A Comprehensive Review of Herbal Supplements Used for Persistent Symptoms Attributed to Lyme Disease

Context

Lyme disease is the most common, tick-borne disease in the USA. While most patients successfully recover with antibiotics, some patients experience persistent symptoms for months to years. Patients who attribute chronic symptoms to Lyme disease commonly use herbal supplements. The complexity, variability in dose and formulation, and lack of data for these herbal compounds make it difficult to assess their efficacy and safety.

Objective

This review examines the evidence for the antimicrobial activity, safety, and drug-drug interactions of 18 herbal supplements that patients commonly use for treatment of persistent symptoms attributed to Lyme disease.

Design

The research team performed a narrative review by searching the PubMed, Embase, Scopus, Natural Medicines databases, and NCCIH website. The search used the keywords for 18 herbal compounds: (1) andrographis (Andrographis paniculate), (2) astragalus (Astragalus propinquus), (3) berberine, (4) cat's claw bark (Uncaria tomentosa), (5) cordyceps (Cordyceps sinensis), (6) cryptolepis (Cryptolepis sanguinolenta), (7) Chinese skullcap (Scutellaria baicalensis), (8) garlic (Allium sativum), (9) Japanese knotwood (Polygonum cuspidatum), (10) reishi mushrooms (Ganoderma lucidum), (11) sarsaparilla (Smilax medica), (12) Siberian ginseng (Eleutherococcus senticosus), (13) sweet wormwood (Artemisia annua), (14) teasle root (Dipsacus fullonum), (15) lemon balm (Melissa officinalis), (16) oil of oregano (Origanum vulgare), (17) peppermint (Mentha x piperita), and (18) thyme (Thymus vulgaris). The team also searched for terms related to protocols, including Dr. Rawls' protocol and the Buhner protocol.

Setting

University of Maryland Medical Center, Baltimore MD.

Results

Seven of the 18 herbs reviewed had evidence for in-vitro activity against B. burgdorferi. These compounds included: (1) cat's claw (2) cryptolepis, (3) Chinese skullcap, (4) Japanese knotweed, (5) sweet wormwood, (6) thyme, and (7) oil of oregano. With the exception of oil of oregano these compounds also have anti-inflammatory activity. In vivo data and clinical trials are lacking. Clinicians should be cautious as many of the identified compounds have drug interactions and additive effects that could lead to increased risks for bleeding, hypotension, and hypoglycemia.

Conclusions

Many of the herbs that alternative and integrative practitioners use to treat Lyme disease have anti-inflammatory effects that may contribute to patients' perceptions of symptomatic improvement. Some herbs have limited demonstrated anti-borrelial activity in vitro, but in-vivo data and clinical trial data is lacking. Further research is required to determine the efficacy, safety and appropriate use of these herbs for this patient population.

Interprofessional Culinary Medicine Training Enhanced Nutrition Knowledge, Nutrition Counseling Confidence, and Interprofessional Experience

Introduction: Culinary medicine training combining evidence-based nutrition instruction with experiential cooking application has improved nutrition knowledge, skills, and attitudes in the professional and personal lives of medical students. However, interprofessional culinary training remains largely unstudied among professional students who will be involved in collaborative patient care. The goal of this study was to evaluate the feasibility and effectiveness of an elective interprofessional culinary medicine course for students in the medical, pharmacy, social work, nursing, law, and dentistry schools at the University of Maryland, Baltimore. Methods: The interprofessional culinary medicine course was offered in-person at the teaching kitchen of the Nova Institute for Health in 2020 and virtually in 2021 during the COVID pandemic. The training featured five workshops combining instruction in a variety of popular diets, cooking a meal inspired by the diet in focus, and group discussion. Paired t tests were utilized to evaluate changes in pre-/post-training nutrition and interprofessional experience outcomes. Linear regression models were constructed to compare outcomes between in-person and virtual delivery. Results: A total of 62 students participated in the culinary medicine training. Confidence in all nutrition knowledge, skills, and attitudes, as well as interprofessional experience outcomes, improved after the training (p < 0.05). Similar improvements were noted in most outcomes with in-person and virtual delivery in linear regression modeling. Discussion: Interprofessional culinary medicine training is feasible, and virtual delivery may help enhance replicability in other settings.

Utility of On-Treatment Viral Loads During Treatment With Direct-Acting Antivirals in Patients Infected With Chronic Viral Hepatitis C

Background: Direct-acting antiviral (DAA) agents have revolutionized the treatment of chronic hepatitis C virus (HCV) infection. Current data regarding the utility of on-treatment HCV viral load (VL) monitoring are conflicting and limited data are available in HIV-coinfected patients. Objective: The objective of the study was to determine whether on-treatment VLs are predictive of HCV cure in a real-world population. Method: A single-center, retrospective cohort study was conducted using patients who received a prescription for DAA therapy for HCV treatment at a large, tertiary ambulatory care clinic. Results: A total of 219 patients were included in the final analysis. The average age was 56 years. Most patients were male (64.4%), African American (73.1%), and insured by Medicaid (61.6%). Most patients were treatment-naive, noncirrhotic, and infected with HCV genotype 1a (73.1%). About 22.4% of patients were coinfected with HIV. The most common regimen was 12 weeks of ledipasvir/sofosbuvir (53.9%). On-treatment VLs were most commonly obtained at treatment week 4 (42.5%), of which 45.2% of patients were detectable. Sustained virologic response (SVR) was achieved in 96.8% of the total population and 95.9% of HIV-coinfected patients. Of the 7 patients who did not achieve SVR, 3 patients had undetectable on-treatment VLs in the first 8 weeks of therapy. Conclusion: Sustained virologic response rates were similar between HCV-monoinfected patients and HCV-HIV-coinfected patients. This research further supports that on-treatment VLs may not be a valuable indicator of treatment failure but may be helpful to engage patients in care and ensure treatment adherence and ultimately cure.

Effectiveness of 8 weeks of ledipasvir/sofosbuvir for hepatitis C in HCV-HIV-coinfected patients

BACKGROUND

Data is limited on the use of 8 weeks of therapy with ledipasvir/sofosbuvir (LDV/SOF) for special populations such as HCV-HIV-coinfected patients. The primary objective of this analysis was to compare sustained virological response at 12 weeks after end of therapy (SVR12) rates among HCV-monoinfected and HCV-HIV-coinfected patients in a real-world clinical setting. Additionally, we compared SVR12 rates among patients receiving 8 versus 12 weeks of therapy.

METHODS

This was a single-centre, retrospective study of HCV-infected patients prescribed LDV/SOF at ambulatory clinics associated with the University of Maryland Medical Center (UMMC) from May 2015 to May 2016. Data were obtained from UMMC electronic medical records and outpatient pharmacy claims database. Comparisons between groups were made using χ² or Fisher's exact test for categorical variables and Student's t-test or Wilcoxon rank-sum for continuous variables. All analyses were per-protocol; patients missing SVR12 data (25.2%) could not be evaluated for our stated objectives.

RESULTS

A total of 274 patients were included. Median age was 58 years; 62.8% were male; 82.5% were Black. SVR12 data was available for 65 HCV-HIV-coinfected patients, of which 62 (95.4%) achieved SVR12. There was no difference in SVR12 rate between HCV-HIV-coinfected patients and HCV-monoinfected patients (86/90; 95.6%; P=0.959). Additionally, there was no difference in SVR12 attainment between HIV-HCV-coinfected patients who received 8 versus 12 weeks of therapy (P=0.101).

CONCLUSIONS

8 weeks of LDV/SOF was effective for treatment-naive, non-cirrhotic, HCV genotype-1 patients in this real-world setting, regardless of HIV status. Increased uptake of the 8-week regimen can decrease costs for patients and payers without compromising outcomes.

Future Considerations for the Evaluation of Hepatitis C Virus Treatments in Pan-Genotypic Therapy for Noncirrhotic Treatment-Naive Patients

Given the recent approval of the first pan-genotypic chronic hepatitis C virus (HCV) therapy, managed care, health systems, and clinicians will need to evaluate current practices related to essential laboratory assessments used to select therapy. Historically, clinicians and payers required a battery of tests to determine HCV genotype, viral load, degree of fibrosis, and organ function. In light of current and forthcoming approvals of pan-genotypic therapy, clinicians and payers can expect a more competitive marketplace and a downward curve in the price of therapy. Ultimately, this development will lead to the cost of screenings and assessments having an increased role in selecting an optimal HCV therapy.

DISCLOSURES

No outside funding supported this study. The authors have nothing to disclose. All authors contributed to study concept and design. Calabrese took the lead in data collection, along with Shaya. Data interpretation was performed by Calabrese and Hynicka, along with Rodriguez de Bittner and Shaya. The manuscript was written and revised by Calabrese and Hynicka, along with Rodriguez de Bittner and Shaya.

Direct-Acting Antivirals to Prevent Vertical Transmission of Viral Hepatitis C: When Is the Optimal Time to Treat?

OBJECTIVE

To describe the most current evidence for the use of direct-acting antivirals (DAAs) to treat hepatitis C along the pregnancy-pediatric continuum in the United States.

DATA SOURCES

The MEDLINE/PubMed databases were searched (January 1995 to February 2018) for articles in English using the terms: hepatitis C, vertical transmission, pregnancy, pediatrics, ribavirin, interferon, direct acting antivirals, daclatasvir, dasabuvir, elbasvir, glecaprevir, grazoprevir, ledipasvir, ombitasvir, paritaprevir, pibrentasvir, simeprevir, sofosbuvir, and velpatasvir.

STUDY SELECTION AND DATA EXTRACTION

All relevant studies, meta-analyses, systematic reviews, guidelines, and review articles were evaluated for inclusion. References from pertinent articles were assessed for additional content that was not found during the initial search.

DATA SYNTHESIS

The primary route of transmission for hepatitis C virus (HCV) in pediatric patients is vertical transmission (VT), with the rate estimated to be 5.8%. Screening for HCV during pregnancy is not routinely part of clinical care, and the data for the use of DAAs in pregnancy is limited. A significant number of infected infants will clear the HCV infection spontaneously, and ledipasvir/sofosbuvir and sofosbuvir have recently been Food and Drug Administration approved for use in pediatric patients older than 12 years.

CONCLUSIONS

Data to determine the best treatment point along the pregnancy-pediatric continuum are limited; however, given the lack of human data for use of DAAs during pregnancy, low rate of VT, high rate of spontaneous pediatric clearance, and recent approval of DAAs for pediatric patients, treatment of chronically infected children seems to be the optimal strategy currently.

Evaluating a Collaborative Approach to Improve Prior Authorization Efficiency in the Treatment of Hepatitis C Virus

OBJECTIVE

A team-based approach to obtaining prior authorization approval was implemented utilizing a specialty pharmacy, a clinic-based pharmacy technician specialist, and a registered nurse to work with providers to obtain approval for medications for hepatitis C virus (HCV) infection. The objective of this study was to evaluate the time to approval for prescribed treatment of HCV infection.

METHODS

A retrospective observational study was conducted including patients treated for HCV infection by clinic providers who received at least 1 oral direct-acting antiviral HCV medication. Patients were divided into 2 groups, based on whether they were treated before or after the implementation of the team-based approach. Student t tests were used to compare average wait times before and after the intervention.

RESULTS

The sample included 180 patients, 68 treated before the intervention and 112 patients who initiated therapy after. All patients sampled required prior authorization approval by a third-party payer to begin therapy. There was a statistically significant reduction (P = .02) in average wait time in the postintervention group (15.6 ± 12.1 days) once adjusted using dates of approval.

CONCLUSIONS

Pharmacy collaboration may provide increases in efficiency in provider prior authorization practices and reduced wait time for patients to begin treatment.

Are Fluoroquinolones Appropriate for the Treatment of Extended-Spectrum β-Lactamase-Producing Gram-Negative Bacilli?

Objective: To review the data analyzing the role of fluoroquinolones in the treatment of extended-spectrum β-lactamase (ESBL)-producing infections and rates and methods of co-transmission of resistance. Data Sources: A MEDLINE literature search was performed using the search terms extended-spectrum beta-lactamase, fluoroquinolone, ciprofloxacin, levofloxacin, plasmid transmission, and resistance from 1996 to June 2015. Additional references were identified from a review of literature citations. Study Selection and Data Extraction: All English-language retrospective studies, prospective studies, and meta-analyses assessing efficacy of fluoroquinolone use in ESBL infections, assessing methods of resistance transmission, or analyzing patient risk factors were reviewed. Data Synthesis: A total of 18 studies that analyzed fluoroquinolone resistance and association to ESBL producing bacteria from either molecular or clinical perspectives were idenitifed. Four studies evaluated the genetic association between ESBL transmission and fluoroquinolone resistance. Plasmid mediated quinolone resistance was found in higher rates in ESBL-producing bacteria. Numerous studies analyzed the risk factors of co-occurring resistance identifying nosocomial acquired infections, recent hospitalization, long-term care facility residence, and intensive care unit stay as the most common. Conclusive clinical data are lacking; however, a meta-analysis showed fluoroquinolones had higher odds of all-cause mortality when used empirically to treat ESBL bacteremia compared with carbapenems. Conclusions: Fluoroquinolone resistance may be co-transmitted in ESBL-producing Enterobacteriaceae. There are limited data on the efficacy for fluoroquinolones in the treatment of ESBL-producing infections. Additional prospective trials are needed to definitively determine the role of fluoroquinolones in ESBL infections.

What does the pharmacological future of treating chronic hepatitis C look like?

Development of direct acting antivirals has revolutionized the standard of care for the treatment of hepatitis C virus. New interferon-free regimens provide sustained virologic response rates of >90% in many genotype 1 patients with only 12 weeks of oral therapy. This review will provide a brief overview of current standards of care with a summary of the evidence supporting the recommended combinations of direct acting antivirals. We will discuss the direction of future therapies, with strategies for shorter durations of therapy and new all-oral combinations in the pipeline.

Treatment Strategy for a Multidrug-Resistant Klebsiella UTI

Objective: To describe the management strategy for a multidrug-resistant (MDR) Klebsiella urinary tract infection (UTI). Case Summary: A 69-year-old Caucasian woman with a past medical history of recurrent UTIs and a right-lung transplant presented with fever to 101.4°F, chills, malaise, and cloudy, foul-smelling urine for approximately 1 week. She was found to have a MDR Klebsiella UTI that was sensitive to tigecycline and cefepime. To further evaluate the degree of resistance Etest minimum inhibitory concentrations were requested for cefepime, amikacin, meropenem, and ertapenem. The patient received a 14-day course of amikacin, which resulted in resolution of her symptoms. One month later, the patient’s UTI symptoms returned. The urine culture again grew MDR Klebsiella, sensitive only to tigecycline. Fosfomycin was initiated and resulted in limited resolution of her symptoms. Colistin was started, however, therapy was discontinued on day 5 secondary to the development of acute kidney injury. Despite the short course of therapy, the patient’s symptoms resolved. Discussion: The case presented lends itself well to numerous discussion items that are important to consider when determining optimal treatment for MDR Gram-negative bacilli (GNBs). Susceptibility testing is an important tool for optimizing antibiotic therapy, however, automated systems may overestimate the susceptibility profile for a MDR GNB. Treatment strategies evaluated to treat MDR GNB, include combination therapy with a carbepenem and synergy using polymyxin. Conclusion: We have described the management strategy for a MDR Klebsiella UTI, the consequences of the initial management strategy, and potential strategies to manage these types of infections in future patients.

Prophylaxis of Thromboembolic Events in Patients with Nephrotic Syndrome

OBJECTIVE

To review published literature regarding use of strategies to prevent thrombotic events in patients with nephrotic syndrome (NS).

DATA SOURCES

The MEDLINE/PubMed, EMBASE, and Cochrane databases were queried from 1980 to December 2012 for articles in English using the search terms nephrotic syndrome, thrombosis, thromboembolism, anticoagulation, warfarin, heparin, low-molecular-weight heparin, enoxaparin, dalteparin, tinzaparin, statin, atorvastatin, fluvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, simvastatin, aspirin, direct thrombin inhibitor, rivaroxaban, argatroban, lepirudin, bivalirudin, dabigatran, factor Xa inhibitor, fondaparinux, rivaroxaban, clopidogrel, ticlopidine, and prasugrel.

STUDY SELECTION AND DATA EXTRACTION

All relevant original studies, meta-analyses, systematic reviews, guidelines, and review articles were assessed for inclusion. References from pertinent articles were examined for additional content not found during the initial search.

DATA SYNTHESIS

NS leads to multiple complications, including hypercoagulability. A small prospective cohort study used enoxaparin for primary prophylaxis and demonstrated successful prevention of thrombotic events with minimal adverse events. Additional information has come in the form of decision analyses, which show potential decreased morbidity and mortality when primary prophylaxis for thrombotic events is used; however, all data have numerous limitations. Other strategies for thrombus prevention, including statins and antiplatelet agents, also have been investigated.

CONCLUSIONS

When patients with NS are admitted to the hospital, develop an acute medical illness, or acquire an additional thrombotic events risk factor such as surgery, active malignancy, or pregnancy, consideration for primary pharmacologic prophylaxis with appropriately dosed low-molecular-weight heparin or other indicated anticoagulant should include the potential for increased thrombotic events risk in this patient population. Consideration may also be given to the use of primary pharmacologic prophylaxis with low-molecular-weight heparin or oral vitamin K antagonist in patients with membranous nephropathy once the albumin level drops below 2.0–2.5 g/dL. Short-term use of pharmacologic prophylaxis during the first 6 months following diagnosis warrants further investigation.

Anemia management in patients with chronic viral hepatitis C

OBJECTIVE

To review the literature regarding current strategies for the management of anemia associated with treatment for chronic viral hepatitis C (HCV) in adults.

DATA SOURCES

The MEDLINE/PubMed, EMBASE, and Cochrane databases were searched (January 1980-October 2012) for articles in English using the search terms anemia, ribavirin, dose reduction, erythropoietin stimulating agents, hepatitis C, HIV, liver transplant, telaprevir, and boceprevir.

STUDY SELECTION AND DATA EXTRACTION

All relevant original studies, meta-analyses, systematic reviews, guidelines, and review articles were assessed for inclusion. References from pertinent articles were examined for additional content not found during the initial search.

DATA SYNTHESIS

Standard of care for patients infected with HCV genotype 1 now requires a triple therapy regimen including an HCV NS3 protease inhibitor. These regimens lead to significantly higher rates of anemia compared to prior dual therapy regimens. Development of an optimal management strategy should begin with risk stratification. Ribavirin dose reductions have been recommended in the package inserts for the pegylated interferon products and studies have demonstrated the need for maintenance of 80% of the initial ribavirin dose to achieve optimal sustained virologic response (SVR) with dual therapy. The use of erythropoietin-stimulating agents has been shown to be effective for anemia caused by peginterferon and ribavirin without compromising SVR rates. Limited data have been published regarding the management of anemia with triple therapy; however, efficacy studies for boceprevir and telaprevir have used ribavirin dose reduction and erythropoietin-stimulating agents to successfully manage anemia.

CONCLUSIONS

Anemia is a common adverse event associated with the use of ribavirin, and, more recently, the new HCV protease inhibitors. Ribavirin dose reduction should continue to be used as an initial anemia management strategy, with the use of erythropoietin alfa 40,000 units once weekly reserved for patients whose hemoglobin does not adequately respond to initial management strategies.

Azithromycin-Induced Hepatotoxicity

Objective

To report a case of hepatotoxicity in a patient receiving azithromycin.

Case Summary

A 38-year-old female was admitted for an acute exacerbation of her liver disease. The patient received a course of azithromycin 2 weeks prior to admission for a respiratory tract infection. On admission, the patient had elevated liver function tests (LFTs), ascites, jaundice with sclera icterus, and abdominal pain. Etiologies such as infection and worsening liver disease were ruled out, and the patient's symptoms and transaminitis were attributed to azithromycin-induced hepatotoxicity. The patient was medically managed with diuretics and discharged after the symptoms stabilized and LFTs were trending down.

Discussion

There are 6 previous case reports of patients experiencing azithromycin-induced hepatotoxicity. The patient's presentation and onset of symptoms after azithromycin initiation were similar to other patients. Although this patient had a history of steatohepatitis, progression of liver disease was ruled out and other etiologies were considered unlikely. The patient's laboratory values supported cholestatic liver injury, and the most likely cause of the transaminitis and symptoms was attributed to azithromycin. Although azithromycin is usually well-tolerated and liver injury is a rare adverse effect, there is increasing literature surrounding azithromycin-induced hepatotoxicity. The Naranjo adverse drug reaction probability scale revealed a possible interaction between azithromycin and the hepatotoxic adverse event.

Conclusions

We report a possible case of azithromycin-induced hepatotoxicity. Even though hepatotoxicity is an uncommon side effect of azithromycin, prescribers should be cognizant of this potential adverse effect in order to discontinue therapy as necessary and prevent re-exposure to the medication.

Prophylaxis and treatment of respiratory syncytial virus in adult immunocompromised patients

OBJECTIVE

To review the literature regarding current strategies and strategies under active development for the prevention and treatment of respiratory syncytial virus (RSV) infections in immunocompromised adults.

DATA SOURCES

The MEDLINE/PubMed, EMBASE, and Cochrane databases were queried from January 1980 to December 2011 for articles in English using these associated search terms: respiratory syncytial virus, ribavirin, intravenous immunoglobulin, IVIG, palivizumab, motavizumab, lung, pneumonia, transplantation, bone marrow, cancer, malignancy, and vaccine.

STUDY SELECTION AND DATA EXTRACTION

All relevant original studies, meta-analyses, systematic reviews, and review articles were assessed for inclusion. References from pertinent articles were examined for additional content not found during the initial search.

DATA SYNTHESIS

RSV in the immunocompromised adult can lead to significant morbidity and mortality. Treatment of RSV-infected adults is limited to antiviral therapy with ribavirin (aerosolized, oral, intravenous) and immunomodulation with intravenous immunoglobulins, corticosteroids, and palivizumab. Existing literature is predominantly case reports, small trials, and retrospective reviews of patients infected with RSV who have undergone lung or hematopoietic stem cell transplantation (HSCT). Palivizumab may be a viable option for prophylaxis against RSV in high-risk adults. Ribavirin is the most studied treatment option and should remain the backbone of multidrug regimens. Of the routes of administration, aerosolized ribavirin carries the preponderance of evidence and, though challenging, is preferred to limit systemic toxicities in the infected patient. Addition of an immunomodulator to ribavirin may provide a survival benefit over ribavirin alone; however, this has only been studied in a subset of HSCT patients with lower respiratory tract RSV infection.

CONCLUSIONS

Research most strongly supports the use of aerosolized ribavirin as the treatment strategy for immunocompromised adults with RSV. Addition of an immunomodulator may provide a survival benefit over ribavirin alone. Strategies and supportive data for the prevention of RSV infection in the high-risk adult are critically needed.

A Review of Oral Antiretroviral Therapy for the Treatment of Chronic Hepatitis B

Objective:

To describe the current evidence for the use of oral antiretroviral (ARV) agents in the treatment of chronic hepatitis B (CHB).

Data Sources:

A search from 1950 to April 2010 was conducted using the databases PubMed and MEDLINE with the search terms chronic hepatitis B, lamivudine, entecavir, adefovir, telbivudine, tenofovir, emtricitabine, clevudine, and pradefovir. The search was limited to trials conducted in humans that were published in the English language.

Study Selection and Data Extraction:

Studies were included if they evaluated the use of oral ARVs in patients with CHB infection who were not coinfected with hepatitis C, hepatitis D, or HIV.

Data Synthesis:

Oral ARVs have revolutionized the treatment of CHB. Studies conducted comparing ARVs have favored entecavir and tenofovir with respect to their ability to decrease hepatitis B virus DNA viral load while minimizing the development of resistance. However, low seroconversion rates, recurrent viremia when ARV therapy is discontinued, and increased resistance rates with longer treatment durations limit the benefit of oral ARVs in the treatment of CHB. Combination therapy has been a suggested solution; however, studies have yet to prove additional benefit over currently recommended monotherapy.

Conclusions:

Oral ARVs should continue to be used in the treatment of CHB; however, research is needed to define the optimal duration of therapy, evaluate the utility of combination therapy, and explore novel targets within the hepatitis B life cycle.

Genetic Testing for Warfarin Therapy Initiation

Objective

To review the literature regarding the efficacy of genetic testing for determining the appropriate initial dose of warfarin and the effect that this testing has on the safety and efficacy of therapy.

Data Sources:

Searches of MEDLINE (1966–May 2008) and Cochrane Database (1993–May 2008) were conducted using the search terms warfarin, anticoagulation, pharmacogenomics, pharmacogenetics, CYP2C9, VKORC1, and interindividual variability. Limits included articles written in English with human subjects. Additional data were identified through bibliographic reviews.

Study Selection And Data Extraction:

All English-language articles identified from the data sources were evaluated. Studies were eligible for inclusion if they evaluated the efficacy of pharmacogenomic testing to improve outcomes with initiation of warfarin therapy.

Data Synthesis:

The use of warfarin presents numerous challenges in clinical practice. Four studies (N = 38, 48, 200, 297) evaluating the efficacy of genetic testing for determining the initial dose of warfarin therapy have been published. Results show that time to therapeutic international normalized ratio (INR) and time to stable warfarin dose are similar regardless of genotype. When conventional warfarin dosing was compared with pharmacogenomic-based dosing, no significant difference was seen between groups in terms of time spent within the target INR range (41.5% vs 41.7%; no p value reported). Similar results were found in a subsequent study in which patients receiving conventional dosing were outside their target INR range 33.1% of the time compared with 30.7% of the lime for patients whose dose was guided by pharmacogenomics (p = 0.47).

Conclusions:

There is growing evidence that variant alleles for CYP2C9 and VKORC1 genotypes account for a proportion of the variability seen in warfarin dosing. The currently available literature related to the use of pharmacogenomic testing in the initiation of warfarin therapy does not show improved outcomes in either safety or efficacy with warfarin therapy and therefore does not support the routine use of pharmacogenomic testing when initiating warfarin therapy.