Relationship between initial therapy and blood pressure control for high-risk hypertension patients in the UK: a retrospective cohort study from the THIN general practice database

OBJECTIVE: To examine the UK practice patterns in treating newly diagnosed hypertension and to determine whether subgroups of high-risk patients are more or less likely to follow particular therapeutic protocols and to reach blood pressure goals. DESIGN: Retrospective cohort study. SETTING: This study examined adults in The Health Improvement Network (THIN) UK general practice medical records database who were initiated on medication for hypertension. PARTICIPANTS: 48 131 patients with essential hypertension diagnosed between 2008 and 2010 who were registered with a participating practice for a minimum of 13 months prior to, and 6 months following, initiation of therapy. We excluded patients with gestational hypertension or secondary hypertension. Patients were classified into risk groups based on blood pressure readings and comorbid conditions. PRIMARY AND SECONDARY OUTCOME MEASURES: Odds of receiving single versus fixed or free-drug combination therapy and odds of achieving blood pressure control were assessed using multivariable logistic regression. RESULTS: The vast majority of patients (95.8%) were initiated on single drug therapy. Patients with high cardiovascular risk (patients with grade 2–3 hypertension or those with high normal/grade 1 hypertension plus at least one cardiovascular condition pretreatment) had a statistically significant benefit of starting immediately on combination therapy when blood pressure control was the desired goal (OR: 1.23; 95% CI: 1.06 to 1.42) but, surprisingly, were less likely than patients with no risk factors to receive combination therapy (OR: 0.53; 95% CI: 0.47 to 0.59). CONCLUSIONS: Our results suggest that combination therapy may be indicated for patients with high cardiovascular risk, who accounted for 60.6% of our study population. The National Institute for Health and Care Excellence guideline CG34 of 2006 (in effect during the study period) recommended starting with single drug class therapy for most patients, and this advice does seem to have been followed even in cases where a more aggressive approach might have been considered.