Current deficits in the rehabilitation psychology literature involving longitudinal studies investigating positive outcomes following acquired disabilities have deserved research attention. In the current study, data on happiness as an enduring mood tone, as measured by the Life Satisfaction Index (LSI) was collected from 1271 individuals ("insiders") having incurred either a traumatic brain injury (TBI), spinal cord injury (SCI), severe burn, or intra-articular fracture (IAF) or from someone who felt close enough to speak on their behalf ("outsiders"). Data on happiness, functional independence as measured by the Functional Independence Measure (FIM), and other variables of interest were collected at 12 months, 24 months, 48 months, and 60 months after being medically discharged. Hierarchical Linear Modeling (HLM) analyses showed that trajectories of happiness remained stable across participants and did not change significantly over five years post-discharge regardless of injury type, FIM, or insider/outsider status. Happiness was significantly predicted by FIM, injury type, and whether the respondent was an insider or outsider. Those who were more impaired and less functionally independent were less happy. Those with a TBI were consistently less happy than those with an IAF or SCI and outsiders reported greater happiness on behalf of the insider than did the insiders themselves. This study shows that there is stability in happiness levels that can be sustained at least five years post-discharge and that there are discrepancies between insider and outsider reports of subjective happiness. Proxy reports can be used as valuable and valid secondary sources of information but should not be used as substitutes for first hand reports unless absolutely necessary.
