Introduction: The prevalence of vitamin D deficiency varied among populations and regions worldwide. In addition, the association between vitamin D deficiency and health outcomes remained controversial. Our study aimed to investigate the prevalence of vitamin D deficiency and its association with mortality risk among non-institutional middle-aged and older adults in the United States.Method: The study population included 11,119 adult participants aged between 50 and 79 years in the 2007–2016 National Health and Nutrition Examination Survey (NHANES). Vitamin D status was divided as ≤ 30 (severely deficient), 30.1–50 (moderately deficient), 50.1–75 (insufficient), 75.1–100 (sufficient), and > 100 nmol/L (very sufficient). NHANES data were linked to National Death Index to ascertain the survival status and cause of death.Results: The population aged 61.5 years (survey-weighted) and 47.9% were men. Among them, 4.6% were severely vitamin D deficient, 15.2% moderately deficient, and 33.6% insufficient. Individuals with higher vitamin D levels tended to be female, older, white people, non-smoker, non-single, more educated, with higher family income, and lower body mass index. During a median follow-up of 97.0 months, a total of 1,585 participants died (15.9 per 10,000 person-months). The crude analysis showed that vitamin D deficiency, but not vitamin D insufficiency, correlated to higher all-cause mortality risk. The association remained similar after adjusting for potential confounders, showing that vitamin D deficiency (HR: 1.38, 95% CI 1.15–1.66), but not vitamin D insufficiency (HR: 1.03, 95% CI 0.88–1.20), correlated to higher all-cause mortality risk. In addition, we showed that vitamin D deficiency was an independent risk factor for death from pneumonia (HR: 3.82, 95% CI 1.14–12.86) but not from cardiovascular diseases, cancer, or cerebrovascular diseases.Conclusion: In summary, among middle-aged and older adults in the United States, nearly 20% were vitamin D deficient. Vitamin D deficiency, but not vitamin D insufficiency, correlated to increased mortality risk.

Background: While the nephrotoxicity of lead and cadmium is well-established, the impact of low-level exposure on risk of chronic kidney disease (CKD) and long-term health outcomes, especially in CKD patients, remains unclear. This study examines the association between low-level lead and cadmium exposure with risks of CKD and long-term mortality. Method: We analyzed data from adult participants of 2003–2012 National Health and Nutrition Examination Survey in the United States. CKD was defined as estimated glomerular filtration rate < 60 ml/min/1.73 m². Elevated blood lead (≥ 1.5 μg/dL) and cadmium (≥ 0.4 μg/L) levels were assessed for their associations with CKD and all-cause mortality, with survival tracked until December 31, 2019. Results: Among the 24,810 participants (mean age 44.4 years, 48.9% male), 1,309 (3.9%) had CKD. Lead and cadmium levels were significantly higher in participants with CKD compared to those without. Elevated lead (OR: 1.41, 95% CI: 1.15–1.74) and cadmium (OR: 1.23, 95% CI: 1.03–1.46) levels were both associated with increased CKD risk, with the highest risk in those with both lead ≥ 1.5 μg/dL and cadmium ≥ 0.4 μg/L (OR: 1.65, 95% CI 1.27–2.14). During a median follow-up of 141 months, 2,255 participants died (7.0 per 10,000 person-months). Elevated cadmium was associated with higher mortality risk in CKD (HR: 1.42, 95% CI: 1.07–1.88) and non-CKD populations (HR: 1.40, 95% CI: 1.24–1.58), while lead levels were not significantly associated with mortality in either group. Participants with both elevated lead and cadmium had a significantly higher mortality risk (HR: 1.32, 95% CI: 1.13–1.54). Conclusion: Low-level cadmium and lead exposure are linked to increased CKD risk, with cadmium also associated with higher long-term mortality in both CKD and non-CKD populations. These findings highlight the need for public health efforts to reduce exposure and further research on long-term impacts.

Introduction: Studies on association of α-klotho levels with mortality risk in general population are relatively scarce and inconclusive. Therefore, we conducted a population-based cohort study to investigate the relationship between soluble α-klotho and all-cause mortality in a nationally representative sample of middle-aged and older adults in the United States (U.S.).Methods: The study population was 2007-2016 National Health and Nutrition Examination Survey (NHANES) participants, totaling 13,583 adults aged 40-79 years. Participants were divided into 7 groups by septile of α-klotho levels. We linked the NHANES data to the National Death Index to determine participants’ survival status. End of follow-up was participants’ death date or December 31, 2019.Results: We observed that males, current smokers, older age, higher body mass index, and lower estimated glomerular filtration rate correlated to lower α-klotho levels, while hepatitis C virus infection correlated to higher α-klotho. The population mortality rate was 11.8 per 10,000 person-months (1,490 deaths); group 1 (the first septile) had higher mortality risk compared with group 2 through group 7. By weighted Cox regression with adjustment for potential confounders, we found that group 2 through group 6, but not group 7, were associated with 25% to 35% lower risk of all-cause mortality compared with group 1. When compared with group 4, we observed that both group 1 (HR: 1.46, 95% CI 1.13-1.88) and group 7 (HR: 1.38, 95% CI 1.09-1.74) were associated with higher mortality risk.Conclusion: In summary, among middle-aged and older U.S. adults, we observed a non-linear association between soluble α-klotho and all-cause mortality, with individuals at the two extremes at increased risk of death.

Key Points: Nearly half of individuals with reduced kidney function had sedentary lifestyle, defined as more than 6 hours of sitting a day. Non-Hispanic White individuals and individuals with younger age, obesity, and with diabetes were more likely to have sedentary lifestyles. Spending more than 6 hours a day sedentary increases the future risk of death from all causes and cardiovascular diseases in individuals with reduced kidney function. Background: Individuals with CKD tend to have sedentary behavior and decreased physical activity; both are independent predictors of mortality in general population. While physical inactivity correlates to adverse health outcomes in patients with reduced kidney function, it is unclear whether this relationship remains significant for sedentary behavior. Our study purpose was to evaluate the association of sedentary lifestyle with mortality risk in individuals with renal insufficiency. Methods: The study population were adult participants of 2007–2016 National Health and Nutrition Examination Survey with eGFR 6 hours per day. Outcome of interest was all-cause and cardiovascular disease (CVD)–related or cancer-related mortality. Results: We observed that non-Hispanic White individuals and individuals with younger age and higher educational level were more likely to have sedentary lifestyle. During a median follow-up of 99 (interquartile range, 70–128) months, a total of 458 participants died (3.98 deaths per 1000 person-months); 120 died from CVD and 92 from cancer, respectively. The crude analysis showed that individuals with sedentary lifestyle have higher risk of all-cause and CVD-related but not cancer-related mortality compared with the nonsedentary population. After adjusting for potential confounders, we showed that all-cause mortality and CVD-related mortality were 1.64-fold (95% confidence interval, 1.26 to 2.12) and 1.66-fold (95% confidence interval, 1.03 to 2.67) higher, respectively, in the sedentary population compared with the nonsedentary population. Similar results were observed in the sensitive analyses, in which we excluded individuals with dialysis, eGFR <15 ml/min per 1.73 m², or mobility disability. Conclusions: Our findings suggest that sedentary lifestyle correlated to greater risk of all-cause and CVD-related mortality among individuals with reduced kidney function. Interventions targeting the individuals with risky behaviors may have practical importance for public health.

Increased water intake correlated to lower vasopressin level and may benefit kidney function. However, results of previous studies were conflicted and inconclusive. We aimed to investigate the association between water intake and risk of chronic kidney disease (CKD) and albuminuria. In this cross-sectional study, the study population were adult participants of 2011–2012 National Health and Nutrition Examination Survey (NHANES) whose estimated glomerular filtration rate (eGFR) were ≥30 ml/min/1.73 m². Data of water intake were obtained from the NHANES 24-h dietary recall questionnaire. Participants were divided into three groups based on volume of water intake: <500 (low, n = 1589), ≥500 to <1200 (moderate, n = 1359), and ≥1200 ml/day (high, n = 1685). CKD was defined as eGFR <60 ml/min/1.73 m², and albuminuria as albumin–to–creatinine ratio (ACR) ≥30 mg/g. Our results showed that 377 out of 4633 participants had CKD; the prevalence inversely correlated to volume of water intake: 10.7% in low, 8.2% in moderate, and 5.6% in high intake groups (P < .001). Prevalence of albuminuria was also lower in high (9.5%) compared with moderate (12.8%) and low intake groups (14.1%), P < .001. Additionally, water intake positively correlated to eGFR and negatively correlated to urinary ACR, as well as plasma and urine osmolality. Multivariable logistic regression showed that low water intake group had higher risk of CKD (OR 1.35, 95% CI 1.01–1.82) and albuminuria when compared to high water intake group (OR 1.42, 95% CI 1.13–1.79). In conclusion, increased water intake was associated lower risk of CKD and albuminuria. Meticulous studies are needed to elucidate the underlying mechanisms.