Lower Income Carried the Heaviest Kidney and Mortality Burden
In a large longitudinal analysis from the All of Us Research Program, socioeconomic position tracked tightly with both survival and kidney health. The signal was strongest for household income: participants with incomes below $25,000 faced substantially higher risks across every major outcome measured, including all-cause mortality, sustained 40% estimated glomerular filtration rate decline, incident recorded chronic kidney disease, CKD category G3a or worse, and kidney failure. In practical terms, lower income was not associated with just one unfavorable endpoint. It was associated with a broader gradient of worsening disease burden across the renal trajectory.
The cohort included 218,098 individuals with follow-up extending to January 1, 2025. Over a median 3.62 years of follow-up for mortality and 2.76 years for kidney outcomes, 4,777 deaths, 6,423 sustained declines, 7,870 incident recorded CKD diagnoses, 4,716 incident G3a-or-worse events, and 1,799 kidney failure events occurred. Those event counts matter because they show this was not a sparse-data analysis limited to a single rare endpoint. The kidney outcomes accumulated quickly enough to permit a direct comparison between early diagnostic capture and harder biological decline.
The pattern across income strata was striking. Compared with participants earning $200,000 or more, those with household income below $25,000 had adjusted hazard ratios of 2.68 for mortality, 3.57 for sustained kidney function decline, 2.13 for incident recorded CKD, 2.15 for incident G3a-or-worse CKD, and 3.08 for kidney failure. The steepest relative association appeared with sustained decline, not first recorded diagnosis. Kidney failure also rose sharply. In a disease where reduced nephron reserve, vascular injury, delayed care access, and cumulative cardiometabolic stress all interact, income appears to map onto the stage at which kidney injury becomes clinically unmistakable.
Kidney Decline Appeared More Sensitive to Inequality Than Recorded Diagnosis
The contrast between sustained eGFR decline and recorded CKD diagnosis was one of the most important features of the analysis. Relative index of inequality estimates were roughly twice as large for sustained decline and kidney failure as for recorded CKD diagnosis. In a clinical sense, this points to a familiar problem in chronic kidney disease epidemiology: diagnosis depends on contact with the health system, laboratory testing, and recognition, while decline reflects underlying renal injury more directly. Lower income may therefore influence both the biology of kidney deterioration and the likelihood that it is detected at all, but the harder endpoints appear less forgiving to differences in access and surveillance.
The study design helps explain why those two layers of risk should not be collapsed into one. A person can cross the threshold for a recorded CKD diagnosis because a clinician orders labs and documents the condition, while another patient with similar renal damage remains unrecognized. Sustained 40% decline and kidney failure are less vulnerable to that kind of documentation noise because they are tied to objective deterioration and advanced loss of kidney function. As a result, the stronger association with those endpoints suggests that socioeconomic disadvantage is not merely changing the label attached to kidney disease. It is shaping the disease process itself.
Baseline kidney state added another useful dimension. Standardized 3-year absolute mortality differences by income did not differ significantly across baseline kidney states. Mortality risk remained elevated overall, but the absolute income gap in death did not expand or shrink meaningfully depending on where participants started along the kidney disease continuum. That finding suggests a broad mortality penalty associated with lower income that is not confined to any single starting renal state.
Education and Neighborhood Deprivation Did Not Mirror Income Exactly
Education and neighborhood deprivation showed different patterns of association, which argues against using socioeconomic position as a single interchangeable construct. Income captured a strong and consistent gradient across every kidney and mortality outcome. Education and neighborhood deprivation contributed additional information, but not in the same shape or magnitude. This matters because household resources, educational attainment, and residential context likely act through overlapping yet distinct pathways: medication affordability, nutrition, transportation, health literacy, environmental exposures, and the ability to navigate longitudinal care.
The biological plausibility is straightforward. Chronic kidney disease is not only a filtration disorder; it is a vascular and inflammatory condition shaped by blood pressure control, diabetes burden, structural heart-kidney interactions, and the cumulative wear of social stressors. Neighborhood deprivation can intensify exposure to those upstream risks, while low income can delay evaluation after kidney injury begins. Education may modify how quickly symptoms are recognized or how consistently care plans are followed. The result is a layered exposure profile rather than a single uniform social determinant.
Because the analysis used the All of Us Research Program, it also drew from a large and diverse national cohort, strengthening the ability to examine these gradients in a real-world setting. Still, the authors were careful to flag key limitations. The study was observational, which prevents causal inference. Baseline creatinine was measured up to a year after the survey in some participants, creating potential misclassification of initial kidney state. Outcome ascertainment relied on health records, and those records may differ by income because access to care changes what gets documented, when, and how often.
Even with those caveats, the central message is difficult to ignore. Lower income was linked to higher mortality and greater risk of every kidney outcome examined, and the strongest relative penalties emerged for sustained decline and kidney failure rather than for recorded CKD alone. For nephrology, the finding argues for a broader view of risk assessment that includes the social conditions surrounding the patient, not just the serum creatinine in front of the clinician.