Objective

To study trends in incidence and outcome of patients with traumatic spinal cord injury in the Netherlands before, during and after the implementation of the ATLS/PHTLS protocol.

Introduction

In 2012, a total of 9690 patients presented at an Emergency Department (ED) with a spinal fracture in The Netherlands (total population; 16.7 million in 2012), an equivalent of 58 per 100.000 people. Of these patients, 2.5–6.4% suffered Traumatic Spinal Cord Injury (TSCI) [1]. Although the fraction of TSCI’s is small, the consequences for the patient are profound, leading to functional impairment, impaired quality of life and increased mortality [2, 3]. Pre-hospital mortality has been reported up to 38% [4]. Additionally, post-admission mortality rates varies from 4.4 to 16.7% [4, 5]. Those who survive often require extensive and lifelong therapy [6]. In extend, despite medical treatment, around 50.0% of these patients face medical complications (e.g. pneumonia, deep vein thrombosis), during and after hospitalization [5, 7].

According to current international guidelines, all trauma patients at risk of TSCI should receive immediate Spinal Motion Restriction (SMR), including a cervical collar [8]. The previously used long spinal board became obsolete after multiple reports of adverse effects after usage, such as pressure ulcers, risk of aspiration and respiratory compromise [8, 9]. SMR-interventions, provided by Emergency Medical Services (EMS), aim to limit motion in potentially unstable spinal segments in prevention of developing further neurological deterioration in patients suspected for spinal fractures. These interventions were first introduced in the Advanced Trauma Life Support (ATLS®) guidelines in 1980 and later adopted in the Pre-Hospital Traumatic Life Support (PHTLS®) guidelines in the United States, partly in response to the increase in motor vehicle accidents [10] (Supplementary Figure S1). The Netherlands started implementing the ATLS principles in 1995 [11]. The last major revision of the protocol in The Netherlands was in 2016 (Supplementary Figure S2).

Implementation of protocols including SMR-intervention in patients at risk for TSCI became common use. However, they were enforced without a compelling scientific basis demonstrating these measures significantly prevent secondary neurological injury [12,13,14]. In fact, a growing body of evidence contradicts the efficacy and shows the burden and adverse effects of spinal immobilization, including pain, respiratory compromise, pressure ulcers and elevated intracranial pressure after immobilization [9, 15,16,17]. Furthermore, there is discussion towards it being inadequate in limiting spinal motion during transport, or towards it being too time-consuming in acute settings causing delay [18,19,20]. Secondary spinal cord detoriation has been linked to vascular mechanisms or inflammatory responses after trauma, rather than mechanical movement [21]. In addition, it is suggested that minmal motion of the spine is unlikely to result in secondary damage, while emphasizing the need to minimize energy deposition to the injured site while minimizing time-delay [19]. In this light, the use of spinal immobilization has already been debunked in penetrating trauma [22]. Historically, spinal immobilization to prevent spinal cord injury can not be explained either r [10].

Despite controversy in literature surrounding SMR in the widely used ATLS/PHTLS protocol, the incidence and outcomes of patients with TSCI in the Netherlands has never been compared to the incidence and outcome before the introduction and implementation over a longer period of time. The purpose of this study is to analyze trends in incidence and outcome of patients with TSCI in the Netherlands before and after the implementation of the ATLS/PHTLS protocol in 1995 (Supplementary Figures S1 and S2).

Materials en methods

Study hypothesis and design

This article was written in adherence to the Strengthening the reporting of observational studies in epidemiology (STROBE) guidelines. For this retrospective observational database study, two different databases were used. First, we used the Dutch Injury Surveillance system (Letsel Inventarisatie Systeem; LIS) which is an ongoing monitoring system established in 1997 [23]. This system records data of all patients with an injury who presented at ED in 12 hospitals in the Netherlands. These 12 hospitals were selected to form a representative sample of the Dutch population based on demographics, size of the hospital and level of trauma center, among others. This sample size is estimated to cover 12.0–15.0% of the Dutch population enabling extrapolation of the data to a nationwide level [23]. All patients recorded in the LIS with a spinal fracture, with and without spinal cord injury, (International Classification of Diseases (ICD) 9th revision codes 805 and 806) in the period of 1997 to 2020 were included in our database. In case of multiple trauma, the primary injury was determined by application of an algorithm providing priority to spinal cord injury, skull and brain injury, and lower extremity injury above injuries in other body parts to determine the most serious injury. This methodology is more elaborately described by Lyons et al. [24].

Second, we used the and the Dutch Admittance Data (Landelijke Basisregstratie Ziekenhuiszorg/Landelijk Medische Registratie; LBZ/LMR), which records every hospital admissions in the Netherlands based on the corresponding primary ICD 9th code. Per ICD 9th -coded condition, it tracks the amount of admissions, the length of hospital admission, the primary treating physician, among many other variables, from 1986 to 2020. In this database the same ICD 9th revision codes 805 (Spinal fractures with spinal cord injury) and 806 (spinal fractures without mention of spinal cord injury) were used.

Outcome measures

The primary outcome was the incidence rate of TSCI in admitted patients with spinal fractures before, during and after the implementation of the SMR protocol, which is expressed as number of spinal fractures per 100.000 persons. The following time intervals were used; (I) 1986–1995 (pre-ATLS protocol), (II) 1996–2005 (adjustment-phase to ATLS-protocol, Supplementary Figure S1), (III) 2006–2015 (fully implemented phase) and (IV) 2016–2020 (renewed protocol phase, Supplementary Figure S2), to determine changes in incidence in spinal cord injury associated with spinal fractures.

The following secondary outcomes were assesed: percentage of patients with spinal cord injuries in patients suffering spinal fractures at different levels of the spinal cord, admission-rate of patients with spinal fractures and the length of hospital admission for spinal fractures with and without TSCI, for men and women serparately. The admission-rate was calculated from the LIS database, in which all discharges were registered as either treated-and-released or treated-and-admitted. These rates were corrected for changes in demographics, using 2020 as the baseline. Where possible, data is presented in one-year intervals. Data related specifically to the cervical, thoracic or lumbosacral spine was only available and thus expressed in five-year intervals. Incidence rates of spinal fractures with TSCI were expressed in percentages of the overall amount of spinal fractures.

Statistical analysis

Overall incidence rates for the population was corrected for demographic changes using ‘’direct standardization’’ [25]. Incidence rates were expressed per 100,000 persons. The association between the implementation phases of the SMR/TSI protocols (pre-ATLS protocol, adjustment phase, fully implemented phase, renewed protocol phase) and the incidence of spinal fractures and TSCI was analyzed using the Spearman rank-order correlation. A p-value < 0.05 was determined to be significant. The statistical analyses were conducted using STATA (StataCorp. 2013. Stata Statistical Software: Release 13. College Station, TX: StataCorp LP).

Results

Based on LBZ/LMR data, an average of 3758 (range 2712–4389) patients with spinal fractures were yearly admitted to the hospital (in total 127,773 patients in the period 1986 to 2020) (Fig. 1). Of these 127,773 spinal fractures, 8,900 were accompanied by TSCI (7.0%). The number of spinal fractures without TSCI varied from 2712 to 4072 per year (Fig. 2a), while the overall incidence rate for spinal fractures with TSCI varied from 176 to 340 per year. Since 1986, the number of spinal fractures with TSCI showed an increase of 39% (from 189 to 263 in the period 1986 to 2020) (Fig. 2b). Similar, the LBZ/LMR data showed an increase in TSCI-incidence from 6.0 to 10.0% (Fig. 2c). A significant increase in spinal fractures with TSCI was described between the time-intervals I to IV, respectively 6.3%, 6.5%, 7.2% and 8.7% (p-value < 0.001), as shown in Table 1. The increase in total spinal fractures over time-intervals I to IV was not significant (p = 0.466).

Fig. 1
figure 1

Total of patients admitted after with a spinal fracture according to Dutch Admittance Data (LBZ/LMR) between 1986 and 2020, corrected for changes in demographic (baseline: 2020)

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Fig. 2
figure 2

Total number of spinal fractures, spinal cord injury and admittances from the LMR database between 1986–2020. (a): Total number of spinal fractures without spinal cord injury, corrected for changes in demographics (baseline: 2020). (b): Total number of spinal fractures with spinal cord injury, corrected for changes in demographics (baseline: 2020), showing a significant increase of 39.0% (p < 0.001) in TSCI’s in admitted patients with spinal fractures. (c): Percentage of admitted patients with spinal fractures that suffered from spinal cord injury

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Table 1 Incidence of traumatic spinal cord injury
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According to the LIS data in the period of 1997–2021, 193,572 patients were presented at the ED with a spinal fracture, of which 110,993 (57.3%) were admitted to the hospital. An increase in spinal fractures presenting at the ED was observed, from 30 to 54 per 100,000 patients between 1997 and 2020, an 80% increase (Fig. 3). Cervical spinal fractures increased the most from 4 to 12 per 100.000 in that time period (200% increase), thoracic spinal fractures from 8 to 14 per 100.000 (75.0% increase) and lumbosacral spinal fractures from 16 to 28 per 100.000 (75% increase) (Fig. 3). In addition, the LIS database showed in 5-year intervals that the percentage of TSCI differs interval-to-interval (Fig. 4a), which is best seen in the cervical spinal fracture group with yearly incidence rates ranging between 5 and 25% (Fig. 4b). The incidence of TSCI appears to decrease in lumbosacral (from 5.0% in 1997 to 0.6% in 2020) and thoracic spinal fractures (from 2.8% in 1997 to 1.8% in 2020) (Fig. 4c and d), respectively an 88.0% and a 64.0% decrease. In the group of patients with a cervical spinal fracture no decrease of TSCI-incidence at 5-year intervals (from 6.2% in 1997 to 14.4% in 2020) was shown, but an increase of 132.2% (Fig. 4b). A decrease in admission-rate was observed after a diagnosed spinal fracture in the ED from 64.0 to 46.0% from 1997 to 2021 (Fig. 5).

Fig. 3
figure 3

Spinal fracture incidence in the emergency department as a number per 100,000, corrected for demographics (baseline: 2020) according to LIS

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Fig. 4
figure 4

- Admittance rate of patients diagnosed with a spinal fracture at the emergency department according to Dutch Injury Surveillance (LIS) at 5-year intervals. (a): Admittance rate of all diagnosed spinal fractures and spinal cord injury (SCI). (b): Admittance rate of all diagnosed cervical spine fractures and SCI. (c): Admittance rate of all diagnosed thoracic spine fractures and SCI, in which a decrease is seen from 5.0% in 1997 to 0.6% in 2020. (d): Admittance rate of all lumbosacral spine fractures and SCI, showing a decrease from 2.8% in 1997 to 1.8% in 2020

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Fig. 5
figure 5

Percentage of spinal cord injury observed in patients who enter the ED with a spinal fracture at different levels of the spinal cord and as a total according to Dutch injury Surveillance (LIS) at 5-year intervals

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Regarding the average duration of hospital admission from 1991 to 2020, in patients with spinal fractures without TSCI was 10 days, decreasing from 17 days in 1991 to 6 days in 2020 (66.0% decrease). The average duration of hospital admission for spinal fractures with TSCI was 17 days in that same study period. It decreased from 24 days in 1991 to 11 days in 2020 (56.0% decrease) (Fig. 6a and b).

Fig. 6
figure 6

– Duration of admittance in patients admitted with a spinal fracture with and without spinal cord injury according to Dutch admittance data (LMR). (a): Duration of admission in men. (b): Duration of admission in women

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Discussion

This study observed a significant increase of 39.0% (p < 0.001) in TSCI’s in admitted patients with spinal fractures over the past 35 years (Fig. 2b). The increase in spinal fractures in admitted patients in total was not statistically significant (p = 0.466, Table 1). In thoracic and lumbosacral spinal fractures, the incidence in TSCI seems to have decreased since 1986, which was not the case for cervical fractures as it showed a 132.2% increase.

We saw an increase of 84.9% in patients presenting with spinal fractures to the ED since 1997 in the Netherlands, which is in line with current literature(Fig. 3) [1, 26]. Multiple explanations for this increase in overall spinal fractures can be given. Most notably, the increase in computed tomography (CT)-scan usage resulted in higher detection rate [27, 28]. Also, the Dutch population is aging, meaning an increasing amount of osteopenia and osteoporosis throughout the population [1]. Smits et al. found a much faster increasing incidence in spinal fractures in the elderly compared to the younger population in The Netherlands [26].

The increase in TSCI in admitted patients (Fig. 2b) without an increase in spinal fractures is worrisome, especially since the SMR-protocol was implemented in order to decrease (secondary) neurological deterioration after spinal injuries. These findings suggest (secondary) detoriation has occurred after the initial trauma while the spine was immobilized, or possibly an improper or missing application of spinal immobilization was performed. In 2020, up to 10.0% of all admitted patients with spinal fractures suffered a TSCI, while this was 6% in 1986. However, the incidence for spinal fractures presented in the ED increased by almost 80.0%, but the admission rate for these patients decreased (Figs. 2c and 3). Nowadays, many trauma patients with neck/back pain will undergo a CT-scan. This might implicate that more minor fractures were found that did not require hospital admission or hospitalized care. Therefore the patient group that met the admission criteria for the database (LBZ/LMR) could have been changed and a relative increase in spinal fractures with TSCI could be expected. The clinical relevance of this significant increase in TSCI’s remains uncertain.

Furthermore, our study showed a notable difference between thoracic/lumbosacral fractures and cervical fractures within this study. TSCI in patients with lumbosacral or thoracic spinal fractures was observed in up to 5.0% of the patients, while the rate of cervical spinal fractures is much higher (up to 25.0%). In addition, during the study period the TSCI-incidence in thoracic/lumbosacral spinal fractures shows signs of decreasing at 5-year intervals, but in the group of patients with a cervical spinal fracture the TSCI-incidence no decrease is seen (Fig. 5). These findings might suggest the SMR-protocol helps preventing secondary (detoriation of) TSCI in thoracic and lumbosacral spinal fractures, but has less impact for the cervical spinal fractures. The admission-rate (Fig. 1) also shows that the admittance number rises for cervical fractures, whereas the admission-rate for thoracic spinal fractures remains even and lumbosacral spinal fractures declined over 50.0%. Given the higher mortality associated with TSCI located higher in the spinal cord, this highlights the importance of improving care for cervical fractures [29].

The results from this study should be interpreted with regard to its limitations. The inability to correct for confounders, such as changes in care and trauma systems that were not simultaneous implemented across all hospitals in the Netherlands, may impact the interpretation of the results. Although the use of a vacuum matress has been added to nationwide protocols in 2016, some EMS still use the obsolete long spinal board today [8, 9]. Second, The LIS-database started recording from 1997 which coincides with the introduction of the ATLS-protocol. The lack of detailed patient characteristics e.g. past medical history, comorbidities, medications) and outcomes (such as survival, treatment given, re-admissions) in both databases limits further in-depth analysis. In addition, spinal injuries with severe expected outcome are more likely to be reffered to the ED of level-1 trauma centers and injuries with a better prognosis are more likely to be referred to smaller, non-university level-2 hospitals. These existing referring logistics may affect the reliability of the LIS [24]. Furthermore, re-admitted patients might have been entered twice within the database, since re-admissions are not scored separately. However, to the best of our knowledge, this is the first review which evaluates the TSI/SMR-protocol by looking at the amount of reported neurological deficit after spinal fractures in The Netherlands. The system of data acquisiton and the LIS procedures have been unchanged during the study period, which allows for detection of trends.

Conclusions

In this study the incidence of TSCI increased significantly during a 35-years periodwithout a significant increase in spinal fractures. This study found no clear correlation between implementation of SMR protocols and TSCI in this period. It therefore contributes to the trend advocating a less rigorous SMR protocol, thus stressing the need for clear, evidencebased spinal immobilization protocol.