Literature Search
The database search yielded 3098 citations. One study was found by gray literature search, three were retrieved from the reference lists of the included studies, and one abstract was included following a search of conference proceedings. In total, 17 studies with 2,804 patients met our inclusion criteria and were included in this systematic review (Figure 1).
Study Characteristics and Methodological Quality
The characteristics of included studies are summarized in Table 1. Studies differed in their definitions of early and late tracheostomy (Supplemental Appendix 6), although the majority utilized a range of <7 days (from either injury, intubation, or surgery) for early tracheostomy [23–33]. In one study, early and late tracheostomy were defined as <7 days and >7 days, respectively, but the time point from which tracheostomy was measured was not specified [34]. Two studies utilized a range of <10 days and >10 days [35][36]. Two studies did not report the specific timing of tracheostomy [37][38]. Patient characteristics from the included studies are reported in Supplemental Appendix 7. In one study of 344 SCI patients, 72 patients also had concomitant traumatic brain injury [34]. One study investigated outcomes of children/adolescents and thus consisted of patients <18 years old [30].
Quantitative Data Synthesis
Primary Outcome
A summary of the study results is included in Supplemental Appendix 8. Early tracheostomy was not found to be associated with short-term mortality (RR 0.84, 95% CI 0.39 to 1.79; p = 0.65; 10 studies; n = 2,072; 125 events; I2 = 52%; Figure 2, Table 4). Flanagan et al. also measured 90-day mortality with a mortality rate of 6.3% in the early tracheostomy group and 3.5% in the late tracheostomy group [28]. In addition to hospital mortality, Jeon et al. also reported ICU mortality (2.6% and 4.7% for the early and late tracheostomy groups, respectively) [36].
Subgroup Analyses
There was no difference in mortality between early and late tracheostomy when a subgroup analysis of study publication year (within the last 5 years versus older) was performed (p = 0.58; 10 studies; n = 2,072; 125 events; I² = 0%). Further planned subgroup analyses could not be completed due to insufficient data.
Secondary Outcomes
Secondary outcomes are reported in Table 4. Early tracheostomy was found to be associated with reduced mean duration of mechanical ventilation by 13.91 days (95% CI -6.70 to -21.11; p = 0.0002; 10 studies; n = 855; I2 = 96%; Supplemental Appendix 10), reduced mean ICU LOS by 10.20 days (95% CI -4.66 to -15.74; p = 0.0003; 10 studies; n = 855; I2 = 90%; Supplemental Appendix 11), as well as reduced mean hospital LOS by 7.39 days (95% CI -3.74 to -11.03; p < 0.0001; 8 studies; n = 423; I2 = 3%; Supplemental Appendix 12). Early tracheostomy was also associated with decreased incidence of VAP (RR 0.86, 95% CI 0.75 to 0.98; p = 0.08; 10 studies; n = 2,043; 691 events; I2 = 41%; Supplemental Appendix 13) as well as the number of tracheostomy-associated complications with early tracheostomy (RR 0.08, 95% CI -0.01 to -0.15; p = 0.02; 8 studies; n = 812; 158 events; I2 = 60%; Supplemental Appendix 14). The other secondary outcomes that we were unable to find data on included long-term benefits such as quality of life measures as well as time to phonation.
Qualitative Assessment of Additional Secondary Outcomes
Bellamy et el. reported over 20 years experience at a single trauma centre of respiratory complications in SCI patients with quadriplegia. Twenty-eight tracheostomies performed within 3 days of injury were associated with 39 pulmonary complications and 14 deaths, while 4 cases of tracheostomy performed after 3 days were associated with 24 pulmonary complications and 1 case of death [26]. Mortality in this study was measured at 1 year and thus considered a long-term outcome; other than the study performed by Babu et al., which measured mortality at 1 year for the total study population, this was the only study to report long-term mortality [24]. Only 1 study reported duration of sedation and found that there was no significant difference for patients who underwent early versus late tracheostomy (14.4 + 10.4 days vs. 10.5 + 7.1 days, respectively, p = 0.283) [25]. The same study also found that timing of tracheostomy did not affect time to initiation of oral nutrition [25]. Vitaz et al. found that implementation of a clinical pathway, including the placement of a tracheostomy approximately 4 days following injury, was associated with a decreased number of both decubitus ulcers and stage III ulcers (25% and 0%, respectively, in the clinical pathway group compared to 54% and 14%, respectively, in the control group) [33]. In a study investigating the impact of performing tracheostomy prior to anterior cervical fusion, three patients who underwent tracheostomy within 7 days of their injury experienced a deep vein thrombosis (DVT), while two patients who underwent tracheostomy after 7 days experienced a DVT [39]. One patient in the late tracheostomy also experienced post-operative decubitus ulcers. In 29 patients with traumatic cervical SCI, late (>24 hours after injury) tracheostomy was associated with decreased time to decannulation compared to early (<24 hours after injury) tracheostomy (35.0 (14-46) days vs. 42.0 (23-104) days, respectively) [40]. In contrast, Flanagan et al. found that early tracheostomy was associated with fewer days to decannulation compared to late tracheostomy (53.0 + 28.1 vs. 74.3 + 45.8 days, p < 0.05) when ASIA Impairment Scale and level of neurological injury were controlled for [28].
Patient and surgical factors associated with timing of tracheostomy
Analysis of spinal cord injury level and timing of tracheostomy found earlier tracheostomy was more likely performed in patients with a thoracic SCI compared to cervical SCI (RR 1.56, 95% CI 1.10 to 2.21; p = 0.01; 2 studies; n = 367; 172 events; I2 = 0%). Evaluating specific SCI levels, there was a trend towards early tracheostomy in patients with a SCI at or below C5, compared with a SCI above C5 (RR 1.29, 95% CI 0.97 to 1.72; p = 0.08; 4 studies; n = 1,243; 352 events; I2 = 43%). There was a trend towards male sex associated with early tracheostomy (RR 1.12; 95% CI 0.98 to 1.29; p = 0.10; 11 studies; n = 2106; 732 events; I2 = 12%). In terms of type of tracheostomy procedure, there was no difference in the timing of tracheostomy when performing a surgical tracheostomy compared to percutaneous tracheostomy (RR 1.09, 95% CI 0.90 to 1.32; p = 0.36; 5 studies; n = 609; 284 events; I2 = 0%). Finally, there was no difference in the timing of tracheostomy in patients that received a posterior spine fixation compared to an anterior fixation (RR 1.14, 95% CI 0.60 to 2.14; p = 0.69; 2 studies; n = 320; 95 events; I2 = 6%).