Adherence to antihypertensive therapy: analysis of initiation, implementation, discontinuation and possible risk factors in Portuguese primary care units

Study identification

• EU PAS number:
  EUPAS7757
• Study ID:
  16947
• Official title and acronym:
  Adherence to antihypertensive therapy: analysis of initiation, implementation, discontinuation and possible risk factors in Portuguese primary care units
• DARWIN EU® study:
  No
• Study countries:
  Portugal
• Study description:
  Non-adherence to antihypertensive therapy is an important component of preventable cardiovascular morbidity and mortality, mostly relevant in the case of a recent diagnosis or prescription of new antihypertensive drugs. It has been estimated that up to 30% of patients fail to initiate prescribed therapy and that during the first year of treatment up to 50% of patients discontinue their therapy. The main objective of the study is to determine adherence to antihypertensive therapy in newly treated hypertensive patients in primary care units from Region of Lisbon and Tagus Valley. The secondary objective is to identify risk factors for non-adherence. We will conduct an observational retrospective cohort study. The study population is formed by all newly diagnosed and treated hypertensive patients in the primary care units of Region of Lisbon and Tagus Valley during the first trimester of 2011. Prescription and claims data will be collected from SIARS for each patient during a follow-up of 2 years after index date and a run-in period of 6 months. Initiation is determined by picking-up the first prescription in a pharmacy within a 180-day period. Implementation of therapy is measured with Medication Possession Ratio and persistence, as a measure of the duration of time from initiation to discontinuation is determined by refill persistence according to a maximum allowed treatment gap of 90 days. This allows us to separate the population in two cohorts: adherents and non-adherents. Differences between the two groups will be handled by logistic regression. Little is known in Portugal about adherence to antihypertensive therapy, especially at a population level. To our best knowledge this will be the first study in the country to measure medication adherence with prescription and claims data. Data emerging from this study will hopefully allow a framework to identify patients at risk for non-adherence is its different manifestations and develop strategies to reduce that risk.
• Study status:
  Finalised

Research institutions and networks

Institutions

Chronic Diseases Research Center of the Faculdade de Ciências Médicas da Universidade Nova de Lisboa (CEDOC/FCM-UNL)

Portugal

Study timelines

Date when funding contract was signed

Planned: 01/09/2014

Actual: 01/09/2014

Study start date

Planned: 15/12/2014

Actual: 15/12/2014

Data analysis start date

Planned: 01/01/2015

Date of final study report

Planned: 30/09/2015

Actual: 31/07/2016

Sources of funding

Other

More details on funding

University

Regulatory

• Was the study required by a regulatory body?:
  No
• Is the study required by a Risk Management Plan (RMP)?:
  Not applicable