The impact of comorbidity on the relationship between life stress and health-related quality of life for Chinese- and Korean-American breast cancer survivors

Objective: The current study aimed to (1) identify the occurrence of comorbidities among Chinese- and Korean-American breast cancer survivors (BCS), (2) examine whether health-related quality of life (HRQOL) scores varied with the occurrence of specific comorbidities, and (3) investigate the mediating effect of comorbidities on the relationship between life stress and HRQOL.Design: Data were drawn from the parent study, a cross-sectional study investigating HRQOL in 86 Chinese- and 71 Korean-American BCS in Southern California. Two comorbidity-related variables, the occurrence of the specific comorbidity and the total number of comorbidities, were used to comprehensively reflect the characteristics of comorbidity.Results: Approximately 60% of participants had at least one comorbid disease, and osteoporosis was the most prevalent comorbidity. HRQOL differences based on the occurrence of a specific comorbidity were evident for arthritis, eye/vision problems, dental and gum problems, lymphedema, and psychological difficulties. Structural equation modeling demonstrated that the nature of the outcome variable, either physical or mental HRQOL, influenced the overall patterns of the findings. For example, life stress was significantly associated with the total number of comorbidities and in turn influenced physical HRQOL. In terms of mental HRQOL, arthritis, dental and gum problems, chronic pain, heart disease, lymphedema, and psychological difficulties mediated the relationship between life stress and mental HRQOL.Conclusion: The current study adds to the existing literature by examining the mediating effects of comorbidity on the relationship between life stress and HRQOL. The findings support the need for health care professionals to clearly assess physical and psychological comorbidities when providing survivorship care for cancer survivors.