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Primary Research

Duration of Symptoms Does Not Affect Clinical Outcome After Lumbar Arthrodesis

Sayari, Arash J. MD; Harada, Garrett K. MD; Basques, Bryce A. MD, MPH; Louie, Philip K. MD; Gandhi, Sapan D. MD; Banks, Landan BS; Sung, Audrey S. BS; Nolte, Michael T. MD; Gosse, Jessica BS; An, Howard S. MD

Author Information
doi: 10.1097/BSD.0000000000001045
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Abstract

Lumbar spinal stenosis and degenerative spondylolisthesis are the most common indications for lumbar spine surgery in patients older than 65 years of age.1 Specifically, lumbar fusion in cases of instability have demonstrated success in large studies at 4 and 8 years.2,3 However, costs and expenses of fusion have ballooned in the United States to more than $30 billion. This increase is partially attributed to accelerated rates of fusion surgeries since the Food and Drug Administration approval of interbody devices and other fusion-promoting implants.4,5 Further cost implications, advances in nonsurgical options, and suggestions for equivalent long-term outcomes to surgery has resulted in a push for exhaustion of nonsurgical treatment before consideration is made for operative intervention. These nonoperative options include nonsteroidal anti-inflammatory medications, activity modification, physiotherapy, and epidural steroid injections.6,7

Although there has been an abundance of literature demonstrating successful outcomes following lumbar fusion,8–11 there have not been adequate randomized controlled trials outlining appropriate nonsurgical protocols.6 The duration of which these nonsurgical modalities should be implemented is also a topic of debate, with suggestions made for 3, 6, and 12 months or more of nonoperative care.6,12–14

The time point at which surgical intervention may become less effective in alleviating lumbar symptoms has not been well established. Studies focused on operative and nonoperative treatment are necessary to aid in preoperative expectation management. The aim of the present study is to corroborate the duration of patient symptomatology with their clinical outcomes after posterolateral lumbar fusion.

MATERIALS AND METHODS

A retrospective cohort study was conducted which included consecutive patients who underwent primary elective open lumbar spinal fusion at a single institution from January 2014 to January 2018. Patients under 18 years of age at the time of surgery and those undergoing lumbar spinal fusion to treat fracture, tumor, or infection, and those undergoing revision lumbar spinal fusion were excluded from the study. Lastly, all patients had a required minimum of 12 months postoperative clinical follow-up.

Patient-specific and operative data were collected. Specifically, individual patient medical records were reviewed to identify when conservative treatment was initiated, which was set as “time zero.” The duration of symptoms was then calculated to be from “time zero” to the date of surgery. Similar to a prior subgroup analysis of the Spine Patients’ Outcome Research Trial (SPORT),10 patients with lumbar symptoms <12 months (DOS<12) were compared with those having symptoms for 12 months or longer (DOS12+) before their spinal fusion. Patient information included: baseline demographics, smoking status, history of psychiatric condition, preoperative opiate use, American Society of Anaesthesiologists physical status classification, spondylolisthesis type and grade, and history of prior lumbar surgery or fusion. Operative characteristics included: number of levels fused, interbody use, intraoperative neuromonitoring, operative time, and postoperative length of stay.

Preoperative and final postoperative visual analog scale (VAS)-back and VAS-leg pain, and Oswestry Disability Index (ODI) were collected. Preoperative, immediate postoperative (postoperative day 1–2), and final radiographs were assessed to measure lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), and the PI-LL difference was calculated. In addition, the rates of dural tears, postoperative complications, postdischarge destination, reoperation, achievement of minimally clinically important difference for VAS-back, VAS-leg, and ODI, and pseudarthrosis were determined. Minimally clinically important difference thresholds were as follows: ODI 14.9, VAS-back pain 2.1, VAS-leg pain 2.8, based on previous thresholds reported in the literature.15,16

Statistical Analysis

All statistical analysis was performed using Stata version 13.1 (StataCorp, College Station, TX). Baseline patient and operative characteristics were compared between symptom duration groups using Student t tests for continuous variables, and χ2 tests for categorical variables. Binary outcome variables were compared between groups with multivariate logistic regression, and continuous outcome variables were compared using multivariate linear regression. Multivariate analyses controlled for baseline patient and operative characteristics.

RESULTS

In total, 526 patients were reviewed and separated into 2 groups based on symptom duration. The DOS<12 group included 167 patients who had lumbar symptoms for <12 months, whereas the DOS12+ group included 359 patients who had lumbar symptoms for 12 months or longer. The average age was 61.8 years, average body mass index was 30.5, and there were 296 females (56.3%) and 230 males. Most patients had diagnoses of spinal stenosis (DOS<12: 91.6%; DOS12+: 87.0%) and degenerative spondylolisthesis at initial clinical presentation (DOS<12: 61.2%; DOS12+: 68.8%) and baseline analysis demonstrated similar demographic and operative characteristics between the 2 groups (Table 1).

TABLE 1 - Baseline Patient/Operative Characteristics
n (%)
Characteristic Pain<12 mo Pain≥12 mo All Patients P
Overall 167 359 526
Demographics
 Age, mean (SD) 62.93 (11.52) 61.29 (12.21) 61.81 (12.21) 0.143
 Body mass index, mean (SD) 31.03 (5.95) 30.27 (5.91) 30.52 (5.91) 0.183
 Female sex 92 (55.09) 204 (56.82) 296 (56.27) 0.709
 Diabetes mellitus 13 (7.78) 38 (10.58) 51 (9.7) 0.312
 Current smoker 16 (9.58) 41 (11.61) 57 (10.96) 0.488
 History of psychiatric condition 20 (11.98) 36 (10.20) 56 (10.77) 0.541
 Preoperative opiate use 52 (31.14) 102 (28.90) 154 (29.62) 0.601
 ASA≥3 76 (45.51) 147 (40.95) 223 (42.40) 0.324
Spondylolisthesis
 Grade 1 93 (55.69) 223 (62.12) 316 (60.08) 0.161
 Grade 2 9 (5.39) 24 (6.69) 33 (6.27) 0.568
 Isthmic 11 (6.59) 31 (9.01) 42 (5.90) 0.456
Degenerative disc disease 41 (25.15) 73 (21.6) 114 (22.44) 0.314
Spinal stenosis 153 (91.62) 309 (87.04) 462 (88.51) 0.126
Operative characteristics
 1 level fusion 108 (64.67) 226 (62.95) 334 (63.50) 0.703
 2 level fusion 50 (29.94) 105 (29.25) 155 (29.45) 0.871
 3 or more level fusion 9 (5.39) 28 (7.80) 37 (7.03) 0.314
 Neuromonitoring used 134 (81.71) 303 (86.08) 437 (84.69) 0.199
ASA indicates American Society of Anesthesiologists; Pct, percent; SD, standard deviation.

On radiographic analysis, preoperative, immediate postoperative, and final LL, PT, PI, and PI-LL difference were similar between the 2 groups (Tables 2, 3). Likewise, the patient-reported outcomes were also similar between the 2 groups. Postoperatively, both groups experienced a similar improvement in VAS-back, VAS-leg, and ODI scores (Tables 4, 5).

TABLE 2 - Radiographic Measurements Stratified by Symptom Duration
Factor Pain<12 mo Mean (SD) Pain≥12 mo Mean (SD) All Patients Mean (SD)
Preoperative
 Lumbar lordosis −48.91 (15.18) −49.17 (15.24) −49.10 (15.21)
 Pelvic tilt 23.67 (13.59) 24.55 (13.25) 24.32 (13.33)
 Pelvic incidence 54.91 (18.17) 55.01 (16.34) 54.98 (16.82)
 PI-LL difference 6.51 (16.28) 5.68 (15.17) 5.90 (15.46)
Postoperative
 Lumbar lordosis −47.14 (15.44) −46.07 (15.94) −46.36 (15.80)
 Pelvic tilt 24.13 (11.50) 26.24 (12.45) 25.69 (12.23)
 Pelvic incidence 55.31 (18.66) 56.09 (14.32) 55.89 (15.54)
 PI-LL difference 7.85 (20.25) 9.90 (18.30) 9.37 (18.82)
Final
 Lumbar lordosis −49.54 (15.15) −47.35 (19.40) −47.95 (18.36)
 Pelvic tilt 23.55 (15.82) 25.58 (13.18) 25.07 (13.89)
 Pelvic incidence 54.89 (17.50) 55.23 (18.44) 55.15 (18.19)
 PI-LL difference 6.07 (17.04) 6.98 (22.26) 6.75 (21.07)
Change preoperative to postoperative
 Lumbar lordosis 1.77 (8.48) 3.11 (12.37) 2.75 (11.45)
 Pelvic tilt 1.90 (6.43) 2.09 (7.51) 2.04 (7.23)
 Pelvic incidence −1.00 (16.65) 0.37 (7.65) 0.01 (10.74)
 PI-LL difference −0.50 (18.40) 3.43 (11.09) 2.41 (13.46)
Change postoperative to final
 Lumbar lordosis 0.52 (8.87) 1.83 (15.95) 1.47 (14.37)
 Pelvic tilt 0.09 (11.38) 1.12 (7.88) 0.86 (8.88)
 Pelvic incidence −0.14 (8.49) −0.33 (13.43) −0.28 (12.36)
 PI-LL difference 0.47 (11.35) 0.65 (18.03) 0.60 (16.57)
Change preoperative to final
 Lumbar lordosis −2.08 (10.17) −1.21 (16.84) −1.45 (15.33)
 Pelvic tilt −2.17 (9.92) −1.28 (6.64) −1.49 (7.55)
 Pelvic incidence 0.75 (16.15) −0.96 (12.14) −0.55 (13.21)
 PI-LL difference −1.52 (20.26) −1.57 (20.00) −1.56 (20.03)
Operative time (min) 180.93 (67.61) 192.22 (71.85) 188.93 (70.78)
Postoperative length of stay (d) 3.62 (1.77) 3.49 (1.59) 3.53 (1.64)
PI-LL indicates pelvic incidence-lumbar lordosis; SD, standard deviation.

TABLE 3 - Multivariate Linear Regression Models for Radiographic Measurements
Radiographic Measurements
LL Pelvic Tilt PI PI-LL Difference
Factor β 95% CI P β 95% CI P β 95% CI P β 95% CI P
Preoperative
 Age 0.07 −0.10 to 0.25 0.407 0.10 −0.11 to 0.30 0.352 0.06 −0.18 to 0.30 0.615 0.18 −0.03 to 0.40 0.098
 BMI −0.01 −0.48 to 0.22 0.455 0.35 −0.04 to 0.74 0.082 0.54 0.07–1.00 0.023 0.26 −0.16 to 0.69 0.225
 Female −2.29 −6.15 to 1.57 0.243 2.47 −1.82 to 6.75 0.257 1.63 −3.43 to 6.70 0.526 −0.41 −5.08 to 4.27 0.864
 Diabetes 7.42 1.24–13.60 0.019 0.97 −6.42 to 8.36 0.797 4.56 −4.18 to 13.31 0.305 9.79 1.79–17.79 0.017
 Psychiatric history −3.42 −9.48 to 2.63 0.266 1.30 −5.44 to 8.04 0.704 −3.11 −11.08 to 4.86 0.442 −3.80 −11.08 to 3.48 0.305
 Opioid use −3.14 −7.71 to 1.43 0.177 −1.32 −6.26 to 3.63 0.600 3.30 −2.55 to 9.15 0.267 0.05 −5.30 to 5.39 0.986
 ASA≥3 3.48 −0.89 to 7.85 0.118 −0.72 −5.62 to 4.17 0.771 −2.49 −8.29 to 3.30 0.397 1.03 −4.31 to 6.37 0.704
 Prior surgery 2.46 −2.04 to 6.95 0.283 2.05 −2.89 to 7.00 0.413 −4.13 −9.98 to 1.72 0.165 −0.10 −5.50 to 5.29 0.970
 2 levels fused 3.06 −0.98 to 7.09 0.137 1.70 −2.76 to 6.16 0.454 −0.69 −5.96 to 4.59 0.798 3.99 −0.86 to 8.83 0.106
 3+ levels fused 6.24 −1.34 to 13.82 0.106 4.44 −5.09 to 13.97 0.359 −1.18 −12.46 to 10.09 0.836 −2.19 −12.89 to 8.51 0.687
 Neuromonitor use 4.19 −0.83 to 9.21 0.102 6.32 0.56–12.08 0.032 −7.23 14.05 to0.41 0.038 −4.08 −10.40 to 2.23 0.204
 Pain≥12 mo 1.59 −2.44 to 5.62 0.437 0.65 −3.90 to 5.21 0.777 0.41 −4.98 to 5.80 0.881 0.26 −4.69 to 5.20 0.919
Postoperative
 Age 0.08 −0.08 to 0.24 0.340 0.14 −0.04 to 0.32 0.118 0.09 −0.11 to 0.28 0.376 0.14 −0.09 to 0.36 0.230
 BMI −0.02 −0.34 to 0.31 0.926 0.15 −0.18 to 0.49 0.374 0.42 0.050.80 0.025 0.29 −0.14 to 0.72 0.180
 Female −0.96 −4.49 to 2.58 0.595 1.44 −2.31 to 5.19 0.451 2.23 −1.90 to 6.37 0.287 1.07 −3.69 to 5.83 0.658
 Diabetes 4.96 −0.82 to 10.74 0.093 −0.29 −6.22 to 5.64 0.921 1.74 −4.78 to 8.27 0.599 5.53 −1.96 to 13.02 0.147
 Psychiatric history −2.95 −8.58 to 2.67 0.302 −2.20 −8.53 to 4.12 0.493 −2.37 −9.33 to 4.59 0.502 −4.03 −12.03 to 3.98 0.323
 Opioid use −1.21 −5.31 to 2.89 0.562 −2.08 −6.48 to 2.31 0.351 3.67 −1.16 to 8.51 0.136 1.39 −4.20 to 6.97 0.625
 ASA≥3 −0.01 −4.00 to 3.98 0.996 2.14 −2.12 to 6.41 0.323 −4.09 −8.78 to 0.61 0.088 −4.47 −9.89 to 0.95 0.106
 Prior surgery 1.23 −2.98 to 5.44 0.565 0.28 −4.47 to 5.02 0.909 −0.11 −5.33 to 5.11 0.967 −1.08 −7.10 to 4.94 0.724
 2 levels fused 3.10 −0.64 to 6.83 0.104 −0.51 −4.52 to 3.50 0.802 −0.11 −4.51 to 4.30 0.962 3.78 −1.31 to 8.86 0.144
 3+ levels fused 8.54 1.75–15.32 0.014 5.61 −1.41 to 12.63 0.117 −4.56 −12.29 to 3.17 0.246 4.43 −4.45 to 13.30 0.327
 Neuromonitor use 3.57 −0.97 to 8.11 0.122 6.24 1.57–10.91 0.009 −4.37 −9.51 to 0.77 0.095 −0.70 −6.60 to 5.20 0.816
 Pain≥12 mo 2.16 −1.60 to 5.91 0.259 2.54 −1.59 to 6.68 0.227 −1.32 −5.87 to 3.24 0.569 1.48 −3.78 to 6.73 0.581
Final
 Age 0.07 −0.14 to 0.28 0.511 −0.02 −0.21 to 0.16 0.809 −0.07 −0.32 to 0.18 0.562 0.08 −0.20 to 0.37 0.564
 BMI −0.27 −0.68 to 0.15 0.206 −0.14 −0.23 to 0.51 0.452 0.26 −0.25 to 0.77 0.311 −0.14 −0.72 to 0.45 0.649
 Female −5.05 9.65 to 0.45 0.032 3.03 −1.04 to 7.11 0.144 2.54 −3.06 to 8.14 0.372 −1.37 −7.82 to 5.08 0.676
 Diabetes 8.57 1.25–15.88 0.022 −0.27 −7.04 to 6.49 0.937 6.05 −3.22 to 15.33 0.200 15.93 5.25–26.61 0.004
 Psychiatric history 0.96 −6.32 to 8.23 0.796 1.52 −5.41 to 8.44 0.666 3.10 −6.39 to 12.58 0.520 6.93 −3.99 to 17.85 0.212
 Opioid use −3.16 −8.44 to 2.11 0.238 −0.14 −4.80 to 4.53 0.954 3.33 −3.06 to 9.73 0.305 1.59 −5.77 to 8.95 0.670
 ASA≥3 0.41 −4.76 to 5.58 0.876 −0.19 −4.74 to 4.36 0.934 2.50 −3.74 to 8.73 0.431 3.50 −3.68 to 10.68 0.338
 Prior surgery 0.55 −4.84 to 5.94 0.841 −0.42 −5.32 to 4.48 0.865 −1.79 −8.50 to 4.92 0.599 −1.71 −9.44 to 6.02 0.663
 2 levels fused 4.98 0.14–9.81 0.044 0.65 −3.60 to 4.90 0.763 1.96 −3.97 to 7.79 0.508 4.66 −2.06 to 11.37 0.173
 3+ levels fused 5.78 −3.12 to 14.67 0.202 5.29 −3.47 to 14.05 0.235 8.05 −3.96 to 20.05 0.188 4.90 −8.93 to 18.72 0.486
 Neuromonitor use 2.77 −3.13 to 8.66 0.356 7.57 2.65–12.50 0.003 −2.10 −8.85 to 4.65 0.540 0.49 −7.28 to 8.27 0.900
 Pain≥12 mo 3.93 −0.92 to 8.78 0.112 0.47 −3.96 to 4.90 0.834 −1.45 −7.53 to 4.63 0.638 0.08 −6.92 to 7.08 0.981
Change preoperative to postoperative
 Age 0.03 −0.10 to 0.17 0.636 0.00 −0.09 to 0.08 0.942 0.11 0.01–0.20 0.025 0.03 −0.09 to 0.15 0.641
 BMI 0.12 −0.15 to 0.38 0.393 −0.10 −0.27 to 0.07 0.240 −0.04 −0.22 to 0.14 0.645 −0.17 −0.41 to 0.06 0.147
 Female 0.83 −2.16 to 3.83 0.585 −0.89 −2.76 to 0.98 0.346 −0.13 −2.14 to 1.88 0.897 −0.90 −3.55 to 1.75 0.502
 Diabetes −1.88 −6.68 to 2.93 0.442 −1.92 −4.97 to 1.12 0.214 0.88 −2.40 to 4.15 0.598 −2.35 −6.64 to 1.94 0.282
 Psychiatric history −0.04 −4.90 to 4.81 0.987 2.80 −0.36 to 5.96 0.082 −2.81 −6.21 to 0.59 0.105 −2.28 −6.74 to 2.17 0.313
 Opioid use 1.90 −1.64 to 5.44 0.292 −1.26 −3.62 to 1.09 0.290 1.02 −1.51 to 3.55 0.427 −0.87 −4.18 to 2.45 0.605
 ASA≥3 −3.15 −6.54 to 0.24 0.069 0.66 −1.50 to 2.83 0.545 −0.62 −2.95 to 1.71 0.598 0.41 −2.66 to 3.48 0.792
 Prior surgery −1.38 −4.86 to 2.11 0.437 0.25 −1.99 to 2.48 0.828 0.95 −1.45 to 3.36 0.435 −1.35 −4.50 to 1.81 0.399
 2 levels fused 1.48 −1.66 to 4.62 0.353 −0.57 −2.57 to 1.43 0.575 −0.21 −2.36 to 1.94 0.848 1.47 −1.35 to 4.28 0.306
 3+ levels fused 4.13 −1.77 to 10.02 0.169 2.75 −1.24 to 6.75 0.175 0.79 −3.51 to 5.09 0.717 6.39 0.53 –12.26 0.033
 Neuromonitor use 0.63 −3.23 to 4.50 0.747 2.45 0.01−4.89 0.049 3.43 0.81−6.06 0.011 4.29 0.85−7.74 0.015
 Pain≥12 mo 0.30 −2.85 to 3.45 0.852 0.22 −1.82 to 2.26 0.830 −0.87 −3.07 to 1.32 0.434 0.34 −2.54 to 3.22 0.815
Change postoperative to final
 Age −0.01 −0.19 to 0.17 0.913 −0.09 −0.19 to 0.00 0.056 −0.11 −0.31 to 0.09 0.274 0.05 −0.24 to 0.34 0.742
 BMI −0.26 −0.62 to 0.10 0.150 −0.03 −0.22 to 0.16 0.743 0.06 −0.32 to 0.44 0.758 −0.12 −0.69 to 0.45 0.679
 Female −4.39 −8.33 to −0.44 0.030 1.80 −0.27 to 3.87 0.088 1.46 −2.78 to 5.70 0.498 −0.05 −6.36 to 6.25 0.987
 Diabetes 2.96 −3.36 to 9.27 0.358 2.69 −0.62 to 6.00 0.111 1.82 −4.97 to 8.61 0.597 8.05 −2.02 to 18.11 0.116
 Psychiatric history 3.55 −2.71 to 9.82 0.266 1.45 −2.20 to 5.11 0.434 2.98 −4.51 to 10.47 0.433 8.50 −2.61 to 19.62 0.133
 Opioid use −2.37 −6.92 to 2.18 0.306 −0.17 −2.55 to 2.21 0.887 1.91 −2.97 to 6.78 0.441 2.70 −4.58 to 9.98 0.465
 ASA≥3 0.83 −3.61 to 5.28 0.713 −0.64 −2.95 to 1.68 0.587 3.09 −1.65 to 7.83 0.200 1.72 −5.34 to 8.78 0.631
 Prior surgery −0.83 −5.48 to 3.81 0.724 −0.94 −3.57 to 1.69 0.483 1.96 −3.43 to 7.35 0.473 2.31 −5.73 to 10.35 0.571
 2 levels fused 1.24 −2.90 to 5.38 0.555 1.13 −1.03 to 3.28 0.303 1.55 −2.87 to 5.97 0.489 0.39 −6.19 to 6.97 0.908
 3+ levels fused −1.47 −9.15 to 6.21 0.707 1.43 −2.91 to 5.77 0.516 4.64 −4.25 to 13.53 0.304 −0.31 −13.48 to 12.86 0.963
 Neuromonitor use −2.30 −7.36 to 2.77 0.373 1.26 −1.21 to 3.72 0.316 1.71 −3.34 to 6.76 0.506 0.83 −6.65 to 8.32 0.826
 Pain≥12 mo 1.28 −2.90 to 5.46 0.546 −1.22 −3.53 to 1.10 0.301 −0.85 −5.60 to 3.89 0.723 0.75 −6.33 to 7.84 0.834
Change preoperative to final
 Age 0.04 −0.14 to 0.23 0.649 −0.13 −0.26 to −0.01 0.037 −0.19 −0.43 to 0.05 0.117 −0.15 −0.41 to 0.12 0.281
 BMI −0.10 −0.46 to 0.26 0.579 −0.11 −0.35 to 0.13 0.373 −0.19 −0.65 to 0.27 0.413 −0.36 −0.87 to 0.14 0.158
 Female −4.18 −8.29 to −0.08 0.046 −0.28 −3.04 to 2.49 0.843 0.32 −4.96 to 5.60 0.905 −0.68 −6.53 to 5.17 0.818
 Diabetes 1.43 −4.99 to 7.85 0.661 −1.53 −5.88 to 2.82 0.489 0.43 −7.88 to 8.73 0.919 −1.89 −11.06 to 7.27 0.684
 Psychiatric history 2.17 −4.51 to 8.85 0.523 2.23 −2.44 to 6.90 0.347 1.12 −7.80 to 10.04 0.804 4.28 −5.55 to 14.12 0.391
 Opioid use −1.70 −6.55 to 3.15 0.490 −2.85 −6.09 to 0.38 0.083 1.70 −4.48 to 7.87 0.588 2.86 −3.96 to 9.68 0.409
 ASA≥3 −2.04 −6.65 to 2.56 0.383 1.42 −1.65 to 4.48 0.363 6.02 0.16–11.87 0.044 5.73 −0.75 to 12.22 0.082
 Prior surgery −2.02 −6.72 to 2.69 0.399 −0.49 −3.59 to 2.61 0.754 −0.36 −6.28 to 5.56 0.904 0.56 −6.06 to 7.17 0.868
 2 levels fused 3.57 −0.71 to 7.85 0.101 1.65 −1.13 to 4.44 0.242 0.97 −4.34 to 6.29 0.718 6.11 0.20–12.01 0.043
 3+ levels fused 2.19 −5.83 to 10.20 0.592 0.37 −6.83 to 7.57 0.919 6.28 −7.47 to 20.03 0.368 7.06 −8.12 to 22.24 0.359
 Neuromonitor use 0.09 −5.23 to 5.40 0.974 2.55 −1.01 to 6.10 0.159 6.50 −0.28 to 13.28 0.060 4.30 −3.18 to 11.78 0.258
 Pain≥12 mo 0.69 −3.59 to 4.97 0.751 −0.40 −3.33 to 2.53 0.789 −2.44 −8.03 to 3.16 0.391 −3.64 −9.83 to 2.55 0.247
Bolded values indicate statistical significance at P<0.05.
ASA indicates American Society of Anesthesiologists physical status class; BMI, body mass index; CI, confidence interval; LL, lumbar lordosis; PI, pelvic incidence.

TABLE 4 - Patient-reported Outcomes
Factor Pain<12 mo Mean (SD) Pain≥12 mo Mean (SD) All Patients Mean (SD)
Preoperative
 VAS back 6.81 (2.58) 6.35 (2.83) 6.47 (2.77)
 VAS leg 6.18 (2.89) 5.81 (2.90) 5.91 (2.90)
 ODI 47.46 (19.08) 42.99 (17.47) 44.13 (17.97)
Final
 VAS back 4.53 (3.02) 4.12 (5.22) 4.23 (4.72)
 VAS leg 3.61 (3.24) 3.31 (3.13) 3.39 (3.15)
 ODI 33.93 (21.21) 29.49 (20.24) 30.73 (20.58)
Change preoperative to final
 VAS back 2.76 (2.50) 2.65 (3.20) 2.68 (3.02)
 VAS leg 3.70 (3.68) 2.68 (3.52) 2.95 (3.58)
 ODI 17.61 (19.01) 14.66 (16.32) 15.44 (17.08)
ODI indicates Oswestry Disability Index; VAS, visual analog scales.

TABLE 5 - Multivariate Linear Regression Models for Patient-reported Outcomes
Patient-reported Outcomes
VAS Back VAS Leg ODI
Factor β 95% CI P β 95% CI P β 95% CI P
Preoperative
 Age 0.01 −0.04 to 0.06 0.835 0.00 −0.06 to 0.05 0.932 −0.03 −0.34 to 0.28 0.860
 BMI 0.06 −0.06 to 0.18 0.302 −0.02 −0.15 to 0.10 0.724 −0.10 −0.79 to 0.58 0.763
 Female 0.22 −0.84 to 1.29 0.677 0.68 −0.48 to 1.84 0.250 −0.03 −6.59 to 6.54 0.994
 Diabetes 2.29 0.15–4.43 0.036 1.17 −1.17 to 3.51 0.323 8.31 −4.52 to 21.13 0.202
 Psychiatric history −0.51 2.23 to 1.20 0.555 −0.93 −2.81 to 0.94 0.326 −2.17 −12.42 to 8.08 0.676
 Opioid use 1.31 0.04−2.58 0.043 0.21 −1.17 to 1.60 0.758 1.65 −5.90 to 9.20 0.666
 ASA≥3 −0.32 −1.66 to 1.02 0.637 0.31 −1.16 to 1.77 0.680 1.81 −6.31 to 9.93 0.659
 Prior surgery 0.87 −0.45 to 2.18 0.193 1.29 −0.15 to 2.73 0.078 4.50 −3.61 to 12.61 0.274
 2 levels fused 0.90 −0.22 to 2.03 0.115 −0.14 −1.37 to 1.10 0.827 1.44 −5.55 to 8.42 0.684
 3+ levels fused 0.57 −1.39 to 2.53 0.566 0.23 −1.91 to 2.37 0.835 5.28 −7.05 to 17.62 0.398
 Neuromonitor use −0.04 −1.63 to 0.55 0.960 1.52 −0.27 to 3.31 0.095 −3.95 −13.25 to 5.35 0.402
 Pain≥12 mo −0.54 −1.69 to 0.60 0.351 −0.38 −1.65 to 0.89 0.553 1.95 −5.21 to 9.11 0.590
Final
 Age 0.00 −0.05 to 0.05 0.856 −0.01 −0.06 to 0.05 0.776 0.00 −0.32 to 0.31 0.988
 BMI 0.06 −0.05 to 0.16 0.275 0.03 −0.08 to 0.14 0.556 0.38 −0.25 to 1.00 0.237
 Female 0.69 −0.34 to 1.72 0.187 0.53 −0.57 to 1.62 0.344 2.04 −4.58 to 8.66 0.544
 Diabetes 0.88 −1.77 to 3.54 0.512 −1.21 −4.33 to 1.91 0.444 1.08 −16.27 to 18.43 0.903
 Psychiatric history −1.65 −3.40 to 0.09 0.063 −0.73 −2.59 to 1.14 0.442 −2.34 −12.79 to 8.12 0.659
 Opioid use 1.53 0.23–2.83 0.021 1.83 0.44–3.21 0.010 12.69 5.01–20.37 0.001
 ASA≥3 0.68 −0.51 to 1.86 0.262 0.86 −0.41 to 2.12 0.183 4.93 −2.58 to 12.44 0.196
 Prior surgery 0.73 −0.50 to 1.96 0.242 0.47 −0.84 to 1.79 0.478 4.57 −3.31 to 12.45 0.254
 2 levels fused 1.52 0.44–2.60 0.006 0.71 −0.46 to 1.87 0.231 9.58 2.66–16.50 0.007
 3+ levels fused 1.79 −0.10 to 3.68 0.063 0.47 −1.54 to 2.48 0.643 8.24 −3.56 to 0.03 0.169
 Neuromonitor use 0.42 −1.22 to 2.06 0.614 0.21 −1.54 to 1.96 0.814 -2.77 −12.67 to 7.13 0.581
 Pain≥12 mo −0.34 −1.46 to 0.78 0.545 −0.45 −1.64 to 0.75 0.461 -2.34 −9.43 to 4.75 0.515
Preoperative to final
 Age −0.01 −0.08 to 0.06 0.865 −0.04 −0.12 to 0.05 0.388 −0.46 −0.86 to −0.06 0.023
 BMI 0.01 −0.16 to 0.17 0.945 −0.04 −0.23 to 0.15 0.690 −0.24 −1.18 to 0.70 0.613
 Female −0.52 −1.87 to 0.82 0.443 0.65 −0.89 to 2.19 0.401 −1.20 −8.72 to 6.32 0.751
 Diabetes 1.47 −1.53 to 4.47 0.332 0.69 −3.22 to 4.61 0.725 11.92 −4.86 to 28.69 0.161
 Psychiatric history 0.76 −1.33 to 2.85 0.470 −0.39 −2.81 to 2.03 0.751 −3.44 −15.13 to 8.26 0.560
 Opioid use 0.10 −1.69 to 1.89 0.913 −2.10 −4.14 to −0.05 0.045 −8.52 −18.52 to 1.47 0.094
 ASA≥3 −0.89 −2.54 to 0.76 0.287 0.27 −1.63 to 2.16 0.780 −1.46 −10.67 to 7.76 0.754
 Prior surgery −0.53 −2.15 to 1.10 0.519 0.43 −1.43 to 2.29 0.647 −4.01 −13.09 to 5.06 0.381
 2 levels fused −1.18 −2.60 to 0.24 0.102 −1.48 −3.14 to 0.18 0.079 −9.21 −17.14 to −1.28 0.023
 3+ levels fused −1.96 −4.35 to 0.43 0.107 −1.11 −3.83 to 1.62 0.421 −6.65 −20.01 to 6.70 0.324
 Neuromonitor use 0.05 −1.91 to 2.01 0.957 2.45 0.10–4.79 0.041 2.79 −8.17 to 13.74 0.613
 Pain≥12 mo −0.62 −2.05 to 0.80 0.385 −0.80 −2.46 to 0.86 0.341 −2.59 −10.54 to 5.36 0.518
Bolded values indicate statistical significance at P<0.05.
ASA indicates American Society of Anesthesiologists physical status class; BMI, body mass index; CI, confidence interval; ODI, Oswestry Disability Index; VAS, visual analog scale.

On multivariate logistic regression analyses of postoperative complications and reoperations, there were no differences between the DOS<12 and DOS12+ groups (Tables 6, 7). There was no difference in rates of dural tear, discharge to rehabilitation facility, or any early adjacent segment degeneration.

TABLE 6 - Postoperative Complications and Reoperation
Factor Pain<12 mo, N (%) Pain≥12 mo, N (%) All Patients, N (%)
Dural tear 16 (6.48) 42 (6.97) 58 (6.82)
Postoperative complication 27 (10.93) 54 (8.96) 81 (9.53)
Discharge to facility 24 (9.72) 49 (8.17) 73 (8.62)
Reoperation 12 (8.51) 19 (5.94) 31 (6.72)
ODI MCID 31 (55.36) 74 (47.74) 105 (49.76)
VAS-back MCID 33 (58.93) 83 (53.9) 116 (55.24)
VAS-leg MCID 31 (56.36) 72 (48) 103 (50.24)
Pseudarthrosis 10 (5.46) 30 (6.58) 40 (6.26)
MCID indicates minimal clinically important difference; ODI, Oswestry Disability Index; VAS, visual analog scales.

TABLE 7 - Multivariate Regression Models for Postoperative Complications and Reoperation
Dural Tear Postoperative Complication Discharge to Facility Reoperation
Factor OR 95% CI P OR 95% CI P OR 95% CI P OR 95% CI P
Model
 Age 1.02 0.99–1.05 0.240 0.99 0.97–1.02 0.586 1.09 1.05–1.13 0.000 1.000 0.96–1.04 0.986
 BMI 1.00 0.94–1.07 0.907 1.02 0.97–1.08 0.421 1.02 0.96–1.08 0.488 1.037 0.95–1.13 0.403
 Female 0.92 0.46–1.82 0.812 1.08 0.61–1.89 0.801 1.95 0.98–3.84 0.056 1.258 0.49–3.22 0.632
 Diabetes 0.99 0.32–3.08 0.980 1.59 0.66–3.85 0.305 2.18 0.94–5.06 0.070 1.828 0.50–6.66 0.360
 Psychiatric history 0.44 0.10–1.94 0.278 0.94 0.38–2.35 0.899 0.72 0.25–2.10 0.550 0.788 0.20–3.06 0.731
 Opioid use 0.88 0.39–1.98 0.758 0.85 0.44–1.63 0.625 0.82 0.38–1.78 0.614 0.928 0.31–2.78 0.894
 ASA≥3 1.04 0.49–2.25 0.912 1.43 0.76–2.70 0.265 2.09 0.99–4.40 0.052 0.829 0.28–2.42 0.732
 Prior surgery 0.92 0.41–2.06 0.836 0.51 0.25–1.06 0.070 1.09 0.50–2.37 0.825 0.419 0.11–1.57 0.198
 2 levels fused 2.34 1.17–4.68 0.016 0.77 0.40–1.46 0.416 1.28 0.62–2.63 0.510 2.181 0.86–5.52 0.100
 3+ levels fused 0.97 0.21–4.50 0.964 2.83 1.07–7.49 0.037 2.84 1.02–7.94 0.047 1.063 0.12–9.37 0.956
 Neuromonitor use 0.93 0.36–2.38 0.872 5.26 1.54–17.92 0.008 0.67 0.31–1.45 0.310 1.617 0.50–5.26 0.425
 Pain≥12 mo 1.23 0.59–2.58 0.582 1.03 0.56–1.88 0.936 1.02 0.52–2.02 0.946 0.548 0.22–1.36 0.195
ODI MCID VAS-back MCID VAS-leg MCID Pseudarthrosis
OR 95% CI P OR 95% CI P OR 95% CI P OR 95% CI P
Model
 Age 0.95 0.90–1.01 0.105 1.00 0.95–1.05 0.949 0.97 0.92–1.02 0.233 0.97 0.94–1.01 0.130
 BMI 0.94 0.83–1.07 0.363 1.02 0.90–1.15 0.745 0.94 0.83–1.07 0.336 0.99 0.92–1.06 0.756
 Female 0.92 0.33–2.54 0.865 0.57 0.21–1.51 0.258 2.00 0.73–5.45 0.177 1.25 0.54–2.89 0.608
 Diabetes 15.70 1.20–2.04 0.036 7.33 0.60–89.33 0.118 1.62 0.13–19.59 0.704 1.19 0.31–4.52 0.799
 Psychiatric history 1.29 0.24–6.92 0.770 1.33 0.30–5.92 0.712 1.82 0.35–9.41 0.472 1.01 0.31–3.27 0.987
 Opioid use 0.24 0.05–1.11 0.067 1.27 0.35–4.54 0.716 0.23 0.06–0.94 0.041 1.89 0.82–4.38 0.135
 ASA≥3 0.56 0.14–2.15 0.395 0.36 0.10–1.22 0.100 1.63 0.47–5.65 0.440 1.18 0.46–3.03 0.739
 Prior surgery 0.52 0.14–1.99 0.339 1.04 0.31–3.43 0.951 1.19 0.34–4.16 0.786 0.55 0.19–1.57 0.261
 2 levels fused 0.41 0.14–1.24 0.115 0.56 0.20–1.54 0.260 0.33 0.11–1.00 0.051 1.12 0.49–2.56 0.788
 3+ levels fused 0.60 0.09–3.84 0.590 0.25 0.04–1.54 0.134 0.78 0.14–4.42 0.780 1.00 1.00–1.00
 Neuromonitor use 1.61 0.32–8.15 0.563 1.89 0.45–7.92 0.385 7.45 1.10–50.59 0.040 1.00 0.35–2.90 0.993
 Pain≥12 mo 0.58 0.20–1.73 0.329 0.68 0.25–1.89 0.462 0.71 0.25–2.05 0.528 0.98 0.42–2.28 0.960
Bolded values indicate statistical significance at P<0.05.
ASA indicates American Society of Anesthesiologists physical status class; BMI, body mass index; CI, confidence interval; MCID, minimal clinically important difference; ODI, Oswestry Disability Index; OR, odds ratio; VAS, visual analog scale.

DISCUSSION

Although lumbar fusion has demonstrated a successful track record,2,3,8–11 most patients with lumbar spine symptoms attempt various durations of nonsurgical treatment options. The varying efficacy of nonoperative treatment leaves patients with a wide-range of duration of symptoms, and there has been conflicting data regarding the appropriate timing of surgical intervention.12–14 To further delineate the effect of delayed lumbar fusion, we divided 850 consecutive patients who underwent lumbar spine fusion into 2 groups—those with symptoms <12 months (DOS<12) and those with symptoms for 12 months or longer (DOS12+). We examined their demographics, operative characteristics, radiographic sagittal parameters, clinical outcomes, and postoperative complications, and found the 2 groups to be similar all findings. To date, this is the largest study directly examining the duration of symptoms and its correlation with clinical and radiographic outcomes after lumbar fusion.

The present study demonstrated similar clinical and radiographic outcomes between those in the DOS<12 and DOS12+ groups. However, there has been obvious difficulty in assessing adequate nonsurgical care throughout the literature. The wide spectrum has been previously demonstrated in a systematic review and meta-analysis of lumbar fusion in degenerative spine disease by Yavin et al,14 which found that 22% of studies included conservative care for <6 months, 39% for 6 months or more, and another 39% for 1–2 years. However, there was no discussion on how variable timelines affected outcomes. A large subgroup analysis of the SPORT trial examined 601 patients with degenerative spondylolisthesis, and compared those with ≤12 months (n=397) and those with >12 months (n=204) of lumbar symptoms.10 A similar number in each group underwent fusion. Their primary and secondary outcome measures included various domains including ODI scores, as well as patient satisfaction, work status, and self-reported improvement measures. Overall, their results suggested no significant difference in either primary or secondary outcome measures between the 2 groups at 6 or 12 months. However, within the same study, patients with spinal stenosis were more likely to experience improved primary outcomes with shorter durations of conservative management. Unlike the degenerative spondylolisthesis cohort, patients with spinal stenosis were primarily treated with an isolated lumbar decompression (85%–90%). Although this procedural difference may in part, explain the disagreement in findings between the SPORT study and our findings, other variations in baseline comorbidities, reflexes, and disease heterogeneity may have also influenced outcomes. Similarly, in a prospective study of 105 patients, 32 of whom had degenerative spondylolisthesis who underwent decompression without fusion, outcomes were not significantly different until a duration of symptoms longer than 4 years.15 Katz et al16 studied 88 patients undergoing spine surgery, 22 of whom had degenerative spondylolisthesis with 8 undergoing arthrodesis, identifying no difference in outcomes between those with a duration of symptoms ≤12, 12–30, and >30 months. However, generalizability of the results was limited by the small number of patients.

Patient demographics were similar between the 2 cohorts in our study, and a majority had grade 1 spondylolisthesis. A prior retrospective review of 163 consecutive patients with degenerative spondylolisthesis found a 6.1% revision rate at 12 months,17 whereas another demonstrated revision at an average of 10.8 months.18 The present study’s analysis was inclusive of only patients undergoing primary lumbar fusions and demonstrated a similar rate of pseudarthrosis or any early adjacent segment degeneration.

Sagittal parameters in lumbar fusions have become an intriguing topic, and the use of interbody devices has been critiqued in correcting these parameters.19 Although PI remains constant, LL, PT, and the PI-LL difference can vary based on patient factors, all of which are attempted to be optimized intraoperatively. One fourth of our entire patient cohort had an interbody placed during their surgery, which may influence sagittal correction.19–21 Therefore, we can expect similar improvement in sagittal parameters in patients undergoing lumbar arthrodesis with symptoms longer than 12 months.

Similarly, in a separate study of 69 patients undergoing a transforaminal lumbar interbody fusion, symptom duration of <24 months was associated with improved leg pain, although there was no significant difference in back pain when compared to those with symptoms 24 months or longer.22 On multivariate linear regression, all patients in our study experienced an improvement in their patient-reported outcomes. In a study of 246 propensity-matched patients with varying body mass index, Owens et al23 reported improvement in ODI (average change of 11.4), VAS-back (average change of 2.38), and VAS-leg (average change of 2.53) scores similar to those in our study, with the exception of lower ODI scores. Other studies have also demonstrated a similar improvement in VAS-back, VAS-leg, and ODI scores.24–26 While our study suggests that even at 12 months of nonoperative care there may be no difference in outcomes, there is more certainty in the timeline of nonoperative care for lumbar spinal stenosis,27 with meta-analyses suggesting no difference at up to 12 months, with a difference in outcome after decompression becoming significant by 24 months.28,29 Unlike the persistency of lumbar spinal stenosis, degenerative spondylolisthesis may be more dynamic, resulting in more intermittent-type symptoms that can be tolerated for longer periods.10

The strengths of this study include its large sample size, its comparative nature, and uniformity of the 2 cohorts. However, the retrospective nature of this study introduces biases that are avoided in a prospective study. We believe that the patients in our study are similar to that of the general population; however, the data within this study are made up from patients of a single institution, limiting some of its generalizability. Further, our threshold for postoperative clinical follow-up (12 mo) may also be insufficient to effectively capture differences in long-term clinical sequelae. Despite this, our study offers valuable information regarding short-to-intermediate length outcomes and may effectively aid in guiding patient and provider expectations before and after surgery. Lastly, due to the retrospective nature of our study, there was limited ability to discern between what types of nonoperative therapies were attempted and the duration for which they were implemented. More specifically, while we expect all conservative treatment to have been thoroughly documented in each patient chart, it is indeed possible that patients had a course of conservative care before their transfer of care to our institution. Any such data that were not documented would thereby skew data towards a shorter course of conservative care than was actually implemented.

There is a need for further delineation of appropriate conservative care, including the duration of which it should be recommended. Our study included 850 consecutive patients undergoing open posterolateral lumbar fusion for degenerative spinal pathology and was able to demonstrate that outcomes were equivalent when delaying surgery for at least 12 months. This is crucial for patient education and surgical planning, and places further emphasis on appropriate conservative care in hopes of avoiding unnecessary lumbar arthrodesis. Future studies are needed to demonstrate why some patients and providers wait longer than others—if they are based on patient/provider reasons such as pain tolerance, patient-doctor relationships, or improvement with nonoperative modalities, or based on societal factors such as specific surgeon dogma or insurers.

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Keywords:

lumbar stenosis; spondylolisthesis; degenerative spine; spinal fusion; lumbosacral spine; conservative care; nonoperative therapy; posterolateral fusion

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