Suboptimal prescribing in elderly outpatients: potentially harmful drug-drug and drug-disease combinations.
OBJECTIVE
To assess the prevalence and correlates of potentially harmful drug-drug combinations and drug-disease combinations prescribed for elderly patients at outpatient settings.


METHODS
Retrospective analysis of the 1995-2000 National Ambulatory Medical Care Survey (NAMCS) and the National Hospital Ambulatory Medical Care Survey (NHAMCS).


METHODS
Physician offices and hospital outpatient departments.


METHODS
Outpatient visits by patients aged 65 and older in the NAMCS and NHAMCS (n=70,203).


METHODS
Incidences of six drug-drug combinations and 50 drug-disease combinations that can place elderly patients at risk for adverse events according to expert consensus panels.


RESULTS
Overall, 0.74% (95% confidence interval (CI)=0.65-0.83) of visits with two or more prescriptions had at least one inappropriate drug-drug combination, and 2.58% (95% CI=2.44-2.72) of visits with at least one prescription had one or more inappropriate drug-disease combinations. Of visits with a prescription of warfarin, 6.60% (95% CI=5.46-7.74) were prescribed a drug with potentially harmful interaction. Of patients with benign prostatic hypertrophy, 4.06% (95% CI=3.06-5.06) had at least one of six drugs that should be avoided. The number of drugs prescribed is most predictive of inappropriate drug-drug and drug-disease combinations.


CONCLUSIONS
Potentially harmful drug-drug and drug-disease combinations occur in various degrees in outpatient care in the elderly population. Targeting combinations such as those involving warfarin that are high in prevalence and potential harm offers a practical approach to improving prescribing and patient safety.
Zhan
Chunliu
C
Agency for Healthcare Research and Quality, Department of Health and Human Services, Rockville, Maryland 20850, USA. czhan@ahrq.gov <czhan@ahrq.gov>
Correa-de-Araujo
Rosaly
R
Bierman
Arlene S
AS
Sangl
Judy
J
Miller
Marlene R
MR
Wickizer
Stephen W
SW
Stryer
Daniel
D
D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care; D000075202:Contraindications; D004347:Drug Interactions; D011307:Drug Prescriptions / Q000706:statistics & numerical data; D005260:Female; D019538:Health Care Surveys; D006801:Humans; D008297:Male; D008508:Medication Errors / Q000706:statistics & numerical data*; D004364:Pharmaceutical Preparations; D015995:Prevalence; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology
D004364:Pharmaceutical Preparations