This study analyzes data collected as part of a larger randomized clinical trial that evaluates the effectiveness of the Prime Time Sister Circles® (PTSC) on health, health care utilization, and behavioral outcomes. Details of the PTSC-RCT have been provided elsewhere [17, 18]. The PTSC-RCT’s primary outcome was hypertension control, and it aimed to assess the impact of the PTSC intervention on hypertension. The study’s secondary outcomes include BMI, health knowledge, self-efficacy, behaviors, and psychosocial health. We originally specified the health behaviors (dietary and physical activities) as secondary outcomes, but the nature of the measures makes them more appropriate as process measures.

Data for this study came from the PTSC-RCT. As a community-based intervention, the PTSC recruited English-speaking women who self-identified as African American, between 40 and 75 years of age, with a history of uncontrolled hypertension diagnosis (systolic blood pressure ≥ 140 mm Hg and diastolic blood pressure ≥ 90). We identified women as uncontrolled if diagnosed with hypertension and deemed resistant to treatment by their health provider, as evidenced by elevated BP (> 140/90) during their last visit. We selected women who received their care from a FQHC, Unity Health Care, and who resided in Wards 6, 7, and 8, the highest poverty Wards in Washington, D.C. Women received an invitation letter from the Medical Director describing the study, incentives for participation, contact information for pursuing enrollment, and the dates and locations for recruitment meeting sessions to learn about the PTSC program and the study at large. We collected baseline data from those who subsequently agreed to participate and a signed, written consent. We randomly assigned participants to the intervention (PTSC group) or control group (usual care group). We collected data from July 2017 through June 2020.

The PTSC is a multifaceted, theory-driven, and community-based intervention characterized by didactic training delivered by trained African American facilitators, content experts (for hypertension, stress management, fitness, and nutrition), and intensive peer-based social support. Marilyn Gaston (a physician) and Gayle Porter (a clinical psychologist) established The Gaston and Porter Health Improvement Center, Inc. (GPHIC), as a National Training Institute. The GPHIC trained PTSC facilitators on cardiovascular conditions, group facilitation and leadership, and on cultural beliefs undergirding self-management of chronic conditions. The facilitators were PTSC program graduates who resided in the communities the program serves [17]. Each Sister Circle is composed of 25–30 mid-life African American women (with mid-life defined as ages 40–75, in accordance with Gaston and Porter’s designation). The intervention targets this age group to as an opportunity for these women to make “mid-course health corrections” in the hopes of avoiding cardiovascular disease complications emerging from hypertension.

PTSC addresses three key modifiable health risk factors for chronic disease: unmanaged stress, physical inactivity, and unhealthy nutritional choices. It addresses additional risk factors that contribute to unhealthy lifestyles: lack of knowledge or misinformation about major illnesses, including hypertension; and it also aims to encourage mid-life African American women to prioritize their health and take proactive steps of primary and secondary prevention to manage their health and health care outcomes. PTSC is structured to support African American women to deepen their grasp of the requisite information, motivation, skills, and consultative support to improve and maintain their health. They are assisted in developing habits of primary and secondary prevention.

Those assigned to the PTSC intervention group attended a two-hour per week facilitator-led Sister Circle for 13 weeks. Sessions featured an educational presentation provided by facilitators or experts on the topic of the week. Facilitators discussed the topics in relation to hypertension and cardiovascular disease and included overall disease prevention, stress management, mental health (depression and anxiety), self-esteem, fitness, nutrition, psychosocial well-being, and effective communication with health care team members. Following the presentations, facilitators guided discussion with all participants, including role playing to model how best to navigate circumstances that could threaten their ability to adopt the recommended lifestyle change (for example, talking with their family members about the changes they are making because of the PTSC, or discussing with their physician and asking health-related questions).

The study’s primary outcomes included systolic and diastolic blood pressure. The secondary outcomes were BMI (defined as a person’s weight in kilograms divided by the square of height in meters) and stress management techniques. To explain the changes in BP and BMI, we collected self-reported physical activity, and dietary behaviors as process measures. Trained research team members measured study participants’ BP, height, and weight and administered surveys at baseline, 3 months, 9 months, and 15 months. These research team members were typically graduate students in the school of public health with medical or nurse training. The self-reported survey covered many other items, including but not limited to self-rated health, health care utilization, and health behaviors. We designed the survey to be self-administered, but we provided additional support to participants who had difficulty reading. A trained assistant read the survey item by item and recorded the participant’s response. We previously described some of these outcomes [17].

To measure physical activity, we used participants’ responses to whether they exercised for 30 min per day or 150 min per week, did strength training at least twice a week, and used a pedometer in the past month. This was a process measure to explain changes in the primary (systolic and diastolic BP) and secondary outcomes (BMI).

We assessed eating habits through a self-report. Participants indicated whether, in a typical day, they ate five servings of vegetables, ate four servings of fruit, watched their portion size, and read the food labels. We also captured their emotional state upon eating (that is, if they ate when full, upset, or not hungry); the type of food consumed (fast foods, snacks, fried foods, or sweets); and beverage consumption (such as non-diet soda). We measured each of these items at baseline, 3 months, 9 months, and 15 months. This is also a process measure.

We measured stress through the Perceived Stress Scale (PSS) [19]. We measured stress management through items focused on techniques they employed to reduce stress. To capture dimensions of stress management strategies, we created two scales: an 11-item scale appraising adaptive techniques (listen to music, pray, exercise, deep breathing, talk with family or friends, meditate, spend time with friends, yoga, talk with minister, talk with therapist, and massage) and a 7-item scale encapsulating non-adaptive techniques (shop, watch television, eat, drink alcohol, smoke cigarettes, avoid it, complain about it). We computed the adaptive technique score by summing the number of techniques used, ranging from 0 to 11. And for the non-adaptive techniques score, we summed the number of techniques not used, ranging from 0 to 7.

We adjusted our estimates for participants’ sociodemographic information: age, marital status (single without partner, married or living with a partner, other status, divorced, separated or widowed), level of educational attainment (less than high school, high school graduate, more than high school), income (under $20,000, $20,001–$40,000, and above $40,000), having any kind of health insurance, currently smoking, currently drinking, health literacy, and numeracy [20, 21].

We excluded 2 participants with missing responses on blood pressure, which reduced the analytical sample to 339. Of the 339 participants, 215 were randomly assigned to receive the PTSC intervention, and 124 were assigned to the usual care group. Of note, 54 participants (25%) assigned to the PTSC intervention did not participate primarily because it was offered at a time or location that was inconvenient for them, although we were able to collect their follow-up data. We designated these participants, who did not receive the intervention as intended, as the Intent-to-Treat (ITT) group (see CONSORT diagram for more details) and then referred to them as the “ITT sample.” To offset the impact of suboptimal intervention receipt among those who make up the ITT sample, we randomly assigned more women to the intervention group (at a 2:1 ratio) to ensure adequate numbers of women completing the PTSC intervention (Supplementary Material Fig. S1).