The literature review identified 583 citations and 37 articles that met the inclusion criteria (). There was good reliability between the two abstractors for their evaluations of these studies (Pearson correlation coefficient = 0.74, p<0.001).
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 pharmacists8, 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) (). 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 ().
Stepwise meta-regression analysis of the effect on blood pressure (n=36 studies)*
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) ().
Effect of Quality Improvement Strategies on Blood Pressure Outcomes
The estimated odds ratio and 95% confidence interval (CI) for controlled BP for nursing studies was OR=1.69 (CI = 1.48, 1.93) (), studies involving community pharmacists was OR=2.89 (CI = 1.83, 4.55) (), and studies involving pharmacists within primary care clinics was OR=2.17 (CI = 1.75, 2.68) ().
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 (more ...)
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 (). 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.
Funnel plot for all studies included in