Patients completed an 8-item instrument assessing satisfaction with their primary healthcare experiences. The scale was previously adapted from the 2007 Health Information National Trends Survey (HINTS). In the pre-intervention survey autistic participants were asked to think about their last visit with their primary care provider. We did not assess patient-provider communication for those who were participating via a proxy as we did not feel that a proxy could adequately rate how satisfied the patient was with communication. Only autistic participants who said they had seen their PCP since using the healthcare toolkit were re-asked these items in the post-intervention survey. Responses used a 5-point Likert scale with anchors of "1 - Strongly Disagree" to "5 - Strongly Agree". We analyzed items by summing the responses into a composite score (range 8-40; higher scores indicate higher satisfaction). Cronbach's alpha = 0.92.

Autistic participants were presented with a list of 16 barriers to healthcare and asked which ones keep them from obtaining good care. We compared the total number of barriers endorsed by participants in the pre- and post-intervention surveys. The proxy version of the survey included a few modified items to differentiate between barriers faced by the autistic individuals and those faced by the supporter. Due to differences in the wording, we could not combine results from those who participated directly with those who participated by proxy. Only data from autistic adults who participated directly is shown.

Autistic participants completed a 21-item healthcare self-efficacy scale before and 1 month after use of the toolkit. The scale was created de novo for this study, based on our prior qualitative work. Items addressed aspects related to healthcare navigation (e.g. "How confident are you that you can make an appointment with your healthcare provider when needed?"), successful interactions with providers, (e.g. "How confident are you that you can describe your symptoms or healthcare concerns to your provider?"), and self-management (e.g. "How confident are you that you can take medications the way you are supposed to take them?"). Response options used a 4-point Likert scale with anchors of "0 - Not at all confident" to "3 - Totally confident". We scored self-efficacy by adding responses from the 21 items, resulting in a possible range of 0 to 63, with higher scores corresponding to higher self-efficacy. Cronbach's alpha was 0.92.

Total of all reporting groups

Providers participated in a brief survey to assess satisfaction with the toolkit. Items addressed overall satisfaction and if they would or would not use the tools with other patients.

Participants' primary care providers. Primary care providers were included in the study to assess their impression of the toolkit, but all other outcomes (e.g. change in barriers, self-efficacy, or satisfaction with healthcare) only apply to the autistic participants, not their primary care providers.

We collected data on whether or not participants completed the Autism Healthcare Accommodations Tool (AHAT) survey and whether or not they allowed the research team to send a copy of the report to their primary care provider.

Patients completed an 8-item instrument assessing satisfaction with their primary healthcare experiences. The scale was previously adapted from the 2007 Health Information National Trends Survey (HINTS). In the pre-intervention survey autistic participants were asked to think about their last visit with their primary care provider. We did not assess patient-provider communication for those who were participating via a proxy as we did not feel that a proxy could adequately rate how satisfied the patient was with communication. Only autistic participants who said they had seen their PCP since using the healthcare toolkit were re-asked these items in the post-intervention survey. Responses used a 5-point Likert scale with anchors of "1 - Strongly Disagree" to "5 - Strongly Agree". We analyzed items by summing the responses into a composite score (range 8-40; higher scores indicate higher satisfaction). Cronbach's alpha = 0.92.

Autistic adults who participated directly (not via a proxy) and who saw their provider in the 1 month between when they participated in the baseline assessment and they completed the post-intervention survey.

Autistic participants were presented with a list of 16 barriers to healthcare and asked which ones keep them from obtaining good care. We compared the total number of barriers endorsed by participants in the pre- and post-intervention surveys. The proxy version of the survey included a few modified items to differentiate between barriers faced by the autistic individuals and those faced by the supporter. Due to differences in the wording, we could not combine results from those who participated directly with those who participated by proxy. Only data from autistic adults who participated directly is shown.

Participants completing the pre and post-test themselves (not via a supporter).

Autistic participants completed a 21-item healthcare self-efficacy scale before and 1 month after use of the toolkit. The scale was created de novo for this study, based on our prior qualitative work. Items addressed aspects related to healthcare navigation (e.g. "How confident are you that you can make an appointment with your healthcare provider when needed?"), successful interactions with providers, (e.g. "How confident are you that you can describe your symptoms or healthcare concerns to your provider?"), and self-management (e.g. "How confident are you that you can take medications the way you are supposed to take them?"). Response options used a 4-point Likert scale with anchors of "0 - Not at all confident" to "3 - Totally confident". We scored self-efficacy by adding responses from the 21 items, resulting in a possible range of 0 to 63, with higher scores corresponding to higher self-efficacy. Cronbach's alpha was 0.92.

Participants completing pre- and post-intervention survey themselves (not via a supporter), who had complete data on the self-efficacy scales on both surveys.

Primary care providers of autistic adults participating in the study.