Presentation (CTI)

OBJECTIVES: Chronic kidney disease (CKD) can be clinically described using estimated glomerular filtration rate (eGFR), a measure associated with end stage renal disease (ESRD) and increased risk of cardiovascular events. Patients can be categorized according to the interval scale defined by the Kidney Disease | Improving Global Outcomes (KDIGO) and risk of clinical events often is presented using this categorization. The objective here was to compare the modeled quality adjusted life years (QALYs) and lifetime costs between categorical and continuous versions of eGFR decline in the same model, while holding all other factors constant.
METHODS: The state transition CKD Care Model followed a hypothetical cohort of US adults with CKD and at risk of ESRD or one of three cardiovascular event states, plus a non-CVD death state. Keeping all inputs the same, we compared the QALYs and costs between a categorical version of the CKD Care Model which models clinical events by KDIGO categories and a continuous version which models clinical events as a continuous function of eGFR.
RESULTS: For CKD patients in KDIGO G3a, G3b, and G4, respectively, the discrete model projected lifetime QALYS of 10.4, 9.4, and 7.6, and the lifetime costs were approximately $421,000, $550,000, and $797,000. Projected QALYs were within 1% of the value projected between the continuous and categorical versions and lifetime costs in the continuous version were 2%, <1% and 3% higher than the projections using a categorical model.
CONCLUSIONS: While inconsistencies were noted between continuous and categorical over shorter time frames (data not shown), differences in the CKD Care Model between continuous and discrete eGFR using the same input parameters led to only small differences in lifetime QALYs and costs. Such information may be useful for analysts modeling continuous physiologic parameters and informing the time frame for the analysis.