Predicting the risk of hyperkalemia in patients with chronic kidney disease starting lisinopril.
OBJECTIVE
Angiotensin-converting enzyme (ACE) inhibitors are recommended for patients with chronic kidney disease (CKD) because they slow disease progression. But physicians' concerns about the risk of hyperkalemia (elevated serum potassium level), a potentially fatal adverse effect, may limit optimal management with ACE-inhibitors. We synthesized known predictors of hyperkalemia into a prognostic risk score to predict the risk of hyperkalemia.


METHODS
We assembled a retrospective cohort of adult patients with possible CKD (at least one estimated glomerular filtration rate (eGFR) value less than 60 ml/min/1.73 m(2)) who started an ACE-inhibitor (i.e., incident users) between 1998 and 2006 at a health maintenance organization. We followed patients for hyperkalemia: (1) potassium value >5.5 mmol/L; or (2) diagnosis code for hyperkalemia. Cox regression synthesized a priori predictors recorded in the electronic medical record into a risk score.


RESULTS
We followed 5171 patients and 145 experienced hyperkalemia, a 90-day risk of 2.8%. Predictors included: age, eGFR, diabetes, heart failure, potassium supplements, potassium-sparing diuretics, and a high dose for the ACE-inhibitor (lisinopril). The risk score separated high-risk patients (top quintile, observed risk of 6.9%) from low-risk patients (bottom quintile, observed risk of 0.7%). Predicted and observed risks agreed within 1% for each quintile. The risk increased gradually in relation to declining eGFR with no apparent threshold for contraindicating ACE-inhibitors.


CONCLUSIONS
The risk score separated high-risk patients (who may need more intensive laboratory monitoring) from low-risk patients. The risk score should be validated in other populations before it is ready for use in clinical practice.
Johnson
Eric S
ES
The Center for Health Research, Kaiser Permanente Northwest, Portland, OR 97227, USA. Eric.S.Johnson@kpchr.org
Weinstein
Jessica R
JR
Thorp
Micah L
ML
Platt
Robert W
RW
Petrik
Amanda F
AF
Yang
Xiuhai
X
Anderson
Sharon
S
Smith
David H
DH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000009:adverse effects* / Q000627:therapeutic use; D002908:Chronic Disease; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D006947:Hyperkalemia / Q000139:chemically induced* / Q000209:etiology; D007674:Kidney Diseases / Q000150:complications / Q000188:drug therapy*; D017706:Lisinopril / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012306:Risk; D012307:Risk Factors
D000806:Angiotensin-Converting Enzyme Inhibitors; D017706:Lisinopril