Cost-Effectiveness of Corrective Fusion Surgeries for Adult Spinal Deformities

A Comparison by Operative Method

Hideyuki Arima, MD, PhD; Tomohiko Hasegawa, MD, PhD; Yu Yamato, MD, PhD; Masashi Kato, BS; Go Yoshida, MD, PhD; Tomohiro Banno, MD, PhD; Shin Oe, MD, PhD; Yuki Mihara, MD, PhD; Hiroki Ushirozako, MD, PhD; Tomohiro Yamada, MD; Yuh Watanabe, MD; Koichiro Ide, MD; Keiichi Nakai, MD; Kenta Kurosu, MD; Yukihiro Matsuyama, MD, PhD

Disclosures

Spine. 2021;46(18):1249-1257.

Abstract and Introduction

Abstract

Study Design: Retrospective cohort study.

Objective: The aim of this study was to summarize the cost-effectiveness of surgical treatment for adult spinal deformity (ASD) according to the operative method over 2 years postoperatively.

Summary of Background Data: Extensive corrective fusion surgery for ASD requires numerous expensive implants, greatly contributing toward the national medical expenses. Previous national studies reported high complication rates in spinal surgeries using instrumentation. However, the cost-effectiveness of such procedures has not been scrutinized.

Methods: In total, 173 ASD patients (151 women; mean age 69.1 years) who underwent corrective fusion between 2010 and 2017 were included. Cost-effectiveness was evaluated according to the cost of obtaining 1 quality-adjusted life year (QALY). Patients were divided into three groups: the "corrective fusion surgery using multiple Grade 2 osteotomy" (Grade-2) group, three-column osteotomy group (three-column), and lateral lumbar interbody fusion (LLIF) group.

Results: The average medical cost for the initial surgery was USD 72,240, and that during the 2 years after the initial surgery was USD 76,294. The medical expenses for the initial surgery and those over the 2 years were higher in the LLIF group. The cumulative improvement in QALY over the 2 years did not significantly differ among the groups (0.13, 0.15, and 0.18 in the Grade-2, three-column, and LLIF groups, respectively). Cost/QALY 2 years after the surgery was USD 509,370, 518,406, and 463,798 in the Grade-2, three-column, and LLIF groups, respectively.

Conclusion: We summarized the medical costs and cost-effectiveness of three different surgical methods for ASD in patients with different backgrounds over 2 years postoperatively. The medical expense for the initial surgery was highest in the LLIF group, and the cumulative improvement in QALY over the 2 years tended to be higher in the LLIF group, but the difference was not significant; the overall cost-effectiveness was lowest in the LLIF group.

Level of Evidence: 3

Introduction

Adult spinal deformity (ASD) includes pathological conditions such as remnants of idiopathic scoliosis, de novo kyphoscoliosis associated with disc degeneration, kyphosis after vertebral body fracture, and iatrogenic kyphosis after spinal fusion.^[1,2] Associated symptoms include gait disorder, back pain, leg pain, visceral disorders, and psychological disorders.^[1,3–5] Conservative treatments for moderate to severe ASD show poor efficacy, and surgical treatment is required to improve health-related quality of life (HRQOL) and gait disturbance.^[6,7] Surgical treatment improves HRQOL more than conservative treatments.^[8] Surgical treatment for ASD requires posterior spinal fusion from the thoracic spine to the pelvis.^[9] This extensive posterior corrective fusion may provide treatment, but the financial burden is comparable to implants. Previous national surveys reported a high incidence of complications in spinal surgeries using spinal instrumentation.^[10] Therefore, it is important to clarify the cost-effectiveness of the expensive and extensive corrective fusion surgeries for ASD. Recently, ASD surgical treatments are reported as more cost-effective than conservative treatments 4 and 5 years postoperatively.^[11] Corrective fusion using multiple Grade 2 osteotomy or three-column osteotomy (Grade 4 or 5) may be used depending on the pathological condition.^[12] The usefulness of staged surgeries using lateral lumbar interbody fusion (LLIF) has also been reported.^[13] The cost-effectiveness of each procedure has not yet been scrutinized. This study summarizes the cost-effectiveness of surgical treatment for ASD by operative method over 2 years postoperatively.

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Table 1. Demographic and Clinical Characteristics of Patients Undergoing Extensive Corrective Fusion Surgery for Adult Spinal Deformity
	Total	Grade 2 Osteotomy (n = 54)	Three-column Osteotomy (n = 54)	LLIF (n = 65)	P*	G2 vs. 3-c, P ^†	G2 vs. LLIF, P ^‡	3-c vs. LLIF, P ^§
No.	173	54	54	65
Age, y	69.1 ± 7.3	69.3 ± 7.3	68.6 ± 7.0	69.4 ± 7.5	0.817	NS	NS	NS
Female, N (%)	151 (87)	47 (87)	47 (87)	57 (88)	0.992
Body mass index, kg/m²	22.8 ± 3.6	22.5 ± 3.0	23.2 ± 4.4	22.6 ± 3.5	0.584	NS	NS	NS
Charlson Comorbidity Index	0.4 ± 0.8	0.5 ± 1.0	0.4 ± 0.6	0.4 ± 0.8	0.624	NS	NS	NS
ASA classification, N (%)
I	24 (14)	6 (11)	6 (11)	12 (19)	0.692
II	141 (81)	45 (83)	45 (83)	51 (78)
III	8 (5)	3 (6)	3 (6)	2 (3)
Pathology, N (%)
Degenerative kyphoscoliosis	94 (54)	38 (70)	5 (9)	51 (79)	<0.001
Degenerative kyphosis	39 (23)	9 (17)	20 (37)	10 (15)
Kyphosis after vertebral fracture	23 (13)	0 (0)	22 (41)	1 (2)
Iatrogenic kyphosis	9 (5)	2 (4)	6 (11)	1 (2)
Adult scoliosis	8 (5)	5 (9)	1 (2)	2 (3)

Mean values are presented as mean ± SD.
P < 0.05 was considered as significant. We defined scoliosis that started during teen years and progressed to adulthood as adult scoliosis. We defined kyphoscoliosis or kyphosis that developed during adulthood and that caused by the degeneration of spinal structures as adult degenerative kyphoscoliosis or degenerative kyphosis scoliosis. 3-c indicates 3-cloumn osteotomy; ASA, American Society of Anesthesiologists; G2, grade 2 osteotomy; LLIF, lateral lumbar interbody fusion; NS, not significant.
*Comparison between groups.
^†Post hoc comparison between Grade 2 osteotomy and three-column osteotomy.
^‡Post hoc comparison between Grade 2 osteotomy and LLIF.
^§Post hoc comparison between three-column osteotomy and LLIF.

Table 2. Surgical details
	Total	Grade 2 Osteotomy (n = 54)	Three-column Osteotomy (n = 54)	LLIF (n = 65)	P*	G2 vs. 3-c, P ^†	G2 vs. LLIF, P ^‡	3-c vs. LLIF, P ^§
No. of fused vertebrae	10.1 ± 1.8	9.8 ± 1.7	10.5 ± 2.0	10.0 ± 1.8	0.133	NS	NS	NS
UIV level, N (%)
T4	10 (6)	2 (4)	5 (9)	3 (5)	0.070
T5	9 (5)	3 (6)	2 (4)	4 (6)
T6	3 (2)	0 (0)	1 (2)	2 (3)
T7	5 (3)	1 (2)	4 (7)	0 (0)
T8	16 (9)	5 (9)	8 (15)	3 (5)
T9	35 (20)	11 (20)	10 (19)	14 (22)
T10	88 (51)	26 (48)	23 (43)	39 (60)
T11	6 (3)	5 (9)	1 (2)	0 (0)
T12	1 (1)	1 (2)	0 (0)	0 (0)
No. of pedicle screws	20.9 ± 3.4	20.3 ± 2.7	20.3 ± 3.7	21.8 ± 3.4	0.021	1.000	0.048	0.045
Screw density	2.1 ± 0.3	2.0 ± 0.4	1.9 ± 0.2	2.2 ± 0.1	< 0.001	0.185	0.053	<0.001
Iliac screw, N (%)	162 (94)	43 (80)	54 (100)	65 (100)	< 0.001
Staged surgery, N (%)	72 (42)	4 (7)	3 (6)	65 (100)	< 0.001
Total surgery time, min	436.0 ± 81.0	402.6 ± 79.7	442.8 ± 87.5	460.8 ± 66.6	< 0.001	0.021	<0.001	0.422
Total intraoperative blood loss, mL	1624.8 ± 1042.3	1863.9 ± 1166.7	2018.9 ± 1032.6	1098.8 ± 670.1	< 0.001	0.746	<0.001	<0.001
Length of hospital stay, days	37.6 ± 12.7	36.5 ± 9.2	37.0 ± 10.8	39.1 ± 16.2	0.488	NS	NS	NS
Overall perioperative complication, N (%)	55 (32)	14 (26)	16 (30)	25 (39)	0.316
Surgical complication	13 (8)	4 (7)	3 (6)	6 (9)	0.750
Neurological complication	15 (9)	3 (6)	2 (4)	10 (15)	0.049
Medical complication	36 (21)	10 (19)	13 (24)	13 (20)	0.761
Revision surgery, N (%)	29 (17)	7 (13)	17 (31)	5 (8)	0.002

Mean values are presented as mean ± SD. Bold type indicates statistical significance.
P < 0.05 was considered as significant. 3-c insicates 3-cloumn osteotomy; G2, grade 2 osteotomy; LLIF, lateral lumbar interbody fusion; NS, not significant; UIV, upper instrumented level.
*Comparison between groups.
†Post hoc comparison between Grade 2 osteotomy and three-column osteotomy.
‡Post hoc comparison between Grade 2 osteotomy and LLIF.
§Post hoc comparison between three-column osteotomy and LLIF.

Table 3. Radiographic Findings Between Groups
Parameter	Total	Grade 2 Osteotomy (n = 54)	Three-column Osteotomy (n = 54)	LLIF (n = 65)	P*	G2 vs. 3-c, P ^†	G2 vs. LLIF, P ^‡	3-c vs. LLIF, P ^§
Baseline
Thoracic kyphosis (°)	25.4 ± 20.1	25.7 ± 18.6	27.0 ± 25.3	23.8 ± 16.2	0.681	NS	NS	NS
Lumbar lordosis (°)	10.7 ± 20.4	15.2 ± 15.6	4.2 ± 27.3	12.3 ± 15.7	0.014	0.033	0.576	0.139
Pelvic tilt (°)	35.7 ± 11.2	33.7 ± 10.9	37.1 ± 12.8	36.0 ± 9.8	0.278	NS	NS	NS
Pelvic incidence minus lumbar lordosis (°)	40.9 ± 21.1	36.5 ± 16.8	48.9 ± 26.4	38.1 ± 17.5	0.003	0.005	0.904	0.013
Sagittal vertical axis, mm	116.3 ± 75.9	104.1 ± 66.9	149.7 ± 93.3	98.7 ± 56.3	<0.001	0.012	0.882	0.002
Cobb angle (°)	29.1 ± 21.0	36.0 ± 21.5	15.4 ± 13.5	34.9 ± 20.5	<0.001	<0.001	0.960	<0.001
2 y Post-surgery
Thoracic kyphosis (°)	44.3 ± 16.1	43.8 ± 12.3	43.6 ± 17.0	45.2 ± 18.2	0.828	NS	NS	NS
Lumbar lordosis (°)	42.4 ± 12.2	43.0 ± 10.7	40.1 ± 14.0	43.9 ± 11.7	0.224	NS	NS	NS
Pelvic tilt (°)	25.5 ± 9.6	26.1 ± 9.3	27.2 ± 9.5	23.7 ± 9.7	0.115	NS	NS	NS
Pelvic incidence minus lumbar lordosis (°)	11.0 ± 14.2	10.8 ± 14.1	15.8 ± 14.8	7.2 ± 12.7	0.004	0.147	0.329	0.002
Sagittal vertical axis, mm	57.9 ± 55.2	62.1 ± 56.3	78.5 ± 67.4	37.3 ± 31.6	<0.001	0.244	0.031	<0.001
Cobb angle (°)	9.3 ± 8.6	10.7 ± 10.7	6.3 ± 6.2	10.6 ± 7.7	0.007	0.026	0.997	0.003

Values are presented as mean ± SD. Bold type indicates statistical significance.
P < 0.05 was considered as significant. 3-c indicates three-cloumn osteotomy; G2, grade 2 osteotomy; LLIF, lateral lumbar interbody fusion; NS, not significant.
*Comparison between groups.
^†Post hoc comparison between Grade 2 osteotomy and three-column osteotomy.
^‡Post hoc comparison between Grade 2 osteotomy and LLIF.
^§Post hoc comparison between three-column osteotomy and LLIF.

Table 4. Clinical Outcomes Between Groups
Parameter	Total	Grade 2 Osteotomy (n = 54)	Three-column Osteotomy (n = 54)	LLIF (n = 65)	P*	G2 vs. 3-c, P ^†	G2 vs. LLIF, P ^‡	3-c vs. LLIF, P ^§
Baseline
SRS-22r Function	2.58 ± 0.68	2.54 ± 0.71	2.53 ± 0.67	2.66 ± 0.67	0.527	NS	NS	NS
SRS-22r Pain	2.98 ± 0.90	2.71 ± 0.86	3.10 ± 0.98	3.10 ± 0.84	0.034	0.065	0.054	1.000
SRS-22r Self-image	1.99 ± 0.70	2.15 ± 0.77	1.89 ± 0.60	1.95 ± 0.69	0.121	NS	NS	NS
SRS-22r Mental	2.70 ± 0.63	2.68 ± 0.69	2.67 ± 0.65	2.74 ± 0.56	0.783	NS	NS	NS
SRS-22r Satisfaction	NA	NA	NA	NA	NA	NA	NA	NA
SRS-22r Subtotal	2.51 ± 0.61	2.45 ± 0.67	2.51 ± 0.60	2.57 ± 0.57	0.550	NS	NS	NS
Oswestry Disability Index	43.6 ± 15.9	46.3 ± 16.9	44.5 ± 16.2	40.5 ± 14.3	0.119	NS	NS	NS
Modeled SF-6D scores	0.56 ± 0.08	0.54 ± 0.09	0.55 ± 0.08	0.57 ± 0.07	0.119	NS	NS	NS
2 y Post-surgery
SRS-22r Function	3.23 ± 0.74	3.07 ± 0.80	3.28 ± 0.67	3.33 ± 0.73	0.148	NS	NS	NS
SRS-22r Pain	3.82 ± 0.85	3.62 ± 0.96	3.76 ± 0.80	4.04 ± 0.75	0.020	0.673	0.025	0.126
SRS-22r Self-image	3.39 ± 0.80	3.23 ± 0.78	3.55 ± 0.73	3.39 ± 0.86	0.112	NS	NS	NS
SRS-22r Mental	3.40 ± 0.88	3.22 ± 0.93	3.50 ± 0.74	3.47 ± 0.94	0.193	NS	NS	NS
SRS-22r Satisfaction	3.60 ± 0.83	3.60 ± 0.83	3.60 ± 0.83	3.58 ± 0.83	0.991	NS	NS	NS
SRS-22r Subtotal	3.47 ± 0.67	3.32 ± 0.71	3.53 ± 0.57	3.55 ± 0.70	0.125	NS	NS	NS
Oswestry Disability Index	28.6 ± 18.1	33.6 ± 18.3	30.1 ± 19.1	23.2 ± 15.6	0.005	0.550	0.004	0.086
Modeled SF-6D scores	0.63 ± 0.09	0.61 ± 0.09	0.63 ± 0.10	0.66 ± 0.08	0.005	0.550	0.004	0.086
QALY improvements
2-y Postoperative	0.16 ± 0.19	0.13 ± 0.20	0.15 ± 0.19	0.18 ± 0.19	0.376	NS	NS	NS

Values are presented as mean ± SD. Bold type indicates statistical significance.
P < 0.05 was considered as significant. 3-c indicates three-cloumn osteotomy; G2, grade 2 osteotomy; LLIF, lateral lumbar interbody fusion; QALY, quality-adjusted life years; NA, not applicable; NS, not significant; SRS, scoliosis research society.
*Comparison between groups.
^†Post hoc comparison between Grade 2 osteotomy and three-column osteotomy.
^‡Post hoc comparison between Grade 2 osteotomy and LLIF.
^§Post hoc comparison between three-column osteotomy and LLIF.

Table 5. Comparison of 2-year Direct Cost Between Groups
Direct Costs (USD)	Total	Grade 2 Osteotomy (n = 54)	Three-column Osteotomy (n = 54)	LLIF (n = 65)	P*	G2 vs. 3-c, P ^†	G2 vs. LLIF, P ^‡	3-c vs. LLIF, P ^§
Medical expenses for initial surgery	72,240 ± 11,649	65,521 ± 12,106	68,387 ± 8038	81,023 ± 7801	<0001	0.327	<0.001	<0.001
Breakdown of the initial surgery costs (USD)
Surgical costs	58,541 ± 9385	51,414 ± 7435	54,262 ± 5335	67,380 ± 5375	<0.001	0.050	<0.001	<0.001
Examination costs	1288 ± 647	1083 ± 536	1241 ± 406	1482 ± 812	0.003	0.226	0.006	0.098
Hospital costs	7842 ± 1850	7096 ± 1947	7974 ± 1632	7974 ± 1779	0.002	0.039	0.001	0.570
2-y Total medical expenses	76,294 ± 16,681	66,942 ± 12,040	77,378 ± 20,550	83,162 ± 12,463	<0.001	0.005	0.001	0.172
Cost per QALY (USD/QALY)
2-y Postoperative	492,276	509,370	518,406	463,798	NA	NA	NA	NA

Values are presented as mean ± SD. Bold type indicates statistical significance.
P < 0.05 was considered as significant. 3-c indicates three-cloumn osteotomy; G2, grade 2 osteotomy; LLIF, lateral lumbar interbody fusion; QALY, quality-adjusted life years; NA, not applicable; NS, not significant.
*Comparison between groups.
^†Post hoc comparison between Grade 2 osteotomy and three-column osteotomy.
^‡Post hoc comparison between Grade 2 osteotomy and LLIF.
^§Post hoc comparison between three-column osteotomy and LLIF.

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Cost-Effectiveness of Corrective Fusion Surgeries for Adult Spinal Deformities

A Comparison by Operative Method

Abstract and Introduction

Abstract

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