In this study, we investigated the relationship between life-satisfaction and self-efficacy and the characteristics of outpatients undergoing hemodialysis. High life-satisfaction scores were observed in females, non-diabetic patients, and working patients. High life-satisfaction scores were associated with high nPCR and CGR. High self-efficacy scores were common among elderly patients. This life-satisfaction questionnaire is simple and related to a patient’s physical condition.
The most important finding was that the simple questionnaire of life-satisfaction was related to prognostic markers for dialysis patients, such as nPCR and CGR, compared to the self-efficacy questionnaire [14]. Of note, life-satisfaction scores were higher in females, non-diabetics, and working patients. Females, non-diabetic and working individuals tend to have a better prognosis than males, diabetic and non-working individuals [15, 16]. Physical conditions can affect mental status. For example, strong monotonic associations have been observed between pruritus severity and lower physical and mental quality of life, increased depressive symptoms, and poorer sleep quality. Compared with the reference group without any pruritus-related symptoms, the adjusted mortality of patients extremely bothered by pruritus was significantly higher [17]. Conversely, mental status can affect a patient’s physical condition. Depression in incident hemodialysis patients was associated with a higher risk of hospitalization and longer hospital stay [18]. Depression influences the prognosis, complications, quality of life, treatment and costs for dialysis patients worldwide [19]. Our cross-sectional study cannot prove a causal relationship between life-satisfaction scores and physical condition; however, it is meaningful to clarify the close relationship between mental and physical conditions in patients undergoing hemodialysis. More randomized interventional studies are required to determine the effectiveness, costs, and opportunity costs of providing supportive care in hemodialysis patients [20, 21] (Table 2, Additional file 3).
In our study, females had a significantly higher life-satisfaction score than males. This can explain why BMI, BSA, height and dry weight were significantly lower when the life-satisfaction score was higher. BMI, BSA, height and dry weight were correlated with each other, except BMI and height (correlation coefficient > 0.6, Additional file 6) (Table 2, Additional file 3).
Self-efficacy is important in managing the physical status of dialysis patients [22]. However, the self-efficacy scores were higher in elderly patients, which is common in all clinics. Elderly patients tend to be confident in controlling their food intake and drug management, which is consistent with previous reports [23–26]. These studies suggest that increasing age is consistently associated with higher adherence to medication and food restrictions (Table 3, Additional file 4).
In our study, the self-efficacy score was not related to physical parameters, even when the relationship was analyzed separately in young and elderly patients (Additional file 5). It is likely that we should analyze the importance of the self-efficacy questionnaire using more patients according to age group [27]. In addition, our study showed that patients without employment and those with lower GNRI had significantly higher self-efficacy scores. These results were inconsistent with those of previous studies, probably because high self-efficacy scores were seen in elderly patients who tended to have low GNRI without employment in our study [28].
Limitations should be noted. First, we used self-report tools, which can lead to social desirability bias. Second, this was a cross-sectional study conducted in a local area in Japan. Our data may be uncommon all over the world. Third, the response rate to the questionnaire was different for each clinic. This may have affected the results. Lastly, the number of participants was not large enough to analyze the age-dependent relationship between self-efficacy scores and patient characteristics.