A Randomized Controlled Trial of Team-Based Care: Impact of Physician-Pharmacist Collaboration on Uncontrolled Hypertension

 

Background:  In the ever-expanding roles of pharmacists, physician-pharmacist collaborative practice clinics can be used to appropriately manage disease states such as hypertension.

 

Objective: The purpose of the study was to determine the effectiveness of primary care pharmacist teams in the management of hypertension.

 

Methods: This was a 12-month prospective, single-blind, randomized, parallel group, controlled trial.  Patients with a diagnosis of hypertension or a last systolic pressure ≥160 mmHg and/or a last diastolic blood pressure of ≥100 mmHg were enrolled from nine primary care clinics within the Providence Primary Care Research Network in Oregon.  Patients were excluded if they had no blood pressure readings in the chart for the previous 2 years, attended a visit with a pharmacy practitioner in the previous 6 months, or transferred care out of the Network.  Overall, 463 patients were randomized to either the control group or intervention group.  Both groups were provided with hypertension self-management material to provide similar awareness of principles at baseline between groups.  In the control group, patients were instructed to continue their normal schedule of medical care.  In the intervention group, pharmacist reviewed medications and lifestyle habits, assessed vital signs, screened for adverse drug reactions, identified barriers to adherence, provided education, optimized the antihypertensive regimen and scheduled follow-up appointments as per the Network-approved collaborative guidelines.  At the end of the study, patients’ blood pressures were evaluated by blinded registered nurses who took three readings using appropriate sized cuffs and mercury sphygmomanometers. Data analysis was based on the mean of the second and third readings.  The primary outcome measure was the difference in mean systolic and diastolic blood pressures between the team-based care arm and the usual care arm at study end.  Secondary outcome measures included proportion of subjects achieving blood pressures <140/90, changes in measures of self-management knowledge and behavior, resource utilization (number and purpose of office visits, antihypertensive use) and changes in quality of life and satisfaction. Intent to treat analysis was used in this study with the last available clinic blood pressure used in the final analysis of drop-outs.  A sample size of 151 patients per group was needed to achieve 90% power to detect a 3 mmHg difference in mean systolic and diastolic blood pressures assuming a standard deviation of 8 mmHg and p<0.05.

 

Results:  Overall, 272 patients (58.7%) patients completed the study with 130 of 233 (55.8%) in the control group and 142 of 230 (61.7%) in the treatment group. The treatment group had significantly lower systolic and diastolic blood pressures (difference of 6 mmHg systolic, p=0.007 and 3 mmHg diastolic, p=0.003) when compared to control. Significantly more of the treatment group achieved a blood pressure of <140/90 mmHg (62% vs 44%, p=0.003).  Odds of achieving blood pressure target in the treatment group was 2.08 times higher than the control group (95%CI=1.29-3.38).  These trends maintained significance when intent-to-treat analysis was conducted.  No significant difference was seen with hypertension-related knowledge between groups.  Significantly more patients in the treatment group reported owning a home blood pressure monitor (70% vs 51%, p=0.007) and reported recording their measurements in a log book (80% vs 53%, p=0.002).  The number of office visits per patient was not statistically associated with systolic blood pressure (treatment 4=0.16, p=0.06 and control r=-0.1, p=0.22) but was negatively associated with diastolic blood pressure in both groups (treatment r=-0.22, p=0.01 and control r=-0.018, p =0.04).  Those in the treatment group used more antihypertensive medicines (2.4 pills per patient vs 2.7 pills per patient, p=0.02) and had a higher use of generic medications (30.7% vs 50.7%, p=0.008).  Patients in the control group scored higher in the general health category of the quality of life evaluation (44 vs 42, p=0.01) but both groups were satisfied with the care they received (8.5 in the treatment group and 8.6 in the control group, p=0.75). 

 

Strengths:  The study’s inclusion criteria and secondary outcomes from blood pressure were both based on JNC-7 guidelines.  Participating pharmacists were all well trained (i.e. residency trained and board certified).  The year-long study allowed adequate time to see the effects of therapy changes on blood pressure.  The final blood pressure results were obtained through blinded nurses limiting the chances of study bias.  Patient assessments of quality of care were included demonstrating the acceptance of pharmacists as disease state managers.

 

Weaknesses:  The clinical significance of an average 6 mmHg difference in systolic blood pressure is questionable.  Physicians treated patients in both groups.  This crossover could have caused patients to emulate recommendations made by pharmacists and treat control group patients in a similar manner.  This would have blunted the differences found between groups. 

 

Conclusion:  While the study found statistically significant differences in blood pressure between the two groups, the clinical significance of these findings is questionable.  However, if considering the effectiveness of well-trained pharmacists in treating hypertension it can be concluded that they do at least as well as physicians at controlling hypertension.  Pharmacy managed hypertension clinics appeared to be well received by the patients but the power was not sufficient for this assessment to guarantee no difference between the groups.  This study supports the rationale for pharmacist run disease clinics and more studies should be conducted to determine the impact of pharmacists in the treatment of other conditions such as dyslipidemia and hypothyroidism.

 

Hunt JS, Siemienczuk J, Pape G, Rozenfeld Y, MacKay J, LeBlanc BH, Touchette D. A randomized controlled trial of team-based care: Impact of physician-pharmacist collaboration on uncontrolled hypertension.  J Gen Intern Med. 2008;23(12):1966-72.

 

Michael A. Biddle, Jr., Doctor of Pharmacy Candidate