Natural Experiments as a Study Method in Spinal Trauma Surgery: A Systematic Review

Study Design: Systematic review. Objectives: To determine if the natural experiment design is a useful research methodology concept in spinal trauma care, and to determine if this methodology can be a viable alternative when randomized controlled trials are either infeasible or unethical. Methods: A Medline, Embase and Cochrane database search was performed between 2004 and 2023 for studies comparing different treatment modalities of spinal trauma. All observational studies with a natural experiment design comparing different treatment modalities of spinal trauma were included. Data extraction and quality assessment with the MINORS criteria was performed. Results: Four studies with a natural experiment design regarding patients with traumatic spinal fractures were included. All studies were retrospective, one study collected follow-up data prospectively. Three studies compared different operative treatment modalities, whereas one study compared different antibiotic treatment strategies. Two studies compared preferred treatment modalities between expertise centers, one study between departments (neuro- and orthopedic surgery) and one amongst surgeons. For the included retrospective studies, MINORS scores (maximum score 18) were high ranging from 12-17 and with a mean (SD) of 14.6 (1.63). Conclusions: Since 2004 only four studies using a natural experiment design have been conducted in spinal trauma. In the included studies, comparability of patient groups was high emphasizing the potential of natural experiments in spinal trauma research. Natural experiments design should be considered more frequently in future research in spinal trauma as they may help to address difficult clinical problems when RCT's are infeasible or unethical.