title: Laboratory evaluation of potassium and creatinine among ambulatory patients prescribed spironolactone: are we monitoring for hyperkalemia?
abstract: BACKGROUND
  Serum potassium and creatinine evaluation is recommended in patients prescribed spironolactone, yet the proportion of ambulatory patients chronically dispensed spironolactone receiving evaluation is not well understood.
  
  
  OBJECTIVE
  To estimate the rate of potassium and creatinine evaluation and identify factors associated with conducting these tests among ambulatory patients dispensed spironolactone.
  
  
  METHODS
  A retrospective cohort study was designed to evaluate patients at 10 health maintenance organizations with ongoing spironolactone dispensing for one year (N = 2257). Potassium and creatinine evaluation were determined from administrative data. Associations between patient characteristics and laboratory testing were assessed, using logistic regression modeling.
  
  
  RESULTS
  Serum creatinine and potassium were evaluated in 72.3% of patients during a 13 month period. The likelihood of potassium and creatinine monitoring was greater among patients who were older (OR 1.28; 95% CI 1.17 to 1.41 per decade of life); male (OR 1.25; 95% CI 1.01 to 1.54); had diabetes (OR 1.63; 95% CI 1.31 to 2.03); received concomitant therapy with angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (OR 2.23; 95% CI 1.74 to 2.87), potassium supplements (OR 1.96; 95% CI 1.51 to 2.54), or digoxin (OR 2.10 95% CI 1.48 to 2.98); or had more outpatient visits (OR 1.31; 95% CI 1.19 to 1.44). Among patients with heart failure (n = 790), factors associated with the incidence of laboratory testing were diabetes (OR 1.64, 95% CI 1.14 to 2.34), outpatient visits (OR 1.20; 95% CI 1.02 to 1.41), and digoxin therapy (OR 2.26; 95% CI 1.38 to 3.69).
  
  
  CONCLUSIONS
  Three-fourths of ambulatory patients dispensed spironolactone receive recommended laboratory evaluation, with monitoring more likely to be completed in patients prescribed concomitant therapy with drugs that increase hyperkalemia risk, older patients, and those with diabetes.
authors.affiliation: Kaiser Permanente Colorado Clinical Research Unit and School of Pharmacy, University of Colorado at Denver and Health Sciences Center, Denver, CO 80237, USA. Marsha.A.Raebel@kp.org
authors.forename: Marsha A
authors.initials: MA
authors.lastname: Raebel
authors.forename: David L
authors.initials: DL
authors.lastname: McClure
authors.forename: K Arnold
authors.initials: KA
authors.lastname: Chan
authors.forename: Steven R
authors.initials: SR
authors.lastname: Simon
authors.forename: Adrianne C
authors.initials: AC
authors.lastname: Feldstein
authors.forename: Jennifer Elston
authors.initials: JE
authors.lastname: Lafata
authors.forename: Susan E
authors.initials: SE
authors.lastname: Andrade
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Gunter
authors.forename: Winnie W
authors.initials: WW
authors.lastname: Nelson
authors.forename: Douglas
authors.initials: D
authors.lastname: Roblin
authors.forename: Richard
authors.initials: R
authors.lastname: Platt
mesh_terms: D000368:Aged; D000553:Ambulatory Care; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood*; D016903:Drug Monitoring; D005260:Female; D006801:Humans; D006947:Hyperkalemia / Q000097:blood / Q000139:chemically induced*; D008297:Male; D011188:Potassium / Q000097:blood*; D012189:Retrospective Studies; D013148:Spironolactone / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use
chemical_list: D013148:Spironolactone; D003404:Creatinine; D011188:Potassium