Hemodialysis (HD) is the main treatment for patients in end-stage renal disease, however, it presents a high risk for adverse patient outcomes¹. HD affects the life of Chronic kidney disease (CKD) patients and it can have negative effects on general health and well-being including mental, social, physical, emotional, spiritual, and subjective aspects. Furthermore, it can have a negative influence on physical performance, mental status, and social relationships². Anxiety, depression and stress are frequent conditions in CKD patients, essentially during the transition from the pre-dialysis period to renal replacement therapy. Nevertheless, it tends to decrease after beginning dialysis³.

The World Health Organization (WHO) points out that subjective wellbeing is considered within the research community as an indicator of Quality of Life evaluation⁴. The subjective wellbeing is characterized by emotional responses, satisfaction domains, and the judgment about global satisfaction with life. The subjective wellbeing components are pleasant affect (e.g. joy, contentment, pride, affection, and happiness), unpleasant affect (e.g. guilt and shame, anxiety and worry, anger, stress, and depression), life satisfaction (e.g. desire to change, satisfaction with current life, past, and future), and a satisfaction domain (e.g. work, family, leisure, health, finances, and self) ⁽⁵.

In the CKD patients the subjective wellbeing (measured by personal wellbeing index) is positively related with subjective happiness, positive affect, and quality of life and is negatively associated with negative affect. Subjective happiness, negative affect, and the physical component of quality of life are associated to the subjective wellbeing⁶. Moreover, higher levels of happiness are associated with higher levels of satisfaction with life in general (personal wellbeing index) ⁽⁷, and also with higher levels of sense of humor⁸.

This study intends to disclose if CKD patients’ subjective well-being, sense of humor, and anxiety, depression and stress are significant predictors of their subjective happiness, further influencing patients’ disease management strategies and health status.

The objective was to investigate the relationship between subjective well-being, sense of humor, and anxiety, depression and stress with subjective happiness in CKD patients undergoing hemodialysis.

The sample consisted of 183 patients diagnosed with CKD, with an average age of 59.17 (±14.64) years, mostly men (59.6%). The nationality of the patients was distributed as follows: most patients are Portuguese (78.7%), followed by Cape Verdean (13.7%), Sao Tomean (3.3%), Angolan (2.2%), Guinean (1.6%), and Bulgarian (0.5%). Concerning literacy level, 3.3% were illiterate, 41.1% had the 4^th grade, 18.9% the 6^th grade, 15% the 9^th grade, 12.2% the 12^th grade and 9.4% university education. In this sample 28% of the patients were single, 53.8% married, 11.5% widowed and 6.6% divorced. Concerning occupation, 76% were retired while 24% had a regular job. Regarding health data, patients underwent hemodialysis for 70.09 (±54.2) months, 61.9% had high blood pressure and 25.8% diabetes.

CKD patients under 63 years of age had higher levels of subjective happiness (p=0.013) than older patients. Portuguese CKD patients had the lowest score for subjective happiness (p=0.013), compared with the remaining population (Cape Verdean; São Toméan; Angolan, Guinean and Bulgarian). Retired patients had lower levels of subjective happiness (p=0.002) than those who have regular jobs. Widowed and divorced patients had lower levels of subjective happiness (p=0.033) in comparison to married and single patients (Bonferroni correction). Finally, CKD patients with diabetes had a lower level of subjective happiness (p=0.012). Table 1 shows both socio demographic and clinical factors related with CKD, that are associated with subjective happiness.

Table 1. Socio demographic and clinical factors associated to subjective happiness.

Mean score of subjective happiness was 19.9 (±6.1), satisfaction with life in general/personal wellbeing index has a mean score of 64.2% (±18.5%). Mean scores for the other variables are as following: stress/anxiety 6.9 (±6.5); depression 4.3 (±4.4); humor production and social use of humor 37.7 (±11.2); adaptive humor and appreciation humor 27.1 (±6.1) and attitude towards humor with 24.7 (±5.1) (Table 2).

Table 2. Mean and standard deviation for the different variables.

Table 3 shows that the subjective happiness was positively correlated with professional activity (ρ=0.256, p<0.01); satisfaction with life in general/personal wellbeing index (ρ=0.627, p<0.001), humor production and social use of humor (ρ=0.476, p<0.001); adaptive humor and appreciation humor (ρ=0.387, p<0.001); and attitude towards humor (ρ=0.364, p<0.001). However, it presented a low negative correlation with stress/anxiety (ρ=-0.239, p<0.01) and depression (ρ=-0.391, p<0.001). Higher scores on subjective happiness were associated with higher levels of satisfaction with life in general/personal wellbeing index, humor production and social use of humor, adaptive humor and appreciation humor and attitude towards humor, though lower levels of subjective happiness were associated with higher levels of stress/anxiety and depression.

Table 3. Regression for Subjective Happiness with other variables and correlations.

*Significance p<0.05, †Significance p<0.01, ‡Significance p<0.001.

Professional activity was negatively correlated with depression (ρ=-0.222, p<0.001), satisfaction with life in general/personal wellbeing index was positively correlated with humor production and social use of humor (ρ=0.353, p<0.001); adaptive humor and appreciation humor (ρ=0.270, p<0.001) and attitude towards humor (ρ=0.211, p<0.001). Nevertheless, it presented a negative correlation with stress/anxiety (ρ=-0.297, p<0.001) and depression (ρ=-0.440, p<0.001). Higher scores on satisfaction with life in general/personal wellbeing index were associated with higher levels of humor production and social use of humor, adaptive humor and appreciation humor, and attitude towards humor, and lower levels of stress/anxiety and depression.

Stress/anxiety showed a significant positive correlation with depression (ρ=0.670, p<0.001) and attitude towards humor (ρ=0.232, p<0.01).

Depression was negatively correlated with humor production, with social use of humor (ρ=-0.164, p<0.05) and with attitude towards humor (ρ=-0.240, p<0.01). When depression values increased, humor production and social use of humor and attitude towards humor values decreased.

Humor production and social use of humor showed a significant positive correlation with adaptive humor and humor appreciation (ρ=0.718, p<0.001); and attitude towards humor (ρ=0.234, p<0.001). Lastly, adaptive humor and humor appreciation were positively correlated with attitude towards humor (ρ=0.338, p<0.001).

The model with professional activity, explains 8% of the subjective happiness variance. This control variable is the one that most contributes to the explanation of subjective happiness (ΔR²=0.115, p<0.01).

In the second step, the adjusted R² for the model was 51.4% for professional activity, satisfaction with life in general/personal wellbeing index, stress/anxiety, depression, humor production and social use of humor, and attitude towards humor, being these the variables that best explain subjective happiness. The resulting R² were statistically significant at the p<0.00 and p<0.05 levels.

Professional activity, satisfaction with life in general/personal wellbeing index, humor production and social use of humor, and attitude towards humor had a positive effect on subjective happiness (respectively, β=0.142, p<0.05; β=0.430, p<0.001; β=0.239, p<0.05; β=0.165, p<0.01). Nevertheless, depression had a negative effect on subjective happiness (β=-0.178, p<0.05).These variables are the ones contributing the most to the explanation of subjective happiness (ΔR²=0.431, p<0.001).

Our study was aimed at examining the relationship between subjective happiness and satisfaction with life in general/personal wellbeing index, stress/anxiety and depression, sense of humor and socio-demographic characteristics, as well as, verifying the relationship between these variables and subjective happiness.

The findings are aligned with the literature on the effects of HD on CKD patients’ life, and on the psychological stressors that may decrease wellbeing and quality of life, therefore contributing to less positive clinical outcomes¹¹.

The highest levels of happiness were found in younger CKD patients with regular employment, married or single, non-Portuguese nationality and without diabetes. These results also corroborate the findings of another study carried out in patients undergoing hemodialysis, namely, standard of living and satisfaction with life achievements carried higher importance in subjective wellbeing¹².

Such results can also be partly explained by the aging process. Older people patients on hemodialysis have peculiar characteristics, not only because of the greater number of associated comorbidities, but because the aging process itself entails physical and psychological changes that directly affect quality and life. Other aspects must also be considered as high stress factors during hemodialysis sessions¹³, such as the vascular access, which includes the cannulation process, bleeding, infection, lack of flow, and the inexperience of the team. Having a job minimizes the impact of the treatment routine, it makes the individual feel useful and socially active, which explains higher levels of personal fulfillment and greater happiness. One study points out that by the end of 2015, approximately 36% of patients undergoing peritoneal dialysis had full-time work, contrasting with 22% of hemodialysis patients¹⁴.

Despite the impact of treatment on the personal routine, married patients find in their family nuclei an informal but more solid support network, which strengthens their emotional component and eventually their perception of happiness. On the other hand, widowers under hemodialysis experience more hopelessness and had lower level of general health¹⁵, probably because they have nobody to share their sorrows, maintaining their feelings on the burden of disease¹⁶. These patients consequently have greater difficulty in finding adaptive strategies that allow maintaining or increasing their levels of happiness.

Concerning nationality, the non-Portuguese patients of our sample are predominantly African. The higher levels of happiness found in this population may be explained by cultural issues, as these individuals live in larger family and social networks with expanded support. This idea is supported, in part, by a study that observed a level of low contentment, and medium to high levels of hedonic affection in a group of black Africans¹⁷.

Happiness can influence socioeconomic phenomena such as consumption activities, behavior at work, investment behavior and political behavior, presenting itself as a determining factor in person´s quality of life¹⁸. In the same way, happiness was associated with higher levels of satisfaction with life in general, humor production and social use of humor, adaptive humor and appreciation humor and attitude towards humor. Though lower levels of subjective happiness were associated with higher levels of stress/anxiety and depression. The psychological disorders are the most common problems in patients undergoing dialysis, such as depression and anxiety. Hemodialysis is considered a long-term treatment and has significant side effects on physical and mental well-being¹⁹. Stress is a common reaction of patients with CKD undergoing HD which appears as a way to deal with the anxiety associated with the threat of the disease. Since they are constantly alert, they are also more vulnerable and have more difficulty in keeping an emotional state of happiness. Such findings may have important clinical implications for these patients. Untreated mental problems increase mortality, decrease quality of life, and increase the risk of suicide¹⁹. Healthcare teams must consider the need for a periodic evaluation of the stressors and their effects on the health and quality of life of the patients, with the consequent development of strategies that offer these individuals interventions that propitiate an improvement in their quality of life.

Patients undergoing hemodialysis with higher levels of subjective happiness were found to be associated with higher levels of satisfaction with life in general⁹. CKD patients with higher levels of sense of humor were associated with higher levels of subjective happiness and satisfaction with life in general⁸.

Professional activity, satisfaction with life in general, humor production and social use of humor, and attitude towards humor had a positive effect on subjective happiness. Thus, depression had a negative effect on subjective happiness.

Fordyce’s happiness program was effective in reducing depression and anxiety^{11), (20} and improving life of quality of patients undergoing hemodialysis²⁰.

Keeping in mind the limitations and implications for practice of this study, we emphasize the need for further studies on nursing interventions under the promotion of happiness in the most diverse contexts of the practice of care for the person with chronic kidney disease. Its disclosure is imperative.