Predictors of Complication Severity Following Adult Spinal Deformity Surgery: Smoking Rate, Diabetes, and Osteotomy Increase Risk of Severe Adverse Events

BACKGROUND

Given the physical and economic burden of complications in spine surgery, reducing the prevalence of perioperative adverse events is a primary concern of both patients and health care professionals. This study aims to identify specific perioperative factors predictive of developing varying grades of postoperative complications in adult spinal deformity (ASD) patients, as assessed by the Clavien-Dindo complication classification (Cc) system.

METHODS

Surgical ASD patients ≥18 years were identified in the American College of Surgeons' National Surgical Quality Improvement Program from 2005 to 2015. Postoperative complications were stratified by Cc grade severity: minor (I, II, and III) and severe (IV and V). Stepwise regression models generated dataset-specific predictive models for Cc groups. Model internal validation was achieved by bootstrapping and calculating the area under the curve (AUC) of the model. Significance was set at P < 0.05.

RESULTS

Included were 3936 patients (59 ± 16 years, 63% women, 29 ± 7 kg/m²) undergoing surgery for ASD (4.4 ± 4.7 levels, 71% posterior approach, 11% anterior, and 18% combined). Overall, 1% of cases were revisions, 39% of procedures involved decompression, 27% osteotomy, and 15% iliac fixation. Additionally, 66% of patients experienced at least 1 complication, 0% of which were Cc grade I, 51% II, 5% III, 43% IV, and 1% V. The final model predicting severe Cc (IV-V) complications yielded an AUC of 75.6% and included male sex, diabetes, increased operative time, central nervous system tumor, osteotomy, cigarette pack-years, anterior decompression, and anterior lumbar interbody fusion. Final models predicting specific Cc grades were created.

CONCLUSIONS

Specific predictors of adverse events following ASD-corrective surgery varied for complications of different severities. Multivariate modeling showed smoking rate, osteotomy, diabetes, anterior lumbar interbody fusion, and higher operative time, among other factors, as predictive of severe complications, as classified by the Clavien-Dindo Cc system. These factors can help in the identification of high-risk patients and, consequently, improve preoperative patient counseling.

CLINICAL RELEVANCE

The findings of this study provide a foundation for identifying ASD patients at high risk of postoperative complications .

LEVEL OF EVIDENCE: 4

Durability of Satisfactory Functional Outcomes Following Surgical Adult Spinal Deformity Correction: A 3-Year Survivorship Analysis

BACKGROUND

Despite reports showing positive long-term functional outcomes following adult spinal deformity (ASD)-corrective surgery, it is unclear which factors affect the durability of these outcomes.

OBJECTIVE

To assess durability of functional gains following ASD-corrective surgery; determine predictors for postoperative loss of functionality.

METHODS

Surgical ASD patients > 18 yr with 3-yr Oswestry Disability Index (ODI) follow-up, and 1-yr postoperative (1Y) ODI scores reaching substantial clinical benefit (SCB) threshold (SCB < 31.3 points). Patients were grouped: those sustaining ODI at SCB threshold beyond 1Y (sustained functionality) and those not (functional decline). Kaplan-Meier survival analysis determined postoperative durability of functionality. Multivariate Cox regression assessed the relationship between patient/surgical factors and functional decline, accounting for age, sex, and levels fused.

RESULTS

All 166 included patients showed baseline to 1Y functional improvement (mean ODI: 35.3 ± 16.5-13.6 ± 9.2, P < .001). Durability of satisfactory functional outcomes following the 1Y postoperative interval was 88.6% at 2-yr postoperative, and 71.1% at 3-yr postoperative (3Y). Those sustaining functionality after 1Y had lower baseline C2-S1 sagittal vertical axis (SVA) and T1 slope (both P < .05), and lower 1Y thoracic kyphosis (P = .035). From 1Y to 3Y, patients who sustained functionality showed smaller changes in alignment: pelvic incidence minus lumbar lordosis, SVA, T1 slope minus cervical lordosis, and C2-C7 SVA (all P < .05). Those sustaining functionality beyond 1Y were also younger, less frail at 1Y, and had lower rates of baseline osteoporosis, hypertension, and lung disease (all P < .05). Lung disease (Hazard Ratio:4.8 [1.4-16.4]), 1Y frailty (HR:1.4 [1.1-1.9]), and posterior approach (HR:2.6 [1.2-5.8]) were associated with more rapid decline.

CONCLUSION

Seventy-one percent of ASD patients maintained satisfactory functional outcomes by 3Y. Of those who failed to sustain functionality, the largest functional decline occurred 3-yr postoperatively. Frailty, preoperative comorbidities, and surgical approach affected durability of functional gains following surgery.

Preoperative MRI predictors of health-related quality of life improvement after microscopic lumbar discectomy

BACKGROUND

Lumbar herniated nucleus pulposus (HNP) is a common spinal pathology often treated by microscopic lumbar discectomy (MLD), though prior reports have not demonstrated which preoperative MRI factors may contribute to significant clinical improvement after MLD.

PURPOSE

To analyze the MRI characteristics in patients with HNP that predict meaningful clinical improvement in health-related quality of life scores (HRQoL) after MLD.

STUDY DESIGN/SETTING

Retrospective clinical and radiological study of patients undergoing MLD for HNP at a single institution over a 2-year period.

PATIENT SAMPLE

Eighty-eight patients receiving MLD treatment for HNP.

OUTCOME MEASURES

Cephalocaudal Canal Migration; Canal & HNP Anterior-Posterior (AP) Lengths and Ratio; Canal & HNP Axial Areas and Ratio; Hemi-Canal & Hemi-HNP Axial Areas and Ratio; Disc appearance (black, gray, or mixed); Baseline (BL); and 3-month (3M) postoperative HRQoL scores.

METHODS

Patients >18 years old who received MLD for HNP with BL and 3M HRQoL scores of PROMIS (Physical Function, Pain Interference, and Pain Intensity), ODI, VAS Back, and VAS Leg scores were included. HNP and spinal canal measurements of cephalocaudal migration, AP length, area, hemi-area, and disc appearance were performed using T2 axial and sagittal MRI. HNP measurements were divided by corresponding canal measurements to calculate AP, Area, and Hemi-Area ratios. Using known minimal clinically important differences (MCID) for each ΔHRQoL score, patients were separated into two groups based on whether they reached MCID (MCID+) or did not reach MCID (MCID-). The MCID for PROMIS pain intensity was calculated using a decision tree. A linear regression illustrated correlations between PROMIS vs ODI and VAS Back/Leg scores. Independent t-tests and chi-squared tests were utilized to investigate significant differences in HNP measurements between the MCID+ and MCID- groups.

RESULTS

There were 88 MLD patients included in the study (Age=44.6±14.9, 38.6% female). PROMIS pain interference and pain intensity were strongly correlated with ODI and VAS Back/Leg (R≥0.505), and physical function correlated with ODI and VAS Back/Leg (R=-0.349) (all p<.01). The strongest MRI predictors of meeting HRQoL MCID were gray disc appearance, HNP area (>116.6 mm²), and Hemi-Area Ratio (>51.8%). MCID+ patients were 2.7 times more likely to have a gray HNP MRI signal than a mixed or black HNP MRI signal in five out of six HRQoL score comparisons (p<.025). MCID+ patients had larger HNP areas than MCID- patients had in five out of six HRQoL score comparisons (116.6 mm²±46.4 vs 90.0 mm²±43.2, p<.04). MCID+ patients had a greater Hemi-Area Ratio than MCID- patients had in four out of six HRQoL score comparisons (51.8%±14.7 vs 43.9%±14.9, p<.05).

CONCLUSIONS

Patients who met MCID after MLD had larger HNP areas and larger Hemi-HNP Areas than those who did not meet MCID. These patients were also 2.7× more likely to have a gray MRI signal than a mixed or black MRI signal. When accounting for HNP area relative to canal area, patients who met MCID had greater Hemi-HNP canal occupation than patients who did not meet MCID. The results of this study suggest that preoperative MRI parameters can be useful in predicting patient-reported improvement after MLD.

Predictors of Hospital-Acquired Conditions Are Predominately Similar for Spine Surgery and Other Common Elective Surgical Procedures, With Some Key Exceptions

STUDY DESIGN

Retrospective review of a prospectively collected database.

OBJECTIVE

To predict the occurrence of hospital-acquired conditions (HACs) 30-days postoperatively and to compare predictors of HACs for spine surgery with other common elective surgeries.

METHODS

Patients ≥18 years undergoing elective spine surgery were identified in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2005 to 2013. Outcome measures included any HACs: superficial or deep surgical site infection (SSI), venous thromboembolism (VTE), urinary tract infection (UTI). Spine surgery patients were compared with those undergoing other common procedures. Random forest followed by multivariable regression analysis was used to determine risk factors for the occurrence of HACs.

RESULTS

A total of 90 551 elective spine surgery patients, of whom 3021 (3.3%) developed at least 1 HAC, 1.4% SSI, 1.3% UTI, and 0.8% VTE. The occurrence of HACs for spine patients was predicted with high accuracy (area under the curve [AUC] 77.7%) with the following variables: female sex, baseline functional status, hypertension, history of transient ischemic attack (TIA), quadriplegia, steroid use, preoperative bleeding disorders, American Society of Anesthesiologists (ASA) class, operating room duration, operative time, and level of residency supervision. Functional status and hypertension were HAC predictors for total knee arthroplasty (TKA), bariatric, and cardiothoracic patients. ASA class and operative time were predictors for most surgery cohorts. History of TIA, preoperative bleeding disorders, and steroid use were less predictive for most other common surgical cohorts.

CONCLUSIONS

Occurrence of HACs after spine surgery can be predicted with demographic, clinical, and surgical factors. Predictors for HACs in surgical spine patients, also common across other surgical groups, include functional status, hypertension, and operative time. Understanding the baseline patient risks for HACs will allow surgeons to become more effective in their patient selection for surgery.