High Fitness Levels Offset the Increased Risk of Chronic Kidney Disease due to Low Socioeconomic Status: A Prospective Study

Predictive risk factors for early-stage renal dysfunction: An analysis of specific health checkup data for the general Japanese population

BACKGROUND AND AIMS

Early prevention of chronic kidney disease is critical. We aimed to identify predictive risk factors for early-stage renal dysfunction.

METHODS AND RESULTS

This retrospective study analyzed specific health checkup data from the general Japanese population. We included 1385 adults who underwent a specific health checkup in 2013 and 2019 and had an estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 in 2013. The composite endpoint was the progression of renal dysfunction for 6 years, including doubling of serum creatinine levels, ≥30 % decline in eGFR, and ≥30 % increase in the urine albumin-to-creatinine ratio (UACR) for individuals with UACR ≥30 mg/gCre at baseline or progression to ≥30 mg/gCre for those with UACR <30 mg/gCre at baseline. Participants were categorized into groups with and without progression of renal dysfunction. Univariate analysis of health checkup data and questionnaire data collected in 2013 was conducted, followed by multiple logistic regression analyses. Significant between-group differences were observed in age, body weight, body mass index (BMI), waist circumference, medication for hypertension and hyperlipidemia, systolic and diastolic blood pressure, high-density lipoprotein cholesterol, diabetes, glycated hemoglobin (HbA1c), urine glucose qualitative, UACR, urine protein-to-creatinine ratio, current smoking, weight gain, and walking habits. Logistic regression analysis showed that BMI (odds ratio [95 % confidence interval]: 1.14 [1.07-1.24], P < 0.001), HbA1c (1.57 [1.24-1.98], P < 0.001), and walking habits (0.51 [0.33-0.80], P = 0.003) were significantly associated with renal dysfunction progression.

CONCLUSIONS

Higher BMI and HbA1c and lower walking habits were associated with early-stage renal dysfunction, even in the general population.

Enhancing Cardiorespiratory Fitness Through Sauna Bathing: Insights From the Kuopio Ischemic Heart Disease Prospective Study

PURPOSE

The physiological adaptations stimulated by a sauna bath (SB) are similar to those produced by moderate- or high-intensity physical activity (PA), but the relationship between SB and cardiorespiratory fitness (CRF) is not clear. The objective of this study was to evaluate the cross-sectional and longitudinal associations between frequency and duration of SB with CRF.

METHODS

Baseline SB habits were assessed in 2012 men aged 42 -61 yr. CRF was directly measured using a respiratory gas exchange analyzer during cardiopulmonary exercise testing at baseline and 11 yr later. The associations of SB frequency and duration with baseline and 11-yr levels of CRF were examined using robust regression analyses adjusted for several confounders, including lifestyle factors such as PA.

RESULTS

In baseline analysis, a unit increase in sauna sessions/wk was associated with an increase in CRF 0.30 mL/kg/min (standard error [SE]: 0.14; P = .034). Alternatively, compared with a single sauna sessions/wk, 2-3 and 4-7 sauna sessions/wk was each associated with significant increases in levels of CRF: 0.84 mL/kg/min (SE: 0.32; P = .008) and 1.17 mL/kg/min (SE: 0.57; P = .041), respectively. In longitudinal analysis, frequent SB was associated with increases in 11-yr CRF levels, but this was only significant for 2-3 sauna sessions/wk compared with a single sauna sessions/wk: 1.22 mL/kg/min (SE: 0.59; P = .038). Duration of SB was not significantly associated with CRF levels in cross-sectional and longitudinal analyses.

CONCLUSIONS

Frequent SB may improve levels of CRF independently of PA. These results warrant replication in robust definitive randomized controlled trials.

Frequent sauna bathing and psychosis: Interrelationship with cardiorespiratory fitness

Frequent sauna bathing and higher cardiorespiratory fitness (CRF) levels may play a role in reducing the risk of mental disorders such as psychosis, however, data on their joint contributions is scanty. We aimed to investigate the interplay between sauna bathing, CRF and psychosis risk using a population-based prospective study. Self-reported frequency of sauna bathing (FSB) and CRF measured by respiratory gas analyses were assessed at baseline in 2221 men aged 42-61 years who had no history of psychosis. Frequency of sauna bathing was categorized as low and high (≤2 and 3-7 sessions/week, respectively) and CRF as tertiles (low, medium and high). Hazard ratios (HRs) with 95% CIs were estimated. During a median follow-up of 25.2 years, 215 psychotic disorders were recorded. Comparing high vs low FSB, the multivariable-adjusted HRs (95% CIs) for psychosis was 0.49 (0.32-0.74), which persisted on further adjustment for CRF 0.50 (0.33-0.75). Compared to low CRF, the multivariable-adjusted HRs (95% CIs) for medium and high CRF levels were 0.65 (0.46-0.90) and 0.75 (0.52-1.07) respectively. Compared to low FSB & low CRF, the HRs (95% CIs) for low FSB & medium-high CRF, high FSB & low CRF, and high FSB & medium-high CRF were 0.62 (0.45-0.84), 0.26 (0.11-0.60), and 0.41 (0.25-0.68) respectively. Frequent sauna baths and medium-high CRF levels appear to each independently decrease psychosis risk. However, frequent sauna bathing may be related to a reduced risk of psychosis irrespective of fitness levels and might be a stronger risk indicator for psychosis than CRF.

Baseline and usual triglyceride-glucose index and the risk of chronic kidney disease: a prospective cohort study

Triglyceride-glucose (TyG) index is an emerging marker of adverse cardiometabolic conditions such as cardiovascular disease and type 2 diabetes. The long-term relevance of TyG index to chronic kidney disease (CKD) is uncertain. We aimed to assess the association of TyG index with CKD risk and its utility in risk prediction in a prospective study. The TyG index was calculated using fasting triglycerides and fasting plasma glucose (FPG) levels measured in 2362 men aged 42-61 years with normal kidney function using the formula: Ln (fasting triglycerides [mg/dL] × FPG [mg/dL]/2). Multivariable adjusted hazard ratios (HRs) (95% confidence intervals, CIs) were estimated for CKD. Correction for within-person variability was made using data from repeat measurements of triglycerides and FPG taken 11 years after baseline. Over a median follow-up duration of 17.5 years, 223 CKD cases were recorded. The age-adjusted regression dilution ratio for the TyG index was 0.54 (95% CI, 0.48-0.60). The risk of CKD increased continuously with increasing TyG index across the range 9.3 to 11.6 (p value for nonlinearity<.001). In analysis adjusted for established risk factors, a unit higher TyG index was associated with an increased risk of CKD (HR 1.59, 95% CI 1.24-2.05). Comparing extreme tertiles of the TyG index, the corresponding adjusted HR (95% CI) for CKD was 1.61 (1.15-2.27). Addition of the TyG index to a CKD risk prediction model containing established risk factors improved risk discrimination and reclassification (p value for difference in -2 log likelihood<.001; NRI=47.66%, p=.014; IDI=0.0164, p<.001). Higher TyG index is associated with an increased risk of CKD and improves the prediction and classification of CKD beyond established risk factors. Using single baseline estimations of the TyG index to investigate its association with CKD risk could considerably under-estimate the true association.

The Interplay between Systolic Blood Pressure, Sauna Bathing, and Cardiovascular Mortality in Middle-Aged and Older Finnish Men: A Cohort Study

OBJECTIVES

Elevated systolic blood pressure (SBP) is associated with an increased risk of cardiovascular disease (CVD) mortality, whereas frequent sauna bathing reduces the risk. Whether frequent sauna bathing mitigates CVD mortality among adults with elevated SBP has not been previously investigated.

DESIGN AND SETTING

We examined the interactions between SBP and frequency of sauna bathing (FSB) with the risk of CVD mortality in a cohort of Caucasian men.

PARTICIPANTS

The Kuopio Ischaemic Heart Disease Study cohort comprising of 2,575 men aged 42-61 years at baseline was employed for this prospective study analysis.

MEASUREMENTS

Resting blood pressure was measured using a standardized protocol and sauna bathing habits were assessed by a self-administered questionnaire. Systolic blood pressure was categorized as normal and high (<140 and ≥140 mmHg, respectively) and FSB as low and high (defined as ≤ 2 and 3-7 sessions/week, respectively).

RESULTS

A total of 744 CVD deaths were recorded during a median follow-up of 27.8 yr. Comparing high vs normal SBP, the multivariable-adjusted HR (95% CI) for CVD mortality was 1.44 (1.23-1.68). Comparing low vs high FSB, the multivariable-adjusted HR (95% CI) for CVD mortality was 1.24 (1.03-1.51). The associations persisted following mutual adjustment for each exposure. Compared with men with normal SBP-high FSB, high SBP-low FSB was associated with an increased risk of CVD mortality 1.81 (1.39-2.36), with attenuated but persisting evidence of an association for men with high SBP and high FSB 1.52 (1.06-2.16). When SBP was categorized as normal and high (<130 and ≥130 mmHg, respectively), there was no evidence of an association for men with high SBP and high FSB 1.11 (0.77-1.61).

CONCLUSION

There might be an interaction between SBP, sauna bathing and CVD mortality risk in middle-aged and older Caucasian males. Frequent sauna baths may offset the increased risk of CVD mortality in men with high-normal SBP but not elevated SBP.

Inflammation, sauna bathing, and all-cause mortality in middle-aged and older Finnish men: a cohort study

Inflammation and sauna bathing are each related to the risk of all-cause mortality. The interplay between inflammation, sauna bathing and all-cause mortality is not well understood. We aimed to evaluate the separate and joint associations of inflammation (high sensitivity C-reactive protein, hsCRP) and frequency of sauna bathing (FSB) with all-cause mortality in a cohort of Caucasian men. We used the Kuopio Ischaemic Heart Disease Study cohort comprising 2575 men aged 42-61 years at baseline. Serum hsCRP was measured using an immunometric assay and sauna bathing habits were assessed by a self-administered questionnaire. High sensitivity CRP was categorized as normal and high (≤ 3 and > 3 mg/L, respectively) and FSB as low and high (defined as ≤ 2 and 3-7 sessions/week respectively). A total of 1618 deaths occurred during a median follow-up of 27.8 years. Comparing high vs normal hsCRP levels, the multivariable-adjusted HR (95% CI) for all-cause mortality was 1.27 (1.13-1.44). Comparing high vs low FSB, the multivariable-adjusted HR (95% CI) for all-cause mortality was 0.86 (0.76-0.97). Compared with normal hsCRP-low FSB, high hsCRP-low FSB was associated with an increased risk of all-cause mortality 1.28 (1.12-1.47), with no evidence of an association for high hsCRP-high FSB and all-cause mortality risk 1.06 (0.81-1.40). Positive additive and multiplicative interactions were found between hsCRP and FSB in relation to mortality. In a general Finnish male population, both hsCRP and FSB are each independently associated with all-cause mortality. However, frequent sauna baths appear to offset the increased all-cause mortality risk related to high hsCRP levels.