Abstract Background There are numerous challenges in including patients in a core outcome set (COS) study, these can vary depending on the patient group. This study describes current efforts to include patients in the development of COS, with the aim of identifying areas for further improvement and study. Methods Using the COMET database, corresponding authors of COS projects registered or published from 1 January 2013 to 2 February 2017 were invited via a personalised email to participate in a short online survey. The survey and emails were constructed to maximise the response rate by following the academic literature on enhancing survey responses. Personalised reminder emails were sent to non-responders. This survey explored the frequency of patient input in COS studies, who was involved, what methods were used and whether or not the COS development was international. Results One hundred and ninety-two COS developers were sent the survey. Responses were collected from 21 February 2017 until 7 May 2017. One hundred and forty-six unique developers responded, yielding a 76% response rate and data in relation to 195 unique COS (as some developers had worked on multiple COS). Of focus here are their responses regarding 162 COS at the published, completed or ongoing stages of development. Inclusion of patient participants was indicated in 87% (141/162) of COS in the published completed or ongoing stages and over 94% (65/69) of ongoing COS projects. Nearly half (65/135) of COS included patient participants from two or more countries and 22% (30/135) included patient participants from five or more countries. The Delphi survey was reported as being used singularly or in combination with other methods in 85% (119/140) of projects. Almost a quarter (16/65) of ongoing studies reported using a combination of qualitative interviews, Delphi survey and consensus meeting. Conclusions These findings indicated that the Delphi survey is the most popular method of facilitating patient participation, while the combination of qualitative interviews, Delphi survey and consensus meetings is the most popular combination of methods. The increased inclusion of patient participants in the development of COS is encouraging, as is the international approach to COS development that some developers are adopting.