Background/Objectives: Obesity is a risk factor for chronic kidney disease (CKD) in Asians. The Asia-Pacific body mass index (BMI) classification sets lower obesity cutoffs than the conventional BMI classification for all races, generally reflecting the lower BMIs in Asians. This longitudinal study evaluated the association between BMI, as classified by the Asia-Pacific BMI system, and CKD development in non-diabetic Asian adults. Methods: A population-based longitudinal study (1998–2023) was conducted in non-diabetic Japanese adults (hemoglobin A1c < 6.5%) in Zentsuji City (Kagawa Prefecture, Japan). The generalized gamma model was used to assess the relationship between time-varying BMI categories and CKD development, stratified by sex. CKD was defined as an estimated glomerular filtration rate of <60 mL/min/1.73 m². BMI was calculated as weight (kg) divided by the square of height (m²) and categorized per the Asia-Pacific classification as overweight (23.0–24.9 kg/m²), obesity class I (25.0–29.9 kg/m²), and obesity class II (≥30.0 kg/m²). Results: CKD developed in 34.2% of 3098 men and 34.8% of 4391 women. The mean follow-up times were 7.41 years for men and 8.25 years for women. During follow-up, the BMI distributions for men were 5.0% underweight, 43.3% normal weight, 25.6% overweight, 24.1% obesity class I, and 2.0% obesity class II; those for women were 7.7%, 50.5%, 20.5%, 18.3%, and 2.9%, respectively. Compared with normal weight, obesity class I was associated with a 6% (95% confidence interval [CI]: 2–10%) shorter time to CKD onset in men and 5% (95% CI: 2–7%) in women. In both sexes, obesity class II showed shorter survival times than normal weight by point estimates, although all 95% CIs crossed the null value. Conclusions: Obesity, as classified by the Asia-Pacific BMI system, shortened the time to CKD onset in non-diabetic Asians. The conventional BMI cutoff for obesity (≥30.0 kg/m²) may be too high to identify CKD risk in this population. The findings of this study may be useful for public health professionals in designing interventions to prevent CKD.

Chronic kidney disease (CKD) is a major global public health problem. Recent studies reported that diabetes and prediabetes are risk factors for developing CKD; however, the exact glycated hemoglobin (HbA1c) cut-off value for prediabetes remains controversial. In this study, we aimed to examine the relationship between HbA1c levels and subsequent CKD development in greater detail than previous studies. Longitudinal data of annual checkups of 7176 Japanese non-diabetic people (male: 40.4%) from 1998 to 2022 was analyzed. HbA1c values were categorized into < 5.0%, 5.0–5.4%, 5.5–5.9%, and 6.0–6.4%. CKD was defined as an estimated glomerular filtration rate < 60 ml/min/1.73 m². The descriptive statistics at study entry showed that higher HbA1c values were associated with male, older, overweight or obese, hypertensive, or dyslipidemic people. During a mean follow-up of 7.75 person-years, 2374 participants (male: 40.0%) developed CKD. The Weibull accelerated failure time model was selected because the proportional hazards assumption was violated. The adjusted time ratios of developing CKD for HbA1c levels of 5.5–5.9% and 6.0–6.4% compared with 5.0–5.4% were 0.97 (95% confidence interval: 0.92–1.03) and 1.01 (95% confidence interval: 0.90–1.13), respectively. There was no association between HbA1c in the prediabetic range and subsequent CKD development.

Follow-up studies evaluating the relationship between dyslipidemia and chronic kidney disease (CKD) in non-diabetic populations are limited. This longitudinal study (1998–2024) examined whether the prevalence of dyslipidemia is associated with the subsequent development of CKD in non-diabetic Japanese adult citizens of Zentsuji, Kagawa Prefecture, Japan. Dyslipidemia was defined as low-density lipoprotein cholesterol concentrations ≥ 140 mg/dL, high-density lipoprotein cholesterol concentrations < 40 mg/dL, and/or triglyceride concentrations ≥ 150 mg/dL. Participants were considered to have developed CKD if their estimated glomerular filtration rate was <60 mL/min/1.73 m². The proportional hazards assumption was violated. Therefore, the Weibull accelerated failure-time model was selected using the Akaike and Bayesian information criteria. The final cohort included 5970 participants, 41.6% of whom were men. The mean follow-up was 7.09 years. After the follow-up, 1890 (31.7%) participants developed CKD. Participants with dyslipidemia had a 5% shorter survival time (95% confidence interval: 3–7%) to incident CKD compared with those without dyslipidemia in the full model. High-density lipoprotein cholesterol concentrations < 40 mg/dL and triglyceride concentrations ≥ 150 mg/dL also reduced the survival time to CKD onset by 5–6%. Our results indicate that controlling the lipid profile to an appropriate range may contribute to reducing the risk of future onset of CKD.

Background/Objectives: Obesity is a risk factor for chronic kidney disease (CKD) in Asians. The Asia-Pacific body mass index (BMI) classification sets lower obesity cutoffs than the conventional BMI classification for all races, generally reflecting the lower BMIs in Asians. This longitudinal study evaluated the association between BMI, as classified by the Asia-Pacific BMI system, and CKD development in non-diabetic Asian adults. Methods: A population-based longitudinal study (1998–2023) was conducted in non-diabetic Japanese adults (hemoglobin A1c < 6.5%) in Zentsuji City (Kagawa Prefecture, Japan). The generalized gamma model was used to assess the relationship between time-varying BMI categories and CKD development, stratified by sex. CKD was defined as an estimated glomerular filtration rate of <60 mL/min/1.73 m ² . BMI was calculated as weight (kg) divided by the square of height (m ² ) and categorized per the Asia-Pacific classification as overweight (23.0–24.9 kg/m ² ), obesity class I (25.0–29.9 kg/m ² ), and obesity class II (≥30.0 kg/m ² ). Results: CKD developed in 34.2% of 3,098 men and 34.8% of 4,391 women. The mean follow-up times were 7.41 years for men and 8.25 years for women. During follow-up, the BMI distributions for men were 5.0% underweight, 43.3% normal weight, 25.6% overweight, 24.1% obesity class I, and 2.0% obesity class II; those for women were 7.7%, 50.5%, 20.5%, 18.3%, and 2.9%, respectively. Compared with normal weight, obesity class I was associated with a 6% (95% confidence interval [CI]: 2%–10%) shorter time to CKD onset in men and 5% (95% CI: 2%–7%) in women. In both sexes, obesity class II showed shorter survival times than normal weight by point estimates, although all 95% CIs crossed the null value. Conclusions: Obesity, as classified by the Asia-Pacific BMI system, shortened the time to CKD onset in non-diabetic Asians. The conventional BMI cutoff for obesity (≥30.0 kg/m ² ) may be too high to identify CKD risk in this population. The findings of this study may be useful for public health professionals in designing interventions to prevent CKD.