A Nationwide Comparison of Outcomes and Resource Use in Staged vs Simultaneous Cervical and Lumbar Fusions: A Retrospective Database Study

Abstract

Background: Although the coexistence of cervical and lumbar spinal conditions is fairly common, surgical treatments are usually staged, even though simultaneous fusion of the cervical and lumbar spine may be a viable option for appropriate candidates. Purpose: We sought to investigate the outcomes of staged vs simultaneous cervical and lumbar fusions in terms of differences in postoperative complications and resource use. Methods: We performed a retrospective cohort study using claims data from the 2006 to 2020 all-payer Premier Health Database. Data were extracted for patients who underwent both a cervical and a lumbar fusion procedure either simultaneously (same hospitalization) or staged (within 1 year). Multivariable regression models measured the association between simultaneous or staged procedures and combined complications (including venous thromboembolism, infection, acute renal failure, or vascular/pulmonary/gastrointestinal complications), intensive care unit (ICU) admission, and prolonged length of stay. We report odds ratios (ORs) and 95% confidence intervals (CI). Results: Overall, 560 (5.2%) and 10 187 (94.8%) of total 10 747 cervical and lumbar fusion procedures were performed simultaneously and staged, respectively. When comparing outcomes after simultaneous procedures to those after staged procedures (for which outcomes from the cervical and lumbar procedures were pooled), simultaneous procedures were associated with higher rates of ICU admission and longer hospital stays, but there were no differences in rates of combined complications. Conclusion: Our retrospective, nationwide database study found that simultaneous cervical and lumbar fusion is relatively rare and its rates of complications do not differ meaningfully from those of staged procedures. However, we found an association between simultaneous cervical and lumbar fusion and higher rates of ICU admission and prolonged length of stay. Further study is warranted.

Introduction

Spine fusion surgeries have become more common; along with an aging population comes an increase in degenerative spinal conditions [1,10]. Indeed, a continued increase in demand is expected for fusion procedures involving the cervical and lumbar spine [3,5,11,14,16]. Although the coexistence of cervical and lumbar spinal conditions is not uncommon, surgical treatments are usually staged, even though simultaneous surgery for both cervical and lumbar spine may be a viable option for appropriate candidates [4].

Research exists on other concurrent orthopedic procedures such as bilateral total knee arthroplasty (TKA) or total hip arthroplasty (THA) [12] and simultaneous anterior/posterior lumbar fusions [8], but data are limited on simultaneous cervical and lumbar fusions. Various benefits of simultaneous cervical and lumbar fusions have been proposed, suggesting that it may reduce patient costs and length of stay while yielding comparable complication rates [2,19]. Understanding the differences in postoperative outcomes between patients undergoing simultaneous and staged procedures is important to determine whether more patients could benefit from one approach or the other.

In this study, we investigated the practice of staged and simultaneous cervical and lumbar fusions to assess several postoperative complications and overall resource utilization. We hypothesized that staged procedures would result in lower complication rates but overall higher resource use and costs.

Methods

This retrospective cohort study was approved by the institutional review board at Hospital for Special Surgery (IRB#2012-050), which waived the requirement for written informed consent given the deidentified nature of the data used from an insurance database. The Premier Health Database is a comprehensive all-payer database containing detailed billing information on >25% of inpatient discharges from over 700 US hospitals [18]. We included information on patients recorded as having undergone both a cervical and a lumbar fusion procedure from January 2006 to June 2020. Inclusion criteria were International Classification of Disease 9th Revision (ICD-9) and 10th Revision (ICD-10) procedure codes: ICD-9 codes 81.02 and 81.03 and ICD-10 codes 0RG1*, 0RG2*, and 0RG4* to identify cervical fusions; ICD-9 codes 81.06, 81.07, and 81.08 and ICD-10 codes 0SG0*, 0SG1*, and 0SG3* to identify lumbar fusions. We then categorized patients into 2 groups: those who underwent both procedures simultaneously during the same hospitalization and those who underwent both procedures in a staged fashion. We excluded patients if the time difference between staged procedures was more than 1 year apart.

Of 10 747 patients who underwent both cervical and lumbar fusions, 560 (5.2%) had simultaneous procedures and 10 187 (94.8%) had staged procedures (Table 1).

Table 1.

Patient and hospital characteristics among patients undergoing simultaneous or staged fusion procedures.

	Simultaneous		Staged		P
	N	(%)	N	(%)
Total	560		10 187
Age, median [IQR]	58 [51–68]		59 [51–67]		.756
Sex					.918
Female	294	52.5	5371	52.7
Male	266	47.5	4816	47.3
Race					.003
White	418	74.6	8252	81.0
Black	55	9.8	792	7.8
Other	87	15.5	1143	11.2
Insurance					.006
Commercial	248	44.3	3999	39.3
Medicaid	27	4.8	748	7.3
Medicare	223	39.8	4504	44.2
Unknown	62	11.1	936	9.2
Comorbidity index					.001
0	396	70.7	7175	70.4
1	104	18.6	2311	22.7
2+	60	10.7	701	6.9
Region					<.0001
Midwest	105	18.8	2048	20.1
Northeast	102	18.2	1336	13.1
South	290	51.8	5086	49.9
West	63	11.3	1717	16.9
Hospital location					.639
Rural	51	9.1	989	9.7
Urban	509	90.9	9198	90.3
Hospital size					<.0001
0–299	116	20.7	2940	28.9
300–499	155	27.7	3548	34.8
500+	289	51.6	3699	36.3
Hospital teaching status					<.0001
Nonteaching	258	46.1	5646	55.4
Teaching	302	53.9	4541	44.6
Discharge status					<.0001
Home	313	55.9	7084	69.5
Facility/others	247	44.1	3103	30.5
Provider type					<.0001
Neurosurgeon	246	43.9	5083	49.9
Orthopedic surgeon	247	48.1	4080	40.1
Other	67	8.0	1024	10.0

Our primary goal was to assess postoperative complications and resource use in both groups. Postoperative complications included venous thromboembolism, vascular complications, pulmonary complications, infections, acute renal failure, and gastrointestinal complications. In addition, we combined all of the above into 1 “combined complications” variable. To assess resource utilization, we looked at intensive care unit (ICU) admission, prolonged length of stay, and median cost of hospitalization. Prolonged length of stay was defined as greater than 5 days (>80th percentile). In addition, using ICD-9 and ICD-10 diagnosis codes, we assessed primary diagnoses for all procedures (simultaneous, first staged procedure, second staged procedure). Other variables related to patients include age, sex, race, insurance type, Deyo-Charlson comorbidity index, and discharge status. Hospital-related characteristics included hospital region, urban or rural location, hospital bed size, hospital teaching status, and primary provider type (neurosurgeon, orthopedic surgeon, other).

Statistical Analysis

Unadjusted analyses (χ² tests, Mann-Whitney U tests) compared the simultaneous group to the staged group, using the data from the second of the staged procedures. Categorical variables were reported as frequencies and percentages, and continuous variables were reported as median and interquartile range. Subsequently, 3 separate multivariable logistic regression models were fitted to assess the adjusted association between simultaneous/staged procedures and (1) combined complications, (2) ICU admission, and (3) prolonged length of stay. Models were adjusted for all available covariates.

We conducted additional multivariable analyses pooling both of the staged procedures to assess the sum of postoperative complications and resource utilization in patients undergoing staged procedures; this was then compared against simultaneous procedures in 3 additional regression models.

Odds ratios (ORs) with 95% confidence intervals (CIs) and P-values are reported. All statistical analyses were conducted using SAS version 9.4 (SAS Institute, Cary, North Carolina).

Results

There was no difference between the simultaneous and staged groups in age, sex, and hospital location (Table 1). Notably, hospitals in urban and rural locations had similar percentages of simultaneous and staged procedures during the study period. We identified differences between the groups in terms of race, insurance, comorbidity index, region, hospital size, hospital teaching status, discharge status, and provider type, all P < .05. Patients with Medicaid/Medicare insurance had higher percentages of staged vs simultaneous procedures (combined 51.5% vs 44.6%, respectively), whereas patients with commercial insurance had higher percentages of simultaneous vs staged procedures (44.3% vs 39.3%, respectively). In addition, patients who had a neurosurgeon as their provider type had a higher percentage of staged vs simultaneous procedures (49.9% vs 43.9%, respectively).

The most common primary diagnoses for patients in the simultaneous group were stenosis (21.3%) and spondylosis (20.2%) (Table 2). Within the staged group, the most common primary diagnoses in the first staged procedure were spondylosis (29.7%) and stenosis (19.9%), and in the second staged procedure, stenosis (24.9%) and spondylosis (19.1%).

Table 2.

Primary diagnosis among patients undergoing simultaneous or staged fusion procedures.

	Simultaneous		Staged (1st)		Staged (2nd)
	N	(%)	N	(%)	N	(%)
Disk degeneration	49	8.8	1025	10.1	1418	13.9
Disk disorder	70	12.5	1258	12.4	889	8.7
Disk herniation	66	11.8	1533	15.1	1252	12.3
Radiculopathy	5	0.9	130	1.3	145	1.4
Spondylolisthesis	38	6.8	624	6.1	1282	12.6
Spondylosis	113	20.2	3029	29.7	1941	19.1
Stenosis	119	21.3	2025	19.9	2538	24.9
Scoliosis/kyphosis	28	5.0	82	0.8	165	1.6
Other	72	12.9	481	4.7	557	5.5

There were unadjusted differences in complications and resource use between the simultaneous group and the first and second staged procedures separately (Table 3), with the staged procedures showing lower rates. However, when data from both staged procedures were pooled, the simultaneous and staged groups had similar complication profiles but different resource use profiles, with higher ICU admission (23.80% vs 12.90%) and prolonged length of stay (41.40% vs 24.99%) but lower hospital costs ($38 736 [$26 211–$59 107] vs $44 916 [$33 644–$61 246]) in the simultaneous procedures group.

Table 3.

Incidence of complications and resource utilization among patients undergoing simultaneous or staged fusion procedures.

	Simultaneous		Staged (1st)			Staged (2nd)			Staged (total)
	N	(%)	N	(%)	P	N	(%)	P	N	(%)	P
Complications
Venous thromboembolism	6	1.10	11	0.10	<.0001	32	0.31	.003	43	0.42	.026
Vascular complications	8	1.43	74	0.73	.0631	86	0.84	.148	148	1.45	.962
Pulmonary complications	20	3.57	118	1.16	<.0001	194	1.90	.006	305	2.99	.438
All infections	30	5.36	161	1.58	<.0001	245	2.41	<.0001	397	3.89	.085
Acute renal failure	12	2.14	71	0.70	.0001	123	1.21	.053	189	1.86	.625
Gastrointestinal complications	10	1.80	85	0.83	.02	188	1.85	.918	269	2.64	.215
Combined complications	63	11.30	433	4.25	<.0001	677	6.65	<.0001	1053	10.34	.491
Resource utilization
ICU admission	133	23.80	736	7.23	<.0001	868	8.52	<.0001	1315	12.90	<.0001
Prolonged LOS (>80%)	232	41.40	1000	9.82	<.0001	1854	18.20	<.0001	2545	24.99	<.0001

After adjusting for other covariates, simultaneous procedures were associated with significantly higher odds of ICU admission (OR = 1.63 [CI = 1.31–2.02], P < .0001) and prolonged length of stay (OR = 1.57 [CI = 1.30–1.89], P < .0001) than staged procedures (Table 4).

Table 4.

Results from multivariable logistic models. ^a

Outcomes	Simultaneous vs staged (2nd)		Simultaneous vs staged (total)
	Odds ratio (95% CI)	P	Odds ratio (95% CI)	P
Intensive care unit admission	2.83 (2.27–3.52)	<.0001	1.63 (1.31–2.02)	<.0001
Combined complications	1.44 (1.08–1.91)	0.0124	0.90 (0.68–1.19)	0.4542
Prolonged length of stay	2.71 (2.23–3.30)	<.0001	1.57 (1.30–1.89)	<.0001

^aAdjusted for age, gender, race, admission type, insurance, comorbidity index, region, hospital location, hospital size, and hospital teaching status.

Discussion

In this nationwide retrospective study, we sought to understand the real-world experience of patients undergoing both cervical and lumbar fusions in a simultaneous or staged fashion. We found that nearly 95% of patients underwent staged cervical and lumbar fusion in a staged fashion. When pooled outcomes of both staged procedures were compared with outcomes of simultaneous procedures, patients in the simultaneous group were more likely to have an ICU admission and prolonged length of stay, although no major differences in combined complications were observed. Interestingly, unadjusted hospitalization costs seem to favor the simultaneous group.

This study has several limitations. First, we used data from a large health insurance database that was not prospectively collected (ie, with the specific study question in mind); we could not review operative or radiology reports, and our analysis was subject to the accuracy of data coding. However, it is expected that any potential inaccuracies in coding would be equally distributed across all groups. Second, this database does not follow patients across different hospitals, and patients who underwent staged procedures in 2 different hospitals would not be identified. Third, we could not determine the complexity of each case and the surgeon’s initial treatment plan. Patients who underwent a staged procedure may not have been indicated for the second procedure when receiving the first surgical treatment. It is also possible that patients who underwent simultaneous procedures may not have proceeded with a second procedure if they had decided to undergo their procedures in a staged fashion. Finally, we could not determine whether ICU admissions were preplanned by the surgeon in certain cases.

These findings suggest the need for an individualized approach regarding the decision to perform staged vs simultaneous cervical and lumbar fusions. This will be increasingly important as the rate of cervical [2–5] and lumbar [3,5] surgeries increase along with the aging population [1,10,15]. That we found only 5% of the procedures performed simultaneously suggests there is room for expansion. It will be crucial to determine factors associated with surgeon decision-making, gaps in the current evidence, and lessons to be learned from other staged vs simultaneous orthopedic procedures, such as anterior/posterior lumbar fusions or bilateral TKAs or THAs. The literature on simultaneous bilateral TKA or THA shows conflicting results [1,12]; for example, they have been shown to have reduced length of stay and cost in comparison to staged surgeries [13], although other studies have shown no difference between the 2 groups [9]. Some studies have shown that simultaneous cervical and lumbar procedures lead to less blood loss and shorter operative time [9,17].

Our study identified differences in several complication outcomes when comparing simultaneous surgery to each stage of the staged procedure separately, although these differences did not hold up after the comparison used combined data for both surgeries of a staged procedure. We also found that patients undergoing simultaneous procedures were more likely to have an ICU admission and prolonged length of stay than patients in the staged group. Given the complexity of the surgeries, it might be expected that simultaneous procedures would lead to a longer hospital stay or ICU admission, but we cannot determine whether either was planned preoperatively by the surgeon or triggered by events during the hospital course. However, when combining complications, we did not find a significant difference between the 2 groups, arguing against the latter. Additional research is needed on the drivers of these differences in resource use, particularly in the context of lower unadjusted costs observed among simultaneous (vs combined staged) procedures. It may be that our observed outcomes were affected by patient selection criteria (ie, that patients able to undergo more extensive surgery are seen as candidates for simultaneous procedures) or by surgeons’ familiarity with performing simultaneous procedures (a potential volume-outcome relationship). Cervical surgery is often performed first in a staged procedure, as lumbar symptoms sometimes resolve after a cervical procedure and a second surgery may not be necessary [6,7,9,10,17]. Hsiesh et al [7] found that a cohort of patients did not require a planned lumbar procedure because symptoms resolved after the cervical procedure. Therefore, the decision to undergo planned cervical and lumbar fusions simultaneously or in a staged fashion should be made on a case-by-case basis with decisions shared between the patient and the surgical team when presented with adequate evidence.

In conclusion, this nationwide retrospective database study found that nearly 95% of patients who underwent both a cervical and lumbar fusion did so in a staged fashion. When compared to combined staged procedures, simultaneous cervical and lumbar fusion was associated with higher rates of ICU admission and prolonged length of stay; no differences were observed in complication rates. More research is needed to determine whether increases in ICU admission and length of stay were planned preoperatively by the surgeon or resulted from severe complications.