Design of the prospective observational study of spinal metastasis treatment (POST)

A new era in the management of spinal metastasis

Despite the recent advances in cancer treatment, the incidence of patients with spinal metastases continues to grow along with the total number of cancer patients. Spinal metastases can significantly impair activities of daily living (ADL) and quality of life (QOL), compared with other types of bone metastases, as they are characterized with severe pain and paralysis caused by skeletal-related events. Reduced ADL can also lead to treatment limitations as certain anticancer agents and radiation therapy are not compatible treatments; thus, leading to a shorter life expectancy. Consequently, maintaining ADLs in patients with spinal metastases is paramount, and spine surgeons have an integral role to play in this regard. However, neurosurgeon, orthopedic and spinal surgeons in Japan do not have a proactive treatment approach to spinal metastases, which may prevent them from providing appropriate treatment when needed (clinical inertia). To overcome such endemic inertia, it is essential for 1) spine surgeons to understand and be more actively involved with patients with musculoskeletal disorders (cancer locomo) and cancer patients; 2) the adoption of a multidisciplinary approach (coordination and meetings not only with the attending oncologist but also with spine surgeons, radiologists, rehabilitation specialists, and other professionals) to preemptive treatment such as medication, radiotherapy, and surgical treatment; and 3) the integration of the latest findings associated with minimally invasive spinal treatments that have expanded the indications for treatment of spinal metastases and improved treatment outcomes. This heralds a new era in the management of spinal metastases.

Determining patients with spinal metastases suitable for surgical intervention: A cost-effective analysis

BACKGROUND

Both nonoperative and operative treatments for spinal metastasis are expensive interventions. Patients' expected 3-month survival is believed to be a key factor to determine the most suitable treatment. However, to the best of our knowledge, no previous study lends support to the hypothesis. We sought to determine the cost-effectiveness of operative and nonoperative interventions, stratified by patients' predicted probability of 3-month survival.

METHODS

A Markov model with four defined health states was used to estimate the quality-adjusted life years (QALYs) and costs for operative intervention with postoperative radiotherapy and radiotherapy alone (palliative low-dose external beam radiotherapy) of spine metastases. Transition probabilities for the model, including the risks of mortality and functional deterioration, were obtained from secondary and our institutional data. Willingness to pay thresholds were prespecified at $100,000 and $150,000. The analyses were censored after 5-year simulation from a health system perspective and discounted outcomes at 3% per year. Sensitivity analyses were conducted to test the robustness of the study design.

RESULTS

The incremental cost-effectiveness ratios were $140,907 per QALY for patients with a 3-month survival probability >50%, $3,178,510 per QALY for patients with a 3-month survival probability <50%, and $168,385 per QALY for patients with independent ambulatory and 3-month survival probability >50%.

CONCLUSIONS

This study emphasizes the need to choose patients carefully and estimate preoperative survival for those with spinal metastases. In addition to reaffirming previous research regarding the influence of ambulatory status on cost-effectiveness, our study goes a step further by highlighting that operative intervention with postoperative radiotherapy could be more cost-effective than radiotherapy alone for patients with a better survival outlook. Accurate survival prediction tools and larger future studies could offer more detailed insights for clinical decisions.

Interpretations of the Role of Plasma Albumin in Prognostic Indices: A Literature Review

This review assesses how publications interpret factors that influence the serum or plasma albumin (PA) level in prognostic indices, focusing on inflammation and nutrition. On PubMed, a search for "albumin AND prognosis" yielded 23,919 results. From these records, prognostic indices were retrieved, and their names were used as search strings on PubMed. Indices found in 10 or more original research articles were included. The same search strings, restricted to "Review" or "Systematic review", retrieved yielded on the indices. The data comprised the 10 latest original research articles and up to 10 of the latest reviews. Thirty indices had 294 original research articles (6 covering two indices) and 131 reviews, most of which were from recent years. A total of 106 articles related the PA level to inflammation, and 136 related the PA level to nutrition. For the reviews, the equivalent numbers were 54 and 65. In conclusion, more publications mention the PA level as a marker of nutrition rather than inflammation. This is in contrast to several general reviews on albumin and nutritional guidelines, which state that the PA level is a marker of inflammation but not nutrition. Hypoalbuminemia should prompt clinicians to focus on the inflammatory aspects in their patients.

Assessing the Performance of Prognostic Scores in Patients with Spinal Metastases from Lung Cancer Undergoing Non-surgical Treatment

STUDY DESIGN

Retrospective study.

PURPOSE

The purpose of this study was to see how well the Tomita score, revised Tokuhashi score, modified Bauer score, Van der Linden score, classic Skeletal Oncology Research Group (SORG) algorithm, SORG nomogram, and New England Spinal Metastasis Score (NESMS) predicted 3-month, 6-month, and 1-year survival of non-surgical lung cancer spinal metastases.

OVERVIEW OF LITERATURE

There has been no study assessing the performance of prognostic scores for non-surgical lung cancer spinal metastases.

METHODS

Data analysis was carried out to identify the variables that had a significant impact on survival. For all patients with spinal metastasis from lung cancer who received non-surgical treatment, the Tomita score, revised Tokuhashi score, modified Bauer score, Van der Linden score, classic SORG algorithm, SORG nomogram, and NESMS were calculated. The performance of the scoring systems was assessed by using receiver operating characteristic (ROC) curves at 3 months, 6 months, and 12 months. The predictive accuracy of the scoring systems was quantified using the area under the ROC curve (AUC).

RESULTS

A total of 127 patients are included in the present study. The median survival of the population study was 5.3 months (95% confidence interval [CI], 3.7-9.6 months). Low hemoglobin was associated with shorter survival (hazard ratio [HR], 1.49; 95% CI, 1.00-2.23; p =0.049), while targeted therapy after spinal metastasis was associated with longer survival (HR, 0.34; 95% CI, 0.21-0.51; p <0.001). In the multivariate analysis, targeted therapy was independently associated with longer survival (HR, 0.3; 95% CI, 0.17-0.5; p <0.001). The AUC of the time-dependent ROC curves for the above prognostic scores revealed all of them performed poorly (AUC <0.7).

CONCLUSIONS

The seven scoring systems investigated are ineffective at predicting survival in patients with spinal metastasis from lung cancer who are treated non-surgically.

A Natural History of Patients Treated Operatively and Nonoperatively for Spinal Metastases Over 2 Years Following Treatment: Survival and Functional Outcomes

STUDY DESIGN

Prospective observational study.

OBJECTIVE

We present the natural history, including survival and function, among participants in the prospective observational study of spinal metastases treatment investigation.

SUMMARY OF BACKGROUND DATA

Surgical treatment has been touted as a means to preserve functional independence, quality of life, and survival. Nearly all prior investigations have been limited by retrospective design and relatively short-periods of post-treatment surveillance.

METHODS

This natural history study was conducted using the records of patients who were enrolled in the prospective observational study of spinal metastases treatment study (2017-2019). Eligible participants were 18 or older and presenting for treatment of spinal metastatic disease. Patients were followed at predetermined intervals (1, 3, 6, 12, and 24-mo) following treatment. We conducted cox proportional hazard regression analysis adjusting for confounders including age, biologic sex, number of comorbidities, type of metastatic lesion, neurologic symptoms at presentation, number of metastases involving the vertebral body, vertebral body collapse, New England Spinal Metastasis Score (NESMS) at presentation, and treatment strategy.

RESULTS

We included 202 patients. Twenty-three percent of the population had died by 3 months following treatment initiation, 51% by 1 year, and 70% at 2 years. There was no significant difference in survival between patients treated operatively and nonoperatively (P = 0.16). No significant difference in HRQL between groups was appreciated beyond 3 months following treatment initiation. NESMS at presentation (scores of 0 [HR 5.61; 95% CI 2.83, 11.13] and 1 [HR 3.00; 95% CI 1.60, 5.63]) was significantly associated with mortality.

CONCLUSION

We found that patients treated operatively and nonoperatively for spinal metastases benefitted from treatment in terms of HRQL. Two-year mortality for the cohort as a whole was 70%. When prognosticating survival, the NESMS appears to be an effective utility, particularly among patients with scores of 0 or 1.Level of Evidence: 2.

Characterizing Health-Related Quality of Life by Ambulatory Status in Patients with Spinal Metastases

STUDY DESIGN

Retrospective review of prospective longitudinal data.

OBJECTIVE

To determine health-related quality of life (HRQL) utilities associated with specific ambulatory states in patients with spinal metastases: independent, ambulatory with assistance, and nonambulatory.

SUMMARY OF BACKGROUND DATA

It is assumed that HRQL is aligned with ambulatory ability in patients with spinal metastases. Few studies have effectively considered these parameters while also accounting for clinical confounders.

METHODS

We used prospective longitudinal data from patients treated at one of three tertiary medical centers (2017-2019). HRQL was characterized using the Euroquol-5-dimension (EQ5D) inventory. We performed standardized estimations of HRQL stratified by ambulatory state using generalized linear modeling that accounted for patient age at presentation, biologic sex, follow-up duration, operative or nonoperative management, and repeated measures within the same participant.

RESULTS

We evaluated 675 completed EQ5D assessments, with 430 for independent ambulators, 205 for ambulators with assistance, and 40 for nonambulators. The average age of the cohort was 61.5. The most common primary cancer was lung (20%), followed by breast (18%). Forty-one percent of assessments were performed for participants treated surgically. Mortality occurred in 51% of the cohort. The standardized EQ5D utility for patients with spinal metastases and independent ambulatory function was 0.76 (95% confidence interval [CI] 0.74, 0.78). Among those ambulatory with assistance, the standardized EQ5D utility was 0.59 (95% CI 0.57, 0.61). For nonambulators, the standardized EQ5D utility was 0.14 (95% CI 0.09, 0.19).

CONCLUSION

Patients with spinal metastases and independent ambulatory function have an HRQL similar to patients with primary cancers and no spinal involvement. Loss of ambulatory ability leads to a 22% decrease in HRQL for ambulation with assistance and an 82% reduction among nonambulators. Given prior studies demonstrate superior maintenance of ambulatory function with surgery for spinal metastases, our results support surgical consideration to the extent that it is clinically warranted.Level of Evidence: 3.

Prospective comparison of the accuracy of the New England Spinal Metastasis Score (NESMS) to legacy scoring systems in prognosticating outcomes following treatment of spinal metastases

BACKGROUND CONTEXT

We developed the New England Spinal Metastasis Score (NESMS) as a simple, informative, scoring scheme that could be applied to both operative and non-operative patients. The performance of the NESMS to other legacy scoring systems has not previously been compared using appropriately powered, prospectively collected, longitudinal data.

PURPOSE

To compare the predictive capacity of the NESMS to the Tokuhashi, Tomita and Spinal Instability Neoplastic Score (SINS) in a prospective cohort, where all scores were assigned at the time of baseline enrollment.

PATIENT SAMPLE

We enrolled 202 patients with spinal metastases who met inclusion criteria between 2017-2019.

OUTCOME MEASURES

One-year survival (primary); 3-month mortality and ambulatory function at 3- and 6-months were considered secondarily.

METHODS

All prognostic scores were assigned based on enrollment data, which was also assigned as time-zero. Patients were followed until death or survival at 365 days after enrollment. Survival was assessed using Kaplan-Meier curves and score performance was determined via logistic regression testing and observed to expected plots. The discriminative capacity (c-statistic) of the scoring measures were compared via the z-score.

RESULTS

When comparing the discriminative capacity of the predictive scores, the NESMS had the highest c-statistic (0.79), followed by the Tomita (0.69), the Tokuhashi (0.67) and the SINS (0.54). The discriminative capacity of the NESMS was significantly greater (p-value range: 0.02 to <0.001) than any of the other predictive tools. The NESMS was also able to inform independent ambulatory function at 3- and 6-months, a function that was only uniformly replicated by the Tokuhashi score.

CONCLUSIONS

The results of this prospective validation study indicate that the NESMS was able to differentiate survival to a significantly higher degree than the Tokuhashi, Tomita and SINS. We believe that these findings endorse the utilization of the NESMS as a prognostic tool capable of informing care for patients with spinal metastases.

Evaluating ambulatory function as an outcome following treatment for spinal metastases: a systematic review

BACKGROUND CONTEXT

Studies regarding treatment of spinal metastases are critical to evidence-based decision-making. However, variation exists in how a key outcome, ambulatory function, is assessed.

PURPOSE

To characterize the sources and tools investigators have used to evaluate ambulatory function as an outcome following treatment of spinal metastases. We also sought to understand the ways ambulatory function has been conceptualized in prior studies.

STUDY DESIGN

Systematic review of the literature.

PATIENT SAMPLE

We identified 44 published studies for inclusion. Samples within these investigations ranged from 20 to 2,096 subjects.

OUTCOME MEASURES

We describe the methods investigators have used to evaluate ambulatory function following treatment for spinal metastases.

METHODS

We conducted a systematic review through PubMed, Scopus and Web of Science following PRISMA guidelines. We included studies that consisted of adult patients receiving operative or non-operative treatment for spinal metastases. We also required that study investigators specified post-treatment ambulatory function as an outcome. We recorded year of publication, study design, types of spinal metastases included in the study, treatments employed, and sample size. We also described the source (medical record, study-specific observer and/or provider, patient and/or participant), tool (standardized measure, quantitative, qualitative) and concept (eg, ambulatory vs. non-ambulatory; independent ambulation vs. ambulatory with assistance vs. non-ambulatory) used to assess ambulatory function.

RESULTS

We found the plurality of studies relied on medical record documentation as their source. Amongst prospective studies, only a minority used a quantitative measure (eg, prespecified degree of walking ability) to assess ambulatory function. Most studies conceptualized ambulatory function as a dichotomized outcome, typically ambulatory versus non-ambulatory or a similar equivalent.

CONCLUSIONS

Wide variation exists in how ambulatory function is defined in studies involving patients with spinal metastases. We suggest several improvements that will allow a more robust assessment of the quality and quantity of ambulatory function among patients treated for spinal metastases.

The Cost-Effectiveness of Surgical Intervention for Spinal Metastases: A Model-Based Evaluation

BACKGROUND

Operative and nonoperative treatments for spinal metastases are expensive interventions with a high rate of complications. We sought to determine the cost-effectiveness of a surgical procedure compared with nonoperative management as treatment for spinal metastases.

METHODS

We constructed a Markov state-transition model with health states defined by ambulatory status and estimated the quality-adjusted life-years (QALYs) and costs for operative and nonoperative management of spine metastases. We considered 2 populations: 1 in which patients presented with independent ambulatory status and 1 in which patients presented with nonambulatory status due to acute (e.g., <48 hours) metastatic epidural compression. We defined the efficacy of each treatment as a likelihood of maintaining, or returning to, independent ambulation. Transition probabilities for the model, including the risks of mortality and becoming dependent or nonambulatory, were obtained from secondary data analysis and published literature. Costs were determined from Medicare reimbursement schedules. We conducted analyses over patients' remaining life expectancy from a health system perspective and discounted outcomes at 3% per year. We conducted sensitivity analyses to account for uncertainty in data inputs.

RESULTS

Among patients presenting as independently ambulatory, QALYs were 0.823 for operative treatment and 0.800 for nonoperative treatment. The incremental cost-effectiveness ratio (ICER) for a surgical procedure was $899,700 per QALY. Among patients presenting with nonambulatory status, those undergoing surgical intervention accumulated 0.813 lifetime QALY, and those treated nonoperatively accumulated 0.089 lifetime QALY. The incremental cost-effectiveness ratio for a surgical procedure was $48,600 per QALY. The cost-effectiveness of a surgical procedure was most sensitive to the variability of its efficacy.

CONCLUSIONS

Our data suggest that the value to society of a surgical procedure for spinal metastases varies according to the features of the patient population. In patients presenting as nonambulatory due to acute neurologic compromise, surgical intervention provides good value (ICER, $48,600 per QALY). There is a low value for a surgical procedure performed for patients who are ambulatory at presentation (ICER, $899,700 per QALY).

LEVEL OF EVIDENCE

Economic and Decision Analysis Level III. See Instructions for Authors for a complete description of levels of evidence.

Clinician Experiences in Treatment Decision-Making for Patients with Spinal Metastases: A Qualitative Study

BACKGROUND

Effective management of metastatic disease requires multidisciplinary input and entails high risk of disease-related and treatment-related morbidity and mortality. The factors that influence clinician decision-making around spinal metastases are not well understood. We conducted a qualitative study that included a multidisciplinary cohort of physicians to evaluate the decision-making process for treatment of spinal metastases from the clinician's perspective.

METHODS

We recruited operative and nonoperative clinicians, including orthopaedic spine surgeons, neurosurgeons, radiation oncologists, and physiatrists, from across North America to participate in either a focus group or a semistructured interview. All interviews were audiorecorded and transcribed verbatim. We then performed a thematic analysis using all of the available transcript data. Investigators sequentially coded transcripts and identified recurring themes that encompass overarching patterns in the data and directly bear on the guiding study question. This was followed by the development of a thematic map that visually portrays the themes, the subthemes, and their interrelatedness, as well as their influence on treatment decision-making.

RESULTS

The thematic analysis revealed that numerous factors influence provider-based decision-making for patients with spinal metastases, including clinical elements of the disease process, treatment guidelines, patient preferences, and the dynamics of the multidisciplinary care team. The most prominent feature that resonated across all of the interviews was the importance of multidisciplinary care and the necessity of cohesion among a team of diverse health-care providers. Respondents emphasized aspects of care-team dynamics, including effective communication and intimate knowledge of team-member preferences, as necessary for the development of appropriate treatment strategies. Participants maintained that the primary role in decision-making should remain with the patient.

CONCLUSIONS

Numerous factors influence provider-based decision-making for patients with spinal metastases, including multidisciplinary team dynamics, business pressure, and clinician experience. Participants maintained a focus on shared decision-making with patients, which contrasts with patient preferences to defer decisions to the physician, as described in prior work.

CLINICAL RELEVANCE

The results of this thematic analysis document the numerous factors that influence provider-based decision-making for patients with spinal metastases. Our results indicate that provider decisions regarding treatment are influenced by a combination of clinical characteristics, perceptions of patient quality of life, and the patient's preferences for care.

Treatment Strategy for Metastatic Spinal Tumors: A Narrative Review

Metastatic spinal tumors are common, and their rising incidence can be attributed to the expanding aging population and increased survival rates among cancer patients. The decision-making process in the treatment of spinal metastasis requires a multidisciplinary approach that includes medical and radiation oncology, surgery, and rehabilitation. Various decision-making systems have been proposed in the literature in order to estimate survival and suggest appropriate treatment options for patients experiencing spinal metastasis. However, recent advances in treatment modalities for spinal metastasis, such as stereotactic radiosurgery and minimally invasive surgical techniques, have reshaped clinical practices concerning patients with spinal metastasis, making a demand for further improvements on current decision-making systems. In this review, recent improvements in treatment modalities and the evolution of decision-making systems for metastatic spinal tumors are discussed.

Predictive Analytics in Spine Oncology Research: First Steps, Limitations, and Future Directions

The potential of big data analytics to improve the quality of care for patients with spine tumors is significant. At this moment, the application of big data analytics to oncology and spine surgery is at a nascent stage. As such, efforts are underway to advance data-driven oncologic care, improve patient outcomes, and guide clinical decision making. This is both relevant and critical in the practice of spine oncology as clinical decision making is often made in isolation looking at select variables deemed relevant by the physician. With rapidly evolving therapeutics in surgery, radiation, interventional radiology, and oncology, there is a need to better develop decision-making algorithms utilizing the vast data available for each patient. The challenges and limitations inherent to big data analyses are presented with an eye towards future directions.