Time Since Injury Is Key to Modeling Trends in Aging and Overall Functioning of Persons With Spinal Cord Injury: A Longitudinal Analysis of a Swiss Community Survey.

OBJECTIVE

The aim of the study is to model the health indicator of functioning for persons with spinal cord injury or disorder living in Switzerland in the long-term context, considering chronological age, time since injury, and age at injury.

DESIGN

This is a longitudinal analysis of three waves of a community survey. An interval-scaled functioning metric was constructed using modern test theory. Random effects within-between mixed models were used to investigate trends in functioning over time.

RESULTS

Persons with complete injuries have lower levels of functioning than persons with incomplete injuries, and persons with complete tetraplegia have the lowest levels of functioning. The person's age when injured, the level and completeness of the injury, the presence of secondary health conditions, and various combinations of these factors significantly influenced how functioning changed over time.

CONCLUSIONS

Our study shows that chronological age is not necessarily the best time variable for understanding the aging process of people with spinal cord injury in terms of changes in functioning over time and that modeling functioning over time since injury provides important insights into how functioning of people with complete or incomplete injuries declines with increasing time living with the injury.