The study hypothesis is that the implementation of a plan for quality improvement at the primary care health teams taking care of hypertensive patients, will increase the level of blood pressure control among those patients.

The study is to compare the results on the hypertension control between two groups of primary health care teams. The intervention group will undertake a quality improvement plan for hypertension control, in which the following aspects will be included in the intervention:

Specific training programme on how to diagnose hypertension , and measure blood pressure correctly To send feed back information to primary care health professionals about poorly controlled hypertensive patients An audit will be performed, every 6 months, to see the adhesion to the recommended clinical guidelines , and the information will be diffused among the participant primary health care professionals Each participant primary health care team will have a designated reference person, that will provide support on any doubts on the programme implementation.

The non intervention group will follow hypertensive patients following the same clinical practice guide as the intervention group, with no intervention on the primary health care professionals

Inclusion Criteria:

• Patients diagnosed with hypertension before January 1st, 2006
• Patients assigned at the primary health team participating, and with clinical electronic records

Exclusion Criteria:

• Patients diagnosed with hypertension after January 1st, 2006
• Patients under 18 years of age
• Patients with a diastolic blood pressure higher than systolic blood pressure as recorded in the clinical records