The impact of sunlight exposure on mortality of ESRD patients: Comparison of the results using case-crossover study design

Abstract

Background

Recent data suggest that reduced sunlight exposure is associated with increased mortality in the general population. To date, the association between sunlight exposure and mortality in dialysis patients has not been examined.

Objective

Among 134,478 dialysis patients in the Korean end-stage renal disease (ESRD) cohort from 2001 to 2014, 31,291 patients were enrolled from seven metropolitan cities, and data were analyzed using bi-directional case-crossover design. We examined the association between short-term sunlight exposure and mortality in ESRD patients. We adjusted for temperature, humidity, and daily concentrations of nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), carbon monoxide (CO), and particle matter (PM10) as confounders.

Method

Among 134,478 dialysis patients in the Korean end-stage renal disease (ESRD) cohort from 2001 to 2014, 31,291 patients were enrolled from seven metropolitan cities, and data were analyzed using bi-directional case-crossover design. We examined the association between short-term sunlight exposure and mortality in ESRD patients. We adjusted for temperature, humidity, and daily concentrations of nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), carbon monoxide (CO), and particle matter (PM10) as confounders.

Result

The characteristics of the study population included age (65.6 ± 12.26 (mean ± standard deviation [SD]) years), sex (male, 59.96%

female, 41.04%), comorbidity (diabetes, 53.58%

hypertension, 40.5%), and kidney dialysis type (hemodialysis, 73.02%

peritoneal dialysis, 26.98 %). The mean ± SD follow-up time was 4.68 ± 4.37 years. The daily sunlight exposure was significantly decreased in the case group compared with the control group (P=0.004). Sunlight exposure was associated with all-cause death overall (ORs [95%CI]: 0.99 [0.98-0.99], P=0.042) in a fully adjusted model. Patients with diabetes (ORs [95%CI]: 0.98 [0.97-0.99], P=0.016) or aged higher than 75 years (ORs [95%CI]

0.97 [0.96 – 0.99], P=0.020) had higher risks of mortality than patients without diabetes or aged below 75 years, respectively.

Conclusion

These findings suggest that sunlight exposure is inversely correlated with all-cause mortality in dialysis patients, especially in high-risk patients with diabetes and older adults.

Keyword : sunlight exposure, mortality, end stage renal disease, ESRD, sunshine vitamin, vitamin D