Perioperative complications in patients aged ≥85 years undergoing spinal surgery: a retrospective comparative study of pre-old and old patients in Japan

Takahiro Mui; Hideki Shigematsu; Masaki Ikejiri; Sachiko Kawasaki; Yasuhito Tanaka

doi:10.31616/asj.2024.0215

Asian Spine J > Volume 18(6); 2024 > Article

Mui, Shigematsu, Ikejiri, Kawasaki, and Tanaka: Perioperative complications in patients aged ≥85 years undergoing spinal surgery: a retrospective comparative study of pre-old and old patients in Japan

Clinical Study

Asian Spine Journal 2024;18(6):856-866.

Online first: October 22, 2024

DOI: https://doi.org/10.31616/asj.2024.0215

Perioperative complications in patients aged ≥85 years undergoing spinal surgery: a retrospective comparative study of pre-old and old patients in Japan

Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Japan

Corresponding author: Hideki Shigematsu, Department of Orthopaedic Surgery, Nara Medical University, 840, Shijo-cho, Kashihara-shi, Nara, 634-8522, Japan,
Tel: +81-744-22-3051, Fax: +81-744-22-4121, E-mail: shideki@naramed-u.ac.jp

Received June 4, 2024 Revised August 21, 2024 Accepted September 1, 2024

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Study Design

A retrospective comparative study.

Purpose

To compare the characteristics of perioperative complications in patients aged ≥85 years with those of younger patients undergoing similar spine surgery and examine factors associated with perioperative complications and clinical outcomes among patients aged ≥85 years.

Overview of Literature

The risk factors for perioperative complications and their effect on outcomes in patients aged ≥85 years remain unclear. Furthermore, no study has compared younger patients with similar surgeries and condition with those aged ≥85 years.

Methods

The study included patients aged ≥65 years who underwent spinal surgeries. The patients aged ≥85, 75–84, and 65–74 years were categorized into the super-old, old, and pre-old groups, respectively. The differences in perioperative age-related complications were compared among the three groups while matching for surgical procedures and general conditions (study 1). Furthermore, preoperative and intraoperative factors were examined for perioperative complications in the super-old group (study 2). Complications were categorized into surgical site and systemic complications.

Results

The analysis included 44 patients from each group. In study 1, the total complication rates were 40.9%, 25%, and 18.2% of the super-old, old, and pre-old groups, respectively. Differences in complication rates were observed between the super-old and pre-old groups (p=0.011). In study 2, 58 patients from the super-old group were analyzed. Surgical site complications were significantly associated with longer surgical duration (p=0.02) and more estimated blood loss (p=0.003). Systemic complications were significantly associated with previous cerebrovascular disease (p=0.014), preoperative motor deficit (p=0.023), and emergency case (p=0.006) and negatively associated with diabetes mellitus (p=0.048).

Conclusions

Perioperative complications increased with advancing age in the super-old, old, and pre-old groups. The complication type is associated with specific background factors; therefore, determining them may help prevent perioperative complications.

Keywords: Spine; Perioperative; Complications; Aged; Retrospective studies

Introduction

Japan is facing a significant demographic shift owing to its rapidly aging population. In 2007, 27.4 million people (22% of the total population) were ≥65 years old, of whom 7.13 million people were ≥80 years old [1]. In 2014, 9.64 million people were ≥80 years old [2]. Spinal degenerative diseases, such as lumbar spinal stenosis, cervical spondylotic myelopathy, and osteoporotic vertebral fractures, occur more frequently in older populations [3]. The combination of this aging society and recent advances in surgical techniques and anesthesia has increased the demand for spinal surgery in older patients and the number of surgeries performed to achieve a better quality of life [4]. Aizawa et al. [5] reported that the spinal surgery rate in 2010–2014 for individuals aged ≥75 years showed a 7.1-fold increase compared with the rate in 1988–1989. In a Japanese nationwide survey, Imajo et al. [6] showed that age 70–79 years was the most frequent age range at which patients underwent spine surgery in 2011. Globally, Japan has the largest aging population, and older patients requiring spine surgery may be a target intervention group in the future.

Older patients are more likely to have comorbidities, consequently increasing the risk of perioperative complications. Imagama et al. [7] revealed that chronological age and degree of invasiveness were associated with more perioperative adverse events. To date, few studies have reported perioperative complications in extremely older patients (patients aged ≥85 years) [2,8,9]. Therefore, the risk factors for perioperative complications and their effect on the outcomes of patients aged ≥85 years remain unclear. Furthermore, no study has compared younger patients with similar surgeries with those aged ≥85 years.

In this study, we aimed to retrospectively (1) compare the characteristics of perioperative complications in patients aged ≥85 years with those of younger patients with similar conditions undergoing similar spine surgery (studies 1) and (2) investigate factors associated with perioperative complications and clinical outcomes among patients aged ≥85 years (study 2).

Materials and Methods

Ethics statement

The appropriate ethics review board approved the study design (IRB no., 3481). The need for informed consent from the patients was waived owing to the study’s retrospective design, and consent for participation was obtained using an opt-out method.

Study design and patients

The study included patients aged ≥65 years who underwent spinal surgeries between January 2007 and December 2021, excluding cases of implant removal, postoperative hematoma removal, and biopsy. Among these patients, those aged ≥85 years were categorized into the super-old group. Furthermore, patients aged 65–74 and 75–84 years were categorized into the pre-old and old groups, respectively [10].

Clinical data were collected retrospectively from patients’ medical records. the differences in perioperative age-related complications were compared among the super-old, old, and pre-old groups while matching for surgical procedures and general conditions (study 1). Furthermore, preoperative and intraoperative factors for perioperative complications in the super-old group were examined. Patients aged ≥85 years were categorized into two groups based on the presence or absence of complications. Postoperative clinical outcomes were also examined (study 2) (Fig. 1).

Demographic data

Patients’ demographic data, such as age, sex, body mass index, and whether an emergency operation was performed, were collected. Emergency operation was defined as a surgery performed within 24 hours of referral to Nara Medical University Hospital (Nara, Japan).

Clinical evaluation of surgical factors

The following data were collected from the medical records: (1) American Society of Anesthesiologists Physical Status (ASA-PS) Classification System [11]; (2) serum albumin concentration, prognostic nutritional index (PNI) [12], and geriatric nutritional risk index (GNRI) [13] to assess preoperative nutritional status; (3) percent vital capacity and forced expiratory volume in 1 second to reflect respiratory function; (4) number of oral, anticoagulant, and antiplatelet medications; (5) past medical history (diabetes mellitus, cerebrovascular disease, peripheral arterial disease, dialysis, hypertension, and ischemic heart disease); and (6) preoperative motor deficits (manual muscle testing score of ≤3).

The ASA-PS classification system summarizes and compares the preoperative health status of patients indicated for surgery [11]. The PNI score is used to assess the preoperative general status of a patient simply and conveniently and is calculated using the following formula: 10×serum albumin (g/dL)+0.005×total lymphocyte count (/μL) [12]. The GNRI is a simple and accurate tool for predicting morbidity and mortality risk in inpatients and is calculated as follows: GNRI=[1.489×serum albumin (g/dL)]+[41.7×(weight/ideal weight)]. The GNRI has the following grading system: major nutrition-related risk (<82), moderate nutrition-related risk (82 to <92), low nutrition-related risk (92 to <98), and absence of nutrition-related risk (≥98) [13].

Complications

Perioperative complications were defined as adverse events that occurred intraoperatively or within 30 days postoperatively. Complications were classified into (1) surgical site and (2) systemic complications [14]. Major systemic complications were defined as potentially life-threatening complications that led to prolonged hospitalization.

Clinical course

Preoperative mobility status and the best ambulatory mobility status at >3 months postoperatively were rated on a 4-point scale (4, independent; 3, requiring an assistive device, such as a cane or walker; 2, wheelchair; and 1, bed-ridden).

Statistical analysis

All statistical analyses were conducted using IBM SPSS Statistics for Windows ver. 28.0 (IBM Corp., Armonk, NY, USA). Operative level, disease type, surgical procedure, sex, and ASA-PS were matched across the three groups (study 1). Differences among groups were analyzed using the chi-square test. When a significant difference was observed, the two groups were further compared using the chi-square test with Bonferroni correction. To investigate factors associated with perioperative complications and clinical outcomes among patients aged ≥85 years, the patients were categorized into those with (P group) and those without (N group) complications (study 2). Between-group differences were analyzed using the t-test, Mann-Whitney U test, and the chi-square test depending on the variable type. Significance was set at p<0.05.

Results

This study included 58, 473, and 591 patients aged ≥85 years (super-old), 75–84 years (old), and 65–74 years (pre-old), respectively. After excluding patients with missing data (ASA-PS), 58 in super-old, 400 in old, and 459 in pre-old patients were analyzed. Patients in the three groups were matched by sex, operative level, disease type, surgical type, and ASA-PS, resulting in 44 patients per group for the analysis of age-related complications. In study 2, data from 58 patients in the super-old group were analyzed to identify risk factors for perioperative complications (Fig. 1).

Comparison of the differences in complications among the super-old, old, and pre-old groups (study 1)

A comparison of the three groups is presented in Table 1. The median patient ages in the three groups were 86, 79, and 70 years, respectively. The total complication rates were 40.9%, 25%, and 18.2% in the super-old, old, and pre-old groups, respectively (p=0.028) (Table 2). Significant differences were observed between the super-old and pre-old groups (p=0.011); in contrast, no significant differences were observed between the other groups (super-old and old groups, p=0.072; old and pre-old groups, p=0.437). Moreover, no significant differences in surgical site complications were observed among the three groups. However, systemic complications showed significant differences among the three groups, becoming more common with increasing age (p=0.013). Significant differences were found between the super-old and pre-old groups (p=0.006); in contrast, no significant differences were found between the other groups (super-old and old groups, p=0.070; old and pre-old groups, p=0.484). Table 2 also shows the details of complications. Two patients aged ≥85 years required reoperation: one for epidural hematoma and the other for screw inside deviation. Major systemic complications occurred in two patients aged ≥85 years (cerebrovascular disease and heart failure) and one patient in the old group (cardiac arrest due to hypoxemia).

Comparison of preoperative and intraoperative factors and clinical course between patients with and without complications in the super-old group (study 2)

Table 3 shows the details of the perioperative complications. The total complication rate was 41.3%, affecting 24 patients. Surgical site and systemic complications occurred in 10 patients (17.2%) and 16 patients (29.3%), respectively. Table 4 shows a comparison between patients with and without surgical site complications among those aged ≥85 years. Surgical site complications were significantly associated with longer surgical duration (p=0.02) and more estimated blood loss (EBL) (p=0.003) (Table 4).

Table 5 shows a comparison between patients with and without systemic complications among those aged ≥85 years. Systemic complications were significantly associated with previous cerebrovascular disease (p=0.014), preoperative motor deficit (p=0.023), and emergency case (p=0.006) and negatively with diabetes mellitus (p=0.048) (Table 5).

Table 6 shows the preoperative and postoperative mobility status. The postoperative mobility status was followed up in 51 of the 58 patients (87.9%). At least one point on the ambulatory status was improved in 37.3%, unchanged in 62.7%, and worsened in 0%. In patients without complications, 41.9% showed an improvement of at least one point postoperatively, whereas in those with complications, 30.0% showed an improvement.

Discussion

In this study, the characteristics of perioperative age-related complications in patients aged ≥85 years were evaluated and compared with those of younger patients undergoing similar spine surgery, In addition, factors associated with perioperative complications and clinical outcomes among patients aged ≥85 years were identified. The study revealed four key findings. First, perioperative complications such as surgical site complications were not significantly different among the super-old, old, and pre-old groups; however, systemic complications increased with advancing age, with significant differences found between the super-old and pre-old groups. Second, in the super-old group, surgical site complications were significantly associated with longer surgical duration and more EBL. Third, systemic complications were significantly associated with previous cerebrovascular disease, preoperative motor deficit, and emergency case and negatively with diabetes mellitus. Finally, the postoperative mobility status of patients aged ≥85 years improved by at least one point in 41.9% and 30.0% of those without and with complications, respectively.

Japan has one of the most rapidly aging populations globally, converting to an increased demand for surgeries among older patients. Spine surgeries improve the quality of life and extend the healthy life expectancy of older individuals [2]. However, to safely perform these procedures, analyzing previous complications and preventing them as early as possible are crucial.

Despite differences in the definitions of surgical complications, level, procedure, and age, previous studies have revealed that complications occur in 12%–66% of patients aged ≥85 years [2,8,9,15]. However, Imajo et al. [6] reported that perioperative complications occurred in 10.4% of all patients undergoing spine surgeries in a 2011 nationwide survey in Japan. In the present study, perioperative age-related complications occurred in 40.9%, 25%, and 18.2% of the super-old, old, and pre-old groups, respectively. Although no significant differences were found in surgical site complications, systemic complications increased with advancing age. These results may present that super-old patients have a reduced reserve capacity for surgical stress, even if their preoperative general condition is comparable with that of younger patients.

Notably, some studies have reported that preoperative motor deficits, emergency operations, comorbidities, surgical duration, EBL, number of spinal levels treated, and fusion with instrumentation are risk factors for perioperative complications [2,4,8,14,15]. In the present study, surgical site complications occurred in 17.2% of patients aged ≥85 years, and surgical duration and greater EBL were identified as risk factors. Factors such as surgical duration and EBL were associated with surgical invasiveness. Surgical invasiveness in spine surgery is a crucial considering with respect to complications, Yoshida et al. [16] showed that a sliding scale, based on preoperative factors, such as age, ASA classification, and the Charlson comorbidity index, could predict acceptable surgical invasiveness in adult spinal deformity surgeries. These predictions decrease the incidence of perioperative complications and improve the outcomes in very old patients.

In this study, systemic complications occurred in 29.3% of the patients, and delirium was the most common systemic complication. Previous studies have also uncovered that postoperative delirium commonly occurs in older patients [17,18]. Onuma et al. [19] revealed that postoperative delirium occurred in 17.7% of patients aged ≥75 years undergoing spinal surgery. Delirium is associated with postoperative mortality, postoperative neurocognitive dysfunction, extended hospitalization, and major postoperative complications and morbidity [20]. A previous study reported that the preoperative risk factors for delirium were a history of stroke, use of nonbenzodiazepine hypnotic drugs, preoperative hyponatremia, and poor nutrition [19]. In the present study, systemic complications, including delirium, were associated with previous cerebrovascular disease, preoperative motor deficit, and emergency case and negatively with diabetes mellitus. According to Deeken et al. [21], a multifaceted, multidisciplinary intervention to prevent delirium reduced the incidence of postoperative delirium and duration in patients aged ≥70 years undergoing elective orthopedic surgery. Therefore, performing surgery at an appropriate time before paralysis worsens symptoms and providing a preoperative multidisciplinary intervention for patients with risk factors for complications are necessary.

In this study, the postoperative mobility status improved in 37.3% of the patients and did not worsen; therefore, improvement can be obtained by performing surgery carefully and appropriately managing patients aged ≥85 years. Furthermore, patient satisfaction is an important treatment goal, along with other objectives. Krauss et al. [22] explored the relationship among patient expectations, satisfaction, and outcomes in cervical spine surgery and found that satisfaction was correlated with pain being the main factor influencing satisfaction. Hikata et al. [23] identified that postoperative lower back or leg pain was a risk factor for poor satisfaction in patients aged ≥80 years after lumbar spine surgery. Despite complication risk, spine surgery for older individuals is a valid option to improve their health-related quality of life. Thus, proposing surgical procedures while focusing on acceptable surgical invasiveness and a patient’s expectations and satisfaction with the procedure is essential. However, insufficient surgery may improve symptoms poorly, leading to diminished improvement in the quality of life and patient satisfaction. Therefore, shared decision-making [24], a collaborative process in which a surgeon and a patient work together to share information about treatment and management options, consider preferred outcomes, and reach an agreement on the best care package for the patient, should be more widely implemented in the future (Fig. 2).

This study has some limitations. First, the sample size was small owing to the single-institutional design, which may have led to the lack of significant differences. In the future, accumulating cases from multiple centers will be necessary. Second, only short-term outcomes were evaluated, and complications such as implant failure or adjacent intervertebral disorders were not assessed. However, in this study, we aimed to clarify perioperative complications in older patients undergoing spinal surgery and consider methods of preventing these complications. Third, selection bias was present. Except for emergency cases and cases of preoperative paralysis, the condition of the patients who opted for surgery was considered relatively well-maintained. However, frailty, which represents a state of increased vulnerability due to age-associated decline in reserve and function leading to reduced ability to cope with every day or acute stressors [25], was not directly assessed. Fourth, this was a retrospective study; thus, some patient information was missing. Particularly, minor complications may not have been recorded, and their incidence may have consequently been rated as “low.” Furthermore, the shared decision-making between patients and surgeons was not evaluated. Therefore, the effect of complications on patients remains unclear. Future prospective studies may eliminate this limitation and reveal the answer to this question. Despite these limitations, the results highlight the characteristics of complications and clinical outcomes after spinal surgery in older patients.

Conclusions

Spine surgery among extremely older patients has relatively high perioperative complication rates. Perioperative complications increased with advancing age, and significant differences were observed in the super-old and pre-old groups.

In surgeries that are expected to be long and involve high EBL, intraoperative and postoperative surgical site complications must be monitored. In addition, patients with previous cerebrovascular disease, preoperative motor deficits, or emergency surgery should be cautious of postoperative systemic complications. The determination of these factors may help prevent perioperative complications.

Key Points

The total complication rates were 40.9%, 25%, and 18.2% in the super-old, old, and pre-old groups, respectively, with significant differences between the super-old and pre-old groups.
Surgical site complications were significantly associated with longer surgical duration and higher estimated blood loss.
Systemic complications were significantly associated with previous cerebrovascular disease, preoperative motor deficit, and emergency case and negatively associated with diabetes mellitus.
The complication type is associated with specific background factors.
The postoperative mobility status of patients aged ≥85 years improved at least one point in 41.9% and 30.0% of those without and with complications, respectively.

Acknowledgments

The authors thank all of the members of the outpatient department for orthopedics in our hospital who supported our efforts and helped with this study.

Notes

Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Author Contributions

Conceptualization: HS. Methodology: TM. Investigation: TM, HS, MI, SK. Data curation: HS. Formal analysis: TM. Writing–original draft: TM. Visualization: TM. Writing–review & editing: HS. Supervision and project administration: YT. All authors read and approved the final manuscript.

Fig. 1

Study design. ASA-PS, American Society of Anesthesiologists Physical Status.

Fig. 2

Conceptual diagram of shared decision-making.

Table 1

A comparison of the patients among super-old, old, and pre-old groups

Characteristic	Patients aged ≥85 yr (n=44)	Patients aged 75–84 yr (n=44)	Patients aged 65–74 yr (n=44)	p-value
Age (yr)	86.0 (85.0–87.0)	79.0 (76.0–82.0)	70.0 (67.5–72.5)	<0.001^*
Sex, female	23 (52.3)	23 (52.3)	23 (52.3)	1
Disease				1
Generative	38 (86.4)	38(86.4)	38 (86.4)
Trauma and fracture	5 (11.4)	5(11.4)	5 (11.4)
Tumor	1 (2.3)	1 (2.3)	1 (2.3)
Cervical	18	18	18	1
Posterior decompression	16	16	16
Posterior fusion with instrumentation	2	2	2
Thoracic	3	3	3	1
Posterior decompression	1	1	1
Posterior fusion with instrumentation	1	1	1
Tumor resection	1	1	1
Lumbar	23	23	23	1
Posterior decompression	18	18	18
Posterior fusion with instrumentation	4	4	4
Anterior and posterior fusion with instrumentation	1	1	1
ASA-PS				1
2	35 (79.5)	35 (79.5)	35 (79.5)
3	9 (20.5)	9 (20.5)	9 (20.5)
No. of spinal levels treated	2.5 (1–4)	2 (0–4)	3 (2–4)	0.573
Duration of surgery (min)	168.5 (133.0–203.5)	160.5 (129.5–191.5)	158.5 (127.5–189.5)	0.823
Estimated blood loss (mL)	130 (65–195)	100 (19–181)	95 (33–157)	0.832

Values are presented as median (interquartile range), number (%), or number.

ASA-PS, American Society of Anesthesiologists Physical Status.

^* p<0.05 (significant difference).

Table 2

Details of perioperative complications for patients in each group (N=44)

Complication	Patients aged ≥85 yr	Patients aged 75–84 yr	Patients aged 65–74 yr	p-value
Total no. of patients	18 (40.9)	11 (25.0)	8 (18.2)	0.028^*
Surgical site complication	7 (15.9)^a)	5 (11.4)^b)	6 (13.6)	0.82
Details	Blood loss with transfusion (3)	Dural tear (4)	Epidural hematoma requiring re-operation (2)
	Dural tear (2)	Surficial SSI (1)	Surficial SSI (1)
	C5 palsy (2)	Nerve injury (1)	Dural tear (1)
	Epidural hematoma requiring re-operation (1)		Nerve injury (1)
	Wound disruption (1)		Pedicle screw deviation (1)
	Pedicle screw deviation (1)
Systemic complication	13 (29.5)^a)	6 (13.6)	3 (6.8)	0.013^*
Details	Delirium (9)	Delirium (4)	Delirium (3)
	Cerebrovascular disease (1)	Cardiac arrest (Hypoxemi^a) (1)
	Cardiac failure (1)	Prostatitis (1)
	Urinary tract infection (1)
	Pressure ulcer (2)
	Pleural effusion and pneumothorax (1)
	CO2 narcosis (1)

Values are presented as number or number (%).

SSI, surgical site infection.

^* p<0.05 (significant difference).

^a) Duplicates in 3 cases.

^b) Duplicates in 1 case.

Table 3

Details of perioperative complications in super-old group

Complication	No. (%)
Total^a)	24 (41.3)
Surgical site complication^b)	10 (17.2)
Blood loss with transfusion	4 (6.9)
Dural tear	3 (5.1)
C5 palsy	2 (3.4)
Epidural hematoma requiring re-operation	1 (1.7)
Deep wound infection	1 (1.7)
Wound disruption	1 (1.7)
Pedicle screw deviation	1 (1.7)
Systemic complication^b)	17 (29.3)
Delirium	11 (19.0)
Cerebrovascular disease	2 (3.4)
Cardiac failure	1 (1.7)
Urinary tract infection	1 (1.7)
Pressure ulcer	3 (5.2)
Pleural effusion and pneumothorax	1 (1.7)
CO₂ narcosis	1 (1.7)

^a) The number of patients who have surgical site complication or systemic complication.

^b) Duplicates in 3 cases.

Table 4

Relation between surgical site complication and pre- and intraoperative factors

Surgical site complication	P group	N group	p-value
No. of cases	10	48
Demographics
Age (yr)	86 (85–87)	86 (85–87)	0.668
Sex, female	6 (60.0)	23 (52.1)	0.459
Body mass index (kg/m²)	22.0±2.83	22.4±3.06	0.726
Preoperative health status
ASA-PS			0.804
1	0	2 (4.2)
2	8 (80.0)	33 (68.8)
3	2 (20.0)	13 (27.1)
Nutritional status
Serum albumin concentration	3.95 (3.8–4.1)	4 (3.8–4.2)	0.389
Prognostic nutritional index	45.8 (42.1–49.4)	45 (41.8–48.2)	0.869
Geriatric Nutritional Risk Index	99.1±8.6	100.9±7.9	0.53
Respiratory function
% vital capacity	97.8±26.5	86.2±23.7	0.195
Forced expiratory volume in 1 second	68.9 (64.7–73.1)	72.6 (66.2–79.1)	0.209
Comorbidity
Hypertension	4 (40.0)	31 (64.6)	0.138
Diabetes mellitus	0	13 (27.1)	0.06
Cerebrovascular disease	0	9 (18.8)	0.157
Ischemic heart disease	1 (10.0)	6 (12.5)	0.653
Peripheral arterial disease	1 (10.0)	1 (2.1)	0.318
Dialysis	0	0
No. of oral medications	7.2±3.0	7.2±3.3	0.79
Anticoagulant medication	1 (10.0)	4 (8.3)	0.626
Antiplatelet medication	6 (60.0)	21 (43.8)	0.278
Preoperative motor deficit	3 (30.0)	12 (25.0)	0.509
Emergency case	1 (10.0)	3 (6.3)	0.541
Lesion			0.602
Cervical	3 (30.0)	18 (37.5)
Thoracic	3 (30.0)	8 (16.7)
Lumbar	4 (40.0)	22 (45.8)
Disease			0.629
Degenerative	6 (60.0)	35 (72.9)
Trauma and fracture	2 (20.0)	7 (14.6)
Tumor	2 (20.0)	5 (10.4)
Surgical procedure			0.27
Decompression	5 (50.0)	34 (70.8)
Fusion with instrumentation	4 (40.0)	7 (14.6)
Tumor resection	1 (10.0)	4 (8.3)
Percutaneous vertebroplasty	0	3 (6.3)
Operative time (min)	251.0±100.0	160.0±65.4	0.02^*
Estimated blood loss (mL)	450 (159–742)	102 (47–157)	0.003^*
No. of spinal levels treated	2.5 (1.5–3.5)	3.0 (1.5–4.5)	0.651

Values are presented as median (interquartile range), number (%), or mean±standard deviation.

ASA-PS, American Society of Anesthesiologists Physical Status.

^* p<0.05 (significant difference).

Table 5

Relation between systemic complication and pre- and intraoperative factors

Systemic complication	P group	N group	p-value
No. of cases	17	41
Demographics
Age (yr)	87.0 (85.5–88.5)	86.0 (85.0–87.0)	0.338
Sex, female	11 (64.7)	20 (48.8)	0.387
Body mass index (kg/m²)	21.6±3.43	22.6±2.81	0.257
Preoperative health status
ASA-PS			0.878
1	0	2 (4.9)
2	12 (70.6)	29 (70.7)
3	5 (29.4)	10 (24.4)
Nutritional status
Serum albumin concentration	4 (3.75–4.25)	4 (3.85–4.15)	0.564
Prognostic nutritional index	44.5 (42.1–46.9)	46.5 (43.0–50.0)	0.113
Geriatric Nutritional Risk Index	98.6±8.0	101.3±8.0	0.247
Respiratory function
% vital capacity	80.4±28.6	90.7±22.5	0.186
Forced expiratory volume in 1 second	73.9 (65.9–81.9)	70.6 (65.0–76.3)	0.438
Comorbidity
Hypertension	10 (58.8)	25 (61.0)	0.879
Diabetes mellitus	1 (5.9)	12 (29.3)	0.048^*
Cerebrovascular disease	6 (35.3)	3 (7.3)	0.014^*
Ischemic heart disease	1 (5.9)	6 (14.6)	0.329
Peripheral arterial disease	1 (5.9)	1 (2.4)	0.504
Dialysis	0	0	1
No. oral medications	7.4±3.7	7.1±3.0	0.79
Anticoagulant medication	1 (5.9)	4 (9.8)	0.632
Antiplatelet medication	9 (52.9)	18 (43.9)	0.53
Preoperative motor deficit	8 (47.1)	7 (17.1)	0.023^*
Emergency case	4 (23.5)	0	0.006^*
Lesion			0.47
Cervical	8 (47.1)	13 (31.7)
Thoracic	2 (11.8)	9 (22.0)
Lumbar	7 (41.2)	19 (46.3)
Disease			0.228
Degenerative	10 (58.8)	31 (75.5)
Trauma and fracture	4 (23.5)	5 (12.2)
Tumor	2 (11.8)	5 (12.1)
Surgical procedure			0.431
Decompression	10 (58.8)	29 (70.7)
Fusion with instrumentation	5 (29.4)	6 (14.6)
Tumor resection	2 (11.8)	3 (7.3)
Percutaneous vertebroplasty	0	3 (7.3)
Operative time (min)	175.0 (144.5–205.5)	152.0 (103.5–200.5)	0.305
Estimated blood loss (mL)	145.0 (55.0–235.0)	72.5 (0–148.0)	0.363
No. of spinal levels treated	3 (1.5–4.5)	2 (0.5–3.5)	0.377

Values are presented as median (interquartile range), number (%), or mean±standard deviation.

ASA-PS, American Society of Anesthesiologists Physical Status.

^* p<0.05 (significant difference).

Table 6

Pre- and postoperative moving status

Preoperative moving status	Postoperative ambulatory moving status
Preoperative moving status	Bed-ridden	Wheel-chair	Assistive device	Independent	Unknown	Total
Bed-ridden	0	2 (1, 1)	4 (2, 2)	1 (0, 1)	4^a) (1, 3)	11
Wheelchair	0	2 (1, 1)	7 (5, 2)	1 (1, 0)	2 (2, 0)	12
Assistive device	0	0	25 (14, 11)	4 (4, 0)	1 (0, 1)	30
Independent	0	0	0	5 (3, 2)	0	5
Total	0	3	36	11	7	58

Values are presented as number (no complication, with complication).

^a) One patient without complication died 63 days after surgery while in the hospital due to deterioration of condition caused by malignancy of primary disease, and one patient with complication died three months after surgery due to aspiration pneumonia at the hospital to which he was transferred.

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