The Potency of Team-based Care Interventions for Hypertension

Abstract

Background

One strategy that has had the greatest effect on improving blood pressure (BP) includes team-based care. The purpose of this systematic review was to determine the potency of interventions for BP involving nurses or pharmacists.

Methods

A Medline search for controlled clinical trials that involved a nurse or pharmacist intervention was conducted. Mean reductions in systolic (S) and diastolic (D) BP were determined by two reviewers who independently abstracted data and classified the different intervention components.

Results

Thirty-seven papers met the inclusion criteria. Education on BP medications was significantly associated with improved BP (−8.75/−3.60 mm Hg). Other strategies that had large effect sizes on SBP included: pharmacist made treatment recommendation (−9.30 mm Hg), nurse did the intervention (−4.80 mm Hg), and a treatment algorithm was used (−4.00 mm Hg). The odds ratio (OR) and 95% confidence interval (CI) for controlled BP were: nurses OR=1.69 (CI = 1.48, 1.93), pharmacists within primary care clinics OR=2.17 (CI = 1.75, 2.68) and community pharmacists OR=2.89 (CI = 1.83, 4.55), Mean reductions in SBP were: nursing studies = 5.84 ± 8.05 mm Hg, pharmacists in clinics = 7.76 ± 7.81 mm Hg and community pharmacists = 9.31 ± 5.00 mm Hg but there was no significant differences between the nursing and pharmacy studies (p≥0.19).

Conclusion

Team-based care was associated with improved BP control and individual components of the intervention appeared to predict potency. Implementation of new hypertension guidelines should consider changes in the health-care organizational structure to include important components of team-based care.

Introduction

Blood pressure (BP) is poorly controlled in the US.^1-5 The 8^th Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC-8) is currently considering strategies to improve the implementation of the guidelines and achieve higher BP control rates. Investigators from the Stanford-UCSF Evidence-based Practice Center conducted an analysis of controlled clinical trials of quality improvement strategies and found that the only strategy that significantly improved BP involved interdisciplinary team-based care.⁶ Most of the quality improvement interventions utilized multiple components. These different strategies or the potency of the intervention may explain why there appears to be differences in effect sizes.⁷

One strategy to improve guideline adherence is to use team-based care involving pharmacists or nurses.^8-13 The purpose of the present study was to conduct a systematic review of the research literature and to evaluate the potency of team-based care involving pharmacists or nurses. We theorized that the effect size would be greater for nurses or pharmacists working in the physician’s office or more independently by protocol than with more distant interventions such as recommendations from a community pharmacist.

Methods

We followed the same process as Walsh et al⁶ by including quasi-randomized trials, controlled before-after studies, interrupted time-series studies, patient-randomized trials and cluster-randomized trials. Quasi-randomized trials were defined as those that included at least two cohorts of patients identified prospectively using an arbitrary, but nonrandom allocation procedure.⁶ Controlled, before-after studies were defined as those with a contemporaneous observation for cohorts that differed primarily with respect to the exposure of the intervention.⁶ Interrupted time series required that the study report outcomes from at least three time points in the pre- and post-intervention periods.⁶

Search Strategy

Walsh et al. performed their search of the MEDLINE database from January 1980 through July 2003 and we extended the search to include papers published from January 1970 through February 2009. The search was conducted by a research librarian. Titles and abstracts were then screened to determine if the article included team-based care of hypertension involving pharmacists or nurses. Next, we searched the reference list of included papers and the reviews by Walsh⁶ to identify additional citations. Once the full text articles were selected, two reviewers (one Pharm.D. clinical pharmacist and one Ph.D. nurse) independently determined if each paper met the study criteria and, if so, the reviewers independently abstracted critical information including study design, setting, type of intervention, components of the intervention and degree of SBP and DBP change. The intervention components included: supplying free medications, education concerning BP medications, counseling on lifestyle modifications, assessing medication compliance, algorithm for treatment, home visits, intervention provider (nurse or pharmacist) could prescribe medications, intervention provider could order laboratory, length of the study, completion of a drug profile/medication history, physical examination was conducted, nurse provided intervention, pharmacist provided intervention and/or whether medication recommendations were made to a physician (as opposed to independent changes). Because every study used different combinations of these components, the two reviewers independently assigned a “potency score” for their predicted potency that the combination of interventions in a study would have on outcomes ranging from 0 (brings about no result) to 10 (brings about best result). Disagreements between the reviewers were resolved by an open dialog to develop consensus. Confirmation of the two reviewers’ findings was adjudicated by a biostatistician.

Evaluation of the Intervention Effect Size

We calculated effect size by determining the change in SBP (or DBP) attributable to the intervention (int) for each study defined as:⁶

$$\text{Net}\Delta \text{in}\mathrm{SBP}={(\mathrm{Postint}\mathrm{SBP}-\mathrm{Preint}\mathrm{SBP})}_{\text{Study group}}-{(\mathrm{Postint}\mathrm{SBP}-\mathrm{Preint}\mathrm{SBP})}_{\text{Control group}}$$

and

$$\text{Net}\Delta \text{in}\mathrm{DBP}={(\mathrm{Postint}\mathrm{DBP}-\mathrm{Preint}\mathrm{DBP})}_{\text{Study group}}-{(\mathrm{Postint}\mathrm{DBP}-\mathrm{Preint}\mathrm{DBP})}_{\text{Control group}}$$

BP control was defined as a BP < 140/90 for patients with uncomplicated BP and <130/80 mm Hg for those with diabetes or chronic kidney disease.¹⁴ The net change in BP control rates attributable to the intervention for each study was defined as:

$$\text{Net}\Delta \text{in}\mathrm{BP}\text{control}={(\mathrm{Postint}\mathrm{BP}\text{control}-\mathrm{Preint}\mathrm{BP}\text{control})}_{\text{Study group}}-{(\mathrm{Postint}\mathrm{BP}\text{control}-\mathrm{Preint}\mathrm{BP}\text{control})}_{\text{Control group}}$$

The odds ratio and 95% confidence interval for controlled BP was calculated (22 studies) and weighted by the sample size of the study.^{8, 15-35} Odds ratios could not be calculated for 15 studies.^36-50 We divided the studies into three groups to evaluate potency: 1) nursing interventions, 2) pharmacist interventions delivered in community pharmacies, and 3) interventions by clinical pharmacists working within a primary care office. We performed a sensitivity analyses to determine the effect of assigning studies to different categories when they had multiple strategies (e.g. involved both community pharmacists and nurses).

Analysis

Stepwise regression analyses and non-parametric analyses were performed using the Mann-Whitney test to evaluate the post-intervention difference between the intervention and control groups for mean SBP and DBP while controlling for study sample size using SPSS 17.0.0 statistical software (SPSS, Inc., Chicago, IL, Aug 23, 2008).

One study had a large number of informed dropouts and found no significant difference between nurse management versus the physician.¹⁵ A stepwise regression analysis was conducted without this study (n=36) to predict the effect of individual intervention components on BP.

Unadjusted odds ratio for controlled BP were calculated so studies could be compared. Odds ratios were compared using a simple logistics regression model using one variable, unadjusted for any other item. We created a funnel plot of the log of the odds ratio plotted against the standard error for each study to assess the possibility that publication bias might exist.

Results

The literature review identified 583 citations and 37 articles that met the inclusion criteria (Figure 1). There was good reliability between the two abstractors for their evaluations of these studies (Pearson correlation coefficient = 0.74, p<0.001).

Figure 1.

Flow diagram for reasons trials were excluded.

Each study involved unique provider qualifications and training. For instance, studies involving community pharmacists may have included bachelor of science (B.S.) trained pharmacists^{8, 22, 51} or those with Doctor of Pharmacy (PharmD) degrees.^{20, 21} Studies that involved “pharmacists in clinics” nearly all involved clinical pharmacists (with Pharm.D. or MS degrees) who had completed postdoctoral residency training in primary care whose duties involved direct patient management,^{24, 26, 28, 30, 34, 36, 48} though several studies did not provide these details.^{25, 27, 35, 46} Most of the studies involving nurses did not specify their qualifications,^{17, 19, 33, 38-41, 44, 45, 47} but some noted that they were registered nurses (RN)^{42, 49} or nurse practitioners.^{16, 18} Training of the intervention nurses or pharmacists typically involved educational training sessions on hypertension guidelines given by an expert,^{8, 17, 19-25, 30, 32, 33, 35, 41, 42, 47, 49} but again, many did not specify the training program.^{16, 18, 26-29, 34, 36-40, 44-46, 48, 50} Only a few studies described patient empowerment or strategies such as home BP monitoring to assist with the intervention.^{23, 34, 35, 40} One finding is that nearly all studies involving nurses or pharmacists in clinics provided for consistent and dedicated case management activities distinct from traditional nursing or pharmacist duties. Pharmacists in community pharmacies, however, usually had to incorporate the intervention around traditional medication dispensing functions.

The stepwise regression compared the studies that included a given intervention strategy, with those studies that did not. Several individual components of the interventions were associated with significant reductions in SBP including “pharmacist recommended medication to physician” (−27.2 mm Hg, p=0.002), “counseling on lifestyle modification (−12.6 mm Hg, p=0.033), “pharmacist performed the intervention” (−11.7 mm Hg, p=0.028), “an algorithm was used” (−8.46 mm Hg, p<0.001), “a drug profile was completed” (−8.28 mm Hg, p=0.001) and the overall intervention potency score assigned by the study reviewers (p<0.001) (Table 1). For example, the regression coefficient for “used algorithm” was significant (9.37, p<0.001) which indicated that given all other factors in the model, the average reduction in SBP of the nine studies using an algorithm was 9.37 less than the change in SBP in the 27 studies not using an algorithm. Assuming that a study used an algorithm and no other intervention, the predicted reduction in SBP was 8.46 mm Hg (Table 1).

Table 1.

Stepwise meta-regression analysis of the effect on blood pressure (n=36 studies)^*

Outcome variable: Change of systolic blood pressure	Regression Coefficient	Predicted Change in SBP (mm Hg)	p
Constant	−1.31	NA	0.664
Pharmacist recommended medication to physician	−9.68	−27.21	0.002
Counseling on lifestyle modification	5.20	−12.63	0.033
Pharmacist performed the intervention	6.13	−11.70	0.028
Algorithm used	9.37	−8.46	0.000
Drug profile was completed	9.55	−8.28	0.001
Overall intervention potency score**	−2.76	NA	<0.001
Outcome variable: Change of diastolic blood pressure	Regression Coefficient	Predicted Change DBP (mm Hg)	P
Constant	−11.90	NA	0.010
Referral was made to specialist	−7.71	−19.61	0.039
Physical Exam was conducted	−6.65	−18.55	0.080
Education on medications	−5.70	−17.60	0.003
Length of intervention	0.04	−10.13	0.060
Algorithm was used	3.12	−8.78	0.051
Drug profile was completed	4.63	−7.27	0.006
Pharmacist performed the intervention	7.87	−4.03	0.044
Nurse performed the intervention	7.96	−3.94	0.041

^*analysis when McClellan et al is excluded.¹⁵

^**controlled in the analyses and only significant for SBP.

The factors associated with a reduction in DBP were: “referral was made to a specialist” (−19.6 mm Hg, p=0.039), “providing patient education about BP medications” (−17.6 mm Hg, p=0.003), “a drug profile was completed” (−7.3 mm Hg, p=0.006), “a pharmacist did the intervention” (−4.0 mm Hg, p=0.044) or “a nurse did the intervention” (−3.9 mm Hg, p=0.041). Next, a nonparametric analysis was performed because the data were not normally distributed. The only individual component that had a significant reduction in BP was education on BP medications (−8.75/−3.60 mm Hg). However, several other intervention components had a large effect size on SBP (−11.0 to −4.8 mm Hg) including: 1) free medications (−10.80 mm Hg), 2) pharmacist made treatment recommendation to the physician (−9.30 mm Hg), 3) pharmacist did the intervention (−8.44 mm Hg), 4) a drug profile was compiled (−8.19 mm Hg), 5) medication compliance was assessed (−7.90 mm Hg), 6) counseling on lifestyle modification was performed (−7.59 mm Hg), 7) provider of the intervention could order laboratory tests (−7.00), and 8) nurse did the intervention (−4.8 mm Hg) (Table 2).

Table 2.

Effect of Quality Improvement Strategies on Blood Pressure Outcomes

Type of Quality Improvement	Median Reduction in Systolic Blood Pressure (mm Hg) [Interquartile range]# n = number of studies	Median Reduction in Diastolic Blood Pressure (mm Hg) [Interquartile range]# n = number of studies
Free medications	−10.8 [−14.9, −9.10] n = 318, 39, 50	−6.4 [−8.70, −3.90] n = 318, 39, 50
Pharmacist recommended medication to physician	−9.30 *[−13.00, −5.00] n = 158, 20-24, 26, 27, 29, 30, 35, 37, 43, 46, 48	−3.60 [−7.03, −1.00] n = 158, 20-24, 26, 27, 29, 30, 35, 37, 43, 46, 48
Education on BP medications	−8.75**[−11.90, −4.25] n = 288, 17-23, 26-30, 32, 34, 35, 37, 39-44, 46-50	−3.60**[−7.03, −1.00] n = 278, 17, 18, 20-23, 26-30, 32, 34, 35, 37, 39-44, 46-50
Pharmacist did intervention	−8.44 [−12.25, −4.00] n = 228, 19-22, 24-30, 34-37, 41, 43, 46, 48, 50, 51	−3.30 [−6.87, −0.90] n = 218, 19-22, 24-30, 34-37, 41, 43, 46, 48, 50, 51
Drug profile was completed	−8.19 [−11.45, −2.93] n = 168, 17, 20, 21, 23, 25-27, 29, 30, 32, 35, 40, 42-44, 46, 48	−3.25 [−4.67, −1.00] n = 168, 17, 20, 21, 23, 25-27, 29, 30, 32, 35, 40, 42-44, 46, 48
Assessed medication compliance	−7.90 [−11.90, −3.48] n = 248, 17, 20, 21, 23, 25-30, 34-37, 39-44, 46, 47, 50	−3.25 [−8.65, −0.85] n = 248, 17, 20, 21, 23, 25-30, 34-37, 39-44, 46, 47, 50
Counseling on lifestyle modification	−7.59 [−11.45, −2.40] n = 288, 16, 17, 19-23, 26-32, 34, 35, 37, 38, 40-42, 45-50	−3.30 [−6.70, −1.00] n = 278, 16, 17, 20-23, 26-32, 34, 35, 37, 38, 40-42, 45-50
Provider in intervention could order laboratory	−7.00 [−8.94, −1.30] n = 916, 22, 25, 31, 33, 44, 48-50	−3.68 [−5.40,−0.15] n = 916, 22, 25, 31, 33, 44, 48-50
Nurse did intervention	−4.80* [−9.63, −0.43] n =1616-19, 31-33, 38-42, 44, 45, 47, 49	−3.10 [−6.00, −0.10] n =1516-18, 31-33, 38-42, 44, 45, 47, 49
Used algorithm for treatment	−4.00* [−8.15, −0.90] n = 916, 23, 25, 32, 33, 35, 37, 44, 49	−1.00* [−4.20, −0.15] n = 916, 23, 25, 32, 33, 35, 37, 44, 49
Made a home visit	−4.00 [−9.95, 0.15] n = 517, 18, 38, 41, 44	−1.00 [−4.95, 0.60] n = 517, 18, 38, 41, 44
Provider of intervention could prescribe medication	−2.40 [−11.28, 4.75] n = 416, 25, 28, 32	−0.65 [−11.35, −0.08] n = 416, 25, 28, 32
Physical examination was conducted	2.10* [−2.80, 7.00] n = 216, 25 #	−0.15* [−0.30, 0.00] n = 216, 25 #

^#When n = 2, brackets show the actual results of each study rather than interpolated interquartile range.

^*p < 0.10

^**p < 0.05 for Mann-Whitney analysis of reduction in systolic blood pressure and diastolic blood pressure comparing studies with the quality improvement strategy with those without it.

The estimated odds ratio and 95% confidence interval (CI) for controlled BP for nursing studies was OR=1.69 (CI = 1.48, 1.93) (Figure 2a), studies involving community pharmacists was OR=2.89 (CI = 1.83, 4.55) (Figure 2b), and studies involving pharmacists within primary care clinics was OR=2.17 (CI = 1.75, 2.68) (Figure 2c).

Figure 2.

The Odds Ratio (confidence interval) that systolic blood pressure is controlled in the intervention group compared to the control group. Figure 2a displays 8 studies involving nurses, Figure 2b displays 5 studies conducted in community pharmacies and Figure 2c figure displays 9 studies involving pharmacists in primary care clinics.

In the non-parametric analyses of the 36 studies, the mean reduction in SBP was 5.84 ± 8.05 mm Hg for nursing studies (n=16) compared to 7.76 ± 7.81 mm Hg in the studies involving pharmacists in clinics (n=7) and 9.31 ± 5.00 mm Hg for studies by community pharmacists (n=13). Reductions in diastolic BP were 3.46 ± 4.15 mm Hg for nursing studies, 4.18 ± 4.25 mm Hg for pharmacists in clinics and 4.59 ± 4.64 mm Hg for community pharmacists (SBP and DBP were not significantly different between any group).

We constructed a funnel plot to evaluate whether there may have been publication bias (Figure 3). Three of four studies with the largest log odds ratios had moderate to low standard error suggesting the absence of publication bias. However, publication bias cannot be ruled out since there are few studies with high log odds ratios and low standard error.

Figure 3.

Funnel plot for all studies included in Figure 2

Discussion

This study found that interventions involving pharmacists or nurses were associated with significantly improved BP control. These findings extended the previous report that found involving pharmacists or nurses was the most potent quality improvement strategy to improve BP control.⁶ We also wanted to determine if specific aspects of team care were more potent. Our analysis found that studies involving pharmacists resulted in not only lower BP but a greater OR of achieving BP control compared to studies involving nurses. However, the reductions in systolic BP and confidence intervals for controlled BP (Figure 2) overlap for the different providers.

We had hypothesized that studies involving community pharmacists would be less potent than those involving nurses or pharmacists within primary care clinics. Interestingly, studies involving community pharmacists had the highest OR (2.89). These findings may be based on how the reviewers categorized the studies. First, one study conducted in community pharmacies in Portugal had an extremely high OR (29.71).²² Another study in community pharmacy had an OR of 4.29 but this pharmacist worked closely with two physicians and reviewed medical records of study patients in the physicians’ office.²⁰ Instead, we could have classified this as a “pharmacist in the clinic” which would have reduced the OR for community pharmacy studies and increased the OR for “pharmacists in clinics.” Second, we classified one study as a nursing intervention for the OR calculations but the intervention involved both a nurse and community pharmacist (OR=1.79).¹⁹ Excluding the first two studies and adding the third study to the analysis of community pharmacy studies would have resulted in an OR closer to 1.8 for the “community pharmacy” group.

Finally, one large study was conducted within a managed care organization that involved education by a pharmacist via the web.³⁵ We classified this study as one within primary care but this study did not have as great of an effect (OR=1.88) compared to studies in which the pharmacist adjusted therapy either alone or in collaboration with physicians (OR=7.38-9.98). Without that study, the OR would have been 3.27 for “pharmacist in clinics”. It may be possible to explain our findings based on the dose, duration and potency of the intervention. For instance, Carter conducted three studies in community pharmacies, where the pharmacists had no prior established relationship with the physicians and the interventions were only 4 and 5 months in length.^{8, 21, 23} These studies had modest OR for controlled BP (1.56, 1.74 and 2.46). Carter recently completed a randomized controlled effectiveness (pragmatic) study of a 6-month pharmacist intervention in 402 patients from six family medicine clinics that was not included in this systematic review because it was unpublished at the time of our evaluation.⁵² In that study, SBP was reduced 12.0 mm Hg more in the intervention group than the control group and the OR for controlled BP was OR= 3.2 (95% CI 2.0, 5.1). Finally, these investigators conducted an efficacy study in which BP was controlled in 54% of patients in the control group and 89% in the intervention group (OR 7.38, CI 3.43, 15.91).³⁰ The main reason for high BP control in this latter study was attributed to assertive and frequent medication intensification recommended by the pharmacist. Thus, the OR for the 5 studies by these investigators were: community pharmacy studies (B.S. trained pharmacists) between 1.56-2.46; the pragmatic trial of clinical pharmacists (Pharm.D. with residency or fellowship) 3.2 and the efficacy trial (ideal intervention delivery) with clinical pharmacists (Pharm.D. with residency) of 7.38.

Therefore, when the literature involving team care is evaluated, it is critical to assess the duration of the intervention, the type of organization in which the intervention is performed (home, worksite, community pharmacy or primary care clinic) and whether the study is an efficacy or effectiveness trial. These factors, as well as the activities of the intervention, predict the potency of the intervention.

Studies involving community pharmacists largely involved making recommendations to physicians by telephone or facsimile. Studies involving pharmacists in clinics typically involved pharmacists employed in the clinic and who worked collaboratively with physician colleagues and/or provided more autonomous care. Pharmacists within primary care clinics work closely with physicians and the expected levels of trust and cooperation might be higher than with community pharmacists where interaction is usually not in person and occurs from distant locations.^{23, 51, 53} In fact, recommendations to change BP medications were accepted 95% of the time from pharmacists within the same clinic³⁰ but only 45-50% when recommendations were made by community pharmacists.^{8, 21, 23} Therefore, lower acceptance for community pharmacists’ recommendations could be due to lower levels of trust and cooperation by physicians.^{51, 53}

Many of the nursing studies did not describe the types of nurses, their educational background or training but four studies used either registered nurses or nurse practitioners.^{15, 16, 18, 42, 49} Nursing interventions seemed more likely to involve home visits, use an algorithm and patient engagement than pharmacy studies. It is likely that many of the interventions involving nurses or pharmacists increased patient empowerment but few studies specifically provided such descriptions. Only 5 nursing studies described a patient-led process^{17, 47, 49} or home BP monitoring^{41, 42} and 3 pharmacy studies used home BP monitoring.^{23, 34, 35} We suspect that nurse practitioners would have more autonomy than registered nurses and in some cases, nurse practitioners can prescribe medications. We could not detect whether nursing degree or training influenced the results. However, using an algorithm or making a home visit both had a predicted reduction in SBP of4 mm Hg.

Each intervention, or combination of intervention components, is/are unique. It is not possible to state that either nurses or pharmacists can improve BP control without first determining the patient population, organizational structure involved and the type of autonomy the interventionist has to change therapy. Strategies that provided medication education were the most effective but this strategy is impossible to evaluate alone since it was usually provided with additional strategies by the nurse or pharmacist who may have recommended therapy changes or personally changed therapy within a primary care office. Any incremental addition of components from Table 2 that a physician office or health system can implement should improve BP control rates but this requires additional research. We believe that nurses possess unique skills in patient management and non-medication counseling techniques that pharmacists usually do not. Likewise, pharmacists receive four years of concentrated education in medication pharmacology, pharmacokinetics, pharmacodyamics, therapeutics and chronic disease drug-therapy guidelines. Including both nurses and pharmacists in an integrated hypertension management program should be even more effective than either alone and should be more cost effective. Consistent with our findings, the pharmacists could adjust medications until BP is controlled while the nurse provides continuity and counseling on lifestyle and social support.^{9, 10} The nurse would continue to serve as a case manager between physician visits when BP is controlled. The pharmacist would then only be re-activated if BP control is lost. Such an approach can not only improve BP control rates but markedly improve the efficiency and productivity of the physician.^{54, 55} Including many of the components of these interventions into hypertension management programs could improve the implementation of the JNC-8 or other chronic disease guidelines.

Strengths and Limitations of the publications

The vast majority of the studies (89%) were randomized controlled trials (Appendix 1). The quality of the studies support the findings that these interventions are likely to be effective. There were, however, large differences in the duration of the intervention (4-24 months), sample size (26-1,534) and subject (patient) dropout (2-62%). Nearly all of the studies adequately described the most important characteristics of the patients but many did not adequately describe the number, education and training of the intervention pharmacists or nurses. Our analysis could not determine if there is a preferred level of qualifications such as a PharmD degree with residency or a MS nurse practitioner degree. Likewise, many studies did not describe the training but those that did typically noted ½ to 2 day training programs on the hypertension guidelines and BP measurement. It is possible that RN nurses or B.S. pharmacists may have required more intense or longer training than nurse practitioners or pharmacists with PharmD degrees with residencies, but this could not be determined from these studies. Future interventional studies of this type should specify the educational background, postgraduate training and specific training programs for the study that were used to implement the intervention.

Only one study performed a cost-effectiveness analysis.⁴⁸ Clinic visit costs were significantly higher in the pharmacist-managed clinic ($131 per patient) than the physician clinic ($74) (p<0.001), but the costs for emergency room visits was significantly lower in the pharmacist-managed clinic than the physician clinic ($0 vs $10.84 per patient, p<0.04). The cost of decreasing SBP/mm Hg was $27 for the pharmacist-managed clinic and $193 for the physician clinic. The cost of decreasing DBP/mm Hg was $48 in the pharmacist-managed clinic and $151 in the physician clinic.

Twelve studies (9 nursing, 2 in community pharmacies, 1 pharmacist in clinics) were conducted in countries other than the U.S.^{16, 17, 19, 22, 31-33, 39, 43-45, 47} It is not know what effects the unique characteristics of the health care system in these countries might have had on the interventions. Likewise, some studies were conducted in integrated managed care settings^{29, 35} or the Department of Defense or Veterans Administration.^{28, 50} Future research should clarify the functional components of a team and how best to utilize the strengths of members of this team as they fit into the chronic care model.^{56, 57} Also, the larger impact of the health care delivery system on the potency of these interventions should be assessed, specifically if incentives might be aligned to optimize performance. Finally, we cannot rule out publication bias in our analyses since only 3 studies had high odds ratios and low standard error.

Conclusion

This evaluation of team-based care in hypertension found that interventions involving nurses or pharmacists are effective strategies to improve BP control. Several individual components were associated with improvements in BP. Research involving team-based care must be carefully designed, reported and interpreted to include the organizational structure in which the intervention is performed, the education and training of the intervention providers and the individual components of the intervention so that similar interventions can be implemented within a given health system.