The American Society of Anesthesiologists (ASA) physical status classification has been used to risk stratify surgical candidates. Our study compares outcomes of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) procedures based on preoperative ASA physical status classification.
A surgical registry was reviewed for primary, single-level MIS TLIF patients. Patients were categorized by preoperative ASA physical status classification: ASA I, ASA II, ASA III+. Perioperative complications were compared among groups. Patient-reported outcome measures (PROMs) for back pain, leg pain, physical function, and disability were recorded preoperatively and at 6-week, 12-week, 6-month, 1-year, and 2-year postoperative timepoints. PROM improvement from baseline (ΔPROM) and minimum clinically important difference (MCID) achievement was calculated for each timepoint and compared among groups. MCID achievement was determined as ΔPROMs that surpassed previously established MCID values.
Of the 487 patients, 64 had an ASA classification of I, whereas 336 had an ASA of II, and 87 had an ASA of III or greater. Rates of complications were not associated with ASA classification (all p>0.050). Neither mean PROM scores nor ΔPROM scores were significantly associated with ASA classification at any timepoint (all p>0.050). MCID achievement was significantly associated with ASA classification for back pain at 1 year only (p=0.041). Overall MCID achievement was not significantly associated with ASA classification for any PROM (p>0.050).
While ASA classification has been commonly used to risk stratify surgical candidates for spinal procedures, patients with an ASA of III or greater may be able to achieve similar long-term outcomes following MIS TLIF given proper selection criteria.
Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) has proven to be an efficacious treatment option for those experiencing degenerative spine pathologies such as central stenosis and spondylolisthesis while minimizing soft tissue trauma and disruption of posterior musculature [
In addition to the more traditional objective assessment of operative outcomes, patient-reported outcome measures (PROMs) are self-reported questionnaires that allow clinicians to understand postoperative pain, disability and physical function from the patient’s perspective [
ASA has been previously used as selection criteria to assess whether a patient is fit for surgery, but beyond this safety profile, there is limited literature to indicate whether the score can successfully predict a patient’s course of recovery. We aim to clarify this relationship and determine the value of ASA classification as a patient selection criterion for minimally invasive spine surgery, which may have important implications for clinical practice. Investigating ASA classification and PROMs, in addition to other perioperative characteristics, will improve the understanding of this scoring system’s effect on longitudinal, clinically significant outcomes.
This study was approved by the Institutional Review Board of Rush University Medical Center (ORA #14051301) and written informed consent were obtained from patient prior to subject enrollment and data collection. Prospectively collected data was retrospectively reviewed via a private surgical database for minimally invasive lumbar fusion patients from January 2014 to February 2020. Inclusion criteria were patients undergoing primary, elective, single-level MIS TLIF procedures for degenerative spinal pathology. Exclusion criteria were patients missing a preoperative ASA classification or whose procedures were indicated for traumatic, infectious, or malignant etiologies. Additionally, to mitigate the confounding effects on outcomes following MIS TLIF, multilevel procedures were also excluded from the study. All procedures were performed by a single attending spine surgeon.
Patient demographic data was collected, including age, gender, body mass index (BMI), smoking status, and workers’ compensation status. Prevalence of various preoperative medical diagnoses were recorded for diabetes mellitus, acute immune deficiency syndrome (AIDS), history of myocardial infarction, neurological disease, arthritis, congestive heart failure, peripheral vascular disease, metastasis, liver disease, renal failure, chronic lung disease, and gastrointestinal bleeding. Prevalence of pre-existing spinal pathology was assessed for recurrent herniated nucleus pulposus, degenerative spondylolisthesis, and isthmic spondylolisthesis. Perioperative characteristics including operative duration (from skin incision to skin closure), estimated blood loss (EBL), and postoperative length of stay were recorded. Incidences of postoperative complications such as aspiration requiring reintubation, urinary retention, urinary tract infection, epidural hematoma, acute renal failure, postoperative anemia, altered mental status, venous thromboembolism, pulmonary embolism, pneumothorax, arrhythmia, ileus, pneumonia, atelectasis, pleural effusion, fever, or pancreatitis were recorded and confirmed via direct review of the electronic medical record. Specific circumstances and outcomes regarding confirmed complications were then reviewed and described.
PROMs were administered preoperatively and at 6-week, 12-week, 6-month, 1-year, and 2-year postoperative timepoints via a secure online portal and completed by patients either in the clinic using a provided electronic tablet prior to the appointment or at home using personal devices. Administered PROMs included the visual analogue scale (VAS) back, VAS leg, Oswestry Disability Index (ODI), 12-Item Short Form health survey physical composite score (SF-12 PCS), and Patient-Reported Outcomes Measurement Information System physical function (PROMIS PF).
Following localization of the appropriate spinal level via lateral fluoroscopy, an incision was made lateral to the midline and sequential dilators were used to gain exposure. A central laminectomy and bilateral partial facetectomy were performed. Following preparation of the endplates, an interbody cage along with bone graft was subsequently positioned in the interbody space. Bilateral pedicle screws were then placed above and below the level of interest and rods were attached to achieve compression.
Patients were grouped according to their preoperative ASA classification based on a score of I, II, or III+. Demographic characteristics, preoperative medical and spinal pathology, and perioperative characteristics were compared between groups using chi-square or 1-way analysis of variance (ANOVA) for categorical and continuous variables, respectively. Rates of individual and total postoperative complications were compared between groups using Fisher exact test.
ΔPROM scores were calculated as the difference between preoperative values and each postoperative timepoint. Mean PROM scores and ΔPROM scores were compared among groups for each measure at each timepoint using 1-way ANOVA. Achievement of an MCID was determined by comparing ΔPROM score to previously established threshold values: 2.2 (VAS back) [
A total of 487 MIS TLIF patients were included with an average age of 52.1 years. Of these, 64 patients had an ASA classification of I, whereas 336 had an ASA classification of II, and 87 had an ASA classification ≥ III. A majority of patients were male (57.1%), nonobese (BMI < 30 kg/m2), and nonsmokers (83.0%) (
Neither mean PROM scores nor ΔPROM scores significantly differed based on ASA group at any timepoint for any measure (all p>0.05) (
ASA classification has been viewed as a concise way of conveying a patients’ general physical health status and thereby, their risk of undergoing general anesthesia. While higher ASA scores have been used by many spine surgeons as a key part of their patient selection criteria, literature supporting the utility of this measure is somewhat limited in the field of spine surgery. Furthermore, beyond the immediate perioperative period, the impact of ASA classification on more long-term patient-reported outcomes is relatively unreported. While ASA classification was clearly associated with increased medical comorbidity in our cohort, differences in perioperative outcomes were relatively minor and impact on long-term clinical improvement was negligible.
Our cohort demonstrated clear associations between a number demographic factors, as well as several significant medical comorbidities. Age was significantly associated with ASA classification, with each progressive ASA group demonstrating older mean ages than the group below. While a majority of the overall cohort had a BMI <30 kg/m2, over 70% of the ASA III+ group was obese. Interestingly, workers’ compensation patients made up the majority of the ASA I group only. To some degree, this is an expected distribution as those individuals who are able to claim workers’ compensation are typically of age or physical ability to participate in the workforce. Past comparative studies have also noted this significant difference, whereby patients categorized as workers’ compensation were significantly younger and had a lower comorbidity burden [
ASA physical status classification has been suggested as a tool for preoperative risk stratification in spine surgery by a number of previous studies [
Our analysis among MIS TLIF patients failed to replicate this predictive value of ASA for perioperative morbidity. Interestingly, operative duration was significantly greater for patients with the highest ASA classifications; however, EBL and length of stay, which might be more expected to correlate with increasing ASA, did not demonstrate significant associations with this measure. Overall, complications were quite rare amongst our cohort, which may be attributable to a combination of careful patient selection, minimally invasive surgical techniques, and the expertise of an experienced surgeon that regularly performs a high volume of MIS TLIF procedures. Nonetheless, the few complications that were observed were distributed relatively evenly among the 3 groups and demonstrated no significant associations with ASA classification. Given previous reports of increased surgical morbidity among patients with an ASA classification > II, some surgeons may view this threshold as an attractive criterion for patient selection, particularly for outpatient/ambulatory orthopaedic surgery [
While a relatively substantial body of literature exists regarding the relationship between ASA classification and propensity for perioperative complications and adverse outcomes, research regarding the impact of ASA classification on patient-reported outcomes is much more limited. McGirt et al. [
Given the conflicting results and methodological limitations of these previous studies, it is important to directly and longitudinally assess the impact of ASA classification on patients’ ability to achieve meaningful clinical improvement following minimally invasive lumbar fusion. Despite our use of a relatively large cohort to facilitate well-powered statistical analysis, we were unable to demonstrate any significant differences between ASA groups either in mean PROM scores or ΔPROM improvement at any of the assessed timepoints. Furthermore, analysis of MCID achievement showed no significant impacts of ASA for any of the assessed PROMs either overall or at individual timepoints through 2-years postoperatively, with the exception of VAS back at 1 year. These results allow for a more pertinent assessment of the relevance (or lack thereof) of ASA classification for this specific population because of our focused selection of only patients undergoing primary, single-level MIS TLIF procedures and our collection longitudinal PROM data throughout the full 2-year postoperative period.
One major potential shortcoming of the ASA classification is its relatively subjective assignment criteria. Several previous studies have demonstrated questionable interrater reliability in ASA classification assignment. Among 97 anesthesiologists in Hong Kong asked to classify 10 hypothetical patients, overall agreement on classification was below 60% for all but 1 patient (for whom agreement was 67%), and was as low as 36% for one patient [
The present study represents one of the most comprehensive assessments of the association of ASA classification with surgical outcomes specifically for MIS TLIF patients. However, our findings should be considered in the context of several limitations. First, while a moderately large sample was included, the single-surgeon, single-institution nature of this analysis may limit generalizability to other providers and populations. Additionally, previous studies have demonstrated variability in the assignment of ASA classification between different institutions and different regions [
Increasing ASA classification was significantly associated with greater prevalence of a variety of medical comorbidities. However, while operative duration was significantly longer for patients with higher ASA classification, other perioperative outcomes were similar for all patients and rates of complications were favorable regardless of ASA classification. Similarly, patient-reported outcomes in pain, disability, and physical function including mean scores, absolute improvement, and achievement of MCID did not significantly vary based on preoperative ASA. Therefore, we recommend that ASA classification > II should not necessarily preclude otherwise appropriate patients from undergoing MIS TLIF procedures, even in the outpatient setting.
The authors have nothing to disclose.
This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Conceptualization: CL, EC, KS; Data curation: CL, EC, CJ, SM, CG, KS; Formal analysis: CL, EC, KS; Methodology: CL, EC, KS; Project administration: CL, EC, CJ, SM, CG, KS; Visualization: CL, EC, CJ, SM, CG, KS; Writing - original draft: CL, EC, CJ, KS; Writing - review & editing: CL, EC, CJ, SM, CG, KS.
Patient demographics and baseline characteristics
Characteristic | Total (n=487) | ASA PS classification |
p-value |
||
---|---|---|---|---|---|
I (n = 64) | II (n = 336) | III+ (n = 87) | |||
Age (yr) | 52.1 ± 11.7 | 42.1 ± 10.2 | 52.4 ± 11.1 | 58.1 ± 10.1 | < 0.001 |
Sex | 0.083 | ||||
Female | 209 (42.9) | 21 (32.8) | 155 (46.1) | 33 (37.9) | |
Male | 278 (57.1) | 43 (67.2) | 181 (53.9) | 54 (62.1) | |
Body mass index (kg/m2) | < 0.001 |
||||
< 30 | 260 (53.4) | 45 (70.3) | 189 (56.3) | 26 (29.9) | |
≥ 30 | 227 (46.6) | 19 (29.7) | 147 (43.8) | 61 (70.1) | |
Smoking status | 0.776 | ||||
Nonsmoker | 404 (83) | 54 (84.4) | 280 (83.3) | 70 (80.5) | |
Smoker | 83 (17) | 10 (15.6) | 56 (16.7) | 17 (19.5) | |
Insurance | 0.003 |
||||
Non-WC | 311 (63.9) | 29 (45.3) | 227 (67.6) | 55 (63.2) | |
WC | 176 (36.1) | 35 (54.7) | 109 (32.4) | 32 (36.8) | |
Medical diagnosis | |||||
Diabetes mellitus | 58 (11.9) | 0 (0) | 30 (8.9) | 28 (32.2) | < 0.001 |
AIDS | 0 (0) | 0 (0) | 0 (0) | 0 (0) | - |
Myocardial infarction | 5 (1) | 0 (0) | 1 (0.3) | 4 (4.6) | 0.001 |
Hypertension | 177 (36.4) | 4 (6.3) | 113 (33.7) | 60 (69) | < 0.001 |
Neurological disease | 9 (1.9) | 0 (0) | 2 (0.6) | 1 (8.1) | < 0.001 |
Arthritis | 87 (17.9) | 1 (1.6) | 63 (18.8) | 23 (26.4) | < 0.001 |
Congestive heart failure | 5 (1) | 1 (1.6) | 1 (0.3) | 3 (3.5) | 0.031 |
PVD | 9 (1.9) | 0 (0) | 4 (1.2) | 5 (5.7) | 0.010 |
Metastasis | 0 (0) | 0 (0) | 0 (0) | 0 (0) | - |
Liver disease | 5 (1) | 0 (0) | 5 (1.5) | 0 (0) | 0.320 |
Renal failure | 4 (0.8) | 0 (0) | 2 (0.6) | 2 (2.3) | 0.216 |
Chronic lung disease | 32 (6.6) | 0 (0) | 24 (7.2) | 8 (9.2) | 0.059 |
GI bleed | 1 (0.21) | 0 (0) | 0 (0) | 1 (1.1) | 0.100 |
Values are presented as mean±standard deviation or number (%).
ASA PS, American Society of Anesthesiologists physical status; WC, workers’ compensation; AIDS, acute immune deficiency syndrome; PVD, peripheral vascular disease; GI, gastrointestinal.
p<0.05, statistically significant differences.
p-values calculated using 1-way analysis of variance (continuous) or chi-square analysis (categorical).
Perioperative characteristics
Characteristic | Total (n = 487) | ASA PS classification |
p-value |
||
---|---|---|---|---|---|
I (n=64) | II (n=336) | III+ (n=87) | |||
Spinal pathology | |||||
Recurrent HNP | 31 (6.4) | 5 (7.8) | 20 (6.0) | 6 (6.9) | 0.834 |
Degenerative spondylolisthesis | 263 (65.8) | 27 (58.7) | 188 (67.6) | 48 (63.2) | 0.432 |
Isthmic spondylolisthesis | 127 (31.8) | 19 (40.4) | 843 (0.3) | 24 (31.6) | 0.388 |
Operative time (min) | 127.9 ± 35.8 | 122.9 ± 32.2 | 126.3 ± 35.3 | 137.9 ± 38.6 | 0.013 |
Estimated blood loss (mL) | 68.6 ± 69.5 | 62.8 ± 44.4 | 69.3 ± 74.9 | 69.7 ± 62.2 | 0.792 |
Length of stay (hr) | 50.5 ± 38.1 | 46.2 ± 30.0 | 49.3 ± 37.8 | 58.4 ± 43.3 | 0.089 |
Values are presented as number (%) or mean±standard deviation.
ASA PS, American Society of Anesthesiologists physical status; HNP, herniated nucleus pulposus.
p<0.05, statistically significant differences.
p-values calculated using 1-way analysis of variance (continuous) or chi-square analysis (categorical).
Postoperative complications
Complication |
Total (n = 487) | ASA PS classification |
p-value |
||
---|---|---|---|---|---|
I (n = 64) | II (n = 336) | III+ (n = 87) | |||
Aspiration/reintubation | 0 (0) | 0 (0) | 0 (0) | 0 (0) | - |
Urinary retention | 5 (1) | 0 (0) | 4 (1.2) | 1 (1.2) | 0.999 |
UTI | 3 (0.6) | 0 (0) | 3 (0.9) | 0 (0) | 0.999 |
Epidural hematoma | 2 (0.4) | 0 (0) | 2 (0.6) | 0 (0) | 0.999 |
Acute renal failure | 1 (0.2) | 0 (0) | 1 (0.3) | 0 (0) | 0.999 |
Postoperative anemia | 3 (0.6) | 0 (0) | 2 (0.6) | 0 (0) | 0.672 |
Altered mental status | 1 (0.2) | 0 (0) | 0 (0) | 1 (1.2) | 0.310 |
Arrhythmia | 1 (0.2) | 0 (0) | 0 (0) | 1 (1.2) | 0.310 |
Ileus | 1 (0.2) | 0 (0) | 1 (0.3) | 0 (0) | 0.999 |
Atelectasis | 1 (0.2) | 1 (1.6) | 0 (0) | 0 (0) | 0.131 |
Pancreatitis | 1 (0.2) | 0 (0) | 1 (0.3) | 0 (0) | 0.999 |
Total | 19 (3.9) | 1 (1.6) | 14 (4.2) | 3 (3.4) | 0.593 |
Values are presented as number (%).
ASA PS, American Society of Anesthesiologists physical status; UTI, urinary tract infection.
p-value calculated using Fisher exact test.
Patients did not have complications associated with a venous thromboembolism, pulmonary embolism, pneumothorax, pneumonia, pleural effusion, or fever of unknown origin.
Individual incidences of complications and associated outcomes
Urinary retention | 5 Patients with significantly elevated PVR required a foley catheter upon discharge but discontinued use by first follow-up appointment. |
UTI | 3 Patients developed a urinary tract infection and were discharged on antibiotics |
Epidural hematoma | 2 Patients developed epidural hematomas, underwent evacuation, and were discharged in stable condition |
Acute renal failure | 1 Patient had acute tubular necrosis on POD1 with a Cr increased 2-fold from baseline on POD4. Monitored in medical ICU until Cr dropped to 2.2 and was discharged safely to a rehab facility. |
Postoperative anemia | 2 Patients required transfusion with 1 unit of PRBC, 1 patient with 2 units. All patients were discharged in stable condition. |
Altered mental status | 1 Patient experienced recurrent staring episodes on POD1. CT scan was concerning for subarachnoid hemorrhage and was transferred to neuro ICU with a negative workup. Mental status returned to baseline on POD6 and was transferred to a rehab facility for concerns of alcohol withdrawal |
Arrhythmia | 1 Patient had atrial fibrillation with RVR on POD1, underwent TTE and cardioversion. Discharged in stable condition and followed up with PCP and cardiology. |
Ileus | 1 Patient experienced abdominal distention on POD3. Gastroenterology consulted. Rectal tube was placed to decompress the large bowel. Patient was tolerating a regular diet by discharge. |
Atelectasis | Linear opacities were identified on chest x-ray with low lung volumes consistent with atelectasis; patient was discharged in stable condition to follow up with sleep study. |
Pancreatitis | 1 Patient had elevated lipase and was thought to be suffering from mild pancreatitis. Lipase significantly decreased by discharge and instructed to follow up with gastroenterology. |
PVR, postvoid residual volume; UTI, urinary tract infection; POD, postoperative day; Cr, creatinine; ICU, intensive care unit; PRBC, packed red blood cells; CT, computed tomography; RVR, rapid ventricular response; TTE, transthoracic echocardiogram; PCP, primary care physician.
Patient-reported outcomes
PROM | ASA PS classification |
p-value |
||
---|---|---|---|---|
I | II | III+ | ||
VAS back | ||||
Preoperative | 6.7 ± 1.5 | 6.7 ± 2.2 | 6.6 ± 2.6 | 0.939 |
6 Weeks | 3.9 ± 2.1 | 3.9 ± 2.4 | 3.9 ± 2.6 | 0.981 |
12 Weeks | 3.6 ± 2.8 | 3.6 ± 2.5 | 4.0 ± 2.6 | 0.479 |
6 Months | 3.8 ± 2.9 | 3.5 ± 2.6 | 3.9 ± 2.9 | 0.439 |
1 Year | 2.2 ± 2.3 | 3.0 ± 2.5 | 4.1 ± 2.8 | 0.126 |
2 Years | 3.8 ± 3.1 | 3.4 ± 2.9 | 4.7 ± 3.3 | 0.367 |
VAS leg | ||||
Preoperative | 4.5 ± 3.2 | 5.6 ± 2.9 | 5.6 ± 2.8 | 0.230 |
6 Weeks | 2.3 ± 3.1 | 3.2 ± 2.8 | 3.2 ± 3.2 | 0.356 |
12 Weeks | 2.7 ± 3.0 | 2.8 ± 2.7 | 3.1 ± 2.8 | 0.798 |
6 Months | 2.1 ± 3.2 | 2.6 ± 2.7 | 2.9 ± 2.9 | 0.553 |
1 Year | 1.3 ± 1.7 | 2.7 ± 2.9 | 2.1 ± 2.8 | 0.274 |
2 Years | 1.9 ± 2.7 | 2.6 ± 2.8 | 4.0 ± 3.6 | 0.264 |
ODI | ||||
Preoperative | 38.5 ± 17.4 | 40.9 ± 16.3 | 44.2 ± 14.5 | 0.553 |
6 Weeks | 33.9 ± 23.0 | 35.4 ± 18.7 | 40.4 ± 17.7 | 0.274 |
12 Weeks | 27.6 ± 20.4 | 29.5 ± 18.4 | 36.0 ± 18.6 | 0.130 |
6 Months | 21.9 ± 21.8 | 24.3 ± 18.8 | 31.5 ± 19.5 | 0.097 |
1 Year | 20.4 ± 15.4 | 24.3 ± 22.3 | 27.3 ± 21.8 | 0.658 |
2 Years | 21.7 ± 17.6 | 23.4 ± 20.2 | 33.9 ± 30.0 | 0.302 |
SF-12 PCS | ||||
Preoperative | 33.3 ± 7.5 | 31.5 ± 9.0 | 29.0 ± 10.1 | 0.149 |
6 Weeks | 33.4 ± 9.2 | 31.8 ± 8.5 | 28.1 ± 8.5 | 0.074 |
12 Weeks | 38.5 ± 9.8 | 35.0 ± 9.8 | 32.6 ± 10.8 | 0.183 |
6 Months | 44.7 ± 9.1 | 39.2 ± 11.3 | 34.7 ± 11.8 | 0.032 |
1 Year | 42.0 ± 10.3 | 40.7 ± 12.3 | 37.2 ± 10.1 | 0.436 |
2 Years | 46.0 ± 7.8 | 41.1 ± 11.5 | 33.4 ± 11.5 | 0.087 |
PROMIS PF | ||||
Preoperative | 37.1 ± 6.4 | 35.7 ± 6.2 | 34.5 ± 5.3 | 0.387 |
6 Weeks | 40.2 ± 7.0 | 38.0 ± 7.1 | 34.9 ± 6.6 | 0.103 |
12 Weeks | 43.9 ± 7.6 | 40.8 ± 7.3 | 41.0 ± 7.5 | 0.397 |
6 Months | 47.0 ± 5.7 | 44.3 ± 7.1 | 40.5 ± 7.5 | 0.066 |
1 Year | 47.4 ± 11.3 | 46.1 ± 9.3 | 40.8 ± 10.0 | 0.126 |
2 Years | 48.6 ± 4.1 | 44.7 ± 9.5 | 36.7 ± 8.2 | 0.088 |
Values are presented as mean±standard deviation.
PROM, patient-reported outcome measure; ASA PS, American Society of Anesthesiologists physical status; VAS, visual analogue scale; ODI, Oswestry Disability Index; SF-12 PCS, 12-item Short Form health survey physical composite score; PROMIS PF, Patient-Reported Outcomes Measurement Information System physical function.
p-values calculated using 1-way analysis of variance.
Postoperative improvement (ΔPROM scores)
PROM | ASA PS classification |
p-value |
||
---|---|---|---|---|
I | II | III+ | ||
ΔVAS back | ||||
6 Weeks | 2.9 ± 2.1 | 2.8 ± 2.8 | 2.7 ± 2.9 | 0.918 |
12 Weeks | 3.0 ± 2.4 | 3.1 ± 2.8 | 2.5 ± 3.0 | 0.330 |
6 Months | 2.9 ± 2.6 | 3.1 ± 3.0 | 2.6 ± 3.0 | 0.435 |
1 Year | 4.5 ± 2.8 | 3.3 ± 3.1 | 2.6 ± 2.8 | 0.296 |
2 Years | 3.2 ± 3.3 | 3.3 ± 3.2 | 1.9 ± 3.0 | 0.426 |
ΔVAS leg | ||||
6 Weeks | 1.9 ± 3.2 | 2.6 ± 3.3 | 2.4 ± 2.9 | 0.589 |
12 Weeks | 2.3 ± 3.0 | 3.0 ± 3.1 | 2.6 ± 2.9 | 0.533 |
6 Months | 1.8 ± 2.7 | 2.9 ± 3.3 | 2.6 ± 3.0 | 0.407 |
1 Year | 2.5 ± 2.4 | 3.2 ± 3.1 | 2.8 ± 3.0 | 0.748 |
2 Years | 2.4 ± 2.5 | 3.6 ± 2.7 | 2.2 ± 3.2 | 0.253 |
ΔODI | ||||
6 Weeks | 6.6 ± 20.8 | 7.2 ± 18.6 | 4.4 ± 16.1 | 0.708 |
12 Weeks | 10.3 ± 13.8 | 13.3 ± 17.6 | 8.5 ± 14.5 | 0.281 |
6 Months | 12.6 ± 19.0 | 17.1 ± 18.3 | 14.4 ± 12.9 | 0.498 |
1 Year | 18.2 ± 15.7 | 17.9 ± 18.8 | 18.5 ± 15.4 | 0.992 |
2 Years | 17.6 ± 19.8 | 17.6 ± 17.3 | 12.7 ± 28.7 | 0.763 |
ΔSF-12 PCS | ||||
6 Weeks | 2.0 ± 11.6 | 1.3 ± 8.3 | -0.7 ± 7.8 | 0.536 |
12 Weeks | 7.0 ± 10.9 | 4.9 ± 9.5 | 3.5 ± 11.7 | 0.611 |
6 Months | 11.8 ± 5.9 | 8.7 ± 11.4 | 5.4 ± 9.6 | 0.320 |
1 Year | 13.5 ± 9.6 | 10.8 ± 10.4 | 9.8 ± 9.6 | 0.748 |
2 Years | 8.1 ± 7.1 | 9.2 ± 10.5 | 6.2 ± 10.2 | 0.687 |
ΔPROMIS PF | ||||
6 Weeks | 2.3 ± 5.8 | 2.3 ± 6.6 | 0.4 ± 4.9 | 0.501 |
12 Weeks | 4.9 ± 5.7 | 5.7 ± 7.3 | 5.3 ± 5.5 | 0.937 |
6 Months | 8.2 ± 5.5 | 8.5 ± 8.1 | 6.1 ± 4.0 | 0.537 |
1 Year | 8.7 ± 6.4 | 10.8 ± 8.3 | 7.0 ± 5.8 | 0.245 |
2 Years | 8.7 ± 6.3 | 9.0 ± 9.2 | 6.0 ± 5.5 | 0.775 |
Values are presented as mean±standard deviation.
PROM, patient-reported outcome measure; ASA PS, American Society of Anesthesiologists physical status; VAS, visual analogue scale; ODI, Oswestry Disability Index; SF-12 PCS, 12-item Short Form health survey physical composite score; PROMIS PF, Patient-Reported Outcomes Measurement Information System physical function.
p-values calculated using 1-way analysis of variance.
MCID achievement
PROM | ASA PS classification |
p-value |
||
---|---|---|---|---|
I | II | III+ | ||
VAS back | ||||
6 Weeks | 31 (60.8) | 155 (56.2) | 41 (56.2) | 0.651 |
12 Weeks | 25 (55.6) | 150 (57.9) | 30 (46.9) | 0.280 |
6 Months | 24 (54.6) | 151 (59.9) | 30 (50.9) | 0.594 |
1 Year | 6 (66.7) | 52 (63.4) | 5 (31.3) | 0.041 |
2 Years | 3 (42.9) | 30 (58.8) | 5 (41.7) | 0.740 |
Overall | 39 (72.2) | 227 (76.4) | 54 (70.1) | 0.657 |
VAS leg | ||||
6 Weeks | 4 (19.1) | 38 (27) | 7 (19.4) | 0.825 |
12 Weeks | 3 (17.7) | 41 (29.9) | 10 (28.6) | 0.562 |
6 Months | 2 (12.5) | 38 (27.3) | 8 (26.7) | 0.421 |
1 Year | 2 (22.2) | 26 (31.3) | 3 (18.8) | 0.653 |
2 Years | 1 (20.0) | 15 (31.3) | 3 (27.3) | 0.903 |
Overall | 7 (29.2) | 71 (44.1) | 15 (37.5) | 0.723 |
ODI | ||||
6 Weeks | 10 (45.5) | 68 (46.6) | 11 (29.7) | 0.146 |
12 Weeks | 7 (43.8) | 82 (58.6) | 15 (41.7) | 0.422 |
6 Months | 11 (68.8) | 95 (67.4) | 22 (71.0) | 0.803 |
1 Year | 6 (66.7) | 58 (69.1) | 11 (73.3) | 0.710 |
2 Years | 3 (60.0) | 32 (65.3) | 7 (63.6) | 0.948 |
Overall | 17 (70.8) | 128 (77.6) | 32 (78.1) | 0.569 |
SF-12 PCS | ||||
6 Weeks | 10 (52.6) | 42 (41.6) | 8 (33.3) | 0.209 |
12 Weeks | 9 (75.0) | 52 (53.1) | 13 (56.5) | 0.466 |
6 Months | 9 (90.0) | 61 (63.5) | 11 (64.7) | 0.289 |
1 Year | 6 (100) | 61 (74.4) | 13 (76.5) | 0.489 |
2 Years | 3 (100) | 48 (75.0) | 6 (54.6) | 0.084 |
Overall | 20 (95.2) | 101 (77.7) | 25 (78.1) | 0.196 |
PROMIS PF | ||||
6 Weeks | 7 (50.0) | 26 (36.1) | 4 (23.5) | 0.131 |
12 Weeks | 7 (63.6) | 32 (52.5) | 10 (66.7) | 0.767 |
6 Months | 8 (88.9) | 37 (66.1) | 8 (57.1) | 0.140 |
1 Year | 6 (66.7) | 38 (80.9) | 10 (71.4) | 0.943 |
2 Years | 3 (75.0) | 34 (70.8) | 3 (60.0) | 0.610 |
Overall | 16 (88.9) | 65 (75.6) | 15 (75.0) | 0.324 |
Values are presented as number (%).
ASA PS, American Society of Anesthesiologists physical status; MCID, minimum clinically important difference; PROM, patient-reported outcome measure; ASA PS, American Society of Anesthesiologists physical status; VAS, visual analogue scale; ODI, Oswestry Disability Index; SF-12 PCS, 12-item Short Form health survey physical composite score; PROMIS PF, Patient-Reported Outcomes Measurement Information System physical function.
p<0.05, statistically significant differences.
p-values calculated using simple logistic regression.