Improving Blood Pressure Management in Patients With Diabetes

Background: Cardiovascular disease (CVD) is the leading cause of mortality in Canada. Diabetes is a strong risk factor for CVD, accounting for 50%-75% of deaths (1). Almost half of patients with diabetes also have hypertension. Recent evidence suggests that blood pressure (BP) control is a more important target than blood glucose for the prevention of complications of diabetes, because reducing BP reduces the risks of both CVD and renal dysfunction (2-4). Despite this, and recommendations from national guidelines, BP control in individuals with diabetes is poor (5-10). We recently performed a systematic review of 43 studies, (72,237 patients), and observed that only about 40% achieve treatment targets (11). This is likely an overestimate, as all studies used BP targets higher than current recommendations. Community pharmacists and advanced nurse practitioners (ANP) are well-positioned to help identify and follow-up patients with diabetes and hypertension.

Objective: To determine the efficacy of a community-based multidisciplinary screening and intervention program on blood pressure control in patients with diabetes.

Design and Methods: Design: Subjects will be randomized to pharmacist/ANP intervention or usual care. Inclusion criteria: Adult patients with diabetes with a BP of >130/80 mm Hg on 2 consecutive visits 2 weeks apart. Exclusion criteria: patients who are institutionalized or unlikely/unable to comply with follow up visits. Procedures: Patients will be recruited via: 1) community pharmacies (patients identified by diabetes drug prescriptions), and 2) referrals via Capital Health Regional Diabetes Intake Program. Patients will be invited by telephone to attend an in-pharmacy clinic. At Visit #1, the ANP will complete a history and physical exam (including a BP taken using the BPTru® device, 6 readings performed 1 minutes apart in the non-dominant arm, with last 5 readings averaged) (12). The pharmacist will review each patient's medication history. If the averaged readings are >130/80 mm Hg, the patient will be invited to attend a 2nd clinic in 2 weeks. If the averaged BPs from both visits are >130/80 mm Hg, the patient will be approached for consent to participate in the randomized trial. Intervention group receives: a BP wallet card with discussion as to the meaning of the BP measures, CVD risk reduction counseling, a hypertension education pamphlet, and referral to their primary care physician for further assessment/management. The BP results will then be faxed along with any recommendations to the patient's primary care physician. Written recommendations from local opinion leaders will be used to reinforce the latest hypertension guidelines. Follow-up: Patients will be followed up at 6 weeks to ensure they have made an appointment with their physician and to re-measure BP. BP will be measured at 6-week intervals (Week 6, 12, 18 with faxing of BP results and recommendations to the primary care physician), with a final follow-up visit at Week 24. Usual care group receives: BP wallet card with recorded BP measures, a pamphlet on diabetes, general diabetes advice given by ANP and usual care by their physician. Follow-up: No scheduled follow up visits. One phone call to patient will occur at 12 weeks to inquire about changes to BP management. A final follow-up visit will occur at week 24 to re-evaluate BP and to offer the patients the intervention program.

Evaluation: Outcome measures: The primary endpoint is the difference in change in systolic BP between intervention and usual care groups at 6 months. Secondary endpoints will include: (1) change in antihypertensive therapy (new medication or dosage increase), (2) % patients achieving BP target of <130/80 mm Hg, and (3) % patients using ACE inhibitors or angiotensin receptor antagonists. Sample Size: A sample size of 85 patients per group will provide 90% power (assuming a standard deviation of 20mmHg and 2-sided alpha=0.05) to detect a 10mmHg difference in the primary endpoint. To account for drop-outs, we will increase this to 110 patients per group. Analysis: Demographic characteristics will be summarized using percentages for categorical variables and medians (interquartile range) for continuous variables. To compare the change in BP between intervention and usual care, we will use a 2-sample independent t-test. Significance of Study: Treatment and control of hypertension in people with diabetes is a major public health problem, and improving detection and control of hypertension is a major goal of the Canadian Hypertension Society. Novel ways of identification and treatment to guideline targets in this patient population are urgently needed.

Inclusion criteria

The following patients will be eligible for study participation:

• Patients with either type 1 or type 2 diabetes. Diabetes will be defined as those patients presently taking either oral hypoglycemic agents or insulin therapy (oral hypoglycemic agents to include all drugs in the drug classes of: alpha-glucosidase inhibitors, biguanides, meglitinides, sulfonylureas, thiazolidinediones and adjunctive therapy) taken for >6 months to rule-out steroid-induced diabetes and gestational diabetes.

Exclusion criteria

Patients will be excluded from the study if they:

• Do not provide or are unable to provide written informed consent
• Refuse or are unlikely to attend follow-up visits for BP measurements
• Are institutionalized
• Are <18 years of age
• Do not understand English
• Enrolled in other diabetes or hypertension trials

Subjects will be recruited whether or not they are receiving antihypertensive therapy.