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Among patients with diabetes, hypertension, group medical clinics improve BP, not A1C, trial findings demonstrate

Wednesday, June 16 2010 | Comments

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What's This? Among individuals who have both diabetes and hypertension, medical care augmented with group medical clinics (GMCs) improves blood pressure (BP) more than usual care alone, according to trial findings. However, the data failed to show a similarly significant effect on glycemic control.

The trial included 239 patients with hypertension (systolic BP >140 mm Hg or diastolic BP >90 mm Hg) and treated yet poorly controlled diabetes (hemoglobin A1C >=7.5%) who were receiving treatment at 1 of 2 Veterans Affairs medical centers in North Carolina and Virginia. The participants were randomized within each center to receive care in a GMC (in addition to their usual primary care) or usual care alone. The primary outcome measures were A1C and BP.

Each GMC comprised 6 to 8 patients and a care team, which consisted of a primary care general internist, a pharmacist, and a nurse or other certified diabetes educator. Patients met every 2 months with the educator in structured group sessions, and the internist and pharmacist developed individualized plans for medication and lifestyle management.

After a median follow-up of 12.8 months, mean systolic BP improved 13.7 mm Hg in the GMC group versus 6.4 mm Hg in the usual-care group, a difference of 7.3 mm Hg (95% CI, 1.7-12.8 mm Hg; P=.011). The between-group difference in SBP was also significant at the midpoint assessment (5.7 mm Hg; 95% CI, 0.06-11.4 mm Hg).

Mean A1C improved 0.8 percentage point in the GMC group compared with an improvement of 0.5 percentage point in the usual-care group, a difference of 0.33 percentage point (95% CI, -0.13 to +0.80; P=.159).

In an analysis of secondary outcome measures, the data showed that mean diastolic BP at endpoint was 3.8 mm Hg (95% CI, 0.76-6.9 mm Hg) lower in the GMC group as compared with the usual-care group. In addition, at the study midpoint, 24% of the GMC group met criteria for adequate BP control compared with 21% of the usual-care group. At endpoint, these percentages were 22% and 12%, respectively (OR, 2.0 [95% CI, 1.0-4.2]; P=.064).

There was no significant between-group difference in the percentage of patients with glycemic control, defined as an A1C level <=7% (17% with GMC vs 12% with usual care; OR, 1.5 [95% CI, 0.7-3.3]; P=.33).

To explain a potential mechanism underlying improved BP control in the GMC group, the researchers analyzed patient-reported medication adherence and the patients' perceived competence (ie, self-efficacy). Although there was no between-group difference in adherence (P=.53), the patients in the GMC group had significantly better scores in assessments of perceived competence (P<.001).

The rates of most adverse events were similar between the 2 groups, although fewer patients in the GMC group reported falls or lightheadedness (47% vs 63%; P=.006). In addition, relative to patients in the usual-care group, patients in the GMC group had fewer emergency care visits (1.3 vs 0.9 visits per patient-year; P<.001) and fewer primary care visits (6.2 vs 5.3 visits per patient-year; P=.01).

In a cost analysis, the estimated costs of the GMC intervention, which were calculated in 2009 dollars and included costs of labor associated with group sessions and follow-up calls as well as nurse training costs, totaled $460 (range, $393-$554) per patient per year.

"[T]he reductions in emergency and primary care visits may offset the costs of the intervention," the authors concluded. "If found to be cost-effective and efficient, GMCs could be implemented in a wide range of settings and become important in the remodeling of long-term care in the United States." (Edelman D, et al. Ann Intern Med 2010;152:689-696.)

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