Laboratory monitoring of drugs at initiation of therapy in ambulatory care.
OBJECTIVE
Product labeling and published guidelines reflect the importance of monitoring laboratory parameters for drugs with a risk of organ system toxicity or electrolyte imbalance. Limited information exists about adherence to laboratory monitoring recommendations. The objective of this study was to describe laboratory monitoring among ambulatory patients dispensed medications for which laboratory testing is recommended at therapy initiation.


METHODS
We conducted a retrospective cross-sectional analysis of patients in 10 geographically distributed health maintenance organizations who were newly prescribed medications with recommended laboratory test monitoring. The main outcome measure was the proportion of initial drug dispensing without recommended baseline laboratory monitoring for 35 newly initiated drugs or drug classes.


RESULTS
One hundred seven thousand, seven hundred sixty-three of 279,354 (39%) initial drug dispensings occurred without recommended laboratory monitoring. Patients without monitoring were younger than patients who had monitoring (median 57 vs 61 years, P<.001). Thirty-two percent of dispensings where a serum creatinine was indicated did not have it evaluated (range across drugs, 12% to 61%); 39% did not have liver function testing (range 10% to 75%); 32% did not have hematologic monitoring (range 9% to 51%); and 34% did not have electrolyte monitoring (range 20% to 62%) (P<.001).


CONCLUSIONS
Substantial opportunity exists to improve laboratory monitoring of drugs for which such monitoring is recommended. This study emphasizes the need for research to identify the clinical implications of not conducting recommended laboratory monitoring, existing barriers to monitoring, and methods to improve practice.
Raebel
Marsha A
MA
Kaiser Permanente of Colorado Clinical Research Unit, Denver, CO 80237-8066, USA. Marsha.A.Raebel@kp.org
Lyons
Ella E
EE
Andrade
Susan E
SE
Chan
K Arnold
KA
Chester
Elizabeth A
EA
Davis
Robert L
RL
Ellis
Jennifer L
JL
Feldstein
Adrianne
A
Gunter
Margaret J
MJ
Lafata
Jennifer Elston
JE
Long
Charron L
CL
Magid
David J
DJ
Selby
Joseph V
JV
Simon
Steven R
SR
Platt
Richard
R
D000553:Ambulatory Care; D003430:Cross-Sectional Studies; D016903:Drug Monitoring; D004358:Drug Therapy / Q000592:standards*; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies