The community survey included basic demographic questions including age range, sex, postcode, education level and employment status. In addition, the community survey included questions related to high BP control and preferences for accessing information related to high BP. Participants from the Australian general public were also asked if a doctor had previously told them they had high BP, if they were currently taking medication for high BP and how often they take their BP medication.

The GP survey was sent to currently practising GPs and included questions on GP demographics, concerns for BP management, currently used information sources, and preferred formats for education and information dissemination about high BP.

The survey questions were developed by the investigator team and revised based on feedback from colleagues including those with qualitative research experience. In addition, the survey questions were piloted among a general public consumer representative and a GP. The surveys were delivered online and promoted via email and social media to members of the Australian public via the High Blood Pressure Research Council of Australia (HBPRCA), the Australian Cardiovascular Alliance memberships, Kidney Health Australia, Heart Foundation, and Stroke Foundation communication channels between November 2020 and April 2021. Anonymous data were collected using REDCap, a secure online web application. This project was approved by the Alfred Hospital human research ethics committee (HREC number 630/20), and all participants provided informed consent to take part in the study.

The survey was promoted to the general public and general practitioners via social media via generic invitation (see Supplementary material 1) from November 2020 to January 2021. Supporting organisations (Australian Cardiovascular Alliance, Kidney Health Australia, Heart Foundation and Stroke Foundation) supported the promotion of the survey via social media using a snowball method of tagging, liking and sharing posts. Three social media posts were shared for the general public survey and two posts were shared for the GP survey between November 2020 and February 2021. A preliminary analysis of responses was undertaken in December 2020 with a final generic invitation posted to social media in February 2021 (no additional responses were received from the final invitation). In addition, Primary Health Networks were contacted to share the invitation to GPs through their networks. Both surveys were closed by April 2021. Neither general public nor GP participants were offered any incentive to complete the survey.

To identify knowledge gaps to inform content needs, participants from the general public were asked to select their concerns related to high BP using a Likert scale ranging from “most concern” through to “least concern”. GPs were asked to select the area of most concern related to BP control using a Likert scale ranging from ‘no concern’, through to “very concerned”. GPs were also asked to select areas that they would like more information related to BP management (e.g., the relationship between BP thresholds and individual risk factors). See Supplementary Table 1 for the questions used in both surveys.

Participants from the general public were asked to select all sources they currently use to access information related to BP including social media, family or friends, their doctor and other health organisations. These participants were also asked to select all sources that they would prefer to access information related to BP management in the future. GPs were asked to select the information sources that they were most likely to use for BP control according to a Likert scale ranging from ‘most likely’, to ‘least likely’ and to select all formats they would prefer to access information in the future (Supplementary Table 1).

Statistical analyses were performed in Stata version 16.1 (StataCorp, USA). Frequencies were completed to summarise the responses to the survey. In general, data are presented as number and percentage. GraphPad Prism (version 8) was used for creating the figures.