Cost and quality of life outcome analysis of postoperative infections after posterior lumbar decompression and fusion

Does surgical site infection affect patient-reported outcomes after spinal surgery? A multicenter cohort study

BACKGROUND

Surgical site infections are common in spinal surgeries. It is uncertain whether outcomes in spine surgery patients with vs. without surgical site infection are equivalent. Therefore, we assessed the effects of surgical site infection on postoperative patient-reported outcomes.

METHODS

We enrolled patients who underwent elective spine surgery at 12 hospitals between April 2017 and February 2020. We collected data regarding the patients' backgrounds, operative factors, and incidence of surgical site infection. Data for patient-reported outcomes, namely numerical rating scale, Neck Disability Index/Oswestry Disability Index, EuroQol Five-Dimensional questionnaire, and 12-Item Short-Form Health Survey scores, were obtained preoperatively and 1 year postoperatively. We divided the patients into with and without surgical site infection groups. Multivariate logistic regression analyses were performed to identify the risk factors for surgical site infection. Using propensity score matching, we obtained matched surgical site infection-negative and -positive groups. Student's t-test was used for comparisons of continuous variables, and Pearson's chi-square test was used to compare categorical variables between the two matched groups and two unmatched groups.

RESULTS

We enrolled 8861 patients in this study; 74 (0.8 %) developed surgical site infections. Cervical spine surgery and American Society of Anesthesiologists physical status classification ≥3 were identified as risk factors; microendoscopy was identified as a protective factor. Using propensity score matching, we compared surgical site infection-positive and -negative groups (74 in each group). No significant difference was found in postoperative pain or dysesthesia of the lower back, buttock, leg, and plantar area between the groups. When comparing preoperative with postoperative pain and dysesthesia, statistically significant improvement was observed for both variables in both groups (p < 0.01 for all variables). No significant differences were observed in postoperative outcomes between the matched surgical site infection-positive and -negative groups.

CONCLUSIONS

Patients with surgical site infections had comparable postoperative outcomes to those without surgical site infections.

Who Needs Surgical Stabilization for Pyogenic Spondylodiscitis? Retrospective Analysis of Non-Surgically Treated Patients

STUDY DESIGN

Retrospective case series analysis.

OBJECTIVE

To identify relevant clinical and radiographic markers for patients presenting with infectious spondylo-discitis associated with spinal instability directly related to the infectious process.

METHODS

We evaluated patients presenting with de-novo intervertebral discitis or vertebral osteomyelitis /discitis (VOD) who initiated non-surgical treatment. Patients who failed conservative treatment and required stabilization surgery within 90 days were defined as "failed treatment group" (FTG). Patients who experienced an uneventful course served as controls and were labeled as "nonsurgical group" (NSG). A wide array of baseline clinical and radiographic parameters was retrieved and compared between 2 groups.

RESULTS

Overall 35 patients had initiated non-surgical treatment for VOD. 25 patients had an uneventful course (NSG), while 10 patients failed conservative treatment ("FTG") within 90 days. Factors found to be associated with poorer outcome were intra-venous drug abuse (IVDA) as well as the presence of fever upon initial presentation. Radiographically, involvement of the same-level facets and the extent of caudal and rostral VB involvement in both MRI and CT were found to be significantly associated with poorer clinical and radiographic outcome.

CONCLUSIONS

We show that clinical factors such as IVDA status and fever as well as the extent of osseous and posterior element involvement may prove to be helpful in favoring surgical treatment early on in the management of spinal infections.

Impact of surgical-site infection on health utility values: a meta-analysis

BACKGROUND

Surgical-site infections (SSIs) are recognized as negatively affecting patient quality of life. No meta-analysis of SSI utility values is available in the literature to inform estimates of this burden and investment decisions in prevention.

METHODS

A systematic search of PubMed, MEDLINE, CINAHL, and the National Health Service Economic Evaluation Database was performed in April 2022 in accordance with PROSPERO registration CRD 42021262633. Studies were included where quality-of-life data were gathered from adults undergoing surgery, and such data were presented for those with and without an SSI at similar time points. Two researchers undertook data extraction and quality appraisal independently, with a third as arbiter. Utility values were converted to EuroQol 5D (EQ-5D™) estimates. Meta-analyses were conducted using a random-effects model across all relevant studies, with subgroup analyses on type and timing of the SSI.

RESULTS

In total, 15 studies with 2817 patients met the inclusion criteria. Six studies across seven time points were used in the meta-analysis. The pooled mean difference in EQ-5D™ utility in all studies combined was -0.08 (95 per cent c.i. -0.11 to -0.05; prediction interval -0.16 to -0.01; I2 = 40 per cent). The mean difference in EQ-5D™ utility associated with deep SSI was -0.10 (95 per cent c.i. -0.14 to -0.06; I2 = 0 per cent) and the mean difference in EQ-5D™ utility persisted over time.

CONCLUSION

The present study provides the first synthesized estimate of SSI burden over the short and long term. EQ-5D™ utility estimates for a range of SSIs are essential for infection prevention planning and future economic modelling.

Intrawound low-dose vancomycin is superior to high-dose in controlling the risk of wound dehiscence in spine surgeries

Wound complications in spine surgeries are common and serious. This study aimed to determine the risk of wound dehiscence with a low-dose of intrawound vancomycin compared to that with a high-dose and no-vancomycin and its effectiveness in the prevention of surgical site infection. Patients were categorized into 3 groups. The first group did not receive any intrawound vancomycin. In the second, patients received a high-dose of vancomycin (1 g). The third group included patients who received a low-dose of intrawound vancomycin (250 mg). Patient demographics, clinical data, and surgical data were also collected. Multivariate linear regression analysis was used to examine factors associated with dehiscence or infection. Of the 391 patients included in our study, 56 (14.3%) received a high-dose of intrawound vancomycin, 126 (32.2%) received a low-dose, and 209 (53.5%) did not receive any treatment. The overall incidence of wound dehiscence was 6.14% (24 out of 391 patients). Wound dehiscence was significantly higher (P = .039) in the high-dose vancomycin group than in the low-dose vancomycin group. The overall incidence of postoperative infection was 2.05% (8 patients) and no statistically significant differences were observed between the low-dose and high-dose vancomycin groups. Patients with higher body mass index were more likely to experience wound dehiscence and postoperative infection, irrespective of the dose of vancomycin used. The use of low-dose intrawound vancomycin (250 mg) resulted in less wound dehiscence compared with high-dose vancomycin. Further trials are required to evaluate the effectiveness of the low-dose in preventing postoperative infections.

Methodology of economic evaluations in spine surgery: a systematic review and qualitative assessment

OBJECTIVES

The present study is a systematic review conducted as part of a methodological approach to develop evidence-based recommendations for economic evaluations in spine surgery. The aim of this systematic review is to evaluate the methodology and quality of currently available clinical cost-effectiveness studies in spine surgery.

STUDY DESIGN

Systematic literature review.

DATA SOURCES

PubMed, Web of Science, Embase, Cochrane, Cumulative Index to Nursing and Allied Health Literature, EconLit and The National Institute for Health Research Economic Evaluation Database were searched through 8 December 2022.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies were included if they met all of the following eligibility criteria: (1) spine surgery, (2) the study cost-effectiveness and (3) clinical study. Model-based studies were excluded.

DATA EXTRACTION AND SYNTHESIS

The following data items were extracted and evaluated: pathology, number of participants, intervention(s), year, country, study design, time horizon, comparator(s), utility measurement, effectivity measurement, costs measured, perspective, main result and study quality.

RESULTS

130 economic evaluations were included. Seventy-four of these studies were retrospective studies. The majority of the studies had a time horizon shorter than 2 years. Utility measures varied between the EuroQol 5 dimensions and variations of the Short-Form Health Survey. Effect measures varied widely between Visual Analogue Scale for pain, Neck Disability Index, Oswestry Disability Index, reoperation rates and adverse events. All studies included direct costs from a healthcare perspective. Indirect costs were included in 47 studies. Total Consensus Health Economic Criteria scores ranged from 2 to 18, with a mean score of 12.0 over all 130 studies.

CONCLUSIONS

The comparability of economic evaluations in spine surgery is extremely low due to different study designs, follow-up duration and outcome measurements such as utility, effectiveness and costs. This illustrates the need for uniformity in conducting and reporting economic evaluations in spine surgery.

Surgical site infection in thoracic and lumbar fractures: incidence and risk factors in 11,401 patients from a nationwide administrative database

BACKGROUND CONTEXT

The rate of surgical site infection (SSI) following elective spine surgery ranges from 0.5%‒10%. Published reports suggest a higher SSI rate in non-elective spine surgery such as spine trauma; however, there is a paucity of large database studies examining this issue.

PURPOSE

The objective of this study was to investigate the incidence and risk factors of SSI in patients undergoing spine surgery for thoracic and lumbar fractures in a large population database.

STUDY DESIGN/SETTING

This is a retrospective study utilizing the PearlDiver Patient Claims Database.

PATIENT SAMPLE

Patients undergoing spine surgery for thoracic and lumbar fractures between 2015-2020 were identified in the PearlDiver Patient Claims Database using ICD-10 codes. Patients were excluded who had another surgery either 14 days before or 21 days after the index spine surgery, or pathologic fracture.

OUTCOME MEASURES

Rate of surgical site infection.

METHODS

Clinical data collected from the PearlDiver database based on ICD-10 codes included gender, age, diabetes, smoking status, obesity, Elixhauser Comorbidity Index (ECI), Charlson Comorbidity Index (CCI), and SSI. Univariate analysis was used to assess the association of potential risk factors and SSI. Multivariable analysis was used to identify independent risk factors of SSI. The authors have no conflicts of interest or funding sources to declare.

RESULTS

A total of 11,401 patients undergoing spine surgery for thoracic and lumbar fractures met inclusion criteria, and 1,065 patients were excluded. 860 patients developed SSI (7.5%). Risk factors significantly associated with SSI in univariate analysis included diabetes (OR 1.50; 95% CI, 1.30‒1.73; p<.001), obesity (OR 1.66; 95% CI, 1.44‒1.92; p<.001), increased age (p<.001), ECI (p<.001), and CCI (p<.001). On multivariable analysis, obesity and ECI were independently associated with SSI (p<.001 and p<.001, respectively).

CONCLUSIONS

Non-elective surgery for thoracic and lumbar fractures is associated with a 7.5% risk of SSI. Obesity and ECI are independent predictors of SSI in this population. Limitations include the reliance on accurate insurance coding which may not fully capture all SSI, and in particular superficial SSI. These findings provide a broad overview of the risk of SSI in this population at a national level and may also help counsel patients regarding risk.

A Machine Learning-Based Online Prediction Tool for Predicting Short-Term Postoperative Outcomes Following Spinal Tumor Resections

Background: Preoperative prediction of short-term postoperative outcomes in spinal tumor patients can lead to more precise patient care plans that reduce the likelihood of negative outcomes. With this study, we aimed to develop machine learning algorithms for predicting short-term postoperative outcomes and implement these models in an open-source web application. Methods: Patients who underwent surgical resection of spinal tumors were identified using the American College of Surgeons, National Surgical Quality Improvement Program. Three outcomes were predicted: prolonged length of stay (LOS), nonhome discharges, and major complications. Four machine learning algorithms were developed and integrated into an open access web application to predict these outcomes. Results: A total of 3073 patients that underwent spinal tumor resection were included in the analysis. The most accurately predicted outcomes in terms of the area under the receiver operating characteristic curve (AUROC) was the prolonged LOS with a mean AUROC of 0.745 The most accurately predicting algorithm in terms of AUROC was random forest, with a mean AUROC of 0.743. An open access web application was developed for getting predictions for individual patients based on their characteristics and this web application can be accessed here: huggingface.co/spaces/MSHS-Neurosurgery-Research/NSQIP-ST. Conclusion: Machine learning approaches carry significant potential for the purpose of predicting postoperative outcomes following spinal tumor resections. Development of predictive models as clinically useful decision-making tools may considerably enhance risk assessment and prognosis as the amount of data in spinal tumor surgery continues to rise.

Surgical wound care preferences and priorities from the perspectives of patients: a qualitative analysis

OBJECTIVE

To explore patients' priorities and preferences for optimal care of their acute or hard-to-heal surgical wound(s).

METHOD

This qualitative study involved semi-structured individual interviews with patients receiving wound care in Queensland, Australia. Convenience and snowball sampling were used to recruit patients from inpatient and outpatient settings between November 2019 and January 2020. Interviews were audio recorded, transcribed verbatim and analysed using thematic analysis. Emergent themes were discussed by all investigators to ensure consensus.

RESULTS

A total of eight patients were interviewed, five of whom were male (average median age: 70.5 years; interquartile range (IQR): 45-80 years). Four interrelated themes emerged from the data that describe the patients' surgical wound journey: experiencing psychological and psychosocial challenges; taking back control by actively engaging in care; seeking out essential clinician attributes; and collaborating with clinicians to enable an individualised approach to their wound care.

CONCLUSION

Findings from this study indicate that patients want to actively collaborate with clinicians who have caring qualities, professional skills and knowledge, and be involved in decision-making to ensure care meets their individual needs.

Risk and economic burden of surgical site infection following spinal fusion in adults

BACKGROUND

Spinal fusion surgery (SFS) is one of the most common operations in the United States, >450,000 SFSs are performed annually, incurring annual costs >$10 billion.

OBJECTIVES

We used a nationwide longitudinal database to accurately assess incidence and payments associated with management of postoperative infection following SFS.

METHODS

We conducted a retrospective, observational cohort analysis of 210,019 patients undergoing SFS from 2014 to 2018 using IBM MarketScan commercial and Medicaid-Medicare databases. We assessed rates of superficial/deep incisional SSIs, from 3 to 180 days after surgery using Cox proportional hazard regression models. To evaluate adjusted payments for patients with/without SSIs, adjusted for inflation to 2019 Consumer Price Index, we used generalized linear regression models with log-link and γ distribution.

RESULTS

Overall, 6.6% of patients experienced an SSI, 1.7% superficial SSIs and 4.9% deep-incisional SSIs, with a median of 44 days to presentation for superficial SSIs and 28 days for deep-incisional SSIs. Selective risk factors included surgical approach, admission type, payer, and higher comorbidity score. Postoperative incremental commercial payments for patients with superficial SSI were $20,800 at 6 months, $26,937 at 12 months, and $32,821 at 24 months; incremental payments for patients with deep-incisional SSI were $59,766 at 6 months, $74,875 at 12 months, and $93,741 at 24 months. Corresponding incremental Medicare payments for patients with superficial incisional at 6, 12, 24-months were $11,044, $17,967, and $24,096; while payments for patients with deep-infection were: $48,662, $53,757, and $73,803 at 6, 12, 24-months.

CONCLUSIONS

We identified a 4.9% rate of deep infection following SFS, with substantial payer burden. The findings suggest that the implementation of robust evidence-based surgical-care bundles to mitigate postoperative SFS infection is warranted.

Independent risk factor for surgical site infection after orthopedic surgery

No significant progress has been made in the study of orthopedic surgical site infection (SSI) after different orthopedic surgery, and the analysis and prevention of risk factors for orthopedic SSI urgently need to be solved. A total of 154 patients underwent orthopedic surgery from April 2018 to December 2020. General information such as gender, age, marriage, diagnosis, surgical site, and anesthesia method was recorded. Statistical methods included Pearson chi-square test, univariate and multivariate logistic regression analyses, and receiver operating characteristic (ROC) curves. Based on Pearson's chi-square test, sex (P = .005), age (P = .027), marriage (P = .000), diagnosis (P = .034), and surgical site (P = .000) were significantly associated with SSI after orthopedic surgery. However, in the multiple linear regression analysis, only the surgical site (P = .035) was significantly associated with SSI after orthopedic surgery. In terms of multivariate logistic regression level, surgical site (odds ratio [OR] = 1.568, P = .039) was significantly associated with SSI. ROC curves were constructed to determine the effect of the surgical site on SSI after different orthopedic surgery (area under the curve [AUC] = 0.577, 95% CI = 0.487-0.0.666). In summary, the surgical site is an independent risk factor for SSI after orthopedic surgery, and "trauma" is more likely to develop SSI than spine, arthrosis, and others.

Use of an intraoperative sodium oxychlorosene-based infection prevention protocol to safely decrease postoperative wound infections after spine surgery

OBJECTIVE

Postoperative infection remains prevalent after spinal surgical procedures. Institutional protocols for infection prevention have improved rates of infection after spine surgery. However, prior studies have focused on only elective surgical patients. The aim of this study was to determine the efficacy of a multiinstitutional intraoperative sodium oxychlorosene-based infection prevention protocol for decreasing rate of infection after instrumented spinal surgery.

METHODS

A retrospective analysis was performed at two tertiary care institutions with level I trauma programs, and patients who underwent posterior instrumented spinal fusion between January 1, 2011, and May 31, 2019, were included. Postoperative deep wound infection rates were captured before and after implementation of a multiinstitutional infection prevention protocol. Possible adverse outcomes related to infection prevention techniques were also examined. In addition, consecutive patients treated from January 1, 2018, to May 31, 2019, were prospectively included in a database to collect preoperative and postoperative spine-specific quality of life measures and to assess the impact of postoperative infection on quality of life.

RESULTS

A total of 5047 patients fit the inclusion criteria. Of these, 1043 patients underwent surgery prior to protocol implementation. The infection rate of this cohort (3.5%) decreased significantly after protocol implementation (1.2%, p < 0.001). Postoperative sterile seroma rates did not differ between the preprotocol and postprotocol groups (0.7% vs 0.7%, p = 0.5). In the 1031 patients who underwent surgery between January 2018 and May 2019, the fusion rate was 89.2%. Quality of life outcomes between patients with infection and those without infection were similar, although statistical power was limited owing to the low rate of infection. Notably, 2 of 10 patients who developed deep wound infection died of infection-related complications.

CONCLUSIONS

An intraoperative sodium oxychlorosene-based infection prevention protocol helped to significantly decrease the rate of infection after spine surgery without negatively impacting other postoperative procedure-related metrics. Postoperative wound infection may be associated with higher-than-expected rate of postoperative mortality.

Is It Cost Effective to Obtain Fungal and Acid-Fast Bacillus Cultures during Spine Debridement?

Study Design

Retrospective study.

Purpose

To identify the rate of positive acid-fast bacillus (AFB) and fungal cultures during spine debridement, determine whether these infections are more common in certain spine segments, identify comorbidities associated with these infections, and determine whether the universal performance of fungal and AFB cultures during spine debridement is cost effective.

Overview of Literature

Spine infections are associated with significant morbidity and costs. Spine fungal and AFB infections are rare, but their incidence has not been well documented. As such, guidance regarding sample procurement for AFB and fungal cultures is lacking.

Methods

A retrospective review of medical record data from patients undergoing spine irrigation and debridement (I&D) at the University of Missouri over a 10-year period was performed.

Results

For patients undergoing spine I&D, there was a 4% incidence of fungal infection and 0.49% rate of AFB infection. Steroid use was associated with a higher likelihood (odds ratio, 5.62; 95% confidence interval, 1.33–23.75) of positive fungal or AFB cultures. Although not significant, patients undergoing multiple I&D procedures had higher rates of positive fungal cultures during each subsequent I&D. Over a 10-year period, if fungal cultures are obtained for each patient, it would cost our healthcare system $12,151.58. This is compared to an average cost of $177,297.64 per missed fungal infection requiring subsequent treatment.

Conclusions

Spine fungal infections occur infrequently at a rate of 4%. Physicians should strongly consider obtaining samples for fungal cultures in patients undergoing spine I&D, especially those using steroids and those undergoing multiple I&Ds. Our AFB culture rates mirror the false positive rates seen in previous orthopedic literature. It is unlikely to be cost effective to send for AFB cultures in areas with low endemic rates of AFB.

Risk factors for prolonged length of stay in patients undergoing surgery for intramedullary spinal cord tumors

Primary spine tumors are rare neoplasms that affect about 0.62 per 100,000 individuals in the US. Intramedullary spinal cord tumors (IMSCTs) are the rarest of all primary tumors involving the spine and can cause pain, imbalance, urinary dysfunction and neurological deficits. These types of tumors oftentimes necessitate surgical treatment, yet there is a lack of data on hospital length of stay and complication rates following treatment. Given that treatment candidacy, quality of life, and outcomes are tied so closely to potential for prolonged length of stay and postoperative complications, it is important to better understand the factors that increase the risk of these outcomes in patients with IMSCTs.

METHODS

The National Surgical Quality Improvement Program (NSQIP) database was queried for all patients undergoing surgery for treatment of intramedullary spinal cord tumors between 2005 and 2017. Univariate and multivariate analysis were performed to assess patient risk factors influencing prolonged length of stay and post-op complications.

RESULTS

A total of 638 patients were included in the analysis. Pre-operative American Society of Anesthesiology (ASA) physical status classification of 3 and above (OR 1.89; p = 0.0005), dependent functional status (OR 2.76; p = 0.0035) and transfer from facilities other than home (OR 8.12; p <0.0001) were independent predictors of prolonged length of stay (>5 days). The most commonly reported complications were pneumonia (5.7%), urinary tract infection (9.4%), septic shock (3.8%), superficial incisional infection (5.7%), organ or space infection (5.7%), pulmonary embolism (11.3%), DVT requiring therapy (15.1%) and wound dehiscence (5.7%).

CONCLUSION

Our study demonstrated the significant influence of clinical variables on prolonged hospitalization of IMSCT patients. This should be factored into clinical and surgical decision making and when counseling patients of their expected outcomes.

Accuracy of hospital-based surveillance systems for surgical site infection after adult spine surgery: A Bayesian latent class analysis

BACKGROUND

Surgical site infections (SSIs) of the spine are morbid and costly complications. An accurate surveillance system is required to properly describe the disease burden and the impact of interventions that mitigate SSI risk. Unfortunately, uniform approaches to conducting SSI surveillance are lacking because of varying SSI case definitions, the lack of a perfect reference case definition and heterogeneous data sources.

AIM

We assessed the accuracy of 4 independent data sources that capture SSIs after spine surgery, with estimation of a measurement error-adjusted SSI incidence.

METHODS

A Bayesian latent class model assessed the sensitivity/specificity of each data source to identify SSI and to estimate a measurement-error adjusted incidence. The four data sources used were: the discharge abstract database (DAD), the National Surgical Quality Improvement Program (NSQIP) database, the Infection Prevention and Control Canada (IPAC) database, and the Spine Adverse Events Severity database.

FINDINGS

A total of 904 patients underwent spine surgery in 2017. The most sensitive data source was DAD (0.799, 95% CrI 0.597, 0.943), while the least sensitive was NSQIP (0.497, 95% CrI 0.308, 0.694). The most specific data source was IPAC (0.997, 95% CrI 0.993, 1.000) and the least specific was DAD (0.969, 95% CrI 0.956, 0.981). The measurement error-adjusted SSI incidence was 0.030 (95% CrI 0.019, 0.045). The crude incidence using the DAD over-estimated the incidence, and the 3 other data sources under-estimated it.

CONCLUSION

SSI surveillance in the spine surgery population is feasible using several data sources, provided that measurement error is considered.

Web-Based Calculator Predicts Surgical-Site Infection After Thoracolumbar Spine Surgery

BACKGROUND

Surgical-site infection (SSI) after spine surgery leads to increased length of stay, reoperation, and worse patient quality of life. We sought to develop a web-based calculator that computes an individual's risk of a wound infection following thoracolumbar spine surgery.

METHODS

We performed a retrospective review of consecutive patients undergoing elective degenerative thoracolumbar spine surgery at a tertiary-care institution between January 2016 and December 2018. Patients who developed SSI requiring reoperation were identified. Regression analysis was performed and model performance was assessed using receiver operating curve analysis to derive an area under the curve. Bootstrapping was performed to check for overfitting, and a Hosmer-Lemeshow test was employed to evaluate goodness-of-fit and model calibration.

RESULTS

In total, 1259 patients were identified; 73% were index operations. The overall infection rate was 2.7%, and significant predictors of SSI included female sex (odds ratio [OR] 3.0), greater body mass index (OR 1.1), active smoking (OR 2.8), worse American Society of Anesthesiologists physical status (OR 2.1), and greater surgical invasiveness (OR 1.1). The prediction model had an optimism-corrected area under the curve of 0.81. A web-based calculator was created: https://jhuspine2.shinyapps.io/Wound_Infection_Calculator/.

CONCLUSIONS

In this pilot study, we developed a model and simple web-based calculator to predict a patient's individualized risk of SSI after thoracolumbar spine surgery. This tool has a predictive accuracy of 83%. Through further multi-institutional validation studies, this tool has the potential to alert both patients and providers of an individual's SSI risk to improve informed consent, mitigate risk factors, and ultimately drive down rates of SSIs.