Research within the areas of cognitive impairment and liver transplantation has demonstrated that a subgroup of liver transplant (LT) recipients experience global as well as domain-specific cognitive impairment (e.g., attention and memory) post-transplant (Ahluwalia et al., 2016; Tryc et al., 2014). Although it has not been clearly identified, it is anticipated that multiple factors, including pre-transplant hepatic encephalopathy, brain ischemia during LT surgery, immunosuppressant treatment, and comorbidity, are potential etiological factors for post-transplant cognitive impairment (Aceto et al., 2015). However, current research has been limited to examining the impacts of LT on reversing pre-transplant cognitive impairment (Campagna et al., 2014; Lin et al., 2014), resulting in an insufficient understanding of lingering post-transplant cognitive impairment in LT recipients. Specifically, there is a lack of knowledge regarding the relationships between LT recipients’ demographic and clinical characteristics and post-transplant cognitive impairment. Furthermore, while cognitive impairment has been associated with poor health outcomes in other chronic conditions due to its negative effect on self-management (Hjelm, Brostrom, Riegel, Arestedt, & Stromberg, 2015), its potential impacts on self-management among LT recipients are largely unexplored. Therefore, the aims of this study were 1) to describe global and domain-specific cognitive function in LT recipients, 2) to examine differences in global and domain-specific cognitive function by demographic and clinical characteristics, and 3) to examine differences in global and domain-specific cognitive function by levels of self-management.
Methods:
A secondary data analysis was performed. The parent study aimed to improve the understanding of self-management in community-dwelling LT recipients, and was cross-sectional in design and collected data from June to October 2017. This study included adult LT recipients, who had a functioning LT for at least six months. LT recipients who had received a multi-organ transplant or any other transplant or diagnosed with dementia were excluded from this study. The Montreal Cognitive Assessment (MoCA) was used to assess both global and domain-specific cognitive function. MoCA scores range from 0 to 30 and are typically categorized as dementia (<17), moderate cognitive impairment (17 to 21), mild cognitive impairment (22 to 25), and normal (≥26) (Athilingam et al., 2013). Four domain-specific cognitive function scores (i.e., visuospatial/executive function, memory, attention, and language) were calculated based on the work of Vogel, Banks, Cummings, and Miller (2015). Demographics such as age, gender, and marital status and clinical characteristics including donor type and time since LT were assessed using a patient information questionnaire. The Health Education Impact Questionnaire and Basel Assessment of Adherence with Immunosuppressive Medication Scale were used to assess self-management. Self-management was classified as low, medium, and high using latent profile analysis, which grouped LT recipients based on the responses to the self-management measures. T-tests or Mann-Whitney tests, depending on normality, and Kruskal-Wallis tests were used to examine differences in cognitive function by demographic and clinical characteristics and levels of self-management.
Results:
Data from 107 LT recipients (mean age 61±11.9, 60% male, 95% White, mean 14.0±3.1 years of education, and mean 7.6±6.5 years post-transplant) were extracted for this study. The mean global cognitive function score was 24.4±3.1, indicating mild cognitive impairment. More than half of LT recipients were classified as cognitively impaired; While 44% of LT recipients scored within the MoCA's normal range, 36% of them scored within the mild cognitive impairment range, 19% scored within the moderate cognitive impairment range, and 0.9% scored within the range of dementia. Global cognitive impairment was shown in older LT recipients (age over 65 years). LT recipients who were older, male, married, less educated, or received deceased donor transplants had lower domain-specific cognitive function than those who were younger, female, single, had higher education, or received living donor transplants. Cognitive function was not significantly different by time since LT. Finally, no significant differences were found in global or domain-specific cognitive function by levels of self-management.
Conclusion:
Findings from this study inform future directions for nursing science. First, this study found that LT recipients at any time point post-transplant experience cognitive impairment. It is necessary to prioritize examination of cognitive function for extended time points post-transplant. Second, the findings of this study imply that there may be other factors which influence self-management of LT recipients. For example, caregivers’ participation in self-management may compensate LT recipients’ reduced ability to self-manage due to cognitive impairment. Caregiver participation should be accounted for in future studies when examining cognitive function and its relationship with self-management in the LT population. Lastly, future longitudinal studies should be conducted to develop profiles of LT recipients at higher risk of developing post-transplant cognitive impairment. A few limitations should be considered in understanding the findings from this study. As a single center study, a selection bias may exist. Cognitive function was assessed with a screening tool, instead of a comprehensive battery. Lastly, there may be a response bias as self-management was self-reported by LT recipients. Future studies should include objective measures of self-management.