Age Matters

The association between the age of onset of hypertension and the subsequent risk of CKD is both a pressing public health issue and a critical area of study in nephrology. According the World Health Organization, hypertension affects over 1.28 billion people worldwide, contributing significantly to the burden of cardiovascular diseases (CVDs) and CKDs.1 Epidemiologic studies have shown that CKD affects approximately 700 million individuals globally, accounting for roughly 9.4% of the population, and is responsible for 1.4 million annual deaths. Particularly, chronic hypertension is recognized as a principal risk factor for CKD, with estimates suggesting that up to 90% of CKD patients have a history of hypertension.2 This highlights the urgency of understanding how factors such as the timing of hypertension onset can influence the likelihood of developing CKD. The growing evidence demonstrates that earlier onset of hypertension is associated with a higher subsequent risk of CKD, including subclinical renal damage, proteinuria, and progression to ESKD. Large population-based cohort studies from diverse populations have shown that the relative risk of CKD, renal decline, and ESKD is highest when hypertension develops at a younger age, with the risk attenuating as the age of hypertension onset increases. For example, in a UK cohort, individuals with hypertension onset at 18–39 years had a hazard ratio (HR) for CKD of 3.69 (95% confidence interval, 3.53 to 3.86), compared with an HR of 2.01 (1.96 to 2.06) for those with onset at 80 years or older; the pattern was similar for ESKD, with HRs of 17.26 (14.34 to 20.77) for the youngest group versus 2.55 (2.12 to 3.07) for the oldest.3 This graded association is corroborated in Asian populations and in patients with diabetes, where the effect of elevated BP on ESKD risk is most pronounced in those younger than 40 years, and diminishes with advancing age at hypertension onset.4,5 Longitudinal studies tracking BP trajectories from childhood into adulthood further support that persistently elevated or increasing BP from a young age is associated with higher urinary albumin-to-creatinine ratios and greater odds of subclinical renal disease in middle age, independent of other risk factors.6 Early-onset hypertension is also associated with albuminuria and other forms of hypertension-mediated organ damage by midlife, whereas hypertension onset at age 45 years or older is not consistently linked to increased risk of renal end-organ damage.7,8 Cross-sectional and longitudinal analyses confirm that the association between hypertension and CKD is strongest at younger ages, with prevalence ratios for stage 3 or 4 CKD and albuminuria associated with hypertension being highest in adults aged 20–49, and progressively lower in older age groups.5 New-onset hypertension, even over short follow-up periods, increases the risk of developing proteinuria, a key marker of CKD, particularly in men and in those with high-normal BP.9 In this issue of Kidney360, Lu et al.10 provide critical insights into this association, leveraging robust data from the UK Biobank. This study, encompassing 485,101 participants, reveals a compelling trend: the younger the age at hypertension onset, the higher the risk of developing CKD. Specifically, individuals diagnosed with hypertension younger than 45 years exhibited the highest HRs for CKD, underscoring the vulnerability of this subgroup. The findings are further strengthened using propensity score matching and Cox proportional hazards models, which ensure methodologic rigor and minimize confounding biases. Overall, the implications of this research are profound. First, it highlights the need for targeted interventions in younger hypertensive populations. Early-onset hypertension not only predisposes individuals to CKD but also amplifies the burden of associated risk factors such as obesity, unhealthy diets, and diabetes. Public health strategies must prioritize early detection, lifestyle modifications, and regular renal function monitoring for these high-risk groups. Second, the study underscores the role of preexisting CVD in exacerbating CKD risk among younger hypertensive patients. This finding calls for integrated care approaches that address both hypertension and CVD to mitigate renal complications. Third, the article opens avenues for future research. Although the observational nature of the study limits causal inference, the authors provide a robust discussion on potential biologic mechanisms, including genetic predispositions and vascular damage. Expanding this research to diverse populations and exploring additional risk factors will enhance the generalizability and depth of these findings.