COMPARING PREOPERATIVE QUALITY OF LIFE QUESTIONNAIRE IN LUMBAR STENOSIS

ABSTRACT Objective: To correlate the four quality of life questionnaires: Oswestry Disability Index (ODI), SF-36, Swiss Spinal Stenosis Questionnaire (SSS), and EQ-5D in patients who have not received surgical treatment of lumbar stenosis. Methods: Prospective cross-sectional study. Forty patients diagnosed with lumbar stenosis at a university hospital answered four quality-of-life questionnaires in a preoperative consultation. The scores of each questionnaire were tabulated and then compared. In statistical analysis, the Spearman correlation was performed. Results: 17 female and 23 male patients with a mean age of 56.5 years. ODI had an average dysfunction of 44.9%; the PCS score averaged 29.9, and the MCS score of 41.3. The general symptoms of SSS presented a mean of 3.2, and the EQ-5D presented an average of 0.491. The EQ-5D presented the best correlation with the other questionnaires. The score that presented a worse correlation with the other questionnaires was the neuroischemic symptomatology of SSS. Conclusion: quality-of-life questionnaires can be correlated; thus, the evaluation of preoperative patients can be simplified. Level of Evidence III; Diagnostic Studies.


INTRODUCTION
Lumbar stenosis is one of the main diagnosed pathologies of the spine and the main cause of spinal surgery in the elderly population; responsible for the generation of significant pain and consequent functional damage to patients. 1 It is increasingly frequent due to the greater life expectancy of the world population. 2 It has been defined as a condition in which there is a decrease in the space available for neural and vascular elements, secondary to degenerative changes in bone structures and soft tissues, with the consequent invasion of the spinal canal. 3,4Neurogenic claudication is a classic alteration related to pain and gait difficulty.][7] Imaging exams are of great importance in propaedeutics to complement the patients' clinic, helping to define the location and degree of involvement.Magnetic resonance imaging (MRI) plays a central role in diagnosing spinal stenosis.Despite this, the correlation between MR imaging characteristics and clinical symptoms remains controversial, as many asymptomatic individuals have spinal stenosis verified by magnetic resonance imaging. 8,9he rational use of health goods and services is always desired, especially during the economic recession, aiming to improve the patient-health institution binomial.In this way, clinical and quality--of-life data should be applied so that, together with the physical examination and imaging tests, treatment is conducted most correctly and least expensively. 10or this, we have lumbar stenosis, questionnaires that stratify the pain complaint, the degree of functional disability, and mental health involvement.Among the most used are the Oswestry Disability Index (ODI), SF-36, Swiss Spinal Stenosis Questionnaire (SSS), and EQ-5D. 11,12he search for simpler and shorter questionnaires is feasible in previous studies without losing their psychometric characteristics. 13,14his study aims to correlate the four quality-of-life questionnaires described above in patients diagnosed with symptomatic lumbar stenosis undergoing conservative treatment and thus define whether it is possible to replace longer questionnaires with one that is simpler and easier to apply.

METHODS
A prospective cross-sectional study was carried out between April 2015 and November 2016 at the spine outpatient clinic of a quaternary university hospital.This study was approved by the Institutional Reviewed Board (IRB) CAAE 68085317.9.0000.5404,and all patients signed an informed consent form.
Patients with clinical and radiological diagnoses of lumbar stenosis, older than 18 years, without gender restriction, who agreed to participate in the study and signed the informed consent form, were included in the study.The following were excluded from the study: patients with a history of spinal surgery, tumor lesions in the spine, deformity greater than 45 degrees in the coronal plane of the spine, those who did not agree to participate in the study, and those with contraindication to magnetic resonance imaging.The patients were submitted to the application of the four quality of life questionnaires by the same orthopedist who was part of the spine group, trained, and with detailed knowledge of the instruments..The Oswestry Index (ODI) is a questionnaire that the patient can perform by interview or self-completed.It analyzes the levels of perceived disability in 10 items and assigns a subjective level score to each assessed function.It is easy to understand and encompasses a broad domain of pain, function, and health status limitation. 15he SF-36 consists of 36 items, encompassed in eight scales or components: functional capacity, physical aspects, pain, general health status, vitality, social aspects, emotional aspects, and mental health.These scales can still be grouped into two summarized measures, physical and mental health measures. 16he Swiss Spinal Stenosis Questionnaire (SSS) is specific to this pathology.Its characteristic is quantifying symptoms' severity, physical function characteristics, and patient satisfaction after treatment.It is designed to complement existing generic assessment measures. 17he EQ-5D is a health-related quality-of-life assessment instrument whose descriptive system consists of five dimensions -mobility, personal care, usual activities, pain/discomfort, and anxiety/ depression -with three levels of severity for each one.It aims to generate a non-specific and standardized instrument to describe and assess health-related quality of life measures. 18,19he data collected and used in the study were: the percentage of dysfunction found in the ODI, the physical (PCS) and mental (MCS) scores found in the SF-36, the symptom severity scales (painful and neuroischemic), and physical function found in the SSS, in addition to the score based on the EQ-5D questionnaire scores.Patient satisfaction was not used, as none had undergone surgical treatment.
Personal characteristics and quality of life scores were described using summary measures (mean, standard deviation, median, minimum, and maximum) or absolute and relative frequencies (Kirkwood  and Sterne, 2006). 20pearman correlations (Kirkwood and Sterne, 2006) were calculated between all quality-of-life scores. 20he analyzes were performed using the IBM-SPSS for Windows version 20.0 software, and the tables were prepared using the Microsoft Excel 2003 software.The tests were performed with a significance level of 5%.

RESULTS
Forty patients completed the study, 17 females (42.5%) and 23 males (57.5%).The mean age was 56.5 years.(Table 1) The Oswestry (ODI) had an average of 44.9.The SF-36 PCS presented an average of 29.9.The MCS had an average of 41.3.The Swiss Spinal Stenosis questionnaire and its subdivisions showed: SSS (symptoms) mean of 3.2; SSS (painful) mean of 3.62; SSS (neuroischemic) mean of 2.65; SSS (physical function) average of 2.6.The EQ-5D presented an average of 0.491.(Table 1) When the statistical analysis of possible correlations between the questionnaires was performed (Table 2), the ODI presented an absolute inverse correlation with the PCS of the SF-36 (r = 0.441), in addition to the EQ-5D, where it found an absolute relationship of 0.564.When correlated with the scores of the Swiss questionnaire, it presented a direct correlation with general symptoms and physical function, 0.443 and 0.577.All with p<0.05.
The SF-36 showed an inverse correlation with general symptoms, mechanical pain, and physical function when correlating PCS with SSS.However, the same correlation was not found with the EQ-5D.Mental health (MCS), on the other hand, showed a direct correlation with EQ-5D (r=0.549).
The Swiss questionnaire showed an inverse correlation with EQ-5D when general symptoms and mechanical pain were considered, in addition to physical function.It was also possible to observe this correlation with the SF-36 PCS.When the neuroischemic symptoms subgroup was evaluated alone, no direct or inverse correlation was found with any other questionnaire.
As previously shown in Table 2, the EQ-5D was the questionnaire that presented the best correlations with the other questionnaires, presenting a direct or inverse absolute relationship above 0.5.The exception was with the PCS subgroup of the SF-36 and the neuroischemic symptoms of the Swiss questionnaire.

DISCUSSION
Lumbar canal stenosis is a prevalent pathology in our population, especially in the elderly population, and generates great economic expenditure.It is one of the main causes of surgical treatment among spinal disorders in many countries. 21][25][26][27] For Higginson et al., to be clinically useful, an instrument that assesses the quality of life should be easy to understand and quick to respond to. 25,28he great challenge in creating quality-of-life assessment instruments with a small number of items is the difficulty in transforming them into multidimensional instruments.In addition, simplified instruments tend to have lower levels of reproducibility. 29On the other hand, studies suggest that short questionnaires have higher response rates (when sent to patients) and lower rates of unanswered items when compared to long questionnaires. 30,31][34] In our study, four questionnaires already established in the literature for evaluating spinal pathologies were used; the EQ-5D, the shortest and easiest to apply among these, correlated well with all the other questionnaires.Among all the questionnaires, it was the one that presented the best correlation with the others.One of the criteria in which no significant correlation was found was the symptomatology triggered by neuroischemic factors evaluated by the SSS, but when compared with the general symptomatology, the correlation was moderate.The other criterion that did not present a significant correlation was the PCS of the SF-36.Studies based on the evaluation and follow-up of patients with degenerative changes in the spine found moderate to low correlations between EQ-5D and SF-36 both in patients with conservative treatment and those undergoing surgical treatment. 35,36Conner-Spady et al. reported similar correlation coefficients at baseline for EQ-5D and SF-36. 37,38oon, it is possible that a surgeon's performance will not be evaluated by its clinical results but also by the economic value spent on the treatment. 10Thus, the idea is inserted that smaller questionnaires, in addition to not being a burden for the patient, would facilitate the operational logistics involved in health systems. 39he ODI questionnaire seeks to define the degree of incapacity of the patient due to the pathology studied, mainly considering physical changes for day-to-day activities. 15In this study, when compared with the SF-36 questionnaire, a moderate correlation was found with the PCS but very small with the MCS.Therefore, the physical changes were similar in the two questionnaires.As might be expected, mental function showed a low correlation, as the ODI does not present this projection.
Recently, Ko et al. (2016) found very similar results when they studied a population with low back pain undergoing surgical treatment. 40hen compared to the SSS, both symptoms and physical function also presented concordant results, leading to the understanding that the incapacity of these patients was directly related to their mechanical pain complaints and physical limitations imposed by lumbar stenosis.A moderate relationship was also found with the EQ-5D.
Our study also showed a moderate correlation between the SSS and the other questionnaires.General symptoms, mainly those related to mechanical pain, showed moderate correlations with all other questionnaires, and physical function did not correlate well with the MCS.
McDonough et al. (2005) believe that all questionnaires measure the quality of life to some degree but do not provide enough information to guide the selection of one instrument over another.When there is no clear superior method, the practical and design aspects of the questionnaires may indicate which tool would be more suitable for measuring the quality of life of people with lumbar stenosis. 35ble 2. Correlation between scores on quality-of-life questionnaires.