title: Frequency of laboratory measurement and hyperkalaemia in hospitalised patients using serum potassium concentration increasing drugs.
abstract: OBJECTIVE
  Although, drug-drug interactions (DDIs) between potassium-increasing drugs (PIDs) are known risk factors for developing hyperkalaemia, not much is known about their risk and management strategies during hospitalisation. This study examines the frequency of serum potassium measurements and hyperkalaemia in hospitalised patients, based on the use of one or more PIDs, and the determinants thereof.
  
  
  METHODS
  Adult patients hospitalised in the University Medical Centre Utrecht between 2006 and 2008 were included in this cross-sectional study. The frequency of serum potassium measurements and of hyperkalaemia were compared between patients using only one PID at a time (monotherapy group) and patients using two or more PIDs concomitantly (interaction group). The determinants studied were renal failure, diabetes mellitus, use of diuretics, type of DDI, start of the PIDs within the hospital versus continued home medication and medical speciality.
  
  
  RESULTS
  Serum potassium was measured more frequently in the interaction group than in the monotherapy group [67 vs. 56%; relative risk (RR) 1.19, 95% confidence interval (CI) 1.14-1.24] and the risk of hyperkalaemia was also increased in the interaction group (9.9 vs. 5.9%, RR 1.7, 95% CI 1.3-2.1). The combination of potassium-sparing diuretics plus a potassium supplement, start of the PID within the hospital and hospitalisation in non-internal medicine departments was associated with higher relative risk estimates for hyperkalaemia.
  
  
  CONCLUSIONS
  Among our patient cohort, even when physicians received a direct pop-up to monitor serum potassium levels when prescribing two PIDs concomitantly, serum potassium levels were not measured in 33% of patients, and 10% of patients developed hyperkalaemia. Improved management strategies and/or clinical decision-support systems are needed to decrease the frequency of hyperkalaemia following DDIs.
authors.affiliation: Department of Clinical Pharmacy, University Medical Centre Utrecht, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands. E.V.Uijtendaal@umcutrecht.nl
authors.forename: Esther V
authors.initials: EV
authors.lastname: Uijtendaal
authors.forename: Jeannette E F
authors.initials: JE
authors.lastname: Zwart-van Rijkom
authors.forename: Wouter W
authors.initials: WW
authors.lastname: van Solinge
authors.forename: Toine C G
authors.initials: TC
authors.lastname: Egberts
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis / Q000706:statistics & numerical data; D015331:Cohort Studies; D016208:Databases, Factual; D004347:Drug Interactions; D016903:Drug Monitoring / Q000706:statistics & numerical data*; D064420:Drug-Related Side Effects and Adverse Reactions; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D006947:Hyperkalemia / Q000097:blood / Q000139:chemically induced*; D009426:Netherlands; D011188:Potassium / Q000097:blood*; D012307:Risk Factors; D012308:Risk Management
chemical_list: D011188:Potassium