The present study aimed to evaluate the effect of baseline frailty status (as measured by modified frailty index-5 [mFI-5]) versus age on postoperative outcomes of patients undergoing surgery for spinal tumors using data from a large national registry.
The National Surgical Quality Improvement Program database was used to collect spinal tumor resection patients’ data from 2015 to 2019 (n = 4,662). Univariate and multivariate analyses for age and mFI-5 were performed for the following outcomes: 30-day mortality, major complications, unplanned reoperation, unplanned readmission, hospital length of stay (LOS), and discharge to a nonhome destination. Receiver operating characteristic (ROC) curve analysis was used to evaluate the discriminative performance of age versus mFI-5.
Both univariate and multivariate analyses demonstrated that mFI-5 was a more robust predictor of worse postoperative outcomes as compared to age. Furthermore, based on categorical analysis of frailty tiers, increasing frailty was significantly associated with increased risk of adverse outcomes. ‘Severely frail’ patients were found to have the highest risk, with odds ratio 16.4 (95% confidence interval [CI],11.21–35.44) for 30-day mortality, 3.02 (95% CI, 1.97–4.56) for major complications, and 2.94 (95% CI, 2.32–4.21) for LOS. In ROC curve analysis, mFI-5 score (area under the curve [AUC] = 0.743) achieved superior discrimination compared to age (AUC = 0.594) for mortality.
Increasing frailty, as measured by mFI-5, is a more robust predictor as compared to age, for poor postoperative outcomes in spinal tumor surgery patients. The mFI-5 may be clinically used for preoperative risk stratification of spinal tumor patients.
Spinal tumors are much less frequent than intracranial tumors, with an estimated overall prevalence of one spinal tumor for every 4 intracranial lesions [
The postoperative morbidity and surgical outcomes of spinal tumor resections represent a unique challenge with an urgent need for effective predictive tools for preoperative risk stratification in these patients [
Previous studies using data from large national databases have reported on preoperative risk stratification of spinal tumor patients [
Patient data from 2015–2019 was obtained from the ACS database, NSQIP. The NSQIP database contains validated, multi-institutional (private and academic centers) data collected from institutions employing a uniform protocol by trained surgical reviewers across institutions [
The current procedural terminology and International Classification of Diseases (ICD)-9 and ICD-10 codes were used to identify patients in the NSQIP data set (2015–2019) ages 18 years or older who, under general anesthesia, underwent resection of extradural, intradural extramedullary, and intramedullary primary or metastatic spinal tumors with a neurosurgeon or an orthopedic surgeon (
We used the mFI-5 as a measure of frailty. Previously, mFI-5 has been documented as an effective predictor of postoperative morbidity and mortality in neurosurgical patients including those undergoing spine surgery [
Outcome measures included mortality, major complications, unplanned readmission, unplanned reoperation, hospital length of stay (LOS), and discharge to nonhome destination. Based on previous studies, patients who experienced one or more of the following postoperative adverse events were considered to have major complications: prolonged intubation of 48 hours or more, unplanned reintubation, sepsis/septic shock, deep vein thrombosis/thrombophlebitis, pulmonary embolism, coma, cerebrovascular accident/stroke with neurological deficit(s), myocardial infraction/cardiac arrest requiring cardiopulmonary resuscitation, surgical site infection (SSI, superficial/deep/organ space), wound disruption/dehiscence, acute renal failure, and pneumonia [
All statistical analyses were performed employing IBM SPSS Statistics ver. 27.0 (IBM Co., Armonk, NY, USA) and GraphPad Prism v 9.0 (GraphPad Software Inc., La Jolla, CA, USA). Continuous variables with skewed data distribution are reported as median (and interquartile range, IQR). The D’Agostino-Pearson, Shapiro-Wilk, and Kolmogorov-Smirnov normality tests were used to determine whether the data were normally distributed or skewed. The incidence of mortality and major complication data in different age groups and frailty tiers are presented as percent incidence. The univariate analyses for age and mFI-5 were performed for the following outcomes: 30-day mortality, major complication, unplanned reoperation, unplanned readmission, hospital LOS, and discharge to a nonhome destination. Multivariable modeling of age and mFI-5, controlling for covariates, was done to define the discriminative ability of each measure. Effect sizes were summarized by odds ratio (OR) (dichotomous outcomes) or beta coefficients (continuous outcomes) and associated 95% confidence intervals (95% CIs). Receiver operating characteristic (ROC) curve analysis was performed to investigate the individual discrimination of age and frailty (by mFI-5) for mortality, and corresponding area under the curve (AUC) was depicted with 95% CI. For all purposes, p-value of < 0.05 was considered as statistically significant.
We identified and extracted data for a total of 4,662 spinal cord tumor patients who met our inclusion criteria. Median age of the study population was 59 years (IQR, 47–68 years); 53% were males with a median BMI of 19 kg/m2 (IQR, 16.3–22 kg/m2). The age distribution analysis showed the highest proportion of spinal tumor patients to be 61–70 years (25.7%), followed by 51–60 (23.4%) and 71–80 years (15.7%). Detailed study population characteristics are summarized in
Univariate analysis demonstrated that frailty status (based on mFI-5 score) was a better predictor than age of 30-day mortality, presence of major complication, unplanned readmission, unplanned reoperation, hospital LOS, and discharge to nonhome destination (
Multivariable regression analysis (adjusting for sex, BMI, tumor location, tumor type, and operative time) confirmed that, with higher effect size, frailty status was a better predictor of adverse surgical outcomes (
The ROC curve analysis showed superior discrimination of frailty (mFI-5) for mortality (AUC=0.743; 95% CI 0.661–0.825; p<0.001) in comparison with age (AUC=0.594; 95% CI, 0.512–0.667; p=0.043) (
Resection of spinal tumors is performed to improve functional (ambulatory) status, reduce pain, and in certain cases, to improve survival chances. However, the associated mortality with the surgical intervention is well documented in both single-center and large national database studies [
Previously, the 30-day mortality rate after surgical intervention for spinal tumor was reported as 4.5% in a 2008–2014 NSQIP study [
In our study, the major and minor postoperative complication rates were 10.6% and 15.6%, respectively. This is comparable to previously reported major and minor postoperative complication rates of 11.5% and 19.8% in 2008–2014 NSQIP spinal tumor data [
LOS was previously reported to be a driver of hospitalization cost in spine surgery patients, and increased LOS was associated with a higher risk of postoperative complications such as infectious and adverse thromboembolic events [
There are a few limitations of the present study, mainly ones inherent to any analysis based on a large national database, and therefore the results need to be interpreted in a prudent manner. Firstly, the NSQIP data only records postoperative outcomes within the initial 30 days of the surgery. As a result, it is impossible to gauge long-term outcomes and survival in spinal tumor patients. Secondly, NSQIP data does not include tumor size, intraoperative complications, and postoperative neurological outcomes, variables relevant to spine tumors patients. Thirdly, the present study is a retrospective analysis of a prospectively collected national dataset and therefore may be subject to inherent selection bias. Despite these limitations, the current study represents the largest series of spinal tumors patients analyzing the effect of baseline frailty status in comparison with age on surgical outcomes. The large sample size provides the necessary statistical power to recognize mFI-5 frailty score as a robust predictor of postoperative outcomes in spinal tumors patients. Furthermore, given that our study is based on a large national data set, it therefore carries significant generalizability beyond single-center data.
In conclusion, our study represents one of the most detailed analyses with a large sample size of postoperative outcomes in spinal tumor patients and is the first to report a direct comparison of age and frailty status employing mFI-5 score. Baseline frailty status is increasingly being used in preoperative risk stratification of neurosurgical patient populations and is emerging as a better predictor of outcomes than chronological age across multiple neurosurgical procedures [
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: SFK, AD, CB, WC, RT, DAC, OT, KC, RM, CC, MS; Data curation: SFK, CB, RM, CC, MS; Formal analysis: SFK, AD, CB, SS, RT, DAC, MC, OT, JV, KC, CR, PS, MS; Funding acquisition: C Bowers, WC, RM, MS; Methodology: SFK, AD, CB, SS, WC, RT, DAC, MC, OT, JV, KC, JD, RM, CR, PS, CC, MS; Project administration: CB, WC, MS; Visualization: SFK, AD, CB, SS, WC, RT, DAC, JV, JD, CR, PS, MS; Writing - original draft: SFK, AD, CB, SS, WC, RT, DAC, MC, OT, JV, KC, JD, CR, PS, MS; Writing - review & editing: SFK, AD, CB, WC, RT, DAC, OT, KC, JD, RM, CR, PS, MS.
The percent incidence of mortality (A) and presence of major complication (B) across different age groups and frailty status are depicted.
(A) Receiver operating characteristic (ROC) curve analysis. (B) Comparison of areas under the curve (AUC) of mFI-5 and age for mortality. mFI-5, modified frailty index-5; CI, confidence interval.
List of CPT, ICD-9, and ICD-10 codes used to extract cases of spinal tumors from NSQIP database 2015–2019
Coding system | Code | Description |
---|---|---|
CPT | 63275–8 | Laminectomy for biopsy/excision of extradural spinal neoplasm |
63280–3 | Laminectomy for biopsy/excision of intradural extramedullary spinal neoplasm | |
63285–7 | Laminectomy for biopsy/excision of intradural intramedullary spinal neoplasm | |
63290 | Laminectomy for biopsy/excision of combined intradural/extradural spinal neoplasm | |
63300–3 | Vertebral corpectomy for excision of extradural spinal neoplasm | |
63304–7 | Vertebral corpectomy for excision of intradural spinal neoplasm | |
ICD-9-CM | 170.2 | Malignant neoplasm of vertebral column excluding sacrum and coccyx |
170.6 | Malignant neoplasm of pelvic bones, sacrum, and coccyx | |
192.2 | Malignant neoplasm of spinal cord | |
192.3 | Malignant neoplasm of spinal meninges | |
198.3-5 | Secondary malignant neoplasm of brain and spinal cord | |
213.2 | Benign neoplasm of vertebral column, excluding sacrum, and coccyx | |
213.6 | Benign neoplasm of pelvic bones, sacrum, and coccyx | |
225.3 | Benign neoplasm of spinal cord | |
225.4 | Benign neoplasm of spinal meninges | |
239.7 | Neoplasm of uncertain behavior other parts of central nervous system | |
ICD-10-CM | C41.2 | Malignant neoplasm of vertebral column |
C72 | Malignant neoplasm of spinal cord | |
C79.49 | Malignant neoplasm of other parts of central nervous system | |
D16.6 | Benign neoplasm of vertebral column | |
D32.1 | Benign neoplasm of spinal meninges | |
D33.4 | Benign neoplasm of spinal cord | |
D43.4 | Neoplasm of uncertain behavior of spinal cord |
CPT, current procedural terminology; ICD, International Classification of Diseases; CM, clinical modification; NSQIP, National Surgical Quality Improvement Project.
NSQIP clinical variables matched to mFI-5
NSQIP variable | mFI-5 score |
---|---|
Non-independent functional status |
1 |
Diabetes mellitus with oral agents or insulin | 1 |
Chronic obstructive pulmonary disease | 1 |
Hypertension requiring medication | 1 |
Congestive heart failure | 1 |
Maximum score | 5 |
NSQIP, National Surgical Quality Improvement Project; mFI-5, modified frailty index-5.
The mFI-5 calculated using the 5 NSQIP variables results in an index ranging from 0 (least frail) to 5 (most frail), with a score of 1 as “prefrail,” 2 as “frail,” and 3 or more as “severely frail” as categorical variables.
Includes both partial and complete dependance.
Baseline demographic and clinical characteristics and outcomes of patients undergoing surgery for spinal tumors from the NSQIP database 2015–2019 (n=4,662)
Variable | Value |
---|---|
Age (yr) |
59 (47–68) |
Age groups (yr) |
|
18–20 | 46 (0.98) |
21–30 | 304 (6.5) |
31–40 | 457 (9.8) |
41–50 | 630 (13.5) |
51–60 | 1,092 (23.4) |
61–70 | 1,200 (25.7) |
71–80 | 731 (15.7) |
> 80 | 185 (4) |
Sex, male:female | 2,470 (53):2,192 (47) |
Body mass index (kg/m2) | 18.99 (16.26–22.05) |
Tumor location | |
Extradural | 2,177 (46.7) |
Intradural extramedullary | 1,918 (41.1) |
Intramedullary | 567 (12.2) |
Tumor type | |
Primary | 1,755 (37.6) |
Secondary | 2,020 (43.3) |
Unknown | 887 (19) |
Distribution of frailty | |
Not frail (mFI-5 = 0) | 2,351 (50.4) |
Prefrail (mFI-5 = 1) | 1,608 (34.8) |
Frail (mFI-5 = 2) | 614 (13.2) |
Severely frail (mFI-5 ≥ 3) | 89 (1.9) |
Preoperative clinical status/comorbidities | |
Functionally dependent | 340 (7.3) |
Diabetes mellitus | 639 (13.7) |
COPD | 171 (3.7) |
CHF | 18 (0.4) |
Current smoker | 793 (17) |
Dyspnea | 177 (3.8) |
Hypertension | 1,944 (41.7) |
Disseminated cancer | 1,344 (28.8) |
Open wound | 63 (1.4) |
Steroid use | 459 (9.8) |
Weight loss | 136 (2.9) |
Bleeding disorders | 164 (3.5) |
Preoperative transfusion | 50 (1.1) |
Preop SIRS | 180 (3.9) |
Operative time (hr) | 187 (133–261) |
Length of stay (day) | 5 (3–9) |
Mortality | 53 (1.6) |
Readmission | 435 (9.3) |
Reoperation | 239 (5.1) |
Major postoperative complications | 495 (10.6) |
Prolonged intubation (≥ 48 hr) | 5 (0.1) |
Unplanned reintubation | 57 (1.2) |
Sepsis | 91 (2) |
Septic shock | 30 (0.6) |
Pneumonia | 107 (2.3) |
DVT/thrombophlebitis | 94 (2) |
Pulmonary embolism | 63 (1.4) |
CVA/stroke with neurological deficit | 21 (0.5) |
Acute renal failure | 9 (0.2) |
Myocardial infarction | 18 (0.4) |
Cardiac arrest requiring CPR | 17 (0.4) |
Superficial SSI | 63 (1.4) |
Deep incisional SSI | 31 (0.7) |
Organ space SSI | 52 (1.1) |
Wound disruption | 28 (0.6) |
Minor postoperative complications | 726 (15.6) |
Intra-/postoperative blood transfusion | 588 (12.6) |
Renal insufficiency | 9 (0.2) |
Urinary tract infection | 163 (3.5) |
Discharge destination | |
Home | 3,000 (64.4) |
Nonroutine (including expired, rehab, SNF, and others) | 1,624 (34.8) |
Unknown | 38 (0.8) |
Values are presented as median (interquartile range) or number (%).
NSQIP, National Surgical Quality Improvement Project; mFI-5, modified frailty index-5; COPD, chronic obstructive pulmonary disease; CHF, congestive heart failure; SIRS, systemic inflammatory response syndrome; DVT, deep venous thrombosis; CVA, cerebrovascular accident; CPR, cardiopulmonary resuscitation; SSI, surgical site infection; SNF, skilled nursing facility.
Age data was missing for 17 patients.
Univariate analysis for age and frailty status (mFI-5 score) on outcomes after surgery in patients with spinal tumors from NSQIP database 2015–2019
Variable | Mortality | Major complication | Unplanned readmission | Reoperation | Hospital LOS | Discharge to nonhome destination | |
---|---|---|---|---|---|---|---|
Age | 1.02 (0.99–1.04) |
1.03 (1.00–1.04) |
0.99 (0.99–1.03) | 0.99 (0.98–1.00) |
0.02 (0.01–0.03) |
1.03 (1.02–1.03) |
|
Frailty status (mFI-5) | |||||||
Prefrail | 1.38 (0.71–2.7) |
1.58 (0.92–2.72) |
1.29 (1.03–1.62) |
1.39 (1.04–1.84) |
1.24 (1.09–1.67) |
1.56 (1.36–1.79) |
|
Frail | 5.73 (3.12–10.52) |
2.14 (1.27–3.61) |
1.77 (1.33–2.34) |
1.10 (0.73–1.68) | 1.89 (1.32–2.13) |
2.52 (2.10–3.02) |
|
Severely frail | 20.2 (9.40–43.4) |
3.09 (1.86–5.16) |
1.78 (0.92–3.4) |
2.13 (1.01–4.53) |
3.01 (2.15–4.35) |
2.00 (1.30–3.07) |
mFI-5, modified frailty index-5; NSQIP, National Surgical Quality Improvement Project; LOS, length of stay.
p<0.05, statistical significance (for all comparisons).
The effect of age and mFI-5 were each analyzed by univariate analyses using simple logistic regression for dichotomous outcomes or linear regression for continuous outcomes. Effect sizes were summarized by odds ratio (dichotomous outcomes) or beta coefficients (continuous outcomes) and associated 95% confidence intervals (95% confidence interval).
Multivariate analysis for age and frailty status (mFI-5 score) on outcome after surgery in patients with spinal tumors from NSQIP database 2015–2019
Variable | Mortality | Major complication | Unplanned readmission | Reoperation | Hospital LOS | Discharge to nonhome destination | |
---|---|---|---|---|---|---|---|
Age | 1.01 (0.91–1.020) |
1.00 (0.96–1.011) |
1.00 (0.976–1.012) |
0.91 (0.85–0.96) |
0.02 (0.01–0.03) |
1.02 (0.98–1.03) |
|
mFI-5 | |||||||
Prefrail | 1.31 (0.85–2.15) |
1.62 (0.98–2.23) |
1.23 (1.01–1.59) |
1.32 (1.01–1.82) |
1.21 (1.01–1.39) |
1.52 (1.33–1.75) |
|
Frail | 4.01 (3.34–9.12) |
2.20 (1.43–3.32) |
1.74 (1.21–2.04) |
1.06 (0.83–1.54) | 1.91 (1.42–2.19) |
2.48 (2.15–2.98) |
|
Severely frail | 16.4 (11.21–35.44) |
3.02 (1.97–4.56) |
1.76 (0.88–3.7) |
2.07 (1.00–4.17) |
2.94 (2.32–4.21) |
1.91 (1.25–2.88) |
mFI-5, modified frailty index-5; NSQIP, National Surgical Quality Improvement Project; LOS, length of stay.
p<0.05, statistical significance (for all comparisons).
The multivariate model was controlled for covariates: sex, body mass index, tumor location, tumor type, and operative time. The effect of age and mFI-5 were evaluated in a multivariate model using simple logistic regression for dichotomous outcomes or linear regression for continuous outcomes. Effect sizes were summarized by odds ratio (dichotomous outcomes) or beta coefficients (continuous outcomes) and associated 95% confidence intervals.