Influence of drugs on blood potassium levels in older, multi-medicated patients - results of two cohort studies focusing on adverse drug reactions.

BACKGROUND

Many drugs influence blood potassium levels and are often prescribed to older adults. Aim of this study was to estimate the extend of potassium level changes of drugs in the case of older, multi-medicated patients respecting renal function.

METHODS

Data of patients from an outpatient clinic (polypharmacy consultations hours) at the University Hospital RWTH Aachen and from a prospective, multicenter study on adverse drug reactions in emergency departments (ADRED) was used. Data of patients aged ≥ 70 years taking ≥ 3 drugs with available blood potassium levels were included. Quantile regression models were used to analyze drug effects in the context of multi-medication.

RESULTS

In total, N = 1097 patient cases were included with hypokalemia in 28.4% (n = 311) and hyperkalemia in 20.3% (n = 223). Male sex, use of low-ceiling diuretics, loop diuretics, mineralocorticoid receptor antagonists (MRAs), angiotensin-converting-enzyme inhibitors/ angiotensin II receptor blockers, number of other drugs, and CKD stage were associated with serum potassium levels and included in quantile regression models. In CKD stages 1 and 2, the use of MRAs (+ 0.49, p = 0.002), together with low-ceiling diuretics (-0.54, p < 0.001) had highest impact on serum potassium levels. In CKD stage 3, use of low-ceiling diuretics (-0.52, p < 0.001) and in CKD stages 4 and 5, the use of MRAs (+ 0.86, p < 0.001) had highest impact on serum potassium levels.

CONCLUSIONS

Hypo- as well as hyperkalemia occur frequently in geriatric, multi-medicated patients. While renal function is an important predictor of blood potassium levels, drug effects can differ per drug class in the context of multi-medication.

TRIAL REGISTRATION: The ADRED-study is registered at the German Clinical Trials Register under: DRKS00008979. The cohort study of the polypharmacy consultation hours at the University Hospital RWTH Aachen is registered at the ClinicalTrials.gov under: NCT05247814.