Spine surgical research: searching for absolute truth in the era of "big data"

Repeat Discectomy or Instrumented Surgery for Recurrent Lumbar Disk Herniation: An Overview of French Spine Surgeons' Practice

STUDY DESIGN

Retrospective multicenter cohort study.

OBJECTIVE

Recurrent lumbar disc herniation (ReLDH) is a common condition requiring surgical intervention in a large proportion of cases. Evidence regarding the appropriate choice between repeat microdiscectomy (RD) and instrumented surgery (IS) is lacking. To understand the indications for either of the procedures and compare the results, we aimed to provide an overview of spine surgeon practice in France.

METHODS

This retrospective, multicenter analysis included adults who underwent surgery for ReLDHs between December 2020 and May 2021. Surgeons were asked which of the following factors determined their therapeutic choice: radio-clinical considerations, non-discal anatomical factors, patient preference, or surgeon background. Data on preoperative clinical status and radiologic findings were collected. Patient-reported outcome measures (PROMs) were assessed and compared using propensity scores preoperatively and at 3 and 12 months postoperatively.

RESULTS

The study included 150 patients (72 IS and 78 RD). Radioclinical elements, anatomical data, patient preferences, and surgeon background influenced the choice of RD in 57.7%, 1.3%, 25.6%, and 15.4% of the cases, respectively, and IS in 34.7%, 6.9%, 13.9%, and 44.5% of the cases, respectively. At 12 months, patient satisfaction, return to work, and changes in PROMs were not significantly different between the groups.

CONCLUSIONS

The decision-making process included both objective and subjective factors, resulting in patient satisfaction in 80.3% to 81.5% of cases, with significant clinical improvement in radicular symptoms in 75.8% to 91.8% of cases, and quality of life in 75.8% to 84.9% of cases, depending on the procedure performed.

Machine Learning Models for Predicting Disability and Pain Following Lumbar Disc Herniation Surgery

Importance

Lumber disc herniation surgery can reduce pain and disability. However, a sizable minority of individuals experience minimal benefit, necessitating the development of accurate prediction models.

Objective

To develop and validate prediction models for disability and pain 12 months after lumbar disc herniation surgery.

Design, Setting, and Participants

A prospective, multicenter, registry-based prognostic study was conducted on a cohort of individuals undergoing lumbar disc herniation surgery from January 1, 2007, to May 31, 2021. Patients in the Norwegian Registry for Spine Surgery from all public and private hospitals in Norway performing spine surgery were included. Data analysis was performed from January to June 2023.

Exposures

Microdiscectomy or open discectomy.

Main Outcomes and Measures

Treatment success at 12 months, defined as improvement in Oswestry Disability Index (ODI) of 22 points or more; Numeric Rating Scale (NRS) back pain improvement of 2 or more points, and NRS leg pain improvement of 4 or more points. Machine learning models were trained for model development and internal-external cross-validation applied over geographic regions to validate the models. Model performance was assessed through discrimination (C statistic) and calibration (slope and intercept).

Results

Analysis included 22 707 surgical cases (21 161 patients) (ODI model) (mean [SD] age, 47.0 [14.0] years; 12 952 [57.0%] males). Treatment nonsuccess was experienced by 33% (ODI), 27% (NRS back pain), and 31% (NRS leg pain) of the patients. In internal-external cross-validation, the selected machine learning models showed consistent discrimination and calibration across all 5 regions. The C statistic ranged from 0.81 to 0.84 (pooled random-effects meta-analysis estimate, 0.82; 95% CI, 0.81-0.84) for the ODI model. Calibration slopes (point estimates, 0.94-1.03; pooled estimate, 0.99; 95% CI, 0.93-1.06) and calibration intercepts (point estimates, -0.05 to 0.11; pooled estimate, 0.01; 95% CI, -0.07 to 0.10) were also consistent across regions. For NRS back pain, the C statistic ranged from 0.75 to 0.80 (pooled estimate, 0.77; 95% CI, 0.75-0.79); for NRS leg pain, the C statistic ranged from 0.74 to 0.77 (pooled estimate, 0.75; 95% CI, 0.74-0.76). Only minor heterogeneity was found in calibration slopes and intercepts.

Conclusion

The findings of this study suggest that the models developed can inform patients and clinicians about individual prognosis and aid in surgical decision-making.

The Anterior Versus Posterior Approach for Interbody Fusion in Patients Who Are Classified as Obese: A Retrospective Cohort Study of 9,021 Patients From a National Database

Introduction Lumbar spine interbody fusions have been performed to relieve back pain and improve stability due to various underlying pathologies. Anterior interbody fusion and posterior interbody fusion approaches are two main approaches that are classically compared. In an attempt to compare these two approaches to the spine, large retrospective national database reviews have been performed to compare and predict 30-day postoperative outcomes; however, they have conflicting findings. Obesity, defined as having a body mass index (BMI) over 30 kg/m2, may also contribute to the extent of spine pathology and is associated with increased rates of postoperative complications. Complication rates in patients who are obese have yet to be thoroughly investigated using a large national database. Our present investigation aims to make this comparison using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. The goal of the present study is to utilize a nationwide prospective database to determine short-term differences in postoperative outcomes between posterior and anterior lumbar fusion in patients with obesity and relate these findings to previous studies in the general population. Methods A retrospective cohort analysis was conducted on 9,021 patient data from the ACS-NSQIP database from 2015 to 2019 who underwent an elective, single-level fusion via anterior or posterior surgical approach. This database captures over 150 clinical variables on individual patient cases, including demographic data, preoperative risk factors and laboratory values, intraoperative data, and significant events up to postoperative day 30. All outcome measures were included in this analysis with special attention to rates of deep venous thrombosis (DVT) and pulmonary embolism (PE), prolonged length of stay (LOS), reoperation, and operation time. Results Multivariable analysis controlling for age, BMI, sex, race, functional status, American Society of Anesthesiologists (ASA) class, and selected comorbidities with P < 0.05 demonstrated that the anterior approach was an independent predictor for all significant outcomes except prolonged length of stay. Compared to the posterior approach, the anterior approach had a shorter total operation time (B = -13.257, 95% confidence interval (CI) [-17.522, -8.992], P < 0.001), higher odds of deep vein thrombosis (odds ratio (OR) = 2.210, 95% CI [1.211, 4.033], P= 0.010), and higher odds of pulmonary embolism (OR = 2.679, 95% CI [1.311, 5.477], P = 0.007) and was protective against unplanned reoperation (OR = 0.702, 95% CI [0.548, 0.898], P = 0.005). Conclusions The obese population makes up a large and growing demographic of those undergoing spine surgery, and as such, it is pertinent to investigate the differences, advantages, and disadvantages of lumbar fusion approaches in this group. While anterior approaches may be protective of longer operation time and unplanned reoperation, this benefit may not be clinically significant when considering an increased risk of DVT and PE. Given the short-term nature of this dataset and the limitations inherent in large de-identified retrospective database studies, these findings are interpreted with caution. Longer-term follow-up studies accounting for confounding variables with spine-centered outcomes will be necessary to further elucidate these nuances.

Big data registries in spine surgery research: the lurking dangers

Spine surgery research has improved considerably over the last few decades. Its' most recent growth is in large part due to the mounting increase in studies conducted using national databases and registries. With easy access to a large number of patients, the benefit of these registries has become evident. However, as with any research, this type of data must be used responsibly with the appropriate strengths and limitations kept in mind. Inappropriate use of these registries continues to be a growing concern as potentially false or inaccurate conclusions can adversely impact clinical practice. It is, therefore, the author and the readers' responsibility to acknowledge and understand the limitations of this type of data. Knowledge of methodological requirements in the use and analyses of registry data is essential to ensuring quality evidence with proper interpretation.

A systematic review of spinal research conducted using the National Surgical Quality Improvement Program

BACKGROUND CONTEXT

Over the course of the last decade, interest in the use of large data repositories for clinical research in orthopedic and spine surgery has grown substantially. Detractors maintain that the clinical relevance of research conducted using large registries is limited, and that the academic influence of such studies is minimal. Such contentions have not been empirically evaluated.

PURPOSE

This study sought to perform a systematic review of spinal research conducted using the National Surgical Quality Improvement Program (NSQIP).

STUDY DESIGN

This is a systematic review.

OUTCOME MEASURES

Impact factor (IF) of the journal of publication and number of citations of published articles conducted using the NSQIP.

METHODS

Orthopedic and spine-specific NSQIP articles published from January 1, 2007 to July 31, 2015, were identified through a query of PubMed or Medline, Embase, Web of Science, and Scopus. Articles were classified by journal of publication, year of publication, study topic, study purpose, and method of statistical analysis. Spine surgical publications were compared with other orthopedic research conducted using the NSQIP. The primary dependent variables for the purposes of statistical testing were IF of the journal in which the article was published and the number of citations for each publication. Negative binomial regression was used to evaluate the characteristics of papers associated with increased IF and number of citations.

RESULTS

Of the 1,525 articles identified in the initial search, 114 studies were considered eligible for inclusion in the systematic review. The average IF for the journals publishing orthopedic NSQIP articles was 2.75 (standard deviation [SD] 1.22, range 0-5.28), whereas it was 2.52 (SD 0.81, range 1.38-5.28) for spinal research. The average number of citations per article was 6.08 (SD 10.9, range 0-69) and 6.4 (SD 12.0, range 0-69) for spine-specific studies. Following negative binomial regression, only IF (regression coefficients [RC] 0.31; 95% confidence intervals [CI] 0.08, 0.55) and the year of publication (RC -1.29; 9% CI -1.64, -0.95) were found to have a statistically significant association with number of citations. Among spine-specific research articles, only the year of publication was found to influence the number of citations (RC -1.29; 95% CI -1.94, -0.64).

CONCLUSIONS

Our findings indicate that the academic impact of orthopedic and spine surgical research conducted using NSQIP is highly variable, with most publications found to have relatively low impact. As our evaluation of study characteristics associated with high-impact publications and increased citations were unable to uncover factors that are likely translatable, we suggest following research design guidelines that highlight best practices when using large datasets for orthopedic research.