Rapid Kidney Function Decline in Older Adults

Inclusion Criteria: 1. Age greater than 70 years; 2. GFR data measured at least twice (two years apart) and ACR data measured once (at baseline); 3. A clear record of the cause of the previous visit; from this, people diagnosed with kidney disease were selected, and kidney disease was defined as various primary nephritis, secondary nephropathy, acute kidney injury (AKI), chronic kidney disease, kidney tumors, or a diagnosis of proteinuria alone. 4. Signed informed consent form. Exclusion Criteria: 1. People with missing baseline biochemical data; 2. Outliers in the population indicators, i.e., data deviating from the mean ± three times the standard deviation; 3. Data with significantly abnormal baseline renal function follow-up (abnormally elevated GFR by more than 10% within 2 years or abnormal ACR value as determined by consultation with a senior nephrologist).