Clinical outcomes of posterior cervical fusion in the setting of increasing age and medical complexity: an American national database analysis from 2012 to 2022

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Asian Spine J. 2025;19(4):583-589

Publication date (electronic) : 2025 June 24

doi : https://doi.org/10.31616/asj.2024.0342

Ryan Le, Ryan Hoang, Joshua Lee, Noah Makaio Ross, Joe Morrissey, Oluwaseun Awosanya, Michael Oh, Hansen Bow, Yu-Po Lee, Nitin Bhatia

School of Medicine, The University of California Irvine, Irvine, CA, USA

Corresponding author: Yu-Po Lee, Department of Orthopaedic Surgery, School of Medicine, University of California Irvine, 1650 Newport Blvd, Costa Mesa, Irvine, CA 92627, USA, Tel: +1-714-456-7752, Fax: +1-714-456-7547, E-mail: yupol1@hs.uci.edu

Received 2024 September 2; Revised 2025 January 16; Accepted 2025 January 17.

Abstract

GRAPHICAL ABSTRACT

Introduction

Posterior cervical fusion (PCF) is a common procedure performed for various pathologies including degenerative conditions, trauma, neoplasm, infection, and deformity. Degenerative conditions, including spondylotic myelopathy and stenosis, account for the majority of PCF indications [1,2]. Cervical spondylotic myelopathy (CSM) is a common degenerative disorder; similar to other degenerative conditions, its incidence is expected to increase with age [3,4]. Symptoms include axial neck pain, upper extremity paresthesia, lack of coordination, gait disturbances, and potential incontinence with increasing severity of the disease [5]. To prevent further decline, current treatment recommendations include surgical intervention for moderate to severe and progressive symptoms. Various surgical interventions for CSM include anterior cervical decompression and fusion (ACDF), laminoplasty, posterior decompression and fusion, and the combined anterior and posterior approach [6,7].

As the US population is projected to age, the incidence of CSM will likely increase. Existing literature has demonstrated that ACDF is routinely performed on a younger population with fewer diseased levels, whereas PCF is performed in the setting of multilevel disease, which more often affects the older patient population [1,6,8]. Despite the aging population of surgical candidates, previous studies have indicated that the average age of patients undergoing cervical fusion is continuing to rise; however, it remains safe in the older population [9,10]. Given the national trend in an aging patient population and the increasing burden of CSM on the healthcare system, this study aimed to focus on the current demographics and outcomes of PCF. Drawing from previous studies of national trends in CSM surgery, this study hypothesizes that a higher number of surgical procedures will be performed on an older patient population with an increasing burden of comorbidities; however, the rates of postoperative complications are expected to remain comparable.

Materials and Methods

Results

In total, 25,537 patients who underwent PCF between 2012 and 2022 were included. The mean age was 62.14±11.89 years, and the mean BMI was 29.25±7.45 kg/m². The patient sample consisted of 10,384 female patients (40.7%) and 15,141 male patients (59.3%), of whom 18,093 (70.5%) were White.

The average patient age increased from 60.02 to 63.72 years between 2012 and 2022 (p<0.001). CHF rates consistently increased from 0.1% in 2012 to 4.3% in 2022 (p<0.001) (Table 1). Hypertension rates increased from 51.3% in 2012 to 61.4% in 2022 (p<0.001) (Table 2). DM consistently increased from 18.1% in 2012 to 24.6% in 2022 (p<0.001) (Table 1). Variations in the annual rates of 30-day pneumonia, unplanned intubation, UTI, deep vein thrombosis, reoperation, and mortality between 201 and 2022 were nonsignificant. The wound infection rates gradually increased from 2.4% in 2012 to 4.0% in 2022 (p=0.003) (Table 2). Over the study period, the LOS initially decreased from 4.18 to 3.67 days between 2012 and 2020 but increased to 4.17 days by the end of the study period (p<0.001) (Table 2). Sepsis rates increased from 1.0% in 2012 to 1.5% by 2022; however, this was not significant (p=0.738) (Table 2). Blood transfusions decreased significantly from 5.6% in 2012 to 2.8% in 2022 (p<0.001) (Table 2). Lastly, readmission within 30 days increased from 6.4% in 2012 to 6.7% in 2022 (p<0.001) (Table 2).

Table 1

Baseline demographics and comorbidities of patients undergoing posterior cervical fusion from 2012–2022

Table 2

Annual complication rates of patients undergoing posterior cervical fusion from 2012–2022

To assess whether the 3-year period following the coronavirus disease 2019 (COVID-19) pandemic was associated with increased postoperative complications, the complication rates in 2020–2022 were compared with those of 2017–2019. Notably, the rates of wound infection increased from 2.9% to 3.6% (p<0.001) and blood transfusions increased from 3.5% to 3.9% (p<0.001) (Table 3).

Table 3

Comparison of postoperative outcomes and complication rates from 2017–2019 versus 2020–2022

Discussion

When treating multilevel cervical degenerative conditions, PCF has remained the gold standard treatment whether in isolation or combination with an anterior approach. As the US population continues to increase, the incidence and average age of patients diagnosed and treated for these conditions have also continued to increase. Given that PCF is typically reserved for the older subset of patients treated for this disease, this study aimed to report the current national demographic trends and short-term outcomes for those undergoing PCF.

During the study period, the average number of cases and age of patients gradually increased, whereas the LOS decreased and postoperative complications remained comparable. The incidence of degenerative conditions such as CSM is expected to increase with age. As the average age of the US population continues to increase, it is not unexpected that the utilization of PCF will also continue to rise. In this study, patients undergoing this procedure were on average older than younger ones with increasing rates of comorbidities. Our patient cohort demonstrated significant increases in the incidence of CHF, hypertension, and DM among those undergoing PCF (Table 1). Despite these factors, spine surgeons have continued to maintain comparable complication rates while shortening LOS.

The growth in the diagnosis and treatment of common cervical degenerative conditions has been well reported in the past literature. Using the National Inpatient Sample, Vonck et al. [8] found that from 2003 to 2013, there was a 291% increase in the number of PCFs being performed and a 210.9% increase in total cervical fusions being performed for CSM. This is in line with our study period where we noted a significant rise in PCFs performed each year from 825 in 2012 to 3,197 in 2022 (p<0.001) (Table 1). Multiple factors contribute to the increased number of PCFs performed each year. Possibilities include advances in preoperative optimization, postoperative care, technology allowing for more cases to be performed safely and increasing the availability of fellowship-trained spine surgeons [8–10].

Previous literature has drawn varying conclusions regarding advanced age as an independent predictor of morbidity and mortality [1,12]. Jalai et al. [12] noted that patients aged ≥65 years had an increased average comorbidity index (0.79 vs. 0.44, p<0.0001), total complications rate (11.39% vs. 5.93%, p<0.0001), LOS (4.76 days vs. 3.26 days, p<0.0001), and risk of mortality (odds ratio, 3.38; 95% confidence interval, 2.93–3.91). Conversely, Vonck et al. [10] noted that octogenarians did not have an increased risk for experiencing multimorbidities, prolonged LOS, readmission, or reoperation when compared with their counterparts in the group aged 60–79 years. Furthermore, Oglesby et al. [9] reported a significant increase in age from 56 to 59 years and a Charlson comorbidity index from 2.79 to 3.27 in 2002–2009. Despite the increasing age and number of comorbidities, they did not note any differences in LOS and mortality rates during their study period. The results of this study support the findings of the studies by Oglesby et al. [9] and Vonck et al. [10]. The present study showed that despite the consistent increase in age and medical complexity of patients undergoing PCF, the complication rates or LOS has not significantly increased.

Aside from an aging patient population, patients had worsening medical complexity. Between 2012 and 2022, significant increases were noted in the rates of CHF, hypertension, and DM (Table 1). These findings are concerning, as multiple studies have indicated that increasing age, DM, CHF, and American Society of Anesthesiologists (ASA) classification as predictors of the overall complication rate in cervical spine surgery including unplanned intubation, prolonged intubation >48 hours, deep vein thrombosis, UTI, and SSI [13–16]. In the present study, CHF and DM rates increased from 0.1% to 4.3% and from 18.06% to 24.6%, respectively (p<0.001) (Table 1), as well as a higher proportion of patients being classified as ASA 3 (from 48.97% to 63.12%). Postoperatively, a consistent trend of increasing infection rates from 2.4% to 4.0% was noted; however, this was not significant (p=0.003). Despite this, a significant change was noted in the mortality or complication rates. Instead, a significant decrease was observed in blood transfusion requirements and LOS (Table 2). Possible protective factors noted in this study were the decrease in the smoking rate (from 27.8% to 19.4%, p<0.001). The increased awareness for preoperative optimization is another factor that potentially contributes to the maintenance of outcomes despite operating on patients with more medically complex diseases. Previous studies have shown that optimizing patients’ comorbidities and modifiable risk factors results in a decreased risk of postoperative complications [17,18]. Wang et al. [16] suggested using a standardized preoperative testing algorithm for optimizing the conditions of patients undergoing elective spine surgery. In their algorithm, possible actions include obtaining consultation from subspecialty providers and canceling or delaying procedures based on the severity of comorbidities. In doing so, surgeons can have a better understanding of their patients’ disease processes to better anticipate and prevent possible postoperative complications.

Notably, multiple complication rates including pneumonia, sepsis, and mortality appeared to transiently increase from 2020 to 2022 but without significance. These findings may be related to the COVID-19 pandemic and its effect on healthcare utilization. Our analysis of surgical cases being performed in 2019–2022 did not include the COVID-19 status; however, Chan et al. [19] reported that patients who underwent cervical spine surgery within 2 weeks of the COVID-19 diagnosis had increased rates of venous thromboembolism, sepsis, and mortality, with the 30-day mortality risk remaining increased in those undergoing PCF 2–6 weeks following the diagnosis. Furthermore, Song et al. [20] noted that those undergoing lumbar spine surgery during the pandemic had increased rates of morbidity, pneumonia, bleeding transfusions, deep venous thrombosis, and sepsis; however, these differences were not significant when controlling for baseline demographics [16]. During the pandemic, multiple recommendations were published recommending the postponement of elective cases not requiring urgent/emergent surgery; additionally, there was a large public hesitancy toward pursuing medical care given the concerns about contracting the virus. Thus, this may have biased the patient population undergoing PCF, selecting for more severe symptomatology and disability, and therefore leading to the transient increase in complications [20,21].

This study has several limitations. First, this study retrospectively examined at patients who had undergone PCF. CPT-22600 was used to screen patients who had undergone posterior arthrodesis of the cervical spine. Patients who did not meet these criteria or were miscoded were excluded, even though their cases would be relevant to the study. Although previous studies analyzed outcomes for patients undergoing PCF for CSM and degenerative conditions alone, this study did not use the International Classification of Diseases, 10th Revision codes to determine surgical indications. Thus, all patients undergoing the procedure for any indication were included in the analysis. Second, the NSQIP database was limited to the 30-day postoperative period and readmission at participating hospitals. Therefore, this study is limited in capturing longitudinal data beyond the follow-up period or at institutions that do not participate in this program. Third, NSQIP data are not specifically collected for spine surgery. Certain surgery-specific variables of interest such as the method of fusion, specific levels fused, inclusion of the upper cervical spine, number of levels fused, and type of graft used were not included in the database. If available, these data could be used to potentially identify risk factors for complications. Lastly, this was an observational study and therefore can only infer association as opposed to correlation between variables.

The strengths of this study include the use of the NSQIP database and the analysis of the dataset. NSQIP is a surgery-specific database that collects information from hundreds of institutions, allowing for a larger sample size. The data are obtained through standardized methods by nurse reviewers and regularly audited to provide highly accurate and uniform data.

Conclusions

Age and rates of comorbidities including DM, CHF, and hypertension have increased among patients undergoing PCF between 2012 and 2022, whereas complication rates have largely remained constant. Notably, the rates of blood transfusion and average LOS appeared to have improved in this time frame. These trends can inform surgeons and patients of postoperative complications where quality improvement has been successful as well as areas for improvement.

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