Bivariate correlations, of study variables.

Background
Family caregivers play a crucial caregiving role for colorectal cancer patients undergoing chemotherapy, and the emotional states of both patients and caregivers can influence each other. A high prevalence of depression and anxiety exists among both patients and caregivers, with their emotional states mutually influencing each other. This significantly impacts the quality of life for both parties. However, there is limited research on the bidirectional relationship between depression and anxiety in both groups.
Objective
This study aims to investigate the longitudinal bidirectional relationship between depression and anxiety in colorectal cancer patients and their family caregivers using a cross-lagged panel model.
Method
A total of 244 pairs of colorectal cancer patients undergoing chemotherapy and their family caregivers were assessed using the Hospital Anxiety and Depression Scale. Data collection was conducted at four time points: the initial chemotherapy session and 1-, 3-, and 6- months post-chemotherapy. A cross-lagged panel model was employed to analyze the longitudinal interrelationship between depression and anxiety within and between the two groups.
Result
The study found high prevalence rates of depression and anxiety in both colorectal cancer patients and their caregivers. The cross-lagged model revealed a dynamic, bidirectional relationship between depression and anxiety in patients and caregivers from the second wave onwards (P <  0.05).
Conclusion
The emotional states of depression and anxiety in colorectal cancer patients and their caregivers show dynamic changes and are longitudinally interrelated. These findings underscore the importance of early psychological assessment and interventions targeting both patients and caregivers.