[Validation of a self-administered functional evaluation questionnaire after surgical treatment of lumbar spine stenosis]

Abstract

Purpose of the study: The main aim of this prospective, multicentric, observational study was to validate a self-administered quality-of-life questionnaire for patients with lumbar spine stenosis treated surgically.

Material and methods: The self-administered questionnaire was composed of eight questions exploring three dimensions: lumbalgia, radiculalgia, radicular ischemia. This questionnaire was associated with an index of neurological involvement (to take into account objective neurological data), and with an index of patient satisfaction (to assess the patient's perception of the impact of surgery on lumbalgia, radiculalgia, and gait disorders). The scoring scale was validated by studying the structure of the questionnaire (to ascertain the pertinence of the proposed three dimensions), by determining the questionnaire's reproducibility (intraobserver variability) and sensitivity to change, and by examining the contents of the questions (to assess the capacity of the scale to effectively measure the parameters it was designed to measure). Cronbach's alpha coefficient and principal component analysis were used to assess the questionnaire's structure. Reproducibility was tested on 49 patients who completed the self-administered questionnaire twice at a 15-day interval; intraclass correlation coefficients were determined. Sensibility was tested by correlating variation in the scores obtained pre- and postoperatively with the index of satisfaction; mean standard responses were determined. The validity of the questionnaire's content was assessed by correlating the scores obtained with the questionnaire to those obtained with three other self-administered questionnaires: SF36, EIFEL2 and GHA38.

Results: This work included 104 patients, 96 of whom were reviewed at consultations 6 and 12 months after surgery. The principal components analysis confirmed the presence of the three dimensions. The global Cronbach alpha coefficient was 0.86. The global intraclass coefficient of correlation was 0.95, varying from 0.86 to 0.97 depending on the dimension studied. There was a good correlation (0.82) between changes in the score studied and the index of satisfaction. All the mean standardized responses were higher than 1, indicating good sensitivity to change. There was also a good correlation between the questionnaire tested and the EIFEL2 self-administered questionnaire and the following dimensions of the SF36: physical activity, physical pain, vitality, and limitation due to physical pain.

Discussion and conclusion: Associating a simple 8-question self-administered questionnaire with an index of satisfaction (4 questions) and an objective index of neurological involvement provided a reliable, sensitive, and reproducible assessment of the changes in functional disorders resulting from lumber stenosis before and after surgical treatment.