Current National Kidney Foundation Kidney Disease Outcomes Quality Initiative staging criteria for chronic kidney disease (CKD) are intended to apply to all age groups. However, it is unclear whether different levels of estimated GFR (eGFR) have the same prognostic significance in older and younger patients. The study cohort was composed of Department of Veterans Affairs (VA) patients who were aged 18 to 100 yr and had at least one outpatient serum creatinine measurement between October 1, 2001, and September 30, 2002 (n ‫؍‬ 2583,911). Patients with ESRD were excluded. GFR was estimated using the Modification of Diet in Renal Disease equation using each patient's first outpatient creatinine measurement during the study period. The association of eGFR with survival was measured by age group. Twenty percent of cohort patients had an eGFR <60 ml/min per 1.73 m 2 , ranging from 3% among 18-to 44-yr-olds to as high as 49% among 85-to 100-yr-olds. Fifty-two percent (n ‫؍‬ 266,421) of cohort patients with an eGFR <60 ml/min per 1.73 m 2 had "very" moderate reductions in eGFR into the 50-to 59-ml/min per 1.73 m 2 range. The association of eGFR with mortality was weaker in the elderly than in younger age groups: Whereas severe reductions in eGFR were associated with an increased risk for death in all age groups, "very" moderate reductions in eGFR (50 to 59 ml/min per 1.73 m 2 ) were associated with an increased adjusted risk for death only among patients who were younger than 65 yr. Age-related attenuation of the association of eGFR with mortality was also present among women and black patients. In the clinical setting, mortality risk stratification in elderly patients should not be based on the same eGFR cut points as for younger age groups and would benefit from finer categorization of the 30-to 59-ml/min per 1.73 m 2 eGFR group.

The objective was to determine the best strategy for identifying outpatients with hypertension-related diagnoses using Veterans Affairs (VA) administrative databases. We reviewed 1176 outpatient charts from 10 VA sites in 1999, taking the presence of 11 diagnoses relevant to hypertension management as the "gold standard" for identifying the comorbidity. We calculated agreement, sensitivity, and specificity for the chart versus several administrative data-based algorithms. Using 1999 data and requiring 1 administrative diagnosis, observed agreement ranged from 0.98 (atrial fibrillation) to 0.85 (hyperlipidemia), and kappas were generally high. Sensitivity varied from 38% (tobacco use) to 97% (diabetes); specificity exceeded 91% for 10 of 11 diagnoses. Requiring 2 years of data and 2 diagnoses improved most measures, with minimal sensitivity decrease. Agreement between the database and charts was good. Administrative data varied in its ability to identify all patients with a given diagnosis but identified accurately those without. The best strategy for case-finding required 2 diagnoses in a 2-year period.

Overall, PPVs were moderate for most of the PSIs. Implementing POA codes and using more specific ICD-9-CM codes would improve their validity. Our results suggest that additional coding improvements are needed before the PSIs evaluated herein are used for hospital reporting or pay for performance.