDC) is the best method for the calculation of the MCIC since you are getting the values above the 95% confidence interval, what is outside of the measurement error, eliminating the potential MCIC that can be obtained if the error of measure is not taken into account. The MCIC for the SF-12 version 1 in low back pain is 0.590 for the PSC and 3.774 for the MSC.