There were a number of patient-level barriers to hypertension control among the CAATCH sample at baseline, including low-income, significant co-morbidity, sedentary lifestyle, smoking, overweight, and obesity. This sample had a considerably lower mean income compared to patients in large-scale epidemiological studies, such as the multi-ethnic Dallas Heart Study [30,31] and the Jackson Heart Study [32,33]. When compared to other large-scale trials in hypertensive African Americans, CAATCH participants were more likely to be in particularly poor health. For example, CAATCH participants were heavier than those in the Dallas Heart Study [30], Jackson Heart Study [33], in Dietary Approaches to Stop Hypertension (DASH), Hypertension Improvement Project (HIP), and PREMIER trials [6,11,34]. Obesity rates reported for African Americans in the National Health and Nutrition Examination Survey (NHANES) were only 45% [35,36], compared to over two-thirds reported in CAATCH. Similar to published data on medication adherence [15,37-39], one-half of the CAATCH participants reported non-adherence, and they experienced diabetes and cardiovascular disease at rates higher than samples in large scale epidemiological trials such as the Jackson Heart Study [33]. In fact, CAATCH participants reported higher co-morbid medical conditions, which are recognized as significant barriers to BP control [40]. Physical activity levels in the CAATCH sample were very low, with most of the participants characterized as sedentary or insufficiently active. This a higher proportion than rates noted in the most recent NHANES data [41]. A noteworthy finding is that prevalence of smoking in the CAATCH trial was higher than those in the Jackson Heart Study [33], the Dallas Heart Study [30], and recent NHANES data on smoking among overweight and obese adults [41]. Further attention is warranted for several of the CAATCH sample's psychosocial and behavioral characteristics. CAATCH participants reported a moderate level of self-confidence in their ability to take antihypertensive medications (as measured by the MASES) [16], and a low level of healthy eating (as measured by the REAP) [18]. While the average general mental health score (Mental Component Summary of the SF-12) [22] of participants fell within normal range of population based norms, the UC participants scored in the mildly depressed range (as assessed by the PHQ-921). Furthermore, participants reported limitations in general physical functioning (Physical Component Summary of the SF-12) [22]. Though, on average, participants scored within the normal range on an index of sleep quality [20,29], problematic levels of daytime sleepiness (Epworth Sleep Scale score ≥ 10) were present among one-fifth. This rate is higher than the prevalence of daytime somnolence observed in recent NHANES data [42], yet lower than rates found in a recent analysis from the Sleep Heart Health Study [43]. The problematic daytime sleepiness observed in CAATCH participants may be due in part to the higher prevalence of obesity, which is a major risk factor for obstructive sleep apnea [44,45]. One-quarter of CAATCH participants had resistant hypertension (defined as any patient with uncontrolled BP who is taking at least three antihypertensive medications, including a diuretic). While thiazide type diuretics are the recommended initial pharmacological treatment [5,46], only one-half of the CAATCH sample had been prescribed one. However, this percentage is higher than the diuretic rate reported for a population of hypertensive patients from a large managed care organization, located in the southeastern United States, based on prescription fill data two years following publication of the JNC-7 guidelines [46].

One of the most striking aspects of the CAATCH trial is how its participants compare demographically and clinically to large-scale efficacy trials of lifestyle modification on BP levels [6,7,11,47], and four recently published effectiveness trials of BP control [34,48-51]. Participation of African Americans in previous efficacy trials ranged from 25 to 50% of the sample [6,7,11,34,49,51], while the CAATCH trial sample consists entirely of African American participants. Of particular note, the CAATCH trial represents a substantive improvement in African American male participation over previous trials in that almost one-third of participants were African American men. By contrast, one-tenth of participants in PREMIER were African American men. To our knowledge, the CAATCH trial includes the largest proportion of African American men in community practice-based trials. Because trust is a major hindrance to recruitment of minorities into clinical research [52], we adopted a two-pronged strategy to increase the participation of African American men, in addition to the traditional compensation provided to patients. First, we solicited the support of the CHC patient care coordinators and clerical staff in referring patients into the study. CHC staff typically interacts with patients over a longer period of time and have built significant rapport and trust with the patients, whereas research staff have a shorter duration and more circumscribed relationship with prospective study participations. Second, we asked the clinicians to refer their patients into the trial. This strategy also addresses the issue of trust, building on the existing relationships between patients and providers. In addition, we oversampled African American men, because women comprise 70% of the adult users of CHCs. Finally, we held series of educational sessions at the study sites to inform patients about the study and to identify and screen potentially eligible patients; refreshments were offered at these sessions.

To our knowledge, CAATCH is the largest practice-based trial of patient and physician targeted interventions for BP control in hypertensive African Americans. We are only aware of three other trials that have targeted both patients and physicians in practice-based settings [34,49,50]. The first is the HIP trial [34], which is a nested, 2 × 2 RCT comparing physician intervention, patient intervention, and both combined versus control condition, among 574 hypertensive patients in eight primary care practices (32 physicians) in central North Carolina. The second is the Veterans Study to Improve the Control of Hypertension (V-STITCH) trial [49], which is a 2-level (primary care provider and patient) cluster RCT among 588 hypertensive patients in a Veterans Affairs Medical Center primary care clinic (17 physicians) in North Carolina. The third is a study by Roumie et al., which is a cluster RCT [50] that evaluated the impact of three quality improvement interventions (provider education, provider education and alert, patient education) of increasing intensity among 1,341 hypertensive patients who received care in two hospital-based and eight community-based outpatient clinics (182 providers) in the Veterans Affairs Tennessee Valley Healthcare System. One qualitative difference between CAATCH and these trials is that CAATCH was focused exclusively on African Americans. Second, the patients in CAATCH all had uncontrolled hypertension and greater co-morbidity than those in the other practice-based trials. Specifically, CAATCH participants had higher baseline BP, were more sedentary, had greater levels of co-morbidity, and higher current smoking rates than participants in the V-STITCH and HIP trials [34,49]. Furthermore, CAATCH participants had comparable rates of smoking and higher rates of diabetes, and lower rates of medication adherence than participants in Roumie et al. VA-based trial of interventions targeting providers and patients [50]. Perhaps of even more interest, participants in the CAATCH trial had lower income than those in the HIP, V-STITCH, DASH, and PREMIER trials, had less education than participants in DASH, and PREMIER, and as a group, were more likely to be underinsured. Thus, the patient population in CAATCH is more representative of low-income African Americans with poorly controlled hypertension and numerous adverse lifestyle behaviors and clinical characteristics that constitute barriers to adequate BP control. As such, the findings from CAATCH will provide needed information on effectiveness of lifestyle and self-management approaches in care of this high-risk population in a more generalizable context. Furthermore, the participating CHCs are distributed widely across upstate New York, four boroughs of New York City, Northern New Jersey, and serve low-income, African American patient populations. Utilization of EHRs among the participating sites at the time of recruitment and intervention was relatively low, and approximately one-half of the CHCs participating in the trial were involved in the HRSA Health Disparities Collaborative, an initiative that focuses on improving access to quality healthcare and improved health outcomes among medically underserved in order to reduce or eliminate health disparities [53].

Several strengths of the CAATCH trial deserve consideration. The first is that CAATCH is an evidence-based multi-level intervention in a very large exclusively African American practice-based sample, in contrast to previous efficacy and recent effectiveness trials in which the rate of African American participation has been more modest [6,7,11,34,48,54]. Second, CAATCH inclusion criteria allowed for the participation of patients with uncontrolled BP and those taking multiple medications, while the exclusion criteria of previous efficacy studies [6,7,11] were more conservative by comparison. Third, CAATCH joins a small number of effectiveness trials (implemented in the VA [49] or community based primary care clinics [34]) in efforts to deliver efficacious treatments in real-world primary care settings. CAATCH is one of few studies to address barriers to BP control in this patient population by evaluating the effectiveness of a practice-based intervention targeted at patients (home BP monitoring, lifestyle intervention plus patient education) and physicians (chart audit and feedback plus physician education). Thus, findings from this trial will extend our understanding of applicability and impact of a multi-level intervention in a population whose hypertension may be particularly difficult to control.

We should note the following limitations of the CAATCH trial. First, similar to other large scale RCTs in African Americans, majority of CAATCH participants were women, making the results less generalizable to African American men. Second, there were imbalances in several important baseline patient characteristics between the IC and UC study sites, which raises potential threats to internal validity of the study findings. The cluster randomized design of the study sought to minimize baseline differences between both groups via matching of CHCs based on practice size. The reason for the observed baseline differences is not clear. One potential explanation for this imbalance may be the small number of sites that were randomized rather than the number of participants. Although the intraclass correlation coefficient (ICC) between the sites on these variables was quite small [24,55], the additional matching of sites by size may have required larger number of sites than the proposed 30 sites. Alternative approaches to mitigate this problem maybe the use of a factorial design with randomization at the level of the providers on characteristics, such as number of years practicing in a community-based setting, size of caseload, and number of hypertensive patients in current caseload. This is the approach adopted by Corsino et al. [56], which often requires matching on lesser number of variables than sites and manageable number of providers and patients needed for the study. Other approaches of randomizing at the patient level with matching may also mitigate this problem, but such an approach is limited by the potential for contamination that is often a problematic in practice-based trials using such design, and the loss of the ability to examine the contribution of matching variables to changes in study outcomes.