A Retrospective Cohort Study of the Association of Inpatient Amlodipine Dose With Renal Complication Rates and Hospital Length of Stay

Background Correct hospital medication reconciliation is important for continuity of care, but optimal home antihypertensive medication ordering has not been adequately studied. Since excessive hospital blood pressure control is associated with adverse renal and cardiovascular outcomes, we assessed the association of inpatient doses of amlodipine (10mg vs. 5mg) with length of stay and renal failure and fluid and electrolyte disorders (RF/FED). Methods In this retrospective cohort study, clinical and demographic data on patients not initially admitted to the ICU between 2008 and 2019 were extracted from the Medical Information Mart for Intensive Care (MIMIC-IV). Multivariable logistic regression was used to assess the association between amlodipine dose during the first 24 hours of admission and RF/FED. Multivariable linear regression was used to assess the association between amlodipine dose and length of stay when controlling for RF/FED or maximum blood urea nitrogen (BUN) concentration and other confounders. Results There were 5,932 patients included in this study, and 3,038 of whom received 10mg of amlodipine. A 10mg dose of amlodipine was associated with an increased likelihood of RF/FED (OR: 1.248, 95% CI (1.104, 1.412), p<0.001). It was also associated with a longer length of stay (coef.: 0.338, 95% CI (0.067, 0.609), p=0.015). This was not significant when controlling for RF/FED (dose coef.: 0.197, 95% CI (-0.070, 0.464), p=0.147) or maximum BUN (dose coef.: 0.082, 95% CI (-0.147, 0.312), p=0.482). Interpretation Higher amlodipine dose was associated with longer length of stay, and this is likely mediated by RF/FED. Randomized trials are needed to determine which home blood pressure medications should be ordered in the hospital.