Characteristics of ambulatory anticoagulant adverse drug events: a descriptive study

Medication adverse events in the ambulatory setting: A mixed-methods analysis

DISCLAIMER

In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

To characterize ambulatory care adverse drug events reported to the Collaborative Healthcare Patient Safety Organization (CHPSO), a network of 400 hospitals across the United States, and identify addressable contributing factors.

METHODS

We abstracted deidentified ambulatory care CHPSO reports compiled from May 2012 to October 2018 that included medication-related adverse events to identify implicated medications and contributing factors. We dual-coded 20% of the sample. We quantitatively calculated co-occurring frequent item sets of contributing factors and then applied a qualitative thematic analysis of co-occurring sets of contributing factors for each drug class using an inductive analytic approach to develop formal themes.

RESULTS

Of 1,244 events in the sample, 208 were medication related. The most commonly implicated medication classes were anticoagulants (n = 97, or 46% of events), antibiotics (n = 24, 11%), hypoglycemics (n = 19, 9%), and opioids (n = 17, 8%). For anticoagulants, timely follow-up on supratherapeutic international normalized ratio (INR) values often occurred before the development of symptoms. Incident reports citing antibiotics often described prescribing errors and failure to review clinical contraindications. Reports citing hypoglycemic drugs often described low blood sugar events due to a lack of patient education or communication. Reports citing opioids often described drug-drug interactions, commonly involving benzodiazepines.

CONCLUSION

Ambulatory care prescribing clinicians and community pharmacists have the potential to mitigate harm related to anticoagulants, antibiotics, hypoglycemics, and opioids. Recommendations include increased follow-up for subtherapeutic INRs, improved medical record integration and chart review for antibiotic prescriptions, enhanced patient education regarding hypoglycemics, and alerts to dissuade coprescription of opioids and benzodiazepines.

Tele-pharmacy Anticoagulation Clinic During COVID-19 Pandemic: Patient Outcomes

Introduction: It is well-established that clinical pharmacist-managed anticoagulation services achieve superior anticoagulation control, with a positive impact. At King Abdulaziz Medical City (KAMC), Riyadh, Saudi Arabia, the structure of anticoagulation management is a pharmacist-managed specialty service. With the current COVID-19 situation, measures were taken to assure the continuity of patient care by establishing tele-pharmacy anticoagulation clinics. Materials and Methods: This was a prospective study with patients prescribed anticoagulation and followed up for 3 months. Since establishing the anticoagulation virtual clinic in March 2020, 270 patients were recruited in the study. The data collected included age, gender, comorbidities, indication for anticoagulation, intended duration of treatment, warfarin dose, testing of International Normalized Ratio (INR), INR target, range of INR values, time INR that was within the therapeutic range (TTR), and complications of therapy (bleeding and/or bruises). The patients were asked to complete the pharmacist satisfaction survey (PSS) after their consultation to assess patient satisfaction with the new virtual consultation system. Linguistic and cultural validation was conducted for the questionnaire. Results: A total of 270 patients were included in the study. The mean percentage of overall INR values in the range was 59.39% ± 32.84, and the mean time with the overall INR was within the therapeutic range 57.81% ± 32.08. Thirty-one percent of the sample had good anticoagulation control (time in therapeutic range >70%). The median satisfaction score was 32 (IQR 28-36) with a maximum score of 40. Conclusion: This is the first study to assess the tele-pharmacy anticoagulation clinic's efficiency and patient satisfaction in Saudi Arabia during the COVID-19 pandemic. This type of consultation was as effective as face-to-face consultations. The study also highlighted that though the reduction in the cost of care was not substantial, there was a significant increase in resource (clinical pharmacist) utilization as a result of this model. The adoption of tele-pharmacy resulted in time savings for the clinical pharmacists who can be utilized in many other improvement projects in adult ambulatory clinics to ensure the delivery of better quality and safe patient care.

Drug-drug interactions and risk of bleeding among inpatients on warfarin therapy: a prospective observational study

Background

Warfarin is known for its interaction with many drugs, resulting in undesired treatment outcomes such as bleeding. The study aimed to assess the prevalence of drug-drug interactions and determinants of bleeding among inpatients on warfarin therapy.

Methods

A cohort of inpatients on warfarin treatment was prospectively followed from date of admission until discharge. The study was carried out from January to October 2013 in Ayder Referral Hospital, Northern Ethiopia. Patients on warfarin therapy during the study period and willing to participate were included as study subjects. Each concurrent medication was collected and checked for drug-drug interactions using Micromedex® online drug reference. Data were analyzed using statistical software, SPSS for windows version 16. The relationship between bleeding complications and independent variables (age, sex, residence, type and number of co-medications, dose and duration of warfarin treatment, INR value) was assessed using binary logistic regression analysis (Odds ratio, 95% confidence interval).

Results

Of the total 133 patients enrolled in the study, 78 (58.9%) were females. The mean age of the study participants was 40.81 ± 17.6 years. The prevalence of drug-drug interactions was 99.2%. Among these, 65 (49.2%) patients had at least one major while the others had moderate level of drug-drug interaction. Twenty two (16.5%) patients have developed bleeding complications. Increase in international normalized ratio value was found to be strongly associated with risk of bleeding (P value = 0.00; OR = 0.03 (0.00-0.46)).

Conclusion

Drug-drug interactions with warfarin were prevalent in the study hospital. Bleeding complications due to warfarin were also high. Thus, clinicians should be aware of potential interactions and monitor patients’ international normalized ratio closely.

Risk of hemorrhage and treatment costs associated with warfarin drug interactions in patients with atrial fibrillation

BACKGROUND

Drug interactions with warfarin are common and may be responsible for increased patient morbidity and treatment costs.

OBJECTIVES

To assess the usage patterns of drugs that potentiate warfarin's anticoagulant activity and discuss their associated relationship with both risk of hemorrhage and treatment costs among warfarin users with atrial fibrillation (AF).

METHODS

A nested case-control study of long-term warfarin-treated AF patients was conducted using a health insurance claims database. Patients with a hemorrhagic event (cases) were matched to control patients using the incidence density sampling method. Drug-potentiating warfarin effects were identified within 30 days before the hemorrhagic event. Conditional logistic regression was used to calculate the association between use of potentiating drugs and hemorrhage risk. Mean treatment costs and CIs were calculated using the bootstrap method and tested using the t-test. Factors associated with treatment costs were determined using generalized linear models with the log-link function and γ distribution.

RESULTS

Approximately 80% of AF patients were prescribed at least 1 warfarin-potentiating medication while taking warfarin. Patients who used these medications had a 26% higher risk of hemorrhage compared with those who did not use these drugs. Likelihood of hemorrhagic events was significantly increased with the use of potentiating drugs from the following therapeutic classes: anticoagulants (odds ratio [OR] = 1.91), anti-infectives (OR = 1.76), antiplatelets (OR = 1.56), and analgesics (OR = 1.33). The risk also increased when patients took ≥3 therapeutic classes of interacting medications (OR = 1.62-1.85). Among patients with a hemorrhagic event, patients who were prescribed potentiating drugs had higher hemorrhage-related treatment costs ($1359) compared with those patients without prescriptions for warfarin-potentiating drugs ($691; P < 0.001).

CONCLUSIONS

Warfarin-potentiating drugs were commonly used among AF patients on warfarin. The use of potentiating drugs increased the risk of a hemorrhage, leading to higher treatment costs. More frequent monitoring or alternative anticoagulant therapies are needed to avoid frequent warfarin drug interactions.

Association of health literacy with medication knowledge, adherence, and adverse drug events among elderly veterans

Health literacy is an important priority in health care delivery, but its effect on clinical outcomes remains incompletely elucidated. This observational cohort study examined the association of health literacy with medication knowledge, adherence, and adverse drug events among cognitively intact veterans older than 65 years old who were taking 5 or more medications and who were enrolled in a Veterans Administration primary care clinic. Health literacy was determined by the Rapid Estimate of Adult Literacy in Medicine. Medication knowledge and adherence were assessed by clinical pharmacist interview and refill data. Adverse drug events were determined by interview and chart review at 3 and 12 months. The 310 subjects had a mean age of 74 years, 99% were White, and 97% were male. Percentage of medications known was 29% for the low health literacy group versus 49% (marginal) and 56% (adequate), p < .001. Known medication purposes were lower in the lower health literacy group (49% vs. 71% vs. 74%; p < .001). Health literacy was not associated with medication adherence: the low health literacy group took 84% of medications by label instructions compared with 80% (marginal) and 77% (adequate), p = .14; or with adverse drug events at 1 year (48% vs. 33% vs. 40%; p = .30). Patients with lower health literacy have poorer medication knowledge but not lower adherence or increased adverse drug events.