Functional limitations before and after cancer diagnosis and contributing factors: findings from the China health and retirement longitudinal study

Background Although there is a general trend of functional decline with age, there lacks an understanding of how cancer diagnosis and other factors may contribute to this trend. This study aimed to examine functional limitation trajectories among adults with and without cancer, and before versus after the cancer diagnosis, and to explore potential contributing factors associated with functional trajectories among cancer survivors. Methods The sample were middle-aged and older Chinese adults who participated in all 3 waves of the China Health and Retirement Longitudinal Study (CHARLS, 2011-2015). Ordinary and multiphase growth curve analyses were conducted to examine (1) differences in functional trajectories between participants with (n = 139) and without cancer (n = 7,313), (2) pre-and post-cancer diagnosis changes in functional limitations among those who reported a cancer diagnosis over the 4-year timeframe, and (3) contributing factors associated with functional trajectories among cancer survivors, guided by the Disablement Process Models, including psychological (depressive symptoms), physical (pain and falls), cognitive (self-reported memory problems), and environmental (social contact and available support) factors. Results There was a trend of increased functional limitations among all participants over time (unstandardized beta = 0.17, p < .0001). However, participants with cancer did not differ from non-cancer participants in neither the level (unstandardized beta = 0.77, p = .08) nor the rate of functional decline (unstandardized beta = -0.43, p = .07). Functional limitation trajectories were different pre- versus post-cancer diagnosis, although not in expected directions (unstandardized beta = -0.48, p < .05). Cancer survivors with greater pain had higher levels of functional limitations which were sustained over time compared to those with less pain (unstandardized beta = 0.93, p < .001). Conclusions The study confirmed that Chinese middle-aged and older adults had overall decreased functional decline over time. A novel finding that cancer survivors experienced less rapidly functional decline after the cancer diagnosis suggested that cancer diagnosis might serve as an inflection point at which early intervention is promising to slow the functional decline. In addition, findings that within-person contributing factors, such as pain, can be influential in functional limitation trajectories suggested that more attention is needed to pay to patients with cancer-pain. These findings demonstrated the heterogeneity of functional limitation trajectories and needs for person-centered interventions among Chinese cancer survivors.