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

Study type

• Study topic:
  Disease /health condition

  Human medicinal product
• Study type:
  Non-interventional study
• Scope of the study:
  Drug utilisation
• Data collection methods:
  Secondary use of data

Non-interventional study

• Non-interventional study design:
  Cohort

Study drug and medical condition

• Anatomical Therapeutic Chemical (ATC) code:
  (C02N) COMBINATIONS OF ANTIHYPERTENSIVES IN ATC-GR. C02

  COMBINATIONS OF ANTIHYPERTENSIVES IN ATC-GR. C02

  (C03) DIURETICS

  DIURETICS

  (C07A) BETA BLOCKING AGENTS

  BETA BLOCKING AGENTS

  (C08) CALCIUM CHANNEL BLOCKERS

  CALCIUM CHANNEL BLOCKERS

  (C09) AGENTS ACTING ON THE RENIN-ANGIOTENSIN SYSTEM

  AGENTS ACTING ON THE RENIN-ANGIOTENSIN SYSTEM
• Medical condition to be studied:
  Hypertension

Population studied

• Short description of the study population:
  Newly diagnosed and treated hypertensive patients in the primary care units of Region of Lisbon and Tagus Valley during the first trimester of 2011.
• Age groups:
  • Adult and elderly population (≥18 years)

    • Adults (18 to < 65 years)

      • Adults (18 to < 46 years)
      • Adults (46 to < 65 years)
    • Elderly (≥ 65 years)

      • Adults (65 to < 75 years)
      • Adults (75 to < 85 years)
      • Adults (85 years and over)
• Special population of interest:
  Other
• Special population of interest, other:
  Hypertensive patients
• Estimated number of subjects:
  10204

Study design details

• Main study objective:
  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.
• Outcomes:
  Patterns in initiation, implementation and discontinuation of antihypertensive therapy. The secondary objective is to identify risk factors for non-adherence.
• Data analysis plan:
  Initiation will be quantified as the proportion of patients not exceeding a 180-day period after index prescription. Will be analyzed using standard survival analysis. Implementation will be quantified by estimation of MPR, expressed as the number of days' suplly obtained during observation period/number of days in the observation period. For patients receiving multiple drugs, MPR will be calculated for each drug separately, and the overall MPR will be the mean of the individual values. A threshold of 80% will be used to dichotomize between good and poor implementation. Logistic regression will be used to estimate relative risk with 95% CI for poor implementation. Persistence will be quantified as the proportion of patients not exceeding the maximum allowed treatment gap during follow-up. Kaplan-Meier analysis will be used to calculate persistence and 95% CI after 1 and 2 years. Cox proportional hazard regression will be used to estimate hazard ratios of predictors for discontinuation.