Goals and Design of the i24ABC

The i24ABC aims to derive 24 hour ambulatory aortic blood pressure reference standards by pooling (de-identified) data from existing 24 hour ambulatory aortic blood pressure databases around the world – all contributing centres will be those using the most widely available validated monitor, which is the Mobil-o-graph, IEM device.

The overall intent is to establish a once-off pooling of data sets rather than a formal ongoing data registry; however, open calls to new centers, as well invitation to old centers to update their datasets will be decided . Data will be received from willing participants in a deidentifiable form (only re-identifiable by the contributing source if needed) and will include;

  • 24 hour ambulatory aortic (and brachial) blood pressure values (individual data points)
  • Basic demographics (age, sex, height, weight, ethnicity, smoking status)
  • Basic clinical characteristics (lipids, glucose/HbA1c, history of cardiovascular disease [stroke, acute myocardial infarction, peripheral arterial disease], and/or chronic kidney disease, and/or hypertension, and/or diabetes, medications [antihypertensives, statins, antidiabetic]).
  • Follow up data on cardiovascular events will be collected in future calls.

Contributing participants will be asked to send Mobil-O-Graph data files as an encrypted, password protected, HMB file. The individual demographic and clinical characteristics will be sent as a separate encrypted, password protected Excel file (with individual participant identification numbers to coalesce with the HMB file data).

Analysis will be conducted by the collaboration of the chief investigator team. The preliminary analysis plan will involve:

  1. pooling and harmonization of data from different centres;
  2. establishing age and sex-specific reference values based on the healthy subpopulation (i.e. free from established cardiovascular risk factors, use of medication and prior CVD);
  3. investigating diurnal profiles for central haemodynamics in relationship to age / gender / risk factors / comorbidities / established diseases and;
  4. defining the prevalence of aortic white coat and aortic masked hypertension phenomena.
  5. defining the prevalence of novel aortic blood pressure guided phenotypes.

Authorship of papers emanating from the consortium will be offered to contributing participants.

The work of the i24ABC has been ethically approved by the Tasmanian Health and Medical Human Research Ethics Committee (Reference H0015062).