Premature aging with a number of different organ systems appears to lead to the higher prevalence of a number of secondary health conditions compared to the normative population (Jensen et al. 2013). Of concern is that more medical attention is required over time to address these secondary health complications (Krause et al. 2013). As with the general population (Roy & Thomas 1986; Gaston-Johansson et al. 1996; Poluri et al. 2005), issues of fatigue and pain can limit the independence of a person with SCI. Fatigue can be defined as an overwhelming sense of tiredness, lack of energy and often a feeling of total exhaustion (Herlofson & Larsen, 2002). Fatigue after SCI is a prevalent issue (Gerhart et al. 1999; McColl et al. 2003; McColl et al. 2004; Fawkes-Kirby et al. 2008). The findings on the associations between age and fatigue after SCI have been somewhat conflicting. For example, one study found that males with SCI reported an increased fatigue with increasing age (Pentland et al., 1995), whereas some have found greater reports of fatigue in younger persons with SCI with short duration of injury (McColl et al. 2003).
Both pain and fatigue have been both found to negatively impact on several domains of function and QoL (Rintala et al. 1998; Ingles et al. 1999; Herlofson & Larsen 2002). As well, there is some evidence of a relationship between fatigue and pain after SCI (Fawkes-Kirby et al. 2008). When examined together, the study by Charlifue and colleagues (1999) and by Putzke and colleagues (2002a) highlight chronological age as a factor that mediates the expression and/or onset of change. In the study by Charlifue et al. (1999), the youngest and oldest group reported no significant changes in fatigue between Time 1 and Time 2. Similarly, in the study by Putzke et al. (2002a) the youngest and oldest group reported the least amount of pain interference between Year 1 and Year 2; however, overall, older individuals were significantly more likely to report pain in both years than younger individuals with SCI. In terms of the influence of pain and the interference of pain on QoL over time, Putzke et al. (2002a) found that those individuals who experienced increased interference over time had decreased life satisfaction scores, whereas those whose interference subsided had increased life satisfaction. Similarly, Stensman (1994) observed over 5 years that individuals with variable pain experienced fluctuating global QoL, those with constant pain experience consistently low QoL, and those with no or little pain had consistently high or improvements to an initially low QoL over time.
The finding by Charlifue and colleagues (1999) that increasing age is associated with increased fatigue and additional physical assistance is congruent with other studies examining the effects of long-term SCI (e.g. Gerhart et al. 1993; Thompson, 1999; Liem et al. 2004). A limitation noted by Charlifue et al. (1999) was that their sample was relatively ‘young’ (M= 37.1 years), and none having lived with their SCI for more than 20 years (M= 9.3), and may not have aged enough to significantly affect overall health and functional status. However, the consistent findings for increased fatigue between Time 1 and Time 2 do highlight that there is a consistent physical decline occurring. Charlifue and colleagues (1999) recognized the systematic changes in their sample (i.e. improved health but declining functionality) but attributed them to external factors such as less contact with the healthcare system, funding changes, which lead to fewer participants reporting particular outcomes. As well, they noted the need for increased physical assistance over time in their sample may have reflected attitude changes in rehabilitation practice where maintaining functionality is preferred over complete physical independence. Although the strength of the study is its provision of several perspectives to aging with a SCI, an alternative analysis strategy might have helped to provide a more cohesive model of how the factors assessed related to one another. For instance, the increases in physical assistance between Time 1 and Time 2 were often accompanied with improvements in health but also with increases in fatigue. Reporting on associations (or lack of) between these variables may have provided additional support for their conclusions.
There is Level 3 evidence (Jensen et al. 2013) from a scoping review that cardiovascular disease, diabetes, bone mineral density loss, fatigue and respiratory complications or infections occur with higher frequency in older individuals or those with longer SCI duration, relative to younger individuals or those with shorter SCI duration.
There is Level 4 evidence (Ullrich et al. 2013) from one longitudinal study that co-occurrence of pain and depression is common among persons who have lived with SCI for many years and remains stable over time. There is also evidence that comorbid pain and depression are associated with higher severity of conditions, more persistent conditions over time, and more utilization of SCI specialty health-care services.
There is Level 4 evidence (Hitzig et al. 2010; Pershouse et al. 2012) that secondary health complications increase over time in persons with SCI, (with the exception of bowel problems, which decrease).
There is Level 4 evidence from a longitudinal study (Charlifue et al. 1999) that fatigue and the need for physical assistance increases over time with SCI.