Limitations
hypertension
HEART, HYPERTENSION
There are several potential limitations of this study’s findings. Despite matching practices prior to randomization, there were substantial differences in the characteristics and numbers of patients and clinicians between intervention and control practices. This is more likely to happen when, as in this study, only a small number of practices are enrolled. There were also differences in preimplementation test ordering. Nevertheless, comparing the pre-post within-condition changes in out-of-office BP monitoring helped control for these differences and represented a strength of the pre-post cluster randomized design. While cluster randomization was applied at the practice level, some implementation strategy components may have been received by control clinicians; this would have biased results toward the null. The implementation strategy was tested in a small number of hospital-affiliated practices that served an underresourced patient population in one geographic region. Findings might not generalize to other settings. Strategies, such as home BP device loaner programs and increased staff training in provision of out-of-office BP monitoring, that were not viewed as feasible in this network may be effective elsewhere. There may have been differences in the extent to which clinicians in the intervention and control practices documented HBPM, such that differences in HBPM completion should be interpreted cautiously. Also, it was not possible to determine whether patients followed the correct HBPM protocol; patients in intervention practices may have received better training on the proper conduct of HBPM. Finally, just prior to the postimplementation period, the 2017 American College of Cardiology/American Heart Association BP guideline recommended lowering the threshold for diagnosing hypertension from 140/90 mm Hg to 130/80 mm Hg. Future studies should assess the impact of these guideline changes on hypertension screening and their implications for developing implementation strategies.