Secondary analysis of electronic opt-out consent in pragmatic research: A study design method to diversify clinical trials?

We conducted a multi-center pragmatic trial of a low-risk intervention focused on medication adherence using an opt-out consent approach, where patients could opt out by letter and then electronically. We focus on the cohort after opt-out by mail. Here, we describe that 8% of patients opted out electronically, resulting in a 92% participation rate. Patients who self-identify as Black or Hispanic were less likely to opt out in the study, and half the study cohort was female. This demographic data is useful for planning future trials employing this approach.

Evaluation of Prophylactic Heparin Dosage Strategies and Risk Factors for Venous Thromboembolism in the Critically Ill Patient.

BACKGROUND: Venous thromboembolism (VTE) occurs frequently in critically ill patients without heparin prophylaxis. Although heparin prevents VTE, VTEs occur frequently despite prophylaxis. A higher heparin dosage may be more effective for preventing VTE. METHODS: A retrospective study was conducted using the Premier Incorporated Perspective Database to evaluate comparatively the effects of different heparin prophylaxis dosing strategies in the critically ill patient. Critically ill adult patients who were mechanically ventilated for at least 1 day and had an intensive care unit (ICU) length of stay of at least 2 days were included. Patients received 5000 units of heparin either twice/day or 3 times/day. The primary outcome was development of a new VTE. Key secondary outcomes included clinically important bleeding, thrombocytopenia, and mortality. Patients were propensity matched to control for confounding. Multivariable analysis was conducted for VTE risk factors. RESULTS: The study included 30,800 patients from 374 hospitals who were propensity matched by heparin dosage. New VTE occurred in 6.16% of patients treated with 3 times/day heparin versus 6.23% with twice/day heparin (p=0.8). No significant differences in the incidence of pulmonary embolism (0.91% vs 0.8%, p=0.29) or deep vein thrombosis (5.56% vs 5.70% p=0.59) were observed between the two types of heparin dosing. No differences were observed between the two types of heparin dosing in in-hospital mortality (15.8% vs 15.15%), bleeding (0.23% vs 0.33%), or thrombocytopenia (5.19% vs 5.34%, p>0.08 for all), respectively. Risk factors associated with VTE included intraabdominal and urinary tract infections, loop diuretics, malnutrition, obesity, thrombocytopenia, paralytics, vasopressors, female sex, peripheral vascular disease, sepsis, neutropenia, and end-stage renal disease. Antiplatelet therapy, heart failure, diabetes, and substance abuse were associated with reduced VTE (p<0.05 for all). CONCLUSIONS: In critically ill patients, prophylactic dosing of heparin 3 times/day versus twice/day was not associated with differences in new VTE or safety outcomes. Several modifiable VTE risk factors were identified.