Healthy Lifestyle and Mortality in Dialysis Patients
Approximately 2.5 million people with stage 5 chronic kidney diseases (CKD) worldwide are treated with long-term dialysis. The prognosis of patients on dialysis is poor, with an annual mortality rate of 10% to 20%, due largely to cardiovascular diseases. Use of statins as pharmacological interventions have yielded few results in reducing mortality in dialysis patients.
There are a number of lifestyle recommendations from the American Heart Association for cardiovascular prevention that have been combined into a health lifestyle score. The recommendations include avoiding smoking, engaging in regular physical exercise, maintaining an appropriate body mass index, adhering to a diet rich in fruits, vegetables, and fish and low in salt and sugar, and maintaining blood pressure, cholesterol, and glucose within recommended targets. There are associations with higher lifestyle scores and 30% to 50% lower cardiovascular disease risk in the general population. Those benefits may be related to reversing or reducing obesity, hypercholesterolemia, diabetes, and hypertension, key risk factors for cardiovascular disease.
There are few data available on the benefits of a healthy lifestyle in patients with CKD receiving maintenance hemodialysis. Guobin Su, MD, PhD, and colleagues conducted a prospective cohort study to examine the association of a modified AHA healthy lifestyle score and its individual components with all-cause and cardiovascular mortality in patients treated with hemodialysis. Results of the study were reported in the American Journal of Kidney Diseases [2022;79(5):688-698].
The study was conducted in a large, multinational private dialysis network. The study exposure was a modified healthy lifestyle score based on the AHA recommendations for cardiovascular prevention, the sum of four components addressing the use of smoking tobacco, physical activity, diet, and control of systolic blood pressure. The outcomes of interest were cardiovascular and all-cause mortality.
Adjusted proportional hazards regression analyses with country as a random effect was used to estimate the associations between lifestyle score and mortality. Lifestyle score was stratified as low (0-2 points) as the referent, medium (3-5 points), and high (6-8 points). Associations were expressed as adjusted hazard ratio (aHR), with 95% CI.
The study utilized data from the DIET-HD (Dietary Intake, Death and Hospitalization in Adults with End-Stage Kidney Disease Treated with Hemodialysis) study. A total of 9757 patients participated in the DIET-HD study and completed the Food Frequency Questionnaire (FFQ). Of those, 5483 (56%) had complete lifestyle data (all individual components of the lifestyle score) and were included in the primary analysis. Compared with patients without complete lifestyle data, those with complete lifestyle data were older, had more comorbidities, and a higher mortality rate.
Overall, the mean age of the cohort was 66 years, 42% were female, 87% had hypertension, 31% had diabetes, and 43% had a history of CKD. Sixty-seven percent had never smoked, 20% engaged in physical activity more than once a week, 25% had systolic blood pressure before dialysis <120 mm Hg, and 20% adhered to a high recommended food score.
A total of 982 participants (18%) had a high lifestyle score (score 6-8), 3945 (72%) had a medium lifestyle score (score 3-5), and 556 (10%), had a low lifestyle score (score 0-2). Across increasing healthy lifestyle score categories, there were more women, a lower proportion of comorbidities, and a shorter dialysis vintage.
Median follow-up was 3.8 years. During the follow-up period, there were 2163 deaths (39%). Of those, 39% (n=826) were attributed to cardiovascular causes. The cumulative incidence of cardiovascular death was 63 per 1000 person-years in the group with low lifestyle score, 47 per 1000 person-years in the group with medium lifestyle score, and 40 per 1000 person-years in the group with high lifestyle score (log-rank P<.001). For all-cause death, the corresponding values were 156, 124, and 105 per 1000-person years (log-rank P=.002).
When the lifestyle score was treated as a continuous variable, the aHRs of cardiovascular death and all-cause death were 0.92 (95% CI, 0.89-0.95) and 0.94 (95% CI, 0.89-0.98), respectively, for every unit greater healthy lifestyle score.
Compared with patients with a low lifestyle score, the aHRs of cardiovascular death among those with medium and high lifestyles scores were 0.73 (95% CI, 0.49-0.85) and 0.65 (95% CI, 0.49-0.85), respectively (P for trend=.003). For all-cause mortality, the aHRs were 0.75 (95% CI, 0.65-0.85) for those with medium lifestyle scores and 0.64 (95% CI, 0.54-0.76) for those with high lifestyle scores (P for trend <.001).
Smoking and physical activity were consistently associated with higher risk of both cardiovascular and all-cause mortality. Compared with being a current smoker, the aHRs for all-cause and cardiovascular mortality for the participants who never smoked were 0.75 (95% CI, 0.65-0.86) and 0.71 (95% CI, 0.57-0.88). Compared with participants who did not engage in physical activity, the aHRs for all-cause and cardiovascular mortality for participants who engaged in physical activity more than once a week were 0.75 (95%CI, 0.66-0.85) and 0.79 (95% CI, 0.65-0.96), respectively. There were no significant associations between either recommended food score or blood pressure targets and mortality.
The researchers cited some limitations to the study findings, including the observational design, the self-reported nature of the FFQ, and the data -driven approach.
In conclusion, the authors said, “A healthier lifestyle is associated with lower all-cause and cardiovascular mortality among patients receiving maintenance hemodialysis.”
- Results of a prospective cohort study evaluating the association of a modified AHA healthy lifestyle score and its individual components with all-cause and cardiovascular mortality.
- The cumulative incidence of cardiovascular death in those with low, medium, and high lifestyle scores was 63, 47, and 40 per 100 person-years, respectively.
- For all-cause death, the corresponding values were 156, 124, and105 per 1000 person-years, respectively.