Metabolic Syndrome and Inflammation from Young to Mid-Adulthood and Subclinical Kidney Damage in Middle-Aged Australians.

Background: Relationships between metabolic syndrome (MetS), inflammation, and chronic kidney disease (CKD) have been reported, but long-term follow-up studies are limited. This study aimed to investigate whether MetS and C-reactive protein (CRP) from young adulthood associated with the risk of subclinical kidney damage (SKD), a surrogate measure for CKD, in mid-adulthood. Materials and Methods: One thousand fifteen participants from the Childhood Determinants of Adult Health study aged 26-36 years at baseline (2004-2006) were followed up at age 36-49 (2014-2019). Log-binomial regression was used to determine whether MetS and high CRP in young adulthood and from young to mid-adulthood predicted the risk of SKD (an estimated glomerular filtration rate [eGFR] of 30-60 mL/min/1.73 m 2 or an eGFR >60 mL/min/1.73 m 2 with a urine albumin-creatinine ratio ≥2.5 mg/mmol [males] or ≥3.5 mg/mmol [females]) in midlife. Results: Having MetS in young adulthood was associated with an increased risk of SKD in midlife (adjusted relative risk [aRR] = 2.67, 95% confidence interval [CI]: 1.24-5.76). Participants with MetS and high CRP as young adults had a greater risk of having SKD in midlife (aRR = 4.27, 95% CI: 1.61-11.30) compared with those without MetS and high CRP. Furthermore, for participants with persistent MetS, the aRR of SKD in midlife was 4.08 (95% CI: 1.84-9.05) compared with those without MetS from young to mid-adulthood. No significant associations were found between CRP in young adulthood, or change in CRP from young to mid-adulthood, and SKD in midlife. Conclusions: MetS in young adulthood, with and without high CRP, and persistent MetS were associated with an increased risk of SKD in middle midlife.