Introduction
On a yearly basis, approximately 266 million individuals worldwide are diagnosed with degenerative disease of the lumbar spine (Ravindra et al. 2018). These degenerative diseases, including disc degeneration, spondylolisthesis, and lumbar spinal stenosis, are frequent causes of back pain and disability (Ravindra et al. 2018; Mobbs et al. 2015). Understandably, the constant symptomatic presentation of these diseases leads many individuals to experience decreased mobility and a reduced quality of life (Ravindra et al. 2018; Mobbs et al. 2015). In an effort to manage the symptoms of lumbar degenerative diseases, conservative treatments, such as physical therapy, are initially performed; however, if conservative measures fail, surgical treatment can be undertaken (Fornari et al. 2020). Lumbar interbody fusion (LIF), which in many cases is an elective procedure, is commonly performed for these degenerative pathologies (Mobbs et al. 2015).
COVID-19 was declared a worldwide pandemic by the World Health Organization (WHO) on March 11, 2020 (Cucinotta and Vanelli 2020). This pandemic immensely increased healthcare utilization, which ultimately halted elective surgical procedures, including LIF (Jain et al. 2020; Verma et al. 2020; Rizkalla et al. 2020). For this reason, it is likely that many patients at the time who wanted to undergo a LIF procedure to improve the symptoms of their degenerative diseases were not able to, unless the procedure was urgent (Rizkalla et al. 2020). Given that Cushnie et al. observed that longer preoperative symptom duration for lumbar degenerative stenosis led to less improvement in patient-reported pain and disability (Cushnie et al. 2019), the COVID-19 pandemic may have played a role in the reported patient-reported outcome measures (PROMs) following LIF.
Furthermore, the COVID-19 pandemic has been associated with higher rates of psychological distress (Xiong et al. 2020). Considering the established role that preoperative mental health plays in worse postoperative outcomes following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) (Yoo et al. 2020), patients’ mental health during the pandemic may have affected their perception of improvement following surgery.
With the ever-evolving nature of this virus, it is important to understand the impact that the COVID-19 pandemic may have on patients’ perception of their surgical outcomes. For this reason, our study compares patient-reported outcome measures (PROMs) and achievement of minimal clinically important difference (MCID) among lumbar fusion recipients before and after the start of the COVID-19 pandemic.
Methods
Patient Population
Patient informed consent and Institutional Review Board Approval (ORA #14051301) were obtained prior to the initiation of this study. A retrospective database of a single surgeon was searched for patients who underwent single- or double-level anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (LLIF), or a minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). Patients were divided into two groups based on a cut-off date for surgery (March 11th, 2020): patients receiving fusion from the cut-off date to October 2021 (19-month period), versus those receiving fusion between August 2018 and the cut-off date (19-month period). Patients who were excluded either did not meet this day of surgery criteria or underwent surgery for etiologies of infection, malignancy, or trauma.
Data Collection
Demographic characteristics and perioperative variables were collected for each cohort. Demographic characteristics included age, gender, obesity status, ethnicity, smoker status, hypertensive status, diabetic status, American Society of Anesthesiologists (ASA) score, and insurance type. Perioperative characteristics included spinal pathology, mean operative time (minutes), mean operative blood loss (milliliters), procedure type, and operative level. Spinal diagnosis listed consisted of recurrent herniated nucleus pulposus, isthmic spondylolisthesis, degenerative spondylolisthesis, degenerative scoliosis, central stenosis, and foraminal stenosis. Patient reported outcome measures (PROMs) were also collected preoperatively and at 6-weeks, 12-weeks, 6-months, and 1-year postoperative timepoints. PROMs collected included Visual Analog Scale (VAS) back/leg, Oswestry Disability Index (ODI), Patient Health Questionnaire-9 (PHQ-9), and Patient Reported Outcome Measurement Information System physical function (PROMIS-PF).
Statistical Analysis
Stata 16.0 (StataCorp LP, College Station, TX) was used to perform data analysis. Demographic, perioperative and PROM characteristics were compared with the Student’s t-test for independent samples and chi-squared analyses for continuous and categorical variables, respectively. To evaluate the effect of pre-pandemic versus pandemic status on mean PROMs, while accounting for baseline difference in type of fusion received, multiple regression analysis was performed. Thresholds established in the literature for delta PROMs determined the MCID achievement values utilized. The intergroup comparison of MCID achievement rate was evaluated with chi-squared analysis.
Results
Descriptive Analysis
The final cohort included 180 subjects, with 124 and 56 in the pre-pandemic and pandemic cohorts, respectively. The mean age was 56.2 years, with most patients being non-obese (52.8%), male (57.2%), and Caucasian (68.0%). The majority of patients were non-diabetic (89.4%), non-smokers (94.4%), without hypertension (67.2%), had an ASA classification <2 (74.6%), and private insurance (67.8%). No differences were observed in demographic characteristics (p>0.050, all; Table 1). The majority of patients presented with degenerative spondylolisthesis (48.3%), followed by isthmic spondylolisthesis (38.3%), recurrent herniated nucleus pulposus (15.0%), and degenerative scoliosis (14.4%). The majority of patients also presented with findings of central stenosis (96.7%) and foraminal stenosis (84.4%). No differences were observed among the proportion of individuals diagnosed with each of the aforementioned pathologies. However, procedure type differed significantly: The pre-pandemic cohort had significantly more LLIF performed, while a significantly greater proportion of patients received ALIF in the pandemic cohort (p=0.019). Nonetheless, the number of levels operated on did not significantly differ (with most being single-level surgeries [87.8%]), and neither did operative duration (mean of 148.4 minutes) or estimated blood loss (mean of 72.2 milliliters) (Table 2).
Primary Outcome Measures
While the pre-pandemic cohort improved from preoperative to all postoperative PROM timepoints (with the exception of the 6-week ODI/PROMIS-PF) (p≤0.025, all), the pandemic cohort experienced significant postoperative improvements at VAS back through 6 months, VAS leg at 6 weeks, ODI/PHQ-9 at 6 months, and PROMIS-PF at 12-weeks/6-months only (p≤0.037, all). Upon comparison of mean PROMs, however, no significant differences were observed between cohorts (p>0.050, all). After accounting for procedure type with multiple regression, while preoperative PHQ-9 was significantly lower in the pandemic cohort (p=0.019), no postoperative differences in any PROM (VAS back/leg, ODI, PHQ-9, PROMIS-PF) were observed between the two cohorts (p>0.050, all) (Table 3). MCID achievement rates were also comparable between the cohorts, with no substantial differences or trends in attainment observed for any PROM studied (p>0.050, all) (Table 4).
Discussion
Patients suffering from spinal disorders resulting in impaired/loss of mobility are vulnerable to aggravation of co-existing medical conditions and at increased risk for urinary tract infection (UTI), deep vein thrombosis (DVT), and pneumonia (Rizkalla et al. 2020). Consequently, the literature has suggested this patient population is at higher risk of contracting coronavirus disease 2019 (COVID-19) infection of the lungs (Rizkalla et al. 2020). On March 11, 2020, COVID-19 was declared a worldwide pandemic by the World Health Organization (WHO) (Cucinotta and Vanelli 2020). At a time when elective procedures were universally shut down, many policies had to be adapted in order for procedures like spinal surgery to resume in a manner that is safe for patients and that reduces transmission and exposure of the coronavirus in the healthcare setting (Verma et al. 2020; Rizkalla et al. 2020). For instance, it was suggested that patients who tested negative for the virus should preferably receive operative treatment at ambulatory surgery centers (ASCs) (Rizkalla et al. 2020). Patients requiring procedural management in an inpatient setting were recommended to be managed in hospitals with separate units for patients with COVID-19 versus those without (Rizkalla et al. 2020). Other effects on healthcare delivery that affected spine practices include regulations restricting volume of surgical cases, in-person clinical endeavors, and access to full staffing, thus exacerbating financial strains for providers (Weiner et al. 2020). These changes induced significantly greater worry among privademic and private practice spine providers versus those practicing in an academic setting (p=0.0025), as revenue in the formerly mentioned settings is largely dependent on the level of clinical output (Weiner et al. 2020). This is evident in the sample sizes between groups in our study, with 124 patients receiving LIF in the pre-pandemic group, but only 56 patients receiving fusion in the pandemic group.
The advent of COVID-19 has also led to considerably higher rates of anxiety (by >40%), depression (by >30%), post-traumatic stress disorder (PTSD) (by >40%), and stress (by >70%), demonstrating the powerful influence of the pandemic on wellness (Xiong et al. 2020). With the introduction of isolation and restrictions on previously routine activities, the pandemic has also induced a decrease in optimism and compromised quality-of-life for many individuals (Öztürk Çopur and Karasu 2021). As Patient-Reported Outcome Measure (PROMs) scores are used by spine surgeons to monitor quality-of-life outcomes from a patient’s perspective, the introduction of the pandemic may have significant implications on spine surgeons’ ability to rely on these scores as an accurate representation (Lee et al. 2020). Therefore, the purpose of this study was to compare patient reported outcome measures (PROMs) and achievement of minimum clinically important difference (MCID) rates across PROMs among lumbar interbody fusion (LIF) recipients before and after the declaration of the pandemic.
Perioperative Characteristics
One difference in perioperative variables was in the proportions of patients receiving a particular procedure. Three approaches of LIF were included in the patient cohort: anterior (ALIF), lateral (LLIF), and minimally invasive transforaminal (MIS TLIF) approach. ALIF in particular has proven to be efficacious and is the predominant surgical technique for discogenic lower back pain (Mobbs et al. 2015). The anterior retroperitoneal approach allows for adequate access to the entire ventral surface of the exposed disc which allows for a comprehensive discectomy and direct insertion of the implant (Mobbs et al. 2015). LLIF involves accessing the disc space through a lateral retroperitoneal, transpsoas approach (Mobbs et al. 2015). LLIF is more suitable for spinal pathologies that require access to the interbody disc from T12/L1 to L4/L5 and is not suitable for the L5/S1 level (Mobbs et al. 2015). Moreover, the TLIF approach offers direct, unilateral access to the intervertebral foraminal space while reducing direct dissection and surgical trauma to spinal muscles (Mobbs et al. 2015). TLIF can be performed via an open procedure, or more recently has moved towards an MIS technique with smaller incisions and the use of microscopy (Mobbs et al. 2015). The MIS TLIF approach may further reduce access-associated muscle injury, reduce blood loss, and improve overall postoperative recovery (Mobbs et al. 2015). Patients in the pandemic group were treated with a higher percentage of ALIF procedures while patients in the pre-pandemic group underwent a higher percentage of LLIF procedures. However, for our PROM comparison analysis, multiple regression was additionally performed to determine differences while accounting for LIF type; however, no significant postoperative differences were noted. Thus, while confounding bias may have affected our results, this effect was likely minor.
No other differences were observed among perioperative characteristics, showing that the presence of the COVID-19 pandemic likely does not influence surgical workflow (i.e., operative duration, estimated blood loss). A recent study highlighting protocols for safe and effective spinal procedures in the current day and age of a pandemic revealed that older patients with a high comorbidity burden were more likely to require ICU admission, ventilation, and/or blood transfusion (Wilson et al. 2020). Therefore, the authors recommended that surgeries should be limited or prioritized for younger, healthier patients during the pandemic (Wilson et al. 2020). Additional factors should also be taken into account when scheduling less common, yet more resource-intensive procedures (Wilson et al. 2020).
Clinical Outcomes
The PROMs evaluated in the present study included: PROM Information System physical function (PROMIS-PF), Patient Health Questionnaire-9 (PHQ-9), Visual Analog Scale (VAS) back/leg, and Oswestry Disability Index (ODI). These surveys were provided preoperatively, and at 6 weeks, 12 weeks, 6 months, and 1 year following LIF.
The patients in the pre-pandemic cohort of our study demonstrated statistically significant and lasting improvement in all PROMs including physical function, mental health, back pain, leg pain, and disability until 1 year postoperatively. One-hundred and twenty-four patients were assessed in the pre-pandemic cohort, which allows the clinical outcomes from our results to provide strong evidence that pre-pandemic lumbar fusion procedures were efficacious across all studied parameters through 1 year following surgery.
Meanwhile, the pandemic cohort (n=56) assessed in this study demonstrated more variable clinical outcomes. Significant improvements were noted, but they were sparse in quantity. Twelve-week and 6-month outcomes for physical function showed significance while only the 6-month results showed significance for depression. Six weeks to 6 months was significant for back pain, but only the 6-week postoperative time point showed significance for leg pain. Moreover, disability showed significance only at the 6-month postoperative time point. As such, no significant improvements were observed at the final timepoint (1 year) for any PROM. The lower frequency of significant improvements may indicate an impediment to recovery in Health-Related Quality of Life (HRQOL) among patients receiving surgery during the COVID-19 pandemic. Terai et al. studied 855 patients receiving spine surgery in a private clinical setting, reporting that exercise routines (p=0.004) and subsequently HRQOL (p<0.001) were significantly lower among pandemic surgical patients (Terai et al. 2021). The authors speculate this may have partially been a result of going out less frequently during the COVID-19 pandemic (Terai et al. 2021). As such, rehabilitation progress among pandemic LIF recipients may be delayed, potentially explaining our findings of scattered improvements among this patient population. Additionally, the COVID-19 pandemic has had dramatic effects on mental wellness, invoking feelings of fear, uncertainty, anxiety, and increasing the risk for psychiatric illness (i.e. panic attacks, depression, PTSD, obsessive compulsive disorder, etc.) (Anjum et al. 2020). With no finite ending to the pandemic, and constant introductions of new strains and isolation recommendations, improvements in PHQ-9 may have been subsequently deterred due to the effects of COVID-19. However, it is worthwhile mentioning that a lack of improvements for the majority of PROM timepoints could be attributed to the smaller size of the pandemic group (n=56), making significance more difficult to discern.
Upon comparison of mean scores using Student’s t-tests, no significant differences were noted between patients receiving surgery before and after declaration of the pandemic for any PROM. MCID achievement rates were also similar between groups. Multiple regression analysis was also utilized to evaluate the influence of pre-pandemic versus pandemic grouping on mean PROMs while accounting for the baseline difference in the type of lumbar fusion received (ALIF, LLIF, MIS TLIF). After accounting for this difference, significance was seen only at the preoperative timepoint for the PHQ-9 survey (with no postoperative differences in depression ratings). Aside from this difference, all other mean PROM scores and MCID achievement were similar between the two cohorts, suggesting that pre-pandemic and pandemic patients observe similar outcomes and clinically meaningful improvements in physical function, mental health, back pain, leg pain, and disability. This aligns with the findings of Cohen et al., an orthopedic study that evaluated PROMs between pre-pandemic and pandemic patients undergoing upper extremity surgery of the hand or wrist (Cohen et al. 2021). As stated by the authors, with little to no influence on difference in mean quality-of-life outcomes (as also demonstrated in our research), physicians can be more confident in the interpretation of PROMs during the COVID-19 pandemic (Cohen et al. 2021). Patients receiving fusion during the pandemic may also be reassured that perceived outcomes and clinically meaningful improvements will likely be uncompromised. This conclusion is unique to our study, as no other spinal literature to our knowledge has evaluated PROMs among spine procedure recipients before and after the inception of COVID-19. Nevertheless, to ensure optimal improvement across mental and physical health, pain, and disability, spine surgeons should encourage patients to continue recommended rehabilitation and exercise during the pandemic.
Limitations
All data was collected from procedures of a single surgeon at an academic institution, limiting the generalizability of our findings. The size discrepancy between the pre-pandemic and pandemic cohorts are a limiting factor of this study. The pandemic cohort had a much smaller sample size which could impact the clinical insight provided by the data. In addition, multiple fusion procedures were included, with discrepancies in the proportion of patients receiving one LIF approach versus another, which may carry their own differences that could confound our results. With this being a longitudinal study, loss to follow-up, especially by the 1-year timepoint, may have contributed selection bias to our results. Finally, as most patients were non-smokers, non-diabetics, non-obese, and without hypertensive disorder, our study evaluates outcomes among most individuals who may be less at risk for acquisition of the COVID-19 infection. Future studies focusing on patients with greater comorbidities may thus provide further insight on this topic. Future multicenter studies with a greater number of subjects are necessary to verify the trends presented in our analysis and increase the statistical power of the results.
Conclusion
The introduction of the COVID-19 pandemic led to a considerable decrease in surgical output, with more than a two-fold decrease in the number of LIF cases performed within the same time period. Demographic and perioperative characteristics (i.e., estimated blood loss, duration of operation) were similar whether patients received LIF prior to or during the pandemic. While pre-pandemic patients improved for almost all PROMs at almost all timepoints, pandemic patients demonstrated limited improvements from preoperative to postoperative timepoints (i.e., depression only improved from pre- to postoperative at 6 months). Nevertheless, postoperative mean PROM scores and MCID achievement rates for pain, disability, physical function, and mental health were comparable pre-pandemic and post-pandemic declaration. This suggests that lumbar spinal fusion procedures are safe and allow for similar outcomes and clinically meaningful improvements. Still, to enhance recovery during the pandemic, spine surgeons are encouraged to promote continued suggested exercise and rehabilitation efforts. A multicenter study with a larger sample size is required to confirm trends presented in this analysis and to provide further insight on this topic.