Study Design
We performed a 3-parallel-arm randomized pragmatic trial to test the effectiveness of proactive population-based outreach. Later, two separate rounds of implementation with refined messaging were performed. The study was conducted as part of the Arizona Community Engagement Alliance (CEAL) Against COVID Disparities Community Task Force, which worked to address misinformation, increase trust in vaccination, and identify and address barriers to COVID-19 preventive services.13 Our approach adapted ongoing strategies at a FQHC that included a survey as part of the CEAL initiative that included items on perceptions about SARS-Cov-2 vaccination. We collaborated with the leadership of the FQHC, which participates in the Arizona CEAL Community Taskforce. The study was registered on clinicaltrials.gov (NCT04952376) and approved by the Mayo Clinic IRB (Protocol # 21-002939), which waived informed consent requirements.
Study Population
The study was conducted among people ≥18 years old who received care between April 13 to June 10, 2021 at Adelante Healthcare, which is a FQHC with community-based ambulatory primary care clinics in Phoenix, Arizona. FQHCs provide comprehensive primary care services regardless of insurance status or ability to pay.12 Eligible patients were identified using the electronic health record (EHR). We excluded people with documented vaccination; no medical visit within the previous year; and an upcoming appointment within 1 month (Figure 1). Among those eligible (n=18,466), we randomly selected and assigned 1,650 patients to one of 3 effectiveness arms in a 3:10:20 ratio per protocol. We subsequently selected an additional group of patients (n=2,328) for two implementation rounds of outreach.
Interventions
The intervention was built on an existing population outreach program at Adelante FQHC that is implemented in partnership with Providertech, a healthcare technology company that operates an outreach platform with automated workflows. Because of observed trends of declining vaccination rates at Adelante and the region at the time the intervention was implemented and in consideration of CEAL’s interest in equitable access and to increase likelihood of engagement, we enabled the ability to respond via 2-way SMS to frequently asked questions (FAQs) for all participants. Thus, all participants, irrespective of the study arm, could use the two-way messaging feature by replying to the text message, and schedule an appointment or speak with clinical staff through a dedicated phone number provided through the Providertech platform (Supplementary Figure S1).
People assigned to Arm 1 (n=150) received the usual practice of proactive SMS outreach to the cell phone on file with a message that “it is your turn” to get vaccinated and an invitation to make a vaccination appointment. In Arm 2 (n=500), the message was personalized by including a statement from the PCP recommending vaccination (Table 1). We included a link in the messaging to FAQs for people assigned to Arms 2. Arm 3 (n=1,000) was similar to Arm 2 plus an explicit nudge to use an available 2-way dialogue option with the clinical team to obtain answers to FAQs.
FAQs were hosted on a cloned Adelante website that was created for the purposes of the study. Messages were developed through a community-engaged process and delivered in English and Spanish, based on patient preferred language on file, at preset times for each patient each week with up to 3 reminders.
The health center subsequently tested two implementation alternative messaging, which were sent separately on May 24, 2021, and 2 weeks later, based on responses to the preliminary survey. Those messaging outreach addressed potential COVID-19 vaccine hesitancy (Message A, n=1,323) or concerns about "side effects" or immune response to vaccination (Message B, n=1,005).
Study Outcome
The primary outcome was the completion of the first COVID-19 vaccine dose as determined from EHR data ascertained at day 14, 30, and 90 after the outreach messaging. Outcome was also assessed in all 3 arms, the implementation groups, and among people not selected for effective or implementation.
Statistical Analysis
Power calculations were based on data from other states in the CEAL program and had assumed a 42% vaccination rate in Arm 1 with a projected 20% higher rate in response to PCP recommendation and an additional 10% higher uptake in Arm 3 than Arm 2. Sample size was therefore estimated as 156 per arm for Arms 1 vs. 2 comparisons and 552 per arm for Arms 2 vs. 3 comparisons for 80% power at a 2-sided Bonferroni-corrected alpha of 0.017. We allowed for the potential for 20% ineligibility after randomization.
We used 2X2 contingency tables with the Chi-square test to perform pairwise comparisons of vaccination rates among the three Arms at each time point. Similar analyses were performed between implementation rounds (n=2,328) and also in people not included in intervention or implementation (n=8,671). Analyses were performed in STATA (StataCorp. 2019. Stata Statistical Software: Release 16. College Station, TX). Consolidated Standards of Reporting Clinical trial (CONSORT checklist) was followed to report the data.