Oral and parenteral anticoagulants: New kids on the block

Total Synthesis and Biological Evaluation of Clavatadines C-E

We described herein the application of a convergent and protecting-group avoidant approach that led to the first total synthesis of the marine natural products clavatadine D (4) and E (5), and the second total synthesis of clavatadine C (3). In each case, a key amide-coupling afforded an immediate precursor of each natural product in a rapid manner from structurally similar western and eastern portions that derived from an ester of l-tyrosine and butane-1,4-diamine, respectively. A deprotection step free of detectable byproducts cleanly provided the remaining known members of the clavatadine family of natural products. Each total synthesis required five steps (longest linear sequence) with overall yields of 30-37%, 26-39%, and 28-50% for clavatadine C (3), D (4), and E (5), respectively. A screen of their potential anticancer activity against the NCI-60 cell line panel revealed cytotoxicity levels up to 38% across a broad spectrum of tumor types. Although clavatadine C (3) was relatively benign, clavatadine D (4) exhibited 20-38% growth inhibition against a wide array of cancer cell types including leukemia, non-small-cell lung, colon, ovarian, and breast. Clavatadine E (5) was active against two types of human brain tumors.

Total Synthesis of Clavatadine B

The first total synthesis of clavatadine B (2), a natural product found to be a selective human blood coagulation factor XIa inhibitor, is described. A convergent approach that exemplifies the advantages of direct, early stage guanidinylation provided an immediate clavatadine B precursor, which was assembled in an efficient manner using known synthetic precursors of the structurally related natural product clavatadine A (1). Global deprotection cleanly provided clavatadine B in only four steps from a known derivative of homogentisic acid lactone (longest linear sequence, 75% overall yield).

Adherence to non-vitamin-K-antagonist oral anticoagulant medications based on the Pharmacy Quality Alliance measure

BACKGROUND

CMS Star Ratings help inform beneficiaries about the performance of health and drug plans. Medication adherence is currently weighted at nearly half of a Part D plan's Star Ratings. Including the adherence to non-vitamin-K-antagonist oral anticoagulants (NOACs) as a measure in the Star Ratings program may increase a plan's incentives to improve patient adherence.

OBJECTIVE

To assess the adherence to medication of patients who used the NOACs rivaroxaban, dabigatran, or apixaban in 2014 based on the Pharmacy Quality Alliance (PQA) adherence measure.

METHODS

Healthcare claims from the Humana database between July 2013 and December 2014 were analyzed. Adult patients with ≥2 dispensings of NOAC agents in 2014, at least 180 days apart, with >60 days of supply, and ≥180 days of continuous enrollment prior to the index NOAC were identified. The PQA measure was calculated as the percentage of patients who had a proportion of days covered (PDC) ≥0.8. Multivariate logistic regression analyses were also conducted adjusting for baseline confounders.

RESULTS

A total of 11,095 rivaroxaban, 6548 dabigatran, and 3532 apixaban users were identified. Based on the PQA adherence measure (PDC ≥0.8), a significantly higher proportion of rivaroxaban users (72.7%) was found to be adherent compared to dabigatran (67.2%: p < 0.001) and apixaban (69.5%: p < 0.001) users. Compared to apixaban users, the adjusted likelihood of being adherent was significantly higher for rivaroxaban users (unadjusted OR [95% CI]: 1.17 [1.08-1.27], p < 0.001; adjusted OR [95% CI]: 1.20 (1.10-1.31), p < 0.001) and significantly lower for dabigatran users (unadjusted OR [95% CI]: 0.90 [0.82-0.98], p = 0.019; adjusted OR [95% CI]: 0.85 [0.77-0.93], p < 0.001).

LIMITATIONS

Limitations of the study are potential inaccuracies in claims data, possible change in patterns over time, and the impossibility of knowing whether all supplied tablets were taken.

CONCLUSION

Using the PQA's adherence measure, rivaroxaban users were found to have significantly higher adherence compared to apixaban and dabigatran users.

Effects of rivaroxaban versus warfarin on hospitalization days and other health care resource utilization in patients with nonvalvular atrial fibrillation: an observational study from a cohort of matched users

PURPOSE

Compared with warfarin, the new target-specific oral anticoagulant agents may have advantages, such as shorter hospital length of stay, in patients with nonvalvular atrial fibrillation (NVAF). The objective of the present study was to assess, among patients with NVAF, the effects of rivaroxaban versus warfarin on the number of hospitalization days and other health care resource utilization in a cohort of rivaroxaban users and matched warfarin users.

METHODS

Data from health care claims dated from May 2011 to December 2012 from the Humana database were analyzed. Adult patients newly initiated on treatment with rivaroxaban or warfarin, with ≥2 diagnoses of AF (ICD-9-CM code 427.31), and without valvular AF were identified. Based on propensity score methods, warfarin recipients were matched 1:1 to rivaroxaban recipients. The end of the observation period was defined as the end of data availability, the end of insurance coverage, death, the date of a switch to another anticoagulant agent, or day 14 of treatment nonpersistence. The total number of hospitalization days and other health care resource utilization parameters (numbers of hospitalizations, emergency department [ED] visits, and outpatient visits) were evaluated using the method by Lin et al.

FINDINGS

Matches for all rivaroxaban recipients were found, and the characteristics of the matched groups (n = 2253 per group) were well balanced. The mean age of both cohorts was 74 years; 46% were female. The estimated mean total numbers of hospitalization days were significantly less in rivaroxaban users compared with those in warfarin users (all-cause, 2.71 vs 3.87 days [P = 0.032]; AF-related, 2.11 vs 3.02 days [P = 0.014]). The numbers of outpatient visits were also significantly less (all-cause, 25.26 vs 35.79 visits [P < 0.001]; AF-related, 5.48 vs 9.06 visits [P < 0.001]). Rivaroxaban users had a lesser estimated mean number of all-cause hospitalizations compared with warfarin users (0.55 vs 0.73; P = 0.084), and a significantly lesser estimated mean number of AF-related hospitalizations (0.40 vs 0.57; P = 0.022). The difference in the estimated mean numbers of all-cause ED visits was not statistically significant between the rivaroxaban and warfarin users.

IMPLICATIONS

In this study conducted in clinical practice, the estimated mean numbers of hospitalization days, outpatient visits, and AF-related hospitalizations associated with rivaroxaban were significantly less than were those associated with warfarin in these patients with NVAF. The corresponding estimated difference in all-cause ED visits was not statistically significant.

Effect of rivaroxaban versus warfarin on health care costs among nonvalvular atrial fibrillation patients: observations from rivaroxaban users and matched warfarin users

Introduction

New target-specific oral anticoagulants may have benefits, such as shorter hospital length of stay, compared to warfarin in patients with nonvalvular atrial fibrillation (NVAF). This study aimed to assess, among patients with NVAF, the effect of rivaroxaban versus warfarin on health care costs in a cohort of rivaroxaban users and matched warfarin users.

Methods

Health care claims from the Humana database from 5/2011 to 12/2012 were analyzed. Adult patients newly initiated on rivaroxaban or warfarin with ≥2 atrial fibrillation (AF) diagnoses (The International Classification of Diseases, Ninth Revision, Clinical Modification: 427.31) and without valvular AF were identified. Based on propensity score methods, warfarin patients were matched 1:1 to rivaroxaban patients. Patients were observed up to end of data, end of insurance coverage, death, a switch to another anticoagulant, or treatment nonpersistence. Health care costs [hospitalization, emergency room (ER), outpatient, and pharmacy costs] were evaluated using Lin’s method.

Results

Matches were found for all rivaroxaban patients, and characteristics of the matched groups (n = 2253 per group) were well balanced. Estimated mean all-cause and AF-related hospitalization costs were significantly lower for rivaroxaban versus warfarin patients (all-cause: $5411 vs. $7427, P = 0.047; AF-related: $2872 vs. $4147, P = 0.020). Corresponding estimated mean all-cause outpatient visit costs were also significantly lower, but estimated mean pharmacy costs were significantly higher for rivaroxaban patients ($5316 vs. $2620, P < 0.001). Although estimated mean costs of ER visits were higher for rivaroxaban users compared to those of warfarin users, differences were not statistically significant. Including anticoagulant costs, mean overall total all-cause costs were comparable for rivaroxaban versus warfarin users due to cost offset from a reduction in the number and length of hospitalizations and number of outpatient visits ($17,590 vs. $18,676, P = 0.542).

Conclusion

Despite higher anticoagulant cost, mean overall total all-cause and AF-related cost remains comparable for patients with NVAF treated with rivaroxaban versus warfarin due to the cost offset from reduced health care resource utilization.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-015-0189-1) contains supplementary material, which is available to authorized users.

Pharmacy quality alliance measure: adherence to non-warfarin oral anticoagulant medications

BACKGROUND

The Pharmacy Quality Alliance (PQA) recently endorsed adherence to non-warfarin anticoagulant agents as a new performance measure, but the Medicare Part D Star Ratings program has not yet adopted the measure. The current study aims to assess the real-world adherence to medication of patients who used non-vitamin-K-antagonist oral anticoagulants (NOACs) based on the PQA's adherence measure.

METHODS

Healthcare claims from the Humana database during the year of 2013 were analyzed. Patients older than 18 with ≥2 dispensings of NOAC agents, at least 180 days apart between two NOAC dispensings in 2013 (a criterion to include chronic users), with ≥60 days of supply, and ≥180 days of continuous enrollment prior to the index NOAC were identified. The PQA measure on the index therapy was calculated as the percentage of patients who had a proportion of days covered (PDC) ≥0.8 during their follow-up.

RESULTS

A total of 9948 NOAC users (rivaroxaban: n = 4194, dabigatran: n = 5489, apixaban: n = 265) were identified. For rivaroxaban users, the proportion of patients with a PDC ≥0.8 (PQA measure) at 75.4% was significantly higher compared to dabigatran users (67.6%; P < 0.001) and higher compared to apixaban users (70.6%; P = 0.076). When allowing switches to other NOAC agents in the PQA measure, rivaroxaban users had a significantly higher PQA measure at 76.9% compared to both dabigatran (72.9%; P < 0.001) and apixaban (71.3%; P = 0.037) users. Multivariate logistic regression analyses corroborated the findings that rivaroxaban had a significantly higher adherence compared to the other NOAC agents.

LIMITATIONS

Claims data may have contained inaccuracies, possible change in patterns over time, and the impossibility of knowing whether all supplied tablets were taken.

CONCLUSION

Based on the PQA's adherence measure, rivaroxaban users were found to have a higher adherence compared to dabigatran and apixaban users. Healthcare providers may want to consider the impact of anticoagulation selection on their ability to achieve quality metrics.

Hospital length of stay of nonvalvular atrial fibrillation patients who were administered Rivaroxaban versus Warfarin with and without pretreatment parenteral anticoagulants therapies

BACKGROUND

Warfarin has been the only anticoagulant used for decades to prevent strokes and systemic embolisms in nonvalvular atrial fibrillation (NVAF) patients. Compared with rivaroxaban, warfarin has a narrow therapeutic range and many genetic and food-drug interactions that could potentially prolong hospital length of stay (LOS).

OBJECTIVE

To compare hospital LOS between NVAF patients who were administered rivaroxaban versus warfarin with and without pretreatment of parenteral anticoagulant agents in a population of rivaroxaban-treated patients.

METHODS

A retrospective matched-cohort analysis was conducted using the Premier Perspective Comparative Hospital Database from November 2010 to September 2012. Adult patients were included in the study if they had a hospitalization for NVAF. Rivaroxaban users were matched with up to 4 warfarin users based on propensity score analyses. Patients with and without pretreatment of parenteral anticoagulant agents were evaluated separately. Hospital LOS was compared between treatment groups using generalized estimating equations.

RESULTS

The matched cohorts' characteristics were well balanced. Among the matched rivaroxaban and warfarin users who were administered parenteral agents, the mean age of the cohorts was 70 years and 47% of patients were female, whereas in the sample of patients who were not administered parenteral agents, the mean age was 72 years and 50% of patients were female. In the sample of patients who were administered parenteral agents, rivaroxaban users had significantly shorter hospital LOS (LOS difference: 1.38 days, P < 0.001) compared with warfarin users among rivaroxaban-treated patients. No significant difference in LOS was found in the sample of patients who were not administered parenteral anticoagulant agents (P = 0.169).

CONCLUSION

In the study sample of NVAF patients who were administered parenteral anticoagulant agents, rivaroxaban was associated with a significantly shorter hospital LOS compared with warfarin. The difference in LOS was not statistically significant in the sample of patients who were not administered parenteral anticoagulant agents.