TIME BEFORE SURGERY VS RECOVERY OF LUMBAR HERNIATION. CHILEAN REALITY IN THE PUBLIC HEALTH SYSTEM

Objective: To evaluate the influence between the time elapsed since the onset of symptoms and the surgery of lumbar HNP in the final functional recovery of the comprehensive treatment of patients. Methods: Retrospective descriptive study of cases of HNP treated by lumbar discectomy between 2009 and 2015 by the spine team of the Hospital San José, using SPSS (version 22 of IBM) for the statistical analysis. Results: Of 110 patients subject to surgery, 54 were recruited (22 women and 32 men), between 18 and 75 years old, with an average age of 43 years. Eighty percent of patients are active workers, 76% without comorbidities. The predominant level affected was L4/L5 with 52% of the cases. The mean progression time of the symptoms before the first consultation was 27 months, the waiting time between the consultation and the surgery was 5.6 months. Conclusions: Eighty-six percent of the patients -presented good results in VAS. The Oswestry questionnaire reached a positive result in 90%, a minimum disability in 40%, moderate in 50% and maximum in 10%. No statistical relationship was achieved between any of the evaluated variables and the outcome of the surgery. Level of Evidence IV; Therapeutic Study - Investigation of Treatment Results. de evolución promedio de la sintomatología antes de la primera consulta fue 27 meses, el tiempo de espera entre la consulta y la resolución quirúrgica, fue 5,6 meses. Conclusiones: Ochenta y seis por ciento de los pacientes presentaron resultados positivos en EVA. El cuestionario Oswestry obtuvo un resultado positivo en 90%, discapacidad mínima en 40%, moderada en 50% y máxima en 10%. No se logró establecer relación estadística entre ninguna de las variables evaluadas y el resultado final de la cirugía. Nivel de Evidencia IV; Estudio terapéutico – Investigación de los resultados de tratamiento. Descriptores: Discectomía; Calidad de Vida; Evaluación de Resultado; Salud Pública.


INTRODUCTION
Sciatalgia due to herniation of the nucleus pulposus of the intervertebral disc is one of the most common symptoms of spinal disease. The lifetime and annual incidence range from 13 to 40% and 1 to 5%, respectively, 1,2 with herniation of the nucleus pulposus being the most common indication for spine surgery. 3 The natural course is usually favorable. 4 According to Anderson et al., 5 surgery is recommended for severe, constant, incapacitating pain that does not respond to conservative treatment and for severe and progressive neurological deficit. 6,7 Since the first lumbar discectomy in 1933, 8 it has become a widely accepted intervention for radiculopathy resulting from acute herniation of the lumbar intervertebral disc. 8,9 Even though today there are new techniques, the main principle of the procedure remains unchanged with respect to that proposed by Mixter and Barr: 8 elimination of the compressive and irritating disc material in the vicinity of the affected nerve root. 10 The advantages of surgical intervention and its efficacy as compared to non-surgical intervention have been highlighted in various publications. 9,11 However, to date there is no conclusive information as to whether the moment of surgery and the duration of symptoms prior to the surgery have a prejudicial impact on the postoperative results. 10,12,13 The studies by Hurme et al. 14 and Nygaard et al. 15 maintain that an increase in the duration of the symptoms decreases the success of the outcome following lumbar discectomy. However, more recently, Suzuki et al., 16 did not observe any association between the moment of the surgical intervention and the postoperative outcome. In their 2014 systematic review, Schoenfeld et al. concluded that the duration of symptoms quite probably has an adverse effect on pain and functional recovery following lumbar discectomy, with a possible cutoff at 6 months following the onset of symptoms. 17 At the same time, Sabnis et al. added that the time with symptomatology alone should not be the basis for a recommendation of surgery, given that there are other variables that negatively affect the outcome, such as social factors (long-standing medical leave, low educational level, single or divorced status), biological (more than 40 years of age) factors, etc. 18 Due to the inconsistent results in the available literature regarding a correlation between duration of symptoms and clinical outcome and to the absence of national studies of this type, we decided to evaluate patients who underwent lumbar discectomy at the Complejo Hospitalario San José (CHSJ). Our hypothesis is that there is a relationship between the time waiting for surgical resolution and the outcome of surgeries for herniation of the nucleus pulposus.

METHODS
This retrospective descriptive study was conducted at CHSJ, a public hospital located in the Northern area of the Metropolitan Region of Santiago, Chile.
Prior to launching the study, approval was obtained from the Institutional Review Board of the Servicio de Salud Metropolitano Norte (CARTA AE Nº 045/2016). In the study, we considered ethical aspects such as the safekeeping of patient identity, the informed consent of each patient, and all the information obtained for purposes related to this research, in compliance with Law 20.584 and the bioethics norms in force. Each patient was assigned a code to safeguard confidentiality and these codes were eliminated at the end of the investigation.
Probability convenience sampling was used to build our sample. The total universe of cases evaluated corresponded to men and women older than 15 years of age who were operated by the CHSJ Spine team for lumbar discectomy for HNP between 2009 and 2015. Patients with immediate surgical complications were excluded, yielding a total of 110 patients in the sample.
The data was collected in telephone interviews.
Using clinical records and surgical protocols, we identified variables such as sex, age, comorbidities, work activity, tobacco use, neurological deficit, and laterality, preoperative treatment received (epidural steroid injection and/or kinesiotherapy), the time transpired from the onset of symptoms to the first consultation in our center, and the time transpired until the final surgical resolution. The level of the herniation of the nucleus pulposus was defined by magnetic resonance of the lumbar spine.
The interviews were conducted in June and July of 2016.

Measurement tools
The Oswestry low back pain disability questionnaire 19 (Attachment 1) and the visual analog scale (VAS) 20 were applied.
We used descriptive statistical tools. The resulting data were tabulated and analyzed using SPSS software (version 22, IBM).

RESULTS
From the universe of 110 patients who underwent surgery during the study period, 54 (59.4%) were recruited for the study; 22 women and 32 men, or 41% and 59%, respectively, with an average age of 43 years for both sexes (ranging from 18 to 75 years of age). Figure 1 Cases, Age in years, Percentage Eighty percent (80%) of the patients were employed, 41% of whom had completed between 1 and 6 months of medical leave.
Regarding comorbidities encountered among the patients evaluated, 76% (41 cases) were healthy and of the remaining 24%, 16% (9 cases) presented high blood pressure as the only medical issue and 12% presented diabetes mellitus with or without insulin dependence and associated or not with high blood pressure. A total of 56% of the patients were active smokers.
In terms of the clinical data about the nucleus pulposus herniation, laterality had equal predominance, 50% right and 50% left. Forty percent (40%) of the patients had sensory and motor deficit, 34% with sensory deficit only, and 26% with motor deficit only. The predominant level (52% of cases) was between L4/L5, followed by L5/S1(40% of cases). Figure 2 Level, Percentage Only 21% (39 cases) of the patients were given corticosteroid infiltration prior to the surgery, while 54% (29 cases) received no type of kinetic therapy prior to surgery.
The average evolution time of the symptoms prior to the first consultation was 27 months (between 2.5 and 613 months) and the average wait time between the consultation and final surgical resolution was 5.6 months (0.5 -24 months).
Applying the VAS at the time of admission, 73% (39 cases) reported that this was the worst pain experienced in their lifetime (VAS 10), with an exit score of 3 in 26% (14 cases). The VAS results were divided into three groups, in which a score of 1 to 4 was considered a good outcome, 5 to 7 a fair outcome, and from 8 to 10 a poor outcome. Eighty-six percent (86%) of the respondents presented positive outcomes in the review (56% good, 30% fair, and 14% poor results).   When we applied the Oswestry low back pain disability questionnaire and grouped the results the same way, we obtained positive results in 90% of cases reviewed, with minimum disability in 40%, moderate in 50%, and maximum disability in 10%.
To assess the relationship between the previously described variables and the lumbar discectomy results, a series of linear regression analyses was performed in which each of the variables evaluated was treated as an independent variable and the surgical outcome was treated as a dependent variable.
By grouping the data and correlating them statistically, we were not able to establish a statistical association between any of the selected variables and the postoperative results. Table 1 The partial regression test correlating the surgical result and wait time obtained a dispersion for which no correlation could be confirmed. Similarly, when the ANOVA test with F-statistic was applied, the critical values were lower than expected (0.52).
When trying to calculate a correlation coefficient with the Spearman test, a Rho equal to 0.06 (p=0.65) was obtained, resulting in the rejection of the original hypothesis. Figure 3 DISCUSSION From the analysis of results obtained from the patients who underwent lumbar discectomy at the Complejo Hospitalario San José (CHSJ), it can be stated that the population served in Figures  1 and 2 is essentially identical to that described by international statistics, 21 which allows adequate which means that the population surveyed is a suitable representation and, therefore, validates the data collection method.
The average patient wait times prior to lumbar discectomy were less than 6 months during the last 6 years, complying fully with the ministerial requirements given in the National Health Ministry (MINSAL) clinical guidelines. 22 When we administered the VAS to the patients, the score improved from an average of 9 at the first control point to a score of 3 at the end (late postoperative control), reflecting satisfactory final outcomes in 90% of the cases at CHSJ.
In their 2014 systematic review, Schoenfeld et. al. pointed out that the duration of symptoms probably has an adverse effect on functional recovery following lumbar discectomy. However, in our study there was no evidence of a temporal correlation between wait times and the final surgical outcome in terms of patient satisfaction, not ruling out the influence that social and biological variables could have on the final results. 18 The foregoing shows that the timeframes described in the international literature 16 and in the MINSAL guidelines 22 are arbitrary and lacking in evidence-based medical fundamentals and are more related to periods of medical leave in the working population. The above is based on the direct correlation in 75% of the cases.
The results from both the VAS and OSWESTRY scales were similar and statistically significant (SD=1,518) (Figure 4), which would be interpreted as the capacity to represent disability related to the pathology, which is directly proportional to personally perceived pain.
The low number of useful cases for a review of the responses from patients who underwent lumbar discectomy for herniation of the nucleus pulposus is mainly due to the inadequacy of telephone records and patient follow-up in the SOME system in our hospital center and it is a weakness to be improved in the future.
The final satisfactory surgical results in our center are close to 90%, demonstrating the great resolution capacity for this pathology in a high-complexity public center.  L5-S1 L5-S1, L4-L5