Longitudinal effects of time since injury and age at injury on outcomes of people with spinal cord injury in Queensland, Australia

STUDY DESIGN: Longitudinal cohort study. OBJECTIVES: To investigate the longitudinal effects of time since injury and age at injury on outcomes of quality of life, physical function, secondary conditions and participation, in people with traumatic spinal cord injury (SCI). SETTING: Community resident people with spinal cord injury in Queensland, Australia. METHODS: A baseline sample of 270 people with SCI was recruited. Telephone surveys on measures of quality of life (WHOQOL-Bref), secondary conditions (Secondary Conditions Surveillance Instrument, subset), physical functioning (Functional Independence Measure motor subscale) and participation (Community Integration Measure) were conducted each year between 2004 and 2008, and again in 2018. Random-effect within-between models were used to determine the effect of time since injury and age at injury on each outcome variable. Inverse probability-of-censoring weights were used to correct for selection bias. RESULTS: There was an effect of time since injury on secondary conditions, with a one-year change associated with 9% higher odds of having worse Secondary Conditions Surveillance Instrument scores (odds ratio = 1.09, 95% confidence interval = 1.02, 1.17; p = 0.006). We did not find any evidence of a time since injury effect on quality of life, physical function, or participation. Similarly, we did not find any evidence of an age at injury effect on any outcome variable. CONCLUSIONS: Secondary conditions may increase with longer time since injury among people with SCI, suggesting appropriate formal and informal supports are required to minimise the impact of these emerging health problems as individuals age.