Modestly Reduced eGFR Associated with Adverse Outcomes in Young Adults

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Modest reductions in kidney function in younger adults are associated with later increases in risk of cardiovascular disease, kidney failure, and death, reports a study in BMJ.

The population-based cohort study included linked Ontario, Canada, health care data on 8.7 million adults (aged 18–65 years; mean age, 41.3 years). All had at least one outpatient estimated glomerular filtration rate (eGFR) value with no history of kidney diseases. Modest reductions in kidney function were identified, based on age-specific eGFR reference levels: 100–110 mL/min/1.73 m2 at aged 18–39 years, 90–100 mL/min/1.73 m2 at aged 40–49 years, and 80–90 mL/min/1.73 m2 at aged 50–65 years. Associations with all-cause mortality, any cardiovascular event, and kidney failure were assessed.

In the study sample, the mean index eGFR value was 104.2 mL/min/1.73 m2, and the median follow-up was 9.2 years. Based on age-specific cutoffs, modest reductions in eGFR were found in 18.0% of patients aged 18–39 years, 18.8% of those aged 40–49 years, and 17.0% of those aged 50–65 years.

“Modest eGFR reductions were consistently associated with higher rates of adverse outcomes,” the researchers write. At an eGFR between 70 and 80 mL/min/1.73 m2, hazard ratios for adverse outcomes were 1.42 in participants aged 18–39 years, 1.13 for those aged 40–49 years, and 1.08 for those aged 50–65 years. Incidence rates were 4.39, 9.61, and 23.4 per 1000 person-years, respectively. Associations were significant for all three types of adverse events.

The effects of age on eGFR and the associated clinical risks are unclear, specifically at values above the 60 mL/min/1.73 m2 cutoff for CKD. Thus, there is limited evidence to guide the management of younger adults with early reductions in eGFR.

The new analysis links modest age-specific reductions in eGFR to increased risks of adverse clinical outcomes. The risks appear more prominent in adults aged 18–39 years, beginning at index eGFR values under 80 mL/min/1.73 m2. The researchers conclude: “These findings suggest a role for more frequent monitoring of kidney function in younger adults to identify individuals at risk to prevent chronic kidney disease and its complications” [Hussain J, et al. Associations between modest reductions in kidney function and adverse outcomes in young adults: Retrospective, population based cohort study. BMJ 2023; 381:e075062. doi: 10.1136/bmj-2023-075062].