Study Design.
Observational study.
Objective.
To identify associations between preoperative symptom duration and postoperative patient satisfaction.
Summary of Background Data.
Sciatica due to lumbar disk herniation (LDH) is a cause of disability and reduced quality life. Patients with severe pain and disability or were recovery is unacceptably slow, surgical intervention can be advised. For these patients, evidence-based recommendations on the timing of the surgical intervention needs to be established.
Methods.
All patients who underwent discectomy at a Spine Centre, due to radicular pain from June 2010 to May 2019 were included. Pre- and postoperative data including demographic data, smoking, consumption of pain medication, comorbidity, back and leg-pain, health-related quality of life as measured by EQ-5D, ODI, previous spine surgery, sick leave, and duration of back and leg-pain before surgery were utilized. The patients were divided into four groups based on their self-reported duration of leg-pain before surgery. To minimize baseline differences between the groups, propensity-score matching was employed in a 1:1 fashion, balancing the groups on all reported preoperative factors.
Results.
Of 1607 patients undergoing lumbar discectomy, four matched cohorts based on their self-reported duration of leg-pain before surgery were created. Each cohort consisted of 150 patients well balanced on preoperative factors. Overall 62.7% of the patients were satisfied with the surgical result ranging from 74.0% in the <3 months group to 48.7% in the >24 months group (P<0.000). The portion of patients achieving a minimum clinically important difference for EQ-5D decreased from 77.4% with early intervention to 55.6% in the late group (P<0.000). The number of surgical complications were not affected by the duration of preoperative leg-pain.
Conclusion.
We found significant difference in patient satisfaction and health-related quality of life in patients related to the duration of preoperative leg-pain due to symptomatic LDH.
Level of Evidence.
3.
Key words: lumbar disk herniation, discectomy, postoperative complications, sciatica, patient satisfaction, propensity match, DaneSpine
Sciatica due to lumbar herniated disk (LDH) is a frequent cause of disability and reduced quality life.1 In general, the natural history of sciatica is favorable with spontaneous remission in the majority of patients.2 Surgical intervention in the form of a decompression or discectomy is clearly indicated in the presence of a neurologic deficit. However, in patients with severe pain and disability or in patients whom recovery is unacceptably slow, surgical intervention can also be recommended.3–6 For these patients, in whom there is no clear-cut surgical indication, evidence-based recommendations on the timing of the surgical intervention have not been established.
The NASS Evidence-Based Clinical Guidelines Committee raised the question regarding optimal timing for surgical intervention in 2012 when they published the Clinical Guidelines for Multidisciplinary Spine Care: “Diagnosis and Treatment of Lumbar Disc Herniation with Radiculopathy”. https://www.spine.org/Portals/0/Assets/Downloads/ResearchClinicalCare/Guidelines/LumbarDiscHerniation.pdf. As there was no literature specifically addressing the question, they made their recommendations based on four available papers addressing the issue of surgical timing.7–10 The committee suggests surgical intervention within six months if the patients’ symptoms are severe enough to warrant surgery. In general, the committee concluded that surgery within one year of symptoms is associated with faster recovery and improved long-term outcomes. Since the publication of the NASS guideline several publications have addressed the timing of surgical intervention.11–13 In a systematic review published in 2015 by Schoenfeld and Bono,11 they conclude “A possible point beyond which outcomes may be compromised is six months after symptom onset”. Siccoli et al.13 suggested reducing the maximum time to surgery down to between 14 to 22 weeks.
The ideal method to determine the optimal timing of surgical intervention of symptomatic LDH would be to perform a randomized study in which patients are assigned surgery at different time points. A similar design has been attempted to reveal whether surgical intervention of LDH was better than non-surgical treatment14,15 but the large group of patients choosing to cross over from the assigned groups complicated the interpretation of these results. Furthermore, there is an ethical problem in conducting a trial where some patients with severe pain are expected to wait for a long time to be treated.
The purpose of this study is to evaluate if the time to surgery is associated with postoperative patient satisfaction, health-related quality of life, leg and back pain, complications, and reoperations following surgery for LDH using propensity-matched cohorts.
MATERIALS AND METHODS
This study utilizes prospectively collected data from DaneSpine - the Danish national surgical spine database.http://drks.ortopaedi.dk/danespine/ DaneSpine collects patient reported outcome measures (PROMs) using pre- and postoperative questionnaires and surgical data collected postoperatively.
The preoperative data are entirely patient reported. This includes age, gender, height, weight, smoking, use pain medication, comorbidities, back and leg pain on a 0-100 VAS scale,16 health-related quality of life as measured by EuroQOL-5D (EQ. 5D-3L),17 low-back-related disability as measured by the Oswestry Disability Index (ODI),18,19 previous spine surgery, sick leave, and duration of back and leg pain before surgery. At one-year follow-up, patients are asked about their satisfaction with the results of their surgery. Data are collected as categorical values with the options: satisfied, neither satisfied or dissatisfied and dissatisfied.
The surgical data are completed by the surgeon immediately after the procedure and include diagnosis, procedure and occurrence of surgical complications such as dural tears and neural lesions. Further data on any reoperations due to postoperative hematomas, infections or re-herniation at the index or other levels are likewise recorded on follow-up visits.
All patients who underwent lumbar discectomy at a single Danish Spine Centre, due to radicular pain from June 1, 2010, to May 31, 2019, were included. None of the patients had cauda equina syndrome or major neurologic deficits at the time of surgery. All patients had a magnetic resonance imaging that demonstrated lumbar disk herniation concordant with their clinical symptoms. Patients who had a concomitant lumbar fusion were excluded from this study.
The patients were divided into four groups based on their self-reported duration of leg pain before surgery. Duration of symptoms are collected as categorical values of <3 months, 3 to <12 months, 12 to 24 months and >24 months. To minimize baseline differences between the groups, propensity-score matching was employed in a 1:1 fashion, balancing the groups on all preoperative factors. Propensity-score matching was performed in R version 4.0.2 with the package MatchIt.20–22 To create propensity-matched cohorts, a propensity score is calculated for each individual patient in each cohort using binary logistic regression.23 The propensity score is the probability of an individual patient being in the experimental cohort (in this case the cohort with the smallest sample size) given the patients’ baseline characteristics. In this study, the cohorts were propensity-matched based on patient demographics, preoperative back and leg pain, health-related quality of life as measured by EQ-5D and ODI, previous spine surgery, and sick leave. These factors have been previously shown to be associated with outcome after spine surgery.24–26 Patients in each cohort with the closest propensity score to each other were selected using closest neighbor matching. Thus, even if the cases in each cohort are not matched on an individual to individual basis, the overall baseline characteristics of the cohorts are similar and comparable.
All subsequent statistical analysis was done in IBM SPSS Statistics release 25.0.0.2 (IBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp.). Categorical data are presented by frequencies and related percentages; continuous data are displayed by means of descriptive statistics (mean, confidence interval, number of observations). Continuous variables were analyzed for significant difference among the four groups using Analysis of Variance (ANOVA), categorical variables using Fisher’s exact test. Significance level was set at P-value<0.01.
RESULTS
From a total number of 4064 patients registered in DaneSpine operated at a single regional spine center 1607 patients were identified as having undergone lumbar discectomy with complete preoperative, surgical and one-year follow-up data (Figure 1). After stratifying the entire cohort according to the duration of leg-pain, we found no difference in the four groups regarding gender, BMI, number of smokers, consumption of pain medication, SF36 MCS or intensity of leg pain (Table 1). However, mean back pain was higher, and the number of patients with prior surgeries were higher in the cohort with the longest duration of symptoms (Table 2).
Figure 1.
Flow diagram delineating the distribution of patients into the study-specific cohorts. Initial data.
TABLE 1.
Preoperative Characteristics of Subgroups Before Propensity Match
| Duration of preoperative leg pain | <3 mo n=486 | 3–<12 mo n=796 | 12–24 mo n=157 | >24 mo n=158 | P |
|---|---|---|---|---|---|
| Age, mean (SD) | 46.9±11.7 | 45.8±12. 5 | 44.7±12.2 | 44.0±12.1 | 0.038 |
| Sex (male), n (%) | 267 (54.9) | 407 (51.1) | 77 (48.4) | 90 (57.0) | 0.254 |
| BMI | 25.6±4.9 | 26.8±4.8 | 26.3±4.3 | 27.0±4.7 | 0.453 |
| Smokers, n (%) | 127 (26.1) | 253 (31.8) | 44 (28.3) | 57 (36.1) | 0.052 |
| Pain medication, n (%) | 486 (100) | 796 (100) | 157 (100) | 158 (100) | 1.000 |
| Comorbidity, n (%) | |||||
| Hearth disease | 3 (0.6) | 9 (1.1) | 2 (1.3) | 0 (0) | 0.449 |
| Neurological disease | 5 (1,0) | 13 (1.6) | 2 (1.3) | 9 (5.7) | 0.001 |
| Cancer | 3 (0.6) | 8 (1.0) | 0 (0) | 0 (0) | 0.336 |
| Leg pain, mean (SD) | 71.1±22.7 | 68.9±21.6 | 69.5±21.3 | 72.6±21.8 | 0.135 |
| Back pain, mean (SD) | 45.0±29.1 | 48,2±28.5 | 53.1±26.8 | 60.2±26.7 | >0.00 |
| EQ-5D, mean (SD) | 0.21±0.35 | 0.33±0.32 | 0.35±0.31 | 0.24±0.33 | >0.00 |
| ODI, mean (SD) | 54.7±19.3 | 47.1±16.2 | 45.1±15.7 | 50.2±16.5 | >0.00 |
| SF36 MCS | 42.7±13.1 | 43.1±12.7 | 40.7±13.1 | 41.3±13.2 | 0.091 |
| Previous spine surgery, n (%) | 58 (11.9) | 58 (15.7) | 37 (23.6) | 53 (33.5) | >0.00 |
| Sick leave, n (%) | 399 (82.1) | 566 (71.1) | 112 (71.3) | 102 (64.6) | >0.00 |
TABLE 2.
Postoperative Satisfaction of Surgical Outcome, Surgical Complications and Reoperation Rates Before Propensity Match
| Duration of preoperative leg ain | <3 months | 3–<12 months | 12–24 months | >24 months | P |
|---|---|---|---|---|---|
| Satisfaction with outcome, n (%) | >0.00 | ||||
| Satisfied | 356 (73,3) | 507 (71.6) | 93 (59.2) | 76 (48.1) | |
| Neither nor | 106 (21.8) | 151 (19.0) | 46 (29.3) | 48 (30.4) | |
| Dissatisfied | 24 (4.9) | 75 (9.4) | 18 (11.5) | 34 (21.5) | |
| Surgical complications, n (%) | |||||
| Dural tear | 15 (3.1) | 22 (3.3) | 3 (1.9) | 6 (3.8) | 0.773 |
| Hematoma | 2 (0.4) | 4 (0.5) | 2 (1.3) | 1 (0.6) | 0.641 |
| Infection | 0 (0) | 1 (0.13) | 0 (0) | 0 (0) | 0.800 |
| Nerve root lesions | 0 (0) | 3 (0.38) | 0 (0) | 0 (0) | 0.388 |
| Cauda equina | 1 (0.21) | 1 (0.13) | 0 (0) | 0 (0) | 0.886 |
| Reoperations, n (%) | |||||
| During primary admission | 8 (1.6) | 13 (1.6) | 6 (3.8) | 1 (0.6) | 0.287 |
| Within 12 months postop. | 10 (6.7) | 12 (8.0) | 18 (12.0) | 13 (8.7) | 0.421 |
The post-matched sample included 150 patients in each cohort and was well balanced on preoperative factors such as age, gender, BMI, smoking, pain medication, comorbidities, leg and back pain, health-related quality of life, previous spine surgery, and sick leave (Table 3).
TABLE 3.
Preoperative Characteristics of Subgroups after Propensity Match
| Duration of preoperative leg pain | <3 mo n=150 | 3–<12 mo n=150 | 12–24 mo n=150 | >24 mo n=150 | P |
|---|---|---|---|---|---|
| Age, mean (SD) | 46.4±11.9 | 44.3±13.8 | 44.8±12.3 | 43.9±12.3 | 0.346 |
| Sex (male), n (%) | 80 (53.9) | 77 (51.3) | 72 (48.0) | 85 (56.7) | 0.501 |
| BMI mean (SD) | 27.1±8.3 | 26.6±5.2 | 26.4±4.3 | 27.0±4.7 | 0.644 |
| Smokers, n (%) | 45 (30.0) | 50 (33.3) | 44 (29.3) | 53 (35.2) | 0.654 |
| Pain medication, n (%) | 150 (100) | 150 (100) | 150 (100) | 150 (100) | 1.000 |
| Comorbidity, n (%) | |||||
| Hearth disease | 1 (0.7) | 0 (0) | 2 (1.3) | 0 (0) | 0.623 |
| Neurological disease | 3 (2) | 7 (4.7) | 2 (1.3) | 5 (3.3) | 0.354 |
| Cancer | 1 (0.7) | 0 (0) | 0 (0) | 0 (0) | 1.000 |
| Leg pain, mean (SD) | 69.8±21.6 | 71.3±20.8 | 69.2±21.5 | 71.7±21.8 | 0.715 |
| Back pain, mean (SD) | 51.7±28.4 | 54.0±28.9 | 53.4±26.8 | 60.1±26.8 | 0.050 |
| EQ-5D, mean (SD) | 0.27±0.33 | 0.28±0.32 | 0.35±0.31 | 0.26±0.32 | 0.071 |
| ODI, mean (SD) | 50.3±18.8 | 48.2±16.6 | 45.3±15.8 | 48.7±15.4 | 0.078 |
| SF36 MCS, mean (SD) | 42.7±13.9 | 42.7±12.5 | 41.1±12.4 | 41.7±12.8 | 0.641 |
| Previous spine surgery, n (%) | 33 (22.0) | 42 (28.0) | 35 (23.3) | 48 (32.0) | 0.188 |
| Sick leave, n (%) | 114 (76.0) | 98 (65.3) | 106 (70.7) | 91 (60.7) | 0.058 |
There was significant difference between the groups in patient satisfaction at one year follow-up (Table 4) and the percentage of patients achieving a clinically important difference in regard to disability, pain scores, and health-related quality of life (Table 5). Intraoperative data showed no difference in number of dural tears, hematomas or major neurological injuries (Table 4).
TABLE 4.
Postoperative Satisfaction of Surgical Outcome, Surgical Complications, and Reoperation Rates
| Duration of preoperative leg pain | <3 mo | 3–<12 mo | 12–24 mo | >24 mo | P |
|---|---|---|---|---|---|
| Satisfaction with outcome, n (%) | >0.000 | ||||
| Satisfied | 111 (74.0) | 104 (69.3) | 88 (58.7) | 73 (48.7) | |
| Neither nor | 32 (21.3) | 28 (18.7) | 45 (30.0) | 44 (29.3) | |
| Dissatisfied | 7 (4.7) | 18 (12.0) | 17 (11.3) | 33 (22.0) | |
| Surgical complications, n (%) | |||||
| Dural tear | 6 (4.0) | 5 (3.3) | 3 (2.0) | 5 (3.3) | 0.844 |
| Hematoma | 1 (0.7) | 0 (0) | 2 (1.3) | 0 (0) | 0.623 |
| Infection | 0 (0) | 0 (0) | 0 (0) | 0 (0) | n/a |
| Nerve root lesions | 0 (0) | 2 (1.3) | 0 (0) | 0 (0) | 0.249 |
| Cauda equina | 0 (0) | 0 (0) | 0 (0) | 0 (0) | n/a |
| Reoperations, n (%) | |||||
| During primary admission | 1 (0.7) | 4 (2.7) | 6 (4.0) | 1 (0.7) | 0.124 |
| Within 12 months postop. | 10 (6.7) | 12 (8.0) | 18 (12.0) | 13 (8.7) | 0.421 |
TABLE 5.
Postoperative Outcome and Achievement of MCID
| Duration of preoperative leg pain | <3 mo | 3–<12 mo | 12–24 mo | >24 mo | P |
|---|---|---|---|---|---|
| EQ-5D Δ, SD (n) | 0.478±0.364 (146) | 0.389±0.394 (145) | 0.247±0.411 (143) | 0.286±0.398 (144) | 0.000 |
| Oswestry Index Δ, SD (n) | −30.1±20.1 (140) | −25.8±20.3 (137) | −17.2±21.7 (138) | −16.5±19.2 (143) | 0.000 |
| Leg pain VAS Δ, SD (n) | −45.1±32.3 (149) | −44.3±34.2 (148) | −33.7±34.0 (150) | −28.9±34.9 (150) | 0.000 |
| Back pain VAS Δ, SD (n) | −28.8±29.7 (149) | −22,4±32.7 (148) | −15.1±31.0 (150) | −17.6±30.8 (150) | 0.01 |
| % achieving MCID | |||||
| EQ-5D MCID, n (%) | 113 (77.4) | 101 (69.7) | 75 (52.4) | 80 (55.6) | 0.000 |
| Oswestry Index MCID, n (%) | 105 (75.0) | 96 (70.1) | 73 (52.9) | 71 (49.7) | 0.000 |
| Leg pain VAS MCID, n (%) | 118 (79.2) | 107 (72.3) | 98 (65.3) | 90 (60.0) | 0.002 |
| Back pain VAS MCID, n (%) | 98 (65.8) | 83 (56.1) | 61 (40.7) | 74 (49.3) | 0.000 |
DISCUSSION
The main goal of discectomy is to decompress the neural structures to relieve leg pain and improve function. This registry-based study was designed to investigate the possible association between the preoperative duration of leg pain and one-year postoperative patient satisfaction and PROM. After propensity-score matching for preoperative factors, surgery before three months duration of radiculopathy resulted in higher patient satisfaction and a higher percentage of patients achieving a minimal clinically important difference in both pain scores and health-related quality of life scores. Surgical complications and reoperation rates were unaffected of the preoperative duration of leg pain.
These findings are aligned with previous published studies showing a beneficial treatment effect of early surgical intervention when treating LDH patients. Nygaard et al 9 published a prospective study of 132 consecutive patients where the results indicated that leg pain lasting more than eight months correlates with an unfavorable postoperative outcome. In a study of 113 consecutive patients, Ng LCL and Sell P8 found a significant association between the duration of radiculopathy and the changes in ODI with less favorable outcome in patients with symptom duration for more than 12 months.8 In a post hoc analysis of SPORT (Spine Patient Outcomes Research Trial) data, a symptom duration of six months or more was associated with a worse outcome than a shorter duration after surgical treatment.27 In a large register based study of 1694 patients by Støttrup et al 12 reported discectomy within the first three months of leg pain achieved significantly better outcome one year after surgery.
The strengths of this study is the use of propensity-score matching in order to decrease the risk of bias in an observational nonrandomized cohort. By matching the cohort on known relevant variables of importance to the outcome, the risk of unknown biases, although not completely eliminated, is reduced.
The current study is not without limitations. Registry-based studies allow for large sample sizes but has a higher risk of incomplete data gathering compared to clinical trials. Data from this prospective registry study rely on patient reported data with the risk of recall bias when recording the duration of symptoms. Further, the preoperative data rely different physicians with the risk of bias in recording complications, but it reflects daily life production from a database with more than 99% preoperative data collection and minimum one-year follow-up of more than 83%. The baseline characteristics in the present cohort differs from all the LDH patients enrolled in DaneSpine http://drks.ortopaedi.dk/danespine/ as the cases were propensity matched mainly to the cohort with the longest symptoms as they had the smallest sample size. Thus only 30% of the less than three-month cohort and 20% of the 3- to 12-month cohort were included in the current analysis.
Despite the results of this study, patients with a history of more than one year of leg pain due to LDH should not be deprived of the option of discectomy but should be informed of the inferior results with only around 50% of the patients achieving a minimal important clinical difference.
Key Points
Overall 62.7% of the patients were satisfied with the surgical result ranging from 74.0% in the <3 months group to 48.7% in the >24 months group (P<0.000).
The proportion of patients achieving a minimum clinically important difference for EQ-5D decreased from 77.4% with early intervention to 55.6% in the late group.
We found significant difference in patient satisfaction and health-related quality of life in patients related to the duration of preoperative leg-pain due to symptomatic LDH. Surgery before three months duration of radiculopathy resulted in higher patient satisfaction.
Footnotes
Data use approval was acquired from the Danish Data Protection Agency ref nr: 16/1586.
The study was reviewed and approved by the Research Board of the Center for Spine Surgery and Research at Lillebaelt Hospital. Subjects provided consent for use of their data at the time patients completed the questionnaires and were enrolled in DaneSpine.
No funding obtained from: National Institutes of Health (NIH); Wellcome Trust; Howard Hughes Medical Institute (HHMI); and other(s).
The authors report no conflicts of interest.
Contributor Information
Mikkel Ø Andersen, Email: Mikkel@dadlnet.dk.
Andreas Killerich Andresen, Email: Andreas.Duch.Kiilerich.Andresen@rsyd.dk.
Leah Y. Carreon, Email: Leah.Carreon@rsyd.dk.
Casper Friis Pedersen, Email: Casper.Friis.Pedersen@rsyd.dk.
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