SCI-POEM highlights the challenges of conducting clinical observational studies on traumatic SCI
Early surgical decompression of the spinal cord has been widely adopted among surgeons as the standard of care for the treatment of traumatic spinal cord injury (tSCI). However, due to a paucity of high-quality evidence, it has remained unclear whether early surgical intervention does indeed result in the best outcomes for patients with acute tSCI. Publication of the results from an AO supported study sheds more light on this controversial topic and highlights the challenges of conducting clinical observational studies on tSCI. It is still not known whether early surgery or active physiological management of the unstable injured spinal cord offers the better chance for recovery.
The results of the SCI-POEM study support an evidence-based approach for the management of tSCI
A range of approaches have been investigated for the management of tSCI. However, there is a lack of high-quality studies demonstrating any convincing long-term improvements to neurological or functional outcomes in tSCI patients following intervention. In particular, studies exploring the value of early interventions have produced conflicting results.
The challenge presented by the lack of robust studies is reflected in the 2017 AO Spine clinical practice guidelines for tSCI, which recommend that early surgery be offered as a “treatment option”. The guidelines acknowledge however, that the recommendation is “weak” and the quality of evidence supporting the recommendation is “low”.
In order to address evidence-gaps surrounding tSCI management, the SCI-POEM study (Prognostic Factors and Therapeutic Effects of Surgical Treatment for Traumatic Spinal Column Injury with Spinal Cord Injury: A Prospective, Observational European Multi-center Study) was initiated. SCI-POEM was supported by AO Spine Europe and the AO Clinical Investigation and Documentation team, and the results have now been published in The Bone & Joint Journal.
SCI-POEM represents the largest prospective, multi-center study comparing early versus late surgical decompression for acute tSCI
SCI-POEM, which was initiated in 2011, involved 17 sites across Europe and almost 300 patients. The aim of the study was to determine whether early (at 12 hours or less following injury) or late (later than 12 hours following injury) surgical spinal decompression, resulted in better neurological recovery 12 months after injury in adult patients with acute tSCI.
To be included in SCI-POEM, patients needed to have diagnosis of blunt spinal column injury and spinal cord injury, including conus medullaris and/or cauda equina injuries in addition to pre-surgery American Spinal Injury Association Impairment Scale (AIS) grade A, B, C, or D. The primary endpoint of the study was the change in Lower Extremity Motor Score (LEMS) from baseline to 12 months.
SCI-POEM has several strengths. For example, the inclusion of a large pan-European population and the availability of validated and detailed information on patients’ pre-surgical neurological impairments assessed by trained and certified clinicians. However, a key factor that differentiates SCI-POEM from other studies in the field, is the use of propensity score adjustment (PSA).
tSCI patients typically present with high heterogeneity. If they are subsequently included in clinical studies, the heterogeneity of the population leads to imbalances in the baseline variables between treatment groups. Ultimately these imbalances can lead to bias and confounding of the study outcomes. However, in SCI-POEM, the use of PSA allowed the authors to control for heterogeneity and correctly estimate treatment effects.
Early surgical spinal decompression was not associated with improved long-term outcomes for tSCI patients
Results from the unadjusted analysis that included patients with an outcome available at both baseline and 12 months, indicated a borderline significant difference that favored the early group in the mean change in LEMS from baseline to 12 months. However, a combination of baseline imbalances, ceiling effects in mild traumatic spinal cord injury, and a higher loss to follow-up rate of severe traumatic spinal cord injury patients in the late treatment group, appeared to result in an overestimation of the effect of early surgical decompression.
Following propensity score adjustment, early (≤ 12 hours) decompression was not associated with a statistically significant neurological improvement at 12 months after injury compared to late (>12 hours) decompression.
Patients benefit most from a dedicated team effort
SCI-POEM study is the first large comparative study in the field to account for heterogeneity in the tSCI patient population. The results indicate that a critical re-evaluation of international clinical practice guidelines on the timing of surgical treatment following tSCI is required. It is important to note however, that the well-established need for acute medical treatment following traumatic spinal cord injury remains. For example, it is still necessary to maintain adequate spinal cord perfusion pressure.
The study also has important repercussions for public health policy, as infrastructural and systemic changes are required in order to implement early surgical management practices for tSCI. Various medico-legal and operational challenges are associated with treating acute tSCI; all which are associated with a substantial financial burden.
Principal Investiagtor Allard Hosman comments on the wider impact of the SCI-POEM study:
"One outcome of SCI-POEM will surely be the awareness that patients benefit most from a dedicated team effort. The chain of dedication should extend beyond surgery, the acute phase and timing of an intervention, and cover also prevention, education, and management of logistical issues such as safety, ambulance services, and availability of staff."
The results of SCI-POEM are just the beginning
In order to leverage the data produced in this study, a second publication is being planned. This follow-up paper will disclose additional findings from the study, including data related to functional and quality of life outcomes. Hypothesis-generating analyses are also planned to assess the impact of the timing of surgical decompression using alternative thresholds.
Thanks goes to the patients that took part in the study and congratulations to the study team for conducting this critical research, which has laid the foundations for further high-quality research in the tSCI field. We look forward to gaining even more understanding around this important topic in the coming years.
Read the Bone and Joint commentary about SCI-POEM, titled "Which treatment provides the best neurological outcomes in acute spinal cord injury?", by Nick C. Birch et al.