Abstract
Study design
Retrospective population based study on traumatic spinal cord injury (SCI) in Ireland.
Objectives
To gather the most recent epidemiological data prior to the implementation of a new national trauma strategy. Also, to consider if the COVID-19 pandemic impacted on SCI epidemiology in Ireland.
Setting
Republic of Ireland.
Methods
All patients with TSCI discharged from the National Rehabilitation Hospital (NRH), the national acute SCI unit and two neurosciences centres were included. The International Spinal Cord Injury Core Data Set was collected on all patients at discharge from rehabilitation between 2017 and 2022.
Results
Overall crude incidence of TSCI was 14 per million per year, ranging between 11.3 and 18.4. 12.7% of patients did not survive to discharge from hospital. In those completing rehabilitation, the mean age of injury onset was 50.1 years (SD 19.9). Males accounted for 75.7%. The most common impairment was incomplete tetraplegia, 45.3% of all TSCI. Leading aetiology was falls, 53.9% of injuries. Patients with incomplete tetraplegia and those whose cause of injury were falls were older than those with all other impairments and injury aetiologies (p < 0.001).
Conclusions
Overall incidence of TSCI is similar to our previous studies. Also similar is the predominant pattern of older people sustaining falls resulting in incomplete tetraplegia.
Subject terms: Epidemiology, Epidemiology
Introduction
The need for good quality epidemiological data in traumatic and non-traumatic spinal cord injury (TSCI/NTSCI) has been well documented [1, 2]. To ensure high standard contributions, we have carried out a number of studies in Ireland during the last decade [3–5]. Although we have recommended the development of a national registry, the infrastructure to support this remains lacking. Our studies have shown that the incidence of TSCI has remained quite constant since the first ever epidemiological study of TSCI in Ireland in 2000 [6], ranging from 11.5–13.3 per million per year while the incidence of NTSCI was at least double this at 26.9 per million per year [3–5].
As for all developed countries, there are persistent efforts to improve the quality and efficiency of health care delivery in Ireland. In 2018, a report entitled A Trauma System for Ireland was launched following 5 years of preparatory work, with the aim of the implementation of a coordinated approach to the management of all trauma including major trauma [https://www.gov.ie/en/publication/c8640e-a-trauma-system-for-ireland-report-of-the-trauma-steering-group/]. Until now, the approach to trauma management was piecemeal even though there has been a reasonably well-established pathway for TSCI care. In July 2023, a new inter-hospital referral process began. The Mater Misericordiae University Hospital, where the National Spinal Injuries Unit (NSIU) is located and now a designated major trauma centre (MTC), commenced acceptance of major trauma referrals from trauma receiving hospitals within the Central Trauma Network, which covers more than two thirds of the population of the Republic of Ireland. As the NSIU is located in the MTC and has always accepted transfers from any hospital in Ireland, it is difficult to anticipate if there will be much change to acute TSCI management. Nevertheless, we were particularly interested in having the most up-to-date data possible, prior to the implementation of the new trauma management system, to monitor what impact, if any, this change will have on TSCI management.
Coincidentally, the COVID-19 pandemic occurred during the time just prior to this change in trauma service delivery. It has recently been reported that the public health restrictions imposed during the pandemic were associated with a lower incidence of TSCI particularly in males, aged over 45 years but with a higher incidence of deliberate self-harm as a cause of TSCI [7].
Our objective was to assemble and summarise retrospective epidemiological data on TSCI since our last study in 2016 until the implementation of the new trauma system in 2023 i.e., from 2017 to 2022 inclusive.
Materials and methods
We have previously documented how we can identify patients who have had a TSCI in Ireland as there is only one specialist acute SCI centre in the country (the National Spinal Injuries Unit, NSIU), 2 neurosciences centres and one specialist rehabilitation facility for SCI, all considered tertiary or quarternary level care. All adult patients with TSCI in the Republic of Ireland were identified at the point of entry to these centres and data collected at the point of hospital discharge between January 1, 2017 and December 31, 2022. The International Spinal Cord Injury Core Data Set, completed at the point of discharge from rehabilitation, was used to collect the relevant information for this study as follows: gender, age at TSCI onset, aetiology of TSCI, level of injury/ ASIA impairment scale (AIS), length of hospital stay and discharge destination. Patients who were referred from the NSIU or neurosciences centres and did not need/were deemed not suitable for specialist rehabilitation and those who died prior to discharge from the acute or the rehabilitation hospital were included in the overall numbers for calculation of incidence, but a full dataset was not available for these patients.
For continuous variables, mean and standard deviation (SD) or median and interquartile range (IQR) are reported. For categorical variables, crude data, frequencies and percentages are reported. To examine if there had been a change in aetiology and neurological impairment, the chi-square test was used. One way analysis of variance (ANOVA) was to examine if there had been any significant change in age at onset over the study period. One way ANOVA, followed by post hoc analysis, was used to examine the relationship between age at onset and each of aetiology, level/completeness of injury, discharge destination. Kruskal-Wallis Test was used to assess the relationship between length of stay and level/completeness of injury. Level of significance was set at 0.05. SPSS version 27 was used. For relevant statistical analyses, assault was included with injury termed “other” as there were just 5 cases in total.
Population denominator was the 2016 national census results, adjusted annually up to the 2022 national census [https://www.cso.ie/en/releasesandpublications/ep/p-cpsr/censusofpopulation2022-summaryresults/data/]. This adjustment is carried out by trending forwards the previous year’s census data i.e., ageing each person by 1 year, adding/subtracting from the national births/deaths registries and using migration flow data from the Quarterly National Household Survey. For this study, children (aged up to 16 years) were excluded from the denominator figures as we will report on paediatric SCI separately in the near future.
Ethical approval was not required as referral data was retrieved from the patient administrative system and the International Spinal Cord Injury Core Data Set is collected at discharge as part of the measurement of NRH Spinal Cord Systems of Care programme outcomes. This information is stored separately to patient records and is pseudonymized, as patient names are not recorded as part of the dataset.
Results
A total of 322 adult patients with new onset TSCI were admitted to hospital over the study period, 2017–2022. Mean crude incidence of TSCI was 14 per million per year, ranging from 11.3 to 18.4. Forty-one patients (12.7%) died before discharge from either the acute or rehabilitation phase of care. Thirty-eight patients (11.8%) did not attend for specialist in-patient rehabilitation at the National Rehabilitation Hospital, either because they were too frail for the programme or recovered adequately such that an in-patient service was not required.
Two hundred and forty-three patients completed an in-patient rehabilitation programme, of whom 184 (75.7%) were male. The mean age of injury onset was 50.1 years (SD 19.9). Table 1 shows comprehensive information on the clinical and demographic details for each year of the study period. Age at injury, aetiology or neurological impairment did not change significantly between 2017 and 2022.
Table 1.
Clinical and demographic details of traumatic spinal cord injury in Ireland, 2017–2022.
| 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | |
|---|---|---|---|---|---|---|
| Total number of cases | 55 | 69 | 57 | 51 | 44 | 46 |
| Incidence (per million) | 14.9 | 18.4 | 14.9 | 13.1 | 11.3 | 11.4 |
| Nos. (%) deceased before discharge from hospital | 7 (12.7) | 10 (14.5) | 3 (5.3) | 6 (11.8) | 6 (13.6) | 9 (19.6) |
| Nos. (%) who did not have in-patient specialist rehabilitation | 10 (18.2) | 8 (11.6) | 8 (14.3) | 6 (11.8) | 0 | 6 (13.0) |
| aNo. of cases discharged from rehabilitation (%) | 38 (69.1) | 51 (73.9) | 46 (80.7) | 39 (76.5) | 38 (86.4) | 31 (67.4) |
| aMales (%) | 29 (76.3) | 42 (82.4) | 34 (73.9) | 28 (71.8) | 27 (71.1) | 24 (77.4) |
| aAge (years – mean, SD) | 55.4 (15.7) | 48.9 (21.3) | 52 (20.5) | 53.1 (18.6) | 47.4 (20.6) | 42 (20.1) |
| aLevel of injury/AIS | ||||||
| C1 – C4 AIS A, B, C | 7 (18.4) | 10 (19.6) | 9 (19.6) | 10 (25.6) | 5 (13.2) | 4 (12.9) |
| C5 – C8 AIS A, B, C | 5 (13.2) | 4 (7.8) | 3 (6.5) | 3 (7.7) | 6 (15.8) | 5 (16.1) |
| T1 – S5 AIS A, B, C | 8 (21.1) | 14 (27.5) | 13 (28.3) | 12 (30.8) | 13 (34.2) | 14 (45.2) |
| AIS D | 18 (47.4) | 23 (45.1) | 21 (45.7) | 14 (35.9) | 14 (36.8) | 8 (25.8) |
| aImpairment, n (%) | ||||||
| Complete tetraplegia | 5 (13.2) | 8 (15.7) | 1 (2.2) | 6 (15.4) | 5 (13.2) | 3 (9.7) |
| Incomplete tetraplegia | 19 (50) | 22 (43.1) | 23 (50) | 17 (43.6) | 17 (44.7) | 12 (38.7) |
| Complete paraplegia | 2 (5.3) | 8 (15.7) | 5 (10.9) | 4 (10.3) | 4 (10.5) | 10 (32.3) |
| Incomplete paraplegia | 12 (31.6) | 13 (25.5) | 17 (37) | 12 (30.8) | 12 (31.6) | 6 (19.4) |
| aAetiology, n (%) | ||||||
| Fall | 23 (60.5) | 25 (49) | 27 (58.7) | 22 (56.4) | 23 (60.5) | 11 (35.5) |
| Transport | 6 (15.8) | 8 (15.7) | 8 (17.4) | 6 (15.4) | 5 (13.2) | 4 (12.9) |
| Sport | 3 (7.9) | 11 (21.6) | 3 (6.5) | 6 (15.4) | 7 (18.4) | 7 (22.6) |
| Assault | 0 | 1 (2) | 2 (4.3) | 0 | 0 | 2 (6.5) |
| Other | 6 (15.8) | 6 (11.8) | 6 (13.0) | 5 (12.8) | 3 (7.9) | 7 (22.6) |
| aTotal length of stay (days - median, IQR) | 184 (72.5) | 185 (110) | 183.5 (103.5) | 204 (107) | 144 (67.5) | 204 (141) |
| aDischarge destination | ||||||
| Home | 27 (71.1) | 32 (62.7) | 31 (67.4) | 28 (71.8) | 31 (81.6) | 16 (51.6) |
| Other hospital | 5 (13.2) | 12 (23.5) | 10 (21.7) | 8 (20.5) | 6 (15.8) | 14 (45.2) |
| Nursing home | 6 (15.8) | 4 (7.8) | 3 (6.5) | 1 (2.6) | 1 (2.6) | 0 |
| Assisted living | 0 | 1 (2) | 0 | 0 | 0 | 0 |
| Group living | 0 | 2 (3.9) | 0 | 0 | 0 | 0 |
| Other/Unknown | 0 | 0 | 2 (4.3) | 2 (5.1) | 0 | 1 (3.2) |
aRefers to the cases who were discharged from rehabilitation.
Figure 1 displays frequency with which each impairment occurred over the 6-year study period. Incomplete tetraplegia, of which there were 110 cases (45.3%), accounted for the highest proportion of impairments.
Fig. 1. Frequency of neurological impairments, 2017–2022.
Figure 1 displays frequency with which each impairment occurred over the 6-year study period. Incomplete tetraplegia, of which there were 110 cases (45.3%), accounted for the highest proportion of impairments.
Figure 2 shows the injury aetiologies per year of study. Falls accounted for 53.9% of all aetiologies while sports and transport each accounted for 15.2%.
Fig. 2. Percentages of injuries by year (2017–2022) based on aetiology.
Figure 2 shows the injury aetiologies per year of study. Falls accounted for 53.9% of all aetiologies while sports and transport each accounted for 15.2%.
Results of mean and standard deviation (SD) calculation examining relationships between age at onset and each of aetiology, impairment and discharge destination are displayed in Table 2. The age at injury was significantly younger in those with transport aetiology (mean age 38.5 years, p < 0.001) and in those injured as a result of sport (mean age 40.8 years, p < 0.001) compared to those who sustained a fall (mean age 56.9 years). The age at onset was significantly higher in those with incomplete tetraplegia (mean age 57 years, p < 0.001) than in those with complete tetraplegia (mean age 42.1 years), complete paraplegia (mean age 40.9 years) and incomplete paraplegia (mean age 46.8 years). Age was significantly younger in those discharged to home (mean age 48.6 years, p < 0.001) compared to those discharged to anursing home (mean age 64 years).
Table 2.
Relationship between age at injury and each of aetiology, impairment and discharge destination.
| Mean (SD) | |
|---|---|
| Aetiologya | |
| Fallb | 56.9 (18.6) |
| Transport | 38.5 (20.8) |
| Sport | 40.8 (17.6) |
| Other | 46.9 (16.7) |
| Level/AIS | |
| Complete tetraplegia | 42.1 (18.3) |
| Incomplete tetraplegiac | 57.0 (19.0) |
| Complete paraplegia | 40.9 (18.9) |
| Incomplete paraplegia | 46.8 (18.7) |
| Discharge destination | |
| Homed | 48.6 (19.4) |
| Other hospital | 51.1 (19.5) |
| Nursing home | 64.0 (18.4) |
| Other | 51.8 (23.3) |
aAssault included with aetiology termed “Other”.
bSignificantly older than those with transport or sport aetiology (p < 0.001).
cSignificantly older than complete tetraplegia, complete paraplegia and incomplete paraplegia (p < 0.001).
dSignificantly younger than those discharged to nursing home (p < 0.001).
There was a significant relationship between total length of stay and impairment over the 6-year study period. Those with complete tetraplegia had significantly longer length of stay (median 339 days, IQR 171) compared to those with incomplete tetraplegia (median 193 days, IQR 115), complete paraplegia (median 179 days, IQR 84) and incomplete paraplegia (median 147 days, IQR 58), p < 0.001.
Discussion
In this retrospective study, we have examined the overall incidence of TSCI and clinical features of those completing specialist in-patient rehabilitation in Ireland during the period 2017–2022 inclusive. Mean crude incidence rate of 14 per million per year (range 11.3–18.4) is similar to other European countries but considerably lower than in North America [8–11].
During the years of the COVID 19 pandemic, 2020, 2021, 2022, incidence was 13.1, 11.3 and 11.4 per million per year respectively, similar to the pre-pandemic years [3, 4]. A study in Scotland found that TSCI incidence was lower during COVID 19 lockdowns [7]. However, we did not find any change in incidence when we examined the first lockdown in Ireland, albeit over a much shorter period, between March and June 2020 [12].
Over the 6 years of this study, 12.7% of the injured did not survive 1 year/until completion of rehabilitation. This is the first time we have reported mortality during acute care/rehabilitation. The mortality rate is higher in older people after TSCI and it has been reported previously that 16.2% of adults aged 65 years or older do not leave hospital after SCI due to death [13, 14]. Although we did not have data on the clinical characteristics of those who died, there are more older people sustaining TSCI in Ireland [15] and it is likely that those who died were older.
Age at onset of injury did not change statistically over the study period. Since 2014, mean age of TSCI onset has been greater than 50 years most years [3, 4]. In this study, it is likely that the reported mean age is an underestimation, given that those who died are likely to have been older. Although not statistically different, the mean age of those discharging from rehabilitation in 2022 was 42 years, which may reflect the change seen in Scotland during the COVID years where the lower TSCI incidence affected those aged over 45 years to a greater extent (8).
Falls in older people has been the most common aetiology of TSCI for some time in Ireland and in other developed countries [3, 4, 16]. In fact, incomplete tetraplegia arising from falls in an older population could be considered a medical triad [17]. This is reflected in our reported associations between age and aetiology, injury and impairment. It is not surprising that fewer older people are discharged to home as is also reported elsewhere [14].
Since this study has been carried out, the implementation of a new trauma system of care in Ireland has commenced. It will be interesting to observe if there will be any impact on TSCI patients’ outcomes, given that there is already an established pathway for TSCI to the NSIU in the MTC. It is possible that the new system will result in the national ambulance service and regional trauma units making contact more rapidly through a new specially designated telephone line [https://www.hse.ie/eng/about/who/acute-hospitals-division/trauma-services/1800-trauma/hse-1800-trauma-process.pdf]. However, it is also possible that stricter repatriation protocols will mean that TSCI patients are not differentiated from those without neurological compromise and discharged more rapidly and with greater frequency to non-specialist SCI services. Therefore, this work should be repeated in 5–7 years to see what impact if any the new trauma system has had on patients with TSCI.
Strengths of this study include that it is population based with ease of identification of cases due to a small population and a limited number of centres taking care of patients with TSCI. This is not always possible in countries with a larger population. We have been able to provide more detailed clinical data than that available from studies using health administrative databases [11].
This study also has some limitations. Cases of TSCI who did not survive to the point of referral to tertiary/quartenary level care are not included in the incidence figures. We could not produce a full dataset on those who did not complete specialist rehabilitation. However, case identification without full data is useful in determining overall incidence rates. This has also been carried out for a recent Canadian study using health administrative data to determine the number of cases admitted to hospital and then the numbers discharged, with the former giving a more accurate indication of overall incidence [11]. Although data was not available on those patients who died before discharge from hospital, the main value in clinical and neurological data is for those surviving their injuries as this is the information needed for service planning. Finally, due to the small numbers, our statistical analysis is limited.
Conclusion
Incidence of TSCI onset has remained constant in Ireland prior/over this study period, as has the pattern of older people sustaining incomplete tetraplegia due to falls. Our first report of mortality figures during acute care/rehabilitation showed that 12.7% did not survive to discharge from hospital. We should continue to strive towards a national registry for TSCI to monitor changes which will arise as a result of reorganisation of trauma services in Ireland.
Author contributions
INBMF collected the data for this study and write the first draft of this manuscript. ES developed the idea for this work, supervised INBMF with data compilation and wrote further drafts of this manuscript.
Data availability
Data can be obtained by contacting the corresponding author, ES.
Competing interests
The authors declare no competing interests.
Ethics approval
Is as outlined in the methods section of this manuscript.
Footnotes
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
Data can be obtained by contacting the corresponding author, ES.