In this study, subjects cared for in the physician-pharmacist team model were 40% more likely to achieve their goal blood pressure compared to those cared for by their physician alone. Among middle-aged patients (i.e., 60–69 years), the 6-mmHg difference in systolic blood pressure observed in this study would be expected to yield a 22% reduction in stroke mortality and a 17% reduction in mortality from ischemic heart disease.17
Thus, inclusion of pharmacy practitioners on the primary care team represents one possible strategy to address this important public health issue.
Alternatively, elucidating the underlying mechanisms by which the team-based model achieved superior outcomes in this study may facilitate modification of physician practice within the current healthcare delivery model. National guidelines recommend combination therapy as a means to intensify treatment without increased complexity, a practice implemented in higher frequency in the team-based arm.6
Patient cost-sharing is another factor in medication adherence.8,18
Although this study did not assess patient medication cost-share, the higher generic prescribing rate in the collaborative arm can be considered a surrogate outcome for cost.
Given the recent findings by Lee et al.19
, it was somewhat surprising that our study found no difference between arms in self-reported medication adherence. The four-item self-reported questionnaire may not have been sensitive enough to detect a difference if it did exist. Subjects in the team-based care intervention appeared more engaged in the management of their hypertension as indicated by increased home blood pressure monitoring. Another commonly proposed mechanism, not evaluated in this study, is time spent with the patient during each visit. Moreover, physicians in the study were undoubtedly confronted with multiple health issues, while in the team-based model pharmacists were able to focus more narrowly on management of hypertension.
Although subjects in the intervention arm were prescribed a higher number of antihypertensive medications, our study found a negligible impact of the team-based care on patient quality of life and satisfaction. Other evidence suggests that the impact of similar pharmacy interventions on patient quality of life represents a neutral20,21
to positive effect.22–24
These results dispel the notion that introducing pharmacists into primary care-based chronic disease management risks jeopardizing the physician-patient relationship.
The fundamental requirements for successful generalization of this strategy include an adequate workforce of trained pharmacy practitioners and third party reimbursement. Given shortfalls in effectiveness of the current healthcare delivery model,25
projected physician shortages, and the preponderance of evidence demonstrating improved outcomes when pharmacists actively participate on patients’ care team,10
the inclusion of pharmacists as healthcare providers eligible for reimbursement for cognitive services warrants serious consideration.
The results of this study add to a growing body of literature demonstrating the positive effect of physician-pharmacist team-based management of hypertension.7,21,23,26–28
This study has several strengths, including (1) prospective, randomized, controlled design with evaluator blinding, (2) large community-based patient population with mixed insurance, (3) multi-site intervention including all physicians practicing in nine clinics, (4) involvement of multiple pharmacy practitioners, (5) 12-month study duration, and (6) inclusion of clinical, patient self-management, economic, quality of life, and satisfaction outcome measures.
This study is further unique compared to other published randomized controlled trials evaluating pharmacists’ role in hypertension management.7,21,23,26,27,29
In contrast to most published studies, with the exception of a study conducted in a VA setting,28
the pharmacists in this study were empowered to alter the antihypertensive regimen, according to guidelines, without consulting the physician in advance. Unlike the VA study, where pharmacists were located in a separate pharmacist-run hypertension clinic,28
our study evaluated pharmacists co-located in the primary care clinic. In this more team-oriented setting, pharmacists were able to quickly consult the physician for cases involving complex co-morbidities or the need for departure from routine guidelines, possibly improving efficiency, communication, and trust.
In this study, randomization at the patient level, as opposed to physician or clinic, may have resulted in contamination bias. Physicians in the study cared for patients in both groups and, further, co-signed the chart note following every pharmacist-patient interaction. In addition, at the request of the physician, six subjects in the control group received pharmacy consultation during the study. Although contamination was considered during study design, investigators recognized that it would conservatively represent bias toward the null hypothesis. Further, subjects in the usual care arm were offered active interventions. These interventions included (1) mailed patient educational information,11
(2) patient prompts where there was not a scheduled appointment, and (3) physician prompts for patients with elevated blood pressure. These interventions may also have blunted the difference in outcomes between arms.
In this study, we observed that only 16% of patients with an active medical record who were solicited to participate via a mailed invitation responded and subsequently consented. In practice, unlike the screening and enrollment methods employed in the study, patients are typically seen by a clinical pharmacy practitioner following a direct verbal referral by the PCP. This more traditional referral process might be expected to yield a higher screening-to-enrollment ratio relative to the low-touch methodology used here. Effective referral and enrollment methodologies, as well as patient acceptance of team-based care involving a pharmacy practitioner, merit further investigation.
The subject withdrawal rate observed in this study is similar to the rate reported in other hypertension management studies.21,23,27
This study used a low intensity screening and consent process, which might contribute to the high withdrawal rate. Analyses published elsewhere demonstrate that the high withdrawal rate observed in this study did not likely create an important imbalance in between-group subject characteristics for those who completed the study.16
When subjects who completed and withdrew from the study were compared, the only factor significantly associated with a higher withdrawal rate was enrollment in commercial insurance. The external validity of this study was also not affected by subject dropout and may even have been enhanced due to the naturalistic subject recruitment strategy. Regardless of the type of analysis conducted (analysis of subjects completing the study or last value carried forward for all enrolled subjects), a similar reduction in blood pressure was observed in the intervention group.