Association between cotinine-verified smoking status and moderately increased albuminuria in the middle-aged and older population in Korea: A nationwide population-based study

Sex disparities in the association between serum cotinine and chronic kidney disease

INTRODUCTION

Despite the existence of numerous studies highlighting the adverse effects of smoking on kidney function, the investigation of the correlation between serum cotinine and chronic kidney disease (CKD) remains inconclusive due to insufficient evidence. Consequently, the primary objective of this study was to ascertain the association between serum cotinine levels and CKD.

METHODS

This study analyzed data from 10900 Americans participating in the National Health and Nutrition Examination Survey between 2005 and 2016. The independent variable under investigation was log serum cotinine, while the dependent variable was the presence of CKD. To investigate the potential linear and non-linear correlations between serum cotinine and CKD, logistic regression models and generalized additive models (GAM) were employed. Furthermore, stratified analyses and interaction tests were conducted to evaluate potential disparities in the relationship between serum cotinine and CKD, based on sex.

RESULTS

The median age in the study participants was 49.28 ± 17.96 years, and the median log serum cotinine (ng/mL) was -0.54 ± 1.68. The prevalence of CKD was found to be 17.04%. Multifactorial regression analysis did not show a statistically significant association between log serum cotinine and CKD (OR=1.02; 95% CI: 0.98-1.06, p=0.4387). A statistically significant non-linear association between log serum cotinine and CKD was also not observed in the GAM analysis (p non-linear value=0.091). Subgroup analyses revealed sex differences in the association between log serum cotinine and CKD. Briefly, males had a positive association between log serum cotinine and incident CKD (OR=1.08; 95% CI: 1.02-1.15, p=0.0049). In females, there was a U-shaped association between log serum cotinine and CKD, with an optimal inflection point for log serum cotinine of -0.30 (serum cotinine=0.5 ng/mL).

CONCLUSIONS

Cross-sectional analyses of NHANES data showed gender differences in the association between serum cotinine and the development of CKD.

Association between elevated serum transaminase and moderately increased albuminuria: a cross-sectional study in western Tokushima, Japan

BACKGROUND

This study aimed to identify the factors relating to moderately increased albuminuria among middle-aged and older individuals in Japan.

METHODS

We conducted specific health examinations in which we measured albuminuria levels, and administered a questionnaire survey to record participants' lifestyles in western Tokushima Prefecture, Japan. A total of 1,660 people whose albuminuria was less than 300 mg/g creatinine (Cr) were analyzed. We divided participants into two groups-those with normal albuminuria (< 30 mg/gCr) and those with moderately increased albuminuria (≥ 30 mg/gCr, > 300 mg/gCr)-and compared their characteristics. To investigate all relevant factors, we conducted a multivariate logistic regression analysis.

RESULTS

The moderately increased albuminuria group were significantly older and had, among them, significantly higher percentages of a body mass index (BMI) ≥ 25 kg/m2, diabetes, hypertension, and mild liver disorder (aspartate transaminase ≥ 31 U/L or alanine aminotransferase ≥ 31 U/L or gamma-glutamyl transferase ≥ 51 U/L). (p < 0.01) In a multivariate logistic regression analysis that used microalbuminuria as an independent variable, we found the adjusted odds ratio (AOR) and 95% confidence interval (CI) to be significantly higher among individuals with diabetes (AOR: 2.04, 95% CI: 1.40-2.99); hypertension (AOR: 1.90, 95% CI: 1.36-2.65); BMI ≥ 25 kg/m2 (AOR: 1.76, 95% CI: 1.27-2.44); and mild liver disorder (AOR: 1.54, 95% CI: 1.10-2.18).

CONCLUSIONS

In addition to diabetes, hypertension, and BMI ≥ 25 kg/m2, this study found that among the middle-aged and older general population living in western Tokushima Prefecture, there were cases of mild liver disorder (elevated serum transaminase), which independently associated with moderately increased albuminuria. Therefore, in health checkups targeting the general population, there is a need to consider measuring albuminuria, even in those who have only mild liver dysfunction (health guidance level).

TRIAL REGISTRATION

N/A.

Early Diagnosis of Kidney Damage Associated with Tobacco Use: Preventive Application

Although long-term smoking has been associated with chronic kidney disease, its effect on kidney function in early stages has not been clarified. Therefore, the proposed objectives were: (1) to identify subclinical kidney damage in smokers, through a panel of biomarkers; (2) to evaluate the progression of subclinical kidney damage after two years of consumption in these patients; and (3) study whether quitting smoking reduces kidney damage. A prospective study was carried out (patients recruited from a primary care centre and a clinical smoking unit). Kidney function was assessed using a panel of biomarkers and compared between smokers and non-smokers, taking into account potential risk factors for kidney damage. These results show, for the first time in the literature, the relationship between smoking and early (subclinical) kidney damage and provide a panel of biomarkers capable of detecting this condition (Neutrophil gelatinase-associated lipocalin, Kidney injury molecule-1, N-acetyl-beta-D-glucosaminidase, transferrin, and ganglioside-activating protein GM2). This study also indicates that subclinical damage is maintained when use continues, but can be reversed if patients stop smoking. The use of these biomarkers as diagnostic tools can be a preventive measure in the development of chronic kidney disease associated with smoking and in the prevention of acute events associated with potentially nephrotoxic pharmacological treatment in smokers. Trial registration number: NCT03850756.

Lifestyle interventions for preventing and ameliorating CKD in primary and secondary care

PURPOSE OF REVIEW

Despite the growth in chronic kidney disease (CKD) epidemics, evidence-based lifestyle recommendations for primary prevention of CKD are limited by reliance on observational studies and predominantly pilot clinical trials.

RECENT FINDINGS

Emerging data have shown lifestyle modification strategies for primary CKD prevention with the most evidence favoring a healthy dietary pattern (rich in fruit, vegetables, potassium and have a higher plant-based to animal protein ratio), and diet low in sodium, being physically active, avoiding tobacco smoking, moderating alcohol consumption and maintaining a healthy body weight. The way these behavioral interventions can be implemented in practice should consider their synergistic benefit as well as mechanisms to facilitate long-term behavior change. Sustaining long-term behavior change remains a challenge in practice, particularly due to a lack of healthcare resources and behavior relapse. Some suggestions to mitigate this include ensuring adequate time is spent in intervention codesign and planning, utilizing adaptive trial/intervention designs with regular intervention tailoring for intervention dose, intensity, duration, and modality.

SUMMARY

A number of modifiable lifestyle behaviors consistently associate with developing CKD in the community. The current evidence base, despite its inherent limitations, may inform both public health recommendations and clinical practice.