Abstract T MP106: Impact of Enrollment Volume on Risk Factor Control and Outcomes in the SAMMPRIS Trial
Background and Purpose: There are limited data on the impact of site enrollment volume on risk factor control and outcome of patients in secondary prevention trials. We sought to compare outcomes and risk factor control between high and low enrolling sites in the stenting and medical groups in SAMMPRIS.
Materials and Methods: 451 patients with recent TIA or stroke attributed to 70%-99% intracranial stenosis were randomized to aggressive medical management alone or stenting plus aggressive medical management. We compared the Kaplan-Meier (K-M) curves for the primary endpoint (any stroke or death within 30 days of enrollment or ischemic stroke in the territory beyond 30 days) using the log-rank test and the percentages of patients with mean LDL < 70 mg/dl and mean systolic blood pressure (SBP) < 140 mmHg (< 130 mmHg if diabetic) during the study using the chi-square test between patients at high (≥ 12 patients) and low enrolling (< 12 patients) sites in the stenting and medical groups.
Results: In the stenting group, the K-M curves for the primary endpoint were not significantly different between high vs. low enrolling sites (p=0.93) with rates of 13.5% vs. 14.7% at 30 days and 19.0% vs. 20.6% at 2 years. In the medical group, the K-M curves for the primary endpoint were significantly different between high enrolling sites vs. low enrolling sites (p=0.0005) with rates of 1.8% vs. 9.8% at 30 days and 7.3% vs. 20.9% at 2 years. Control of LDL and SBP during the study at high vs. low enrolling sites in the medical and stenting groups are shown in the table.
Conclusions: High enrolling sites had significantly lower 30-day and 2 years rates of the primary endpoint in the medical group but not in the stenting group compared with low enrolling sites in SAMMPRIS. One contributing factor to the lower event rate in the medical group at high enrolling sites may be the significantly higher percent of patients who achieved a mean LDL < 70 mg/dl during follow-up at high enrolling sites.
Author Disclosures: D. Chiu: Employment; Significant; salary support-NINDS. R.P. Klucznik: None. T.N. Turan: Employment; Significant; salary support-NINDS. M.J. Lynn: Employment; Significant; salary support-NINDS. A. Nizam: Employment; Significant; salary support-NINDS. C.P. Derdeyn: Expert Witness; Modest; Acute stroke diagnosis and treatment. Ownership Interest; Modest; Pulse Therapeutics. Consultant/Advisory Board; Modest; Penumbra, Inc, Microvention, Inc. Employment; Significant; U01 NS058728, NINDS SAMMPRIS NeuroInterventional co-PI. Honoraria; Significant; W.L. Gore and Associates. D. Fiorella: Employment; Significant; salary support-NINDS. B.F. Lane: Employment; Significant; salary support-NINDS. J. Montgomery: Employment; Significant; salary support-NINDS. L.B. Katz: None. C.D. McCane: None. L.S. Janis: None. M.I. Chimowitz: Employment; Significant; salary support NINDS. Research Grant; Significant; U01 NS058728, Neurology PI SAMMPRIS. Other Research Support; Significant; SAMMPRIS corporate support: Stryker Neurovascular, AstraZeneca.
- © 2014 by American Heart Association, Inc.