Trauma and amyotrophic lateral sclerosis: a systematic review and meta-analysis

Background: Trauma especially head trauma is considered a potential risk factor of amyotrophic lateral sclerosis (ALS), but their association has not been well established. We aimed to determine the association of prior trauma with ALS risk. Methods: This study was performed according to the Meta-Analysis of Observational Studies in Epidemiology guideline to assess related literatures, and a random-effects model was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Results: Twenty-nine eligible articles involving 18,390 cases and 6,519,391 controls were included in this meta-analysis. The results showed that trauma was associated with an increased risk of ALS (pooled OR = 1.51, 95% CI: 1.32-1.73). Besides, patients with trunk trauma, head trauma and lower limb trauma had an increased risk of ALS, whereas no evidence suggested that upper limb trauma and spine trauma could increase ALS risk. Considering the number of traumatic events, the association between trauma and ALS risk was significant for patients with repeated trauma events (pooled OR = 1.21, 95% CI: 1.07-1.38). The results showed that individuals with a history of trauma within 5 years were more likely to be diagnosed with ALS (pooled OR = 1.84, 95% CI: 1.56-2.17). Importantly, both old trauma and very old trauma were found to be associated with an increased risk of ALS (pooled OR = 1.24, 95% CI: 1.12-1.38; pooled OR = 1.28, 95% CI: 1.10-1.49; respectively). Conclusions: This meta-analysis indicated that trauma could increase ALS risk, which may be applied for the clinicians to tailor targeted treatment regimens and make prophylactic strategies for ALS in traumatic patients.