Is Adherence to the American College of Chest Physicians Recommended Anticoagulation Treatment Duration Associated with Different Outcomes Among Patients with Venous Thromboembolism?

Introduction: Venous thromboembolism (VTE) represents a major clinical and economic burden. The American College of Chest Physicians (ACCP) Guideline 9^th Edition on the treatment of VTE recommends a minimum duration of anticoagulation (AC) therapy depending on patient risk profiles. The objectives of this study were to evaluate the clinical and economic outcomes associated with adherence to the AC treatment duration recommendation among VTE patients in the real world setting.

Methods: Adult patients (≥18 years of age) with at least 1 inpatient diagnosis or 2 outpatient diagnoses on two different dates of deep vein thrombosis (DVT) and/or pulmonary embolism (PE), based on ICD-9-CM codes, were identified from the IMS Pharmetrics Plus database during 1/1/2009 through 3/31/2013. The first VTE diagnosis was defined as the index event. Study patients were required to have continuous insurance coverage during the 12 months before (baseline) and after (follow-up) the index event and no prior VTE diagnosis in the baseline period. They were also required to have received at least one outpatient anticoagulant treatment within 30 days of the initial VTE diagnosis with a minimum medication days of supply of 30 days. ACCP recommend that patients with provoked VTE or unprovoked VTE and high bleeding risks receive AC treatment for at least 3 months and that patients with unprovoked VTE and low or moderate bleeding risks or patients with cancer receive AC treatment for at least 6 months. Patient records in the database including ICD-9-CM codes and RIETE bleeding risk scores were used to group patients into 2 cohorts, one comprised of patients who received AC treatment for a duration as recommended by the ACCP (adherent group, AD) and the other comprised of patients who received AC treatment for a duration less than that recommended by the ACCP (non-adherent group, non-AD). Patient demographics and clinical characteristic were evaluated during the baseline period. Healthcare resource utilization, including hospital admissions, outpatient medical services, and prescription drug usage, were measured during the baseline and follow-up periods. VTE recurrence, defined as hospitalization or ER visit with a VTE diagnosis code, was also measured during the follow-up period. Multivariate regression analysis was utilized to compare clinical and economic outcomes of study cohorts while controlling for key patient characteristics.

Results: The study population included 81,827 patients with a mean age (standard deviation) of 55.3 (13.8) years. For the index VTE event, 61% had DVT only, 26% had PE only, and 13% had DVT/PE. Of the study population, the minimum ACCP recommended AC treatment durations were 3 and 6 months for 27% (n=22,157) and 73% (n=59,670) of patients, respectively. Among all patients, 74% (n=60,550) received AC therapy for the ACCP recommended duration. The proportion of patients with VTE risks, including recent hospitalization (17% vs. 9%, p<0.001), recent surgery (9% vs. 6%, p<0.001), index diagnosis of PE only (28% vs. 20%, p<0.001), and index diagnosis of DVT/PE (15% vs. 8%, p<0.001) was greater in the AD cohort than in the non-AD cohort. Furthermore, mean Charlson Comorbidity Index score (1.67 vs. 1.59, p<0.001) and RIETE bleeding risk score (RIETE ≥1: 66% vs. 55%, p<0.001) were higher for the AD cohort compared to the non-AD cohort. The most prevalent anticoagulants used for treatment were warfarin (89% vs. 96%, p<0.001) and low molecular weight heparin (58% vs. 59%, p<0.01). After controlling for key patient characteristics, risks for all-cause hospitalization (Odds ratio (OR): 0.80, confidence interval (CI): 0.77-0.83, p<0.001) and VTE recurrence (OR=0.91, CI: 0.86-0.95, p<0.001) were lower among VTE patients in the AD cohort vs. the non-AD cohort, as were differences in all-cause total healthcare payments (-$3,416, p<0.001) and VTE-related healthcare payments (-$2,139, p<0.001) during the follow-up period.

Conclusions: Approximately a quarter of the study population with VTE did not receive treatment with AC therapy for the minimum duration as recommended by the ACCP guideline. Patients who did not receive outpatient AC therapy for the recommended duration had more VTE recurrences, utilized more inpatient services, and had higher healthcare costs than patients who received AC therapy for the ACCP recommended duration.