A Novel Approach to Developing a Discordance Index for Older Adults With Chronic Kidney Disease

Abstract Background Older adults with chronic kidney disease (CKD)-discordant conditions (comorbid conditions with treatment recommendations that potentially complicate CKD management) have higher risk of hospitalization and death. Our goal is to develop a CKD-Discordance Index using electronic health records to improve recognition of discordance. Methods This retrospective cohort study included Kaiser Permanente Southern California patients aged ≥65 years and older with incident CKD (N = 30,932). To guide inclusion of conditions in the Index and weight each condition, we first developed a prediction model for 1-year hospitalization risk using Cox regression. Points were assigned proportional to regression coefficients derived from the model. Next, the CKD-Discordance Index was calculated as an individual’s total points divided by the maximum possible discordance points. The association between CKD-Discordance Index and hospitalizations, emergency department visits, and mortality was accessed using multivariable-adjusted Cox regression model. Results Overall, mean (SD) age was 77.9 (7.6) years, 55% of participants were female, 59.3% were white, and 32% (n = 9,869) had ≥1 hospitalization during 1 year of follow-up. The CKD-Discordance Index included the following variables: heart failure, gastroesophageal reflux disease/peptic ulcer disease, osteoarthritis, dementia, depression, cancer, chronic obstructive pulmonary disease/asthma, and having four or more prescribers. Compared to those with a CKD-Discordance Index of 0, adjusted hazard ratios (95% confidence interval) for hospitalization were 1.39 (1.27–1.51) and 1.81 (1.64–2.01) for those with a CKD-Discordance Index of 0.001–0.24 and ≥0.25, respectively (ptrend < .001). A graded pattern of risk was seen for emergency department visits and all-cause mortality. Conclusion A data-driven approach identified CKD-discordant indicators for a CKD-Discordance Index. Higher CKD-Discordance Index was associated with health care utilization and mortality.