Potential drug-drug and drug-disease interactions in prescriptions for ambulatory patients over 50 years of age in family medicine clinics in Mexico City.
BACKGROUND
In Mexico, inappropriate prescription of drugs with potential interactions causing serious risks to patient health has been little studied. Work in this area has focused mainly on hospitalized patients, with only specific drug combinations analyzed; moreover, the studies have not produced conclusive results. In the present study, we determined the frequency of potential drug-drug and drug-disease interactions in prescriptions for ambulatory patients over 50 years of age, who used Mexican Institute of Social Security (IMSS) family medicine clinics. In addition, we aimed to identify the associated factors for these interactions.


METHODS
We collected information on general patient characteristics, medical histories, and medication (complete data). The study included 624 ambulatory patients over 50 years of age, with non-malignant pain syndrome, who made ambulatory visits to two IMSS family medicine clinics in Mexico City. The patients received 7-day prescriptions for non-opioid analgesics. The potential interactions were identified by using the Thompson Micromedex program. Data were analyzed using descriptive, bivariate and multiple logistic regression analyses.


RESULTS
The average number of prescribed drugs was 5.9 +/- 2.5. About 80.0% of patients had prescriptions implying one or more potential drug-drug interactions and 3.8% of patients were prescribed drug combinations with interactions that should be avoided. Also, 64.0% of patients had prescriptions implying one or more potential drug disease interactions. The factors significantly associated with having one or more potential interactions included: taking 5 or more medicines (adjusted Odds Ratio (OR): 4.34, 95%CI: 2.76-6.83), patient age 60 years or older (adjusted OR: 1.66, 95% CI: 1.01-2.74) and suffering from cardiovascular diseases (adjusted OR: 7.26, 95% CI: 4.61-11.44).


CONCLUSIONS
The high frequency of prescription of drugs with potential drug interactions showed in this study suggests that it is common practice in primary care level. To lower the frequency of potential interactions it could be necessary to make a careful selection of therapeutic alternatives, and in cases without other options, patients should be continuously monitored to identify adverse events.
Doubova Dubova
Svetlana Vladislavovna
SV
Epidemiology and Health Services Research Unit, National Medical Center Century XXI, Mexican Institute of Social Security, Mexico City, Mexico. svetlana.doubova@imss.gob.mx
Reyes-Morales
Hortensia
H
Torres-Arreola
Laura del Pilar
Ldel P
Suárez-Ortega
Magdalena
M
D000368:Aged; D000369:Aged, 80 and over; D000554:Ambulatory Care Facilities / Q000592:standards* / Q000706:statistics & numerical data; D003430:Cross-Sectional Studies; D004347:Drug Interactions; D011307:Drug Prescriptions / Q000592:standards*; D004359:Drug Therapy, Combination; D004363:Drug Utilization / Q000706:statistics & numerical data*; D064420:Drug-Related Side Effects and Adverse Reactions; D005194:Family Practice / Q000592:standards* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008485:Medical Audit; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged