Secondary complications of spinal cord injury : risk, inter-relationships, and effects on neurological outcomes

Background: Although there have been major advances in acute care following spinal cord injury (SCI), individuals surviving the acute period experience a reduced life expectancy. Historically, acute respiratory and renal dysfunction were the most prevalent complications, and remain important contributors to mortality. However, all-cause cardiovascular disease (CVD) has now emerged as the leading cause of mortality in chronic SCI. Although it has been long speculated that individuals with SCI may be at a higher risk of complications such as CVD, quantitative data are currently limited. Furthermore, the inter-relationships among secondary complications are currently unknown, as is the relationship with changes in neurological function. Objectives: to examine the risk of secondary complications among individuals with SCI; to examine the relationships among secondary complications in individuals with SCI; to examine the relationship among secondary complications and neurological outcomes. Methods: Data were compiled from the Canadian Community Health Survey, the SCI Community Health Survey, the European Multi-Centre Study on Spinal Cord Injury dataset, and the Simon Fraser University SCI dataset. Several methods were employed for analysis of these data, including: multivariable logistic and linear regression, mixed effects models, and unbiased recursive partitioning. Results: Findings identified elevated odds of heart disease, stroke, Type 2 diabetes, chronic respiratory conditions, and chronic pain among individuals with SCI when compared with non-SCI individuals. Complex correlations were also identified among secondary complications following SCI. These include positive associations between neuropathic pain and CVD, and between blood pressure fluctuations and CVD. Lastly, secondary complications (specifically neuropathic pain) following SCI were positively correlated with neurological decline in chronic phases of injury, and neurological motor recovery in acute phases. These relationships may be partly related through treatments for the secondary complications rather than the secondary complications themselves. Implications: These novel findings update current knowledge of secondary complications among individuals with SCI. These data are useful in guiding the prospective collection of data elements within SCI-specific registries, as well as the design/analysis of studies (i.e., issues of confounding in multivariable analyses). These epidemiological data will also be useful for refined, hypothesis-driven physiological studies exploring precise biological mechanisms.Medicine, Faculty ofPopulation and Public Health (SPPH), School ofGraduat