We found very high BP control rates (89%) and mean BP reductions which confirms reviews that suggest interdisciplinary management of BP is a highly effective approach.15, 22
Most studies involving pharmacists reviewed for AHRQ found control rates of 45−70% and a difference of approximately 14 mm Hg in systolic BP.13
Our controlled efficacy trial found a BP control rate of 89% and a difference in SBP of 8.7 mm Hg for research-measured BP and 8.8 mm Hg with 24-hour BP.
There are several explanations for the good BP results in the control group including: the research nurse reinforced the goal BP, adherence and lifestyle modifications and provided written material on hypertension which are known to reduce BP. The protocol required all patients see their physicians at the baseline visit and this increased surveillance probably caused physicians in the control group to provide medical care once they were alerted to the lack of BP control. There was also the possibility of a Hawthorne effect. Thus, the control group cannot be considered usual care. Even so, our intervention was still much more effective at achieving BP control. The effect in the control group appeared to peak at 6 months and then wane at the 9-month period. In contrast, BP control was continuing to increase in the intervention group. It is not known if longer follow-up would increase the differences between groups or if the effect in the intervention group might also wane with time.
Controlling BP within six months reduces cardiovascular risks.36
Most of the pharmacists' recommendations were made in the first two months and BP was controlled in 73% of patients at 6 months and 89% at 9 months. Importantly, BP was controlled to current standards in 81.8% of patients with diabetes. BP began to diverge at the 2-month visit and became significant at 4−6 months that was likely due to the pharmacodynamic delay in antihypertensive response.37
A recent study provided a clinical pharmacist educational intervention along with unit dose blister packages, both intended to improve medication adherence in patients with hypertension.16
Following a six month intervention, systolic BP decreased from 133.2 ± 14.9 mm Hg to 129.9 ± 16.0 mm Hg (p=0.02). Patients (n=159) were then randomized to continued clinical pharmacist intervention with unit dose medications or usual care with standard prescription bottles for another six months. This study did not attempt to intensify medication doses, but focused on medication adherence. SBP continued to decline in the intervention group to 124.4 ± 14.0 mm Hg but deteriorated slightly in the usual care group 133.3 ± 21.5 mm Hg (p=0.005). It is not possible to determine, however, if the improvement was due to the clinical pharmacists, the unit dose packaging or both. It is interesting that SBP after 12 months was similar to our study at 9 months; 133.3 vs 133.0 mm Hg in the control group, respectively, and 124.4 vs 124.2 mm Hg in the intervention group respectively. However, our baseline systolic BP values were much higher (151 vs 134 mm Hg) and most of our patients had good medication adherence.
The usual strategy to overcome suboptimal therapy or poor guideline adherence has been to provide educational lectures and information on the guidelines. These approaches in our study, along with increased surveillance noted above achieved BP control in 53% of patients with previous uncontrolled BP in our control group. The present study suggests that educational approaches will not be optimal. Our findings suggest that poor BP control was due to sub-optimal medication regimens and support our previous cross sectional study in the same group of physicians that found no relationship between knowledge and BP control.17
The majority of recommendations in our study involved adding medications or increasing dosages and doing this early in the intervention. In most cases decisions were made collaboratively by the physician and pharmacist. Physicians agreed with the pharmacists' recommendations 95% of the time. We did not capture the instances when physicians actually turned care over to the pharmacists. However, since pharmacists in our state cannot prescribe medications independently, any new prescriptions had to be at least signed by the physician.
It may appear that the interventions to change drug therapy were simple and it might be questioned why physicians did not make these changes on their own. However, Berlowitz found that physicians frequently did not increase medication dosages even though patients continued to have uncontrolled BP in spite of up to six physician visits per year.5
Oliveria and coworkers found that the primary barrier for poor BP control was related to physicians who were satisfied with poorly controlled BPs.6
Garg et al evaluated the causes of “resistant” hypertension referred to a specialty hypertension clinic.4
The most common reasons for “resistant” hypertension were: drug-related causes (61% including sub-optimal regimens), patient nonadherence (13%), secondary hypertension (7%) or other (18%). These findings are consistent with our study, which found that the lack of BP control was primarily due to suboptimal regimens. Primary care physicians are required to deal with multiple competing priorities during short office visits. Our intervention was probably effective because pharmacists could focus on achieving therapeutic goals for patients taking medications for hypertension.38
Importantly, the greater use of antihypertensives in the intervention group did not lead to higher side effect scores, which may seem counterintuitive. Other studies have demonstrated increased quality of life and reduced adverse symptoms when BP becomes controlled following the use of medications including thiazides.28, 39, 40
Patient nonadherence was a less common cause of poor BP control in our study which is also consistent with the studies by Garg and Oliveria.4, 6
Nevertheless, medication adherence based on pill counts improved from 71% to 94% in the intervention group. It is not known if this improvement was due to the counseling by the pharmacists or by the increased attention in the study or both. It may also seem unusual that medication adherence was so high at both the baseline and 9-month periods, especially in the control group. Caro et al found medication adherence was 97% after one year of follow-up and 82% after 4.5 years of follow-up in patients with established hypertension.41
Our patients and those of Caro et al, continued to receive care and are likely to be more adherent than patients who have dropped out of care. In addition, studies have also found that patients taking more medications may adhere at a higher rate possibly explained by the Health Belief Model.42