The incidence rate of CKD stages 3-5 by age in VA is the highest among those that are aged 70 years or older across all the years.
Chart Explanation: Incidence of CKD stages 3-5 was calculated as the sum of new patients in Stages 3, 4, and 5 for a given year divided by the number of patients with an eGFR ≧ 60 ml/min/1.73 m² in the previous calendar year; newly incident patients may have progressively decreasing eGFR or may have no serum creatinine result on record for the first year. The incidence of CKD stages 3-5 increases with higher age, particularly for individuals 40 years of age and older.
The Veteran’s Affairs (VA) data presented are from a national sample of health care visits to the VA Health System by eligible U.S. veterans and their dependents. During any given year, ~ 70% of the outpatient population receives a serum creatinine test. While the demographics of VA Health System users are distinct from the general U.S. population, the VA data allow a ‘snapshot’ of clinical practices across the nation.
National VA data were examined for veterans with at least one outpatient visit during the federal fiscal year. To estimate prevalence of CKD, outpatient serum creatinine laboratory results (averaged if a patient had more than one test during the fiscal year) were used to calculate an estimated glomerular filtration rate (eGFR) for each patient using the CKD-EPI equation, excluding dialysis and transplant patients. Estimated GFR (kidney function) was classified into five CKD categories (eGFR =90, eGFR 60-89, stage 3=eGFR 30-59, stage 4=eGFR 15 to 29, and stage 5 without dialysis=eGFR<15 ml/min/1.73 m² and “eGFR Unmeasured” for those patients without serum creatinine testing. Inpatient serum creatinine data were not used as they would be affected by the presence of acute illnesses. Due to the infrequency of testing, albuminuria was not included in the definition of CKD. Dialysis patients were defined by clinic stop-codes (602-611), outpatient procedure codes for dialysis (CPT4: 90921 and 90925), outpatient diagnosis codes (ICD-9-CM: 585.6, V56, V45.1 and E87.91) and inpatient and outpatient diagnosis codes (ICD-9-CM: 5856) to indicate dialysis. Kidney transplant patients were identified by inpatient and outpatient ICD-9-CM diagnosis code V420 and inpatient procedure and surgery codes (55.69).
There are several pertinent issues when calculating incidence of CKD, a measure not addressed significantly in the published literature. To calculate incidence of a given CKD stage by year, we calculated the percentage of new patients in that eGFR category/CKD stage that were present in an earlier stage/eGFR category in the prior year. Thus, the denominator for this calculation included patients (20+ years) with outpatient visits in both years under analysis, who were either classified at an earlier stage of CKD or without a serum creatinine measurement in prior year.
This material is the result of work supported with resources and the use of facilities at the Veterans Affairs Ann Arbor Health Care System, Ann Arbor, Michigan.
| Field | Data |
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| Period Currently Available | 2006-2018 |
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| Secondary (5) Indicator Method of Measurement | Outpatient visit, Inpatient visit, and Pharmacy data for diabetes medication |
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| Frequency of Measurement (Primary) | Multiple measurements per patient |
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| Secondary (2) Indicator Method of Measurement | Outpatient Visit |
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| Secondary (3) Variable | Race/ethnicity |
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| Primary Indicator Method of Measurement | Laboratory |
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| Secondary (1) Variable | Age = (30Sep(study year) - Dob)/365.25 |
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| Secondary (1) Indicator Method of Measurement | Outpatient Visit |
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| Secondary (2) Variable | Sex: Gender |
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| Secondary (3) Indicator Method of Measurement | Outpatient Visit |
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| Secondary (4) Variable | Diabetes |
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| Secondary (4) Indicator Method of Measurement | Outpatient visit, Inpatient visit, and Pharmacy data for diabetes medication |
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| Secondary (5) Variable | Hypertension |
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| Health Care System Data | Yes |
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| Regional or National? | National |
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| Demographic Group | Patients in VA system |
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| Description of Measure | Incidence of stages 3-5T CKD by eGFR (kidney function) |
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| Data Source | VA |
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| Type of Data Source | Administrative Data |
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| Data Set | VA National Data, using the MedSAS data files |
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| Numerator | Patients in denominator with creatinine testing and GFR meeting CKD criteria for stages 3-5T in the second year. |
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| Denominator | Patients aged >20 who have at least one outpatient visit in both years |
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| Primary Data Source Indicator | Serum Creatinine Lab Result Value |
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| Limitations of Indicator | Determination of incidence is directly related to frequency of testing (both serum creatinine and urinary albumin).
The earlier categories of eGFR (≥90 and 60-89 ml/min/1.73 m² ) are not definitively classifiable into CKD stages 1 and 2 because of absence of albuminuria information in the vast majority of these patients. |
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| Glomerular Filtration Rate | Estimated using the CKD-EPI equation: eGFR=141 X min(SCR/K,1)**A X max(SCR/K,1)**-1.209 X 0.993**Age X 1.018[if female] X 1.159[if black] where SCR is serum creatinine in mg/dl, min is the minimum of SCR/K or 1, max is the maximum of SCR/K or 1, K=0.7 for female or K=0.9 for male, A is -.329 for female and -.411 for male. Missing race/ethnicity was coded as white. ** signifies "raised to the power of". |
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