Incidence and Preventability of Medication Errors and ADEs in Ambulatory Care Older Patients.

OBJECTIVE: To assess the incidence of medication errors, adverse drug events (ADEs), and potential ADEs (poADEs) in patients 65 years of age and older. DESIGN: This is a retrospective cohort study (2011 to 2014). SETTING: The study was performed at a section 330 federally funded ambulatory health care center. PATIENTS: The study was a convenience sample selected in a nonrandomized way from event reports filed in those years. INTERVENTION: Data were collected through event reports and medical record review. Descriptive statistics and chi-square were employed to analyze data. RESULTS: During the study period, at least one medication error, poADE, or ADE report was documented in 170 out of 2,218 older patients (incidence: 12.5, 9.4, and 5.0 per 100 patient-years, respectively); 42.9% of ADEs were preventable. The chronic conditions most frequently related to ADEs were diabetes (18%), hypertension (18%), and hyperlipidemia (12%). The use of hypoglycemic agents was commonly associated with ADEs (14%; P = 0.001). An increased number of prescribed medications were significantly associated with all the adverse events. CONCLUSIONS: Medication errors, poADEs, and ADEs are common in patients 65 years of age or older taking more than three medications. Almost half of the detected ADEs were preventable.

Prediction of warfarin dose reductions in Puerto Rican patients, based on combinatorial CYP2C9 and VKORC1 genotypes.

BACKGROUND: The influence of CYP2C9 and VKORC1 polymorphisms on warfarin dose has been investigated in white, Asian, and African American populations but not in Puerto Rican Hispanic patients. OBJECTIVE: To test the associations between genotypes, international normalized ratio (INR) measurements, and warfarin dosing and gauge the impact of these polymorphisms on warfarin dose, using a published algorithm. METHODS: A retrospective warfarin pharmacogenetic association study in 106 Puerto Rican patients was performed. DNA samples from patients were assayed for 12 variants in both CYP2C9 and VKORC1 loci by HILOmet PhyzioType assay. Demographic and clinical nongenetic data were retrospectively collected from medical records. Allele and genotype frequencies were determined and Hardy-Weinberg equilibrium (HWE) was tested. RESULTS: Sixty-nine percent of patients were carriers of at least one polymorphism in either the CYP2C9 or the VKORC1 gene. Double, triple, and quadruple carriers accounted for 22%, 5%, and 1%, respectively. No significant departure from HWE was found. Among patients with a given CYP2C9 genotype, warfarin dose requirements declined from GG to AA haplotypes; whereas, within each VKORC1 haplotype, the dose decreased as the number of CYP2C9 variants increased. The presence of these loss-of-function alleles was associated with more out-of-range INR measurements (OR = 1.38) but not with significant INR >4 during the initiation phase. Analyses based on a published pharmacogenetic algorithm predicted dose reductions of up to 4.9 mg/day in carriers and provided better dose prediction in an extreme subgroup of highly sensitive patients, but also suggested the need to improve predictability by developing a customized model for use in Puerto Rican patients. CONCLUSIONS: This study laid important groundwork for supporting a prospective pharmacogenetic trial in Puerto Ricans to detect the benefits of incorporating relevant genomic information into a customized DNA-guided warfarin dosing algorithm.