The Potential Risk Factors for Prolonged Length of Stay Despite an Enhanced Recovery After Surgery Protocol for Elderly Patients Undergoing Short-Level Lumbar Fusion Surgery

Abstract

Objective

To identify the risk factors associated with prolonged length of stay (LOS) despite an enhanced recovery after surgery (ERAS) protocol in short-level lumbar fusion surgery.

Methods

We gathered data for all patients undergoing short-level lumbar fusion surgery from January to November 2021. Given the discharge criteria, a threshold was set according to mean LOS, and two groups were spontaneously formed: LOS shorter than the threshold for discharge (control group, n = 114) and LOS longer or equal to the threshold for discharge (delayed group, n = 72). Preoperative metrics were compared to identify risk factors associated with prolonged LOS.

Results

A total consecutive 186 patients with complete medical records were enrolled (77 males and 109 females; mean age 71.08 ± 5.70 years). After dichotomization according to the threshold for discharge, there were 114 patients in control group and 72 in delayed group. Statistical analysis demonstrated that age ≥75 years (P = .002), female sex (P < .001), American Society of Anesthesiologists grade ≥ 3 (P = .035), operation time (P < .001), anesthesia time (P < .001), ambulation time >1 day (P = .027), removal of urinary catheter time >1 day (P = .019), fusion levels (P < .001), Clavien-Dindo grade > 1 (P <.001) and allogeneic transfusion (P = .009) were significantly related to prolonged LOS. Binary logistic regression revealed that age (odds ratio (OR) 5.149; 95% confidence interval (CI) 2.045-12.966, P = .001), sex (OR 5.185, 95% CI 2.183-12.317, P < .001) and Clavien-Dindo grade > 1(OR 15.936, 95% CI 5.220-48.652, P < .001) were independent risk factors of prolonged LOS.

Conclusions

In this retrospective study, we analyzed the potential risk factors associated with delayed LOS despite implementing ERAS, further, binary logistic regression exhibited that age ≥75 years old, female sex and Clavien-Dindo grade >1 were independently correlated with prolonged LOS.

Introduction

Kehlet proposed enhanced recovery after surgery (ERAS) in 1997,¹ which provides a multimodal, multidisciplinary management strategy.^2,3 The primary purpose of ERAS is to reduce postoperative adverse events and accelerate recovery by decreasing stress responses, shortening the length of stay (LOS) and hospitalization costs.^2,4 Compared with conventional perioperative care, ERAS has demonstrated its superiority in reducing postoperative complications and LOS.^5-9 While ERAS has been widely applied in many surgical fields,¹⁰ its use in spine surgery is in an early stage.⁷

Although there is a reduction in LOS and lower complication rates, specific patients cannot be discharged as quickly as expected despite ERAS, demonstrating that there were potential risk factors related to prolonged LOS. Hence, it is critical to elucidate the risk factors and implement customize perioperative management stratege. Previous studies reported satisfactory results after implementing ERAS in spine surgery^2,11,12; however, few studies report the risk factors correlated with prolonged LOS despite ERAS for short-level lumbar fusion surgery. Therefore, this study aimed to identify the perioperative prognostic risk factors associated with prolonged LOS and to identify customized prophylaxis protocols to facilitate function recovery and earlier discharge.

Patients and Methods

Study Design

This was a retrospective study. ERAS was implemented in January 2019. Since then, the protocol has been a part of routine perioperative care protocol in our center. The detailed information of our ERAS items is displayed in Table 1. Most of the elements follow recently published ERAS society recommendations in lumbar fusion surgery.¹³ A period from January to December 2021 was selected, and inclusion criteria were as follows: 1) lumbar disk herniation, lumbar spinal stenosis, and lumbar spondylolisthesis according to radiographic examination and magnetic resonance imaging by two experienced surgeons; 2) no history of spine surgery; 3) age greater than 65 years; and 4) short-level lumbar fusion surgery, defined as the number of fusion levels no more than two. The exclusion criteria were 1) emergency operation; 2) lack of clinical data; 3) combined surgery. Ultimately, 186 consecutive patients were recruited. And all of these patients strictly followed the same discharge criteria published by our department previously: no clinical complications; visual analog scales < 3 with oral analgesics; independent ambulation or ambulation with minimal assistance; absence of fever in the last 48 hours.¹⁴ The collected preoperative clinical data included age, sex, body mass index (BMI), smoking status, concomitant diseases, American Society of Anesthesiologists (ASA) grade, preoperative albumin, and hemoglobin levels, operation time, anesthesia time, estimated blood loss (EBL), and need for allogenic transfusion. Postoperative complications (nausea and vomiting, electrolyte imbalance, urinary retention, deep venous thrombosis, postoperative hypoproteinemia, surgical site infection, and myocardial ischemia), LOS, urinary catheter extraction time, and mobilization time were also extracted. Patient baseline characteristics are displayed in Table 2. Given one person could have more than one postoperative complications, and to simplify the impact of complications on LOS, the Clavien-Dindo Classification of Surgical Complications was utilized.¹⁵ According to the discharge criteria, in order to identify the potential risk factors for prolonged LOS, a threshold was set according to mean LOS, and two groups were spontaneously formed: LOS shorter than the threshold for discharge (control group, n = 114) and LOS longer or equal to the threshold for discharge (delayed group, n = 72). Then preoperative factors (age, sex, BMI, smoker, ASA, preoperative albumin level and hemoglobin level), intraoperative data (EBL and perioperative transfusion), and postoperative indexes (urinary catheter extraction time, mobilization time and Clavien-Dindo grade) were dichotomized as follows: age 75 years, BMI (18.5-24 kg/m², and < 18.5 kg/m² or > 24 kg/m²), ASA ≥ 3 or < 3, preoperative albumin (≥ 35 or < 35 g/L), hemoglobin level (normal: > 120 g/L in males and > 110 g/L in females or abnormal), ambulation time (≤ 1 or > 1 day), removal of urinary catheter time (≤ 1 or >1 day), Clavien-Dindo grade (≤ 1 or > 1), smoking (Yes or No) and allogeneic transfusion (Yes or No). EBL, operation time, and anesthesia time were treated as continuous variables. Univariate analysis was performed to identify the risk factors resulting in prolonged LOS. Multivariate analysis was performed to determine the independent risk factors associated with prolonged LOS for the significant factors.

Table 1.

Enhanced Recovery After Surgery Items for Short Level Lumbar Fusion Surgery.

Preoperative
Education and counseling	Informing the patients about the risk of surgery, ensuring patients to learn and understand ERAS pathway
Preoperative nutritional	Nutrition screening during the perioperative period, Dietitians provide personalized diet guidance and nutritional supplement to patients in need
Cessation of smoking and alcohol	Two weeks before operation
Anemia management	Screening routinely during the perioperative period, EPO is utilized if necessary
Fasting	Clear fluids including carbohydrate drink allowed up to 2 hours before surgery
Preanesthetic medication	The preoperative administration of acetaminophen, NSAIDs, and gabapentinoids as part of a multimodal opioid sparing analgesia strategy
Intraoperative
Antimicrobial prophylaxis	Antibiotic prophylaxis within 1 hour of incision
Tranexamic acid	Used routinely
Standard anesthetic protocol	Multimodal analgesia; TIVA-based anesthetic technique with propofol, lidocaine, ketamine, ketorolac, antiemetics and with up to .5% MAC inhaled anesthetics, avoid N2O; depth of anesthesia monitoring
Maintenance of normothermia	Keeping temperature at 36-37°C
Local infiltration analgesia	A mixture of 10 mL 2% lidocaine and 10 mL ropivacaine
Fluid management	Maintain fluid balance
Postoperative
Antithrombotic prophylaxis	Active/passive limb movement and antithrombotic stockings, venous ultrasonography of lower limbs was performed on the second day after surgery
Early oral feeding	Oral feeding at will after recovery from anesthesia
Multimodal analgesia	Visual analog scales <4: no analgesia or oral minimal dose of nonopioid; visual analog scales: 4-6: oral or intravenous nonopioid visual analog scales ≥ 7: opioid
Nausea and vomiting prophylaxis	Antiemetic drugs such as ondansetron; scopolamine were used in necessary
Ambulation on postoperative day (POD) 1	Encourage patients to ambulate as early as possible
Removal of bladder catheter on POD 1	Consider to remove bladder catheter within 24 hours in short level lumbar fusion surgery

Table 2.

Baseline Characteristics of all Patients (n = 186).

Variable	n	%
Age, years	71.08 ± 5.70
Sex
Female	109	58.6
Male	77	41.3
BMI, kg/m2	25.65 ± 3.63	15.6
Smoker	29
Operation time, min	187.61 ± 55.94
Anesthetic time, min	246.88 ± 58.35
EBL, ml	247.43 ± 199.20
Allogenetic transfusion
Yes	28	15.1
No	158	84.9
ASA
<3	93	50.0
≥3	93	50.0
LOS, day	7.16 ± 2.83
Preoperative albumin level, g/L	38.14 ± 3.02
Preoperative hemogldbin level,g/L	132.26 ± 15.30
Concomitant diseases
Hypertension	121	65.1
Diabetes	58	31.2
Cardiovascular system disease	36	19.4
Gastrointestinal	9	4.8
Osteoporosis	30	16.1
Fusion levels
1	84	45.2
2	102	54.8
Postoperative complications
Nausea and vomiting	14	7.5
Electrolyte imbalance	19	10.2
Postoperative hypoproteinemia	123	66.1
Urinary retention	1	0.5
Urinary tract infection	3	1.6
Deep venous thrombosis	8	4.3
Surgical site infection	13	7.0
Myocardial ischemia	13	7.0
Preoperative ODI,%	52.68 ± 13.12
Preoperative VAS (back)	5.04 ± 1.48
Preoperative VAS (leg)	5.63 ± 1.53

BMI: body mass index; EBL: estimated blood loss; ASA: American Society of Anesthesiologists grade; LOS: length of stay; ODI: Oswestry Disability Index; VAS: visual analog scale.

Statistical Analysis

Continuous variables were expressed as mean value ± standard deviation for normally distributed data. For non-normally-distributed data, the median and interquartile range was used. Categorical variables were expressed using proportions. Continuous variables were analyzed using the two-sample T-test, while statistical analysis for categorical variables was performed using the Chi-square test or the Fisher exact test. Binary logistic regression for multivariate analysis was used to identify the independent risk factors of prolonged LOS. All statistical analyses were performed using SPSS software version 25.0 (SPSS, Inc, Armonk, NY, USA), and P-values <.05 were considered statistically significant.

Results

Demographic Data

A total consecutive 186 patients were enrolled (77 males and 109 females; mean age 71.08 ± 5.70 years; mean BMI 25.65 ± 3.63 kg/m²; operation time and anesthesia time were 187.61 ± 55.94 mins and 246.88 ± 58.35 mins, respectively). There were 84 patients with one fusion level and 102 patients with two fusion segments. The mean EBL was 247.43 ± 199.20 mL. Twenty-eight received an allogeneic transfusion. There were 22 patients with preoperative albumin levels lower than 35 g/L and 13 patients with preoperative hemoglobin levels lower than the standard value, respectively. The preoperative Oswestry disability index was 52.68 ± 3.12, and the preoperative visual analog scale for back and leg were 5.04 ± 1.48 and 5.63 ± 1.53, respectively. The detailed demographic data are displayed in Table 2.

After dichotomization according to the threshold for discharge, there were 25 (21.9%) patients aged 75 years or older in control group with 46.5% being female and 31 (43.1%) patients in delayed group with 77.8% being female, respectively. In control group, the mean operation and anesthesia times were 175.47 ± 48.99 mins and 233.91 ± 51.37 mins, respectively, and in delayed group they were 206.84 ± 61.00 mins and 267.41 ± 63.05 mins, respectively. There were 80 (70.2%) patients ambulating and 88 (77.2%) patients who had the urinary catheter removed on postoperative day (POD) 1 in control group while 39 (54.2%) and 44 (61.1%) patients in delayed group, respectively. There were no significant difference in preoperative functional status between groups. The characteristics of these groups are detailed in Table 3.

Table 3.

Risk Factors for Prolonged Length of Stay.

Variable	Control group (n = 114)	Delayed group (n = 72)	p
Age,years			.002
<75	89	41
≥75	25	31
Sex			.000
Female	53	56
Male	61	16
ASA			.035
<3	64	29
≥3	50	43
BMI, kg/m2			.264
18.5-24	44	22
<18.5 or >24	70	50
Operation time, min	175.47 ± 48.99	206.84 ± 61.00	.000
Anesthesia time, min	233.91 ± 51.37	267.41 ± 63.05	.000
Preoperative albumin level, g/L			.104
≥35	104	60
<35	10	12
Preoperative hemoglobin level, g/L			.245
Normal	108	65
Abnormal	6	7
Ambulation time, days			.027
≤1	80	39
>1	34	33
Removal urinary catheter time, days			.019
≤1	88	44
>1	26	28
Smoker			.356
Yes	20	9
No	94	63
Allogenetic transfusion			.009
Yes	11	17
No	103	55
Fusion levels			.000
1	63	21
2	51	51
Clavien-Dindo grade			.000
≤1	105	43
>1	9	29
Preoperative ODI,%	51.04 ± 11.58	53.51 ± 13.15	0.412
Preoperative VAS (back)	4.89 ± 1.78	5.48 ± 1.57	.114
Preoperative VAS (leg)	5.56 ± 1.68	5.89 ± 1.87	.786

LOS: length of stay; ASA: American Society of Anesthesiologists grade; BMI: body mass index; ODI: Oswestry Disability Index; VAS: visual analog scale.

Compliance With the ERAS Protocol

Compliance was recorded as the number of achieved items by trained nurses and the compliance rate was defined as the number of program items observed divided by the total number of items.¹⁴ According to previous studies, higher compliance with ERAS protocols yields better outcomes.^14,16 In the present study, the overall compliance with the ERAS pathway was 92.1% (Table 4). The items with lower compliance were ambulation on POD 1 (63.9%) and removal of bladder catheter on POD 1 (70.9%). After dichotomization according to the threshold for discharge, the compliance of ambulation and removal of bladder catheter on POD 1 in control group was 70.2% (n = 80) and 77.2% (n = 88), respectively while in delayed group, they were 54.1% (n = 39) and 61.1% (n = 44), respectively (Table 3).

Table 4.

Compliance to Enhanced Recovery After Surgery Pathway.

Variable	n(%)
Preoperative
Education and counseling	180(96.8%)
Preoperative nutritional	164(88.2%)
Cessation of smoking and alcohol	186(100%)
Anemia management	173(93.1%)
Fasting	186(100%)
Preanesthetic medication	186(100%)
Intraoperative
Tranexamic acid	186(100%)
Standard anesthetic protocol	186(100%)
Maintenance of normothermia	186(100%)
Fluid management	186(100%)
Local infiltration analgesia	186(100%)
Antimicrobial prophylaxis	180(96.8%)
Postoperative
Ambulation on POD 1	119(63.9%)
Nausea and vomiting prophylaxis	176(94.6%)
Early oral feeding	162(87.1%)
Multimodal analgesia	138(74.2%)
Antithrombotic prophylaxis	171(91.9%)
Removal of bladder catheter on POD 1	132(70.9%)
Overall compliance	92.1%

Risk Factors for Prolonged LOS

There were 72 patients whose LOS was longer or equal to the threshold for discharge. Age $\ge$ 75 years (P = .002), female sex (P < .001), ASA $\ge$ 3 (P = .035), operation time (P < .001), anesthesia time (P < .001), ambulation time > 1 day (P = .027), removal of the urinary catheter time >1 day (P = .019), Clavien-Dindo grade > 1(P < .001), and allogeneic transfusion (P = .009) were significantly related to prolonged LOS. Multivariate logistic regression revealed that age older than 75 years (odds ratio (OR) 5.149; 95% confidence interval (CI) 2.045-12.966, P = .001), female (OR 5.185, 95% CI 2.183-12.317, P < .001) and Clavien-Dindo grade > 1(OR 15.936, 95% CI 5.220-48.652, P < .001) were independent risk factors for prolonged LOS (Table 5).

Table 5.

Multivariate Logistic Regression Analysis of Factors Associated with Prolonged Length of Stay.

Variable	B	OR(95%CI)	p
Operation time	.011	1.009(.953-1.027)	.576
Anesthesia time	.018	1.018(.982-1.056)	.339
Female	1.646	5.185(2.183-12.317)	.000
Age	1.639	5.149(2.045-12.966)	.001
ASA	.199	1.119(.345-1.945)	.651
Allogenetic transfusion	.635	1.888(.696-5.118)	.212
Fusion level	.517	1.678(.665-4.232)	.273
Delayed ambulation	.184	1.202(.502-2.881)	.680
Clavien-Dindo grade	2.769	15.936(5.220-48.652)	.000
Delayed removal of urinary catheter	.486	1.625(.654-4.038)	.295

Discussion

Substantial attention has been paid to the effects of compliance with ERAS and the reduction of LOS.^17-19 To our knowledge, few studies are focusing on the risk factors associated with prolonged LOS in short-level lumbar fusion surgery despite the implementation of ERAS protocol. In our study, we found that age $\ge$ 75 years, female sex, ASA $\ge$ 3, operation time, anesthesia time, delayed postoperative ambulation, prolonged removal of urinary catheter, Clavien-Dindo grade >1 and allogeneic transfusion were associated with prolonged LOS. Multivariate logistic regression revealed that age, female sex and more severe postoperative complications were independently related to prolonged LOS in short-level lumbar fusion surgery, following a previous study to some extent.^20,21 Regarding other risk factors, a rational interpretation for such an outcome was the distribution differences in the number of fusion levels. There were 51 (27.4%) patients with two fusion segments in control group and 51 (70.8%) patients in delayed group, leading to different operation and anesthesia times and the number of patients undergoing allogeneic transfusion.

In a retrospective cohort study, Li et al showed elderly patients with comorbidities are at a higher risk for complications after lumbar spine surgery.²⁰ Analogously, in a retrospective analysis of 585 patients who underwent lumbar spine surgery, Kanaan et al found male patients walked significantly longer distance than female patients, although clinically insignificant.²² In our study, we found that age older than 75 years and females were independently related to prolonged LOS despite ERAS, which reminds us of the importance of age and gender on postoperative complications, and more attention should be paid to these patients in perioperative management to prevent postoperative complications.

The increasing proportion of the aging population is generally associated with comorbidities and the postoperative complication rate following lumbar fusion surgery.^23,24 ERAS results in shorter LOS and fewer postoperative complications than conventional perioperative care.^5,10,25,26 Although ERAS has been widely applied in other surgical fields, its implementation in spine surgery, though promising, is still in the early stages.⁷ In a retrospective propensity score matching, D’Astorg et al revealed that the ERAS protocol decreased the hospital LOS (2.6 vs 4.4 days, P < .0001), while postoperative complications were similar in two groups.¹¹ In current study, according to Clavien-Dindo complication grade, we found patients with delayed LOS had more severe postoperative complications (P < .001, Table 3), and Clavien-Dindo grade > 1 was independently correlated with prolonged LOS (Table 5). What’ more, it is worth noting that despite meticulous preoperative nutritional care and early oral feeding, there were 123 patients with postoperative hypoproteinemia (Table 2). According to previous studies, preoperative nutritional status is critical for recovery after major surgery and correlated with postoperative complications and prolonged LOS,^27,28 therefore, it is essential to take additional measures to prevent severe postoperative hypoproteinemia.

Patients must actively participate in ERAS programs even though there may be reduced compliance with specific ERAS items.⁷ In our study, the items with lower compliance were ambulation on POD 1 (63.9%) and removal of bladder catheter on POD 1 (70.9%). Previously, because of the reduction of bladder function and the longer functional recovery of spine surgery, few studies explicitly illustrated the time of ambulation and removal of a bladder catheter and only stressed the concept of early ambulation and early removal of the bladder catheter.^29,30 Given the adverse events associated with prolonged bed rest and the importance of early ambulation in reducing LOS,^29,31 attention should also be paid to adverse events related to prolonged urinary drainage (urinary tract infections and surgical site infections).^32,33 In a before and after cohort study on elderly patients who underwent elective spine and peripheral nerve surgery, Ifrach et al³⁴ showed improved mobilization and ambulation on POD 0 in ERAS group, and proved the safety and feasibility of early mobilization and ambulation in this population. In the present study, patients were explicitly requested to ambulate and remove the bladder catheter on POD 1 unless there were contraindications. Only one patient developed urinary retention (Table 2) in 132 patients (Table 3) who had the bladder catheter removed on POD 1, and there were no adverse events associated with early mobilization.

The present study has several limitations. First, this was a monocentric, retrospective study, and there were some offsetting and confounding factors. Second, the small sample size limits the robustness of our findings. Thirdly, due to the characteristic of spine surgery, the severe stress response and longer functional recovery, and the feature of the elderly population, patients with more than two fusion levels were excluded. This decision may have introduced selection bias. Finally, the imbalance of distribution of fusion levels between two groups may be the results of current study, hence, studies with comparable fusion levels are needed to further explore the risk factors associated with prolonged LOS.

Conclusion

In this retrospective study, we analysed the potential risk factors associated with delayed LOS despite implementing ERAS, further, binary logistic regression exhibited that age ≥75 years old, female sex and Clavien-Dindo grade >1 were independently correlated with prolonged LOS.

ORCID iD

Shibao Lu https://orcid.org/0000-0002-6508-4458