Among 10 PCPs, 200 adult smokers with an active patient portal who had been seen by a PCP within 12 months were randomly selected and randomly assigned to one of four conditions to compare the quit attempts of patients sent electronic outreach with and without asynchronous care link and to compare the quit attempts of patients who recieved the portal message from PCP or the health system.

The investigators compared the effects of four technology-based smoking cessation messaging strategies on quit attempts by smokers identified in the health system. Specifically, investigators used a fully crossed between-subjects 2 (link to survey on smoking cessation guide: yes/no) × 2 (message source: PCP-generated vs. health system-generated) experimental design to which participants were randomly assigned to one of four intervention groups using a computerized random number generator:

• Group 1 was sent the message from their physician without a link to a survey;
• Group 2 was sent the message from their physician with the link to the survey (which constitutes the asynchronous care);
• Group 3 was sent the message from the health system without a link to the survey; and
• Group 4 was sent the message from the health system with the link to the survey (which constitutes the asynchronous care).

Electronic outreach was a message sent to patients via the patient portal. It encouraged a quit attempt; offered physician assistance; advised the patient on medication use to control cravings; and offered counseling support in the form of a Quitline. Patients in Groups 1 and 3 were invited to schedule an in-person appointment with their PCP if they wanted help. Patients in Groups 2 and 4 received the message with an embedded link to Tobacco Cessation Survey to receive PCP assistance asynchronously. If patients clicked through to access the survey, they answered 17 questions, confirming smoking status, reporting safety information for medication selection, describing prior quit attempts and sharing treatment preferences. The intervention was "asynchronous" because it did not involve direct, simultaneous interaction (e.g., face-to-face, chat, video conference) between the physician and the patient. After patient responses were submitted, they were stored and forwarded to their PCP. Physicians communicated the care plan and instructed patients via the portal message. If the plan included medication, a prescription was sent to the patient's EHR-documented preferred pharmacy without an in-person visit.

Inclusion Criteria:

• Adults aged 18 years and older who were designated as a smoker in the EHR who had at least one face-to-face visit with their PCP in the prior 12 months and had a patient portal account
• To ensure equal representation across the 10 physicians, we randomly selected 20 patients under each physician to serve in the sample.

Exclusion Criteria:

• Patients were excluded if they no longer see the PCP, had a diagnosis for which the outreach program would be insensitive (e.g., lung cancer), previously expressed not wanting smoking cessation counseling, or were no longer a smoker.
• (Patients were post-hoc excluded if EHR indicated that they had received smoking cessation treatment 60 days prior to portal message intervention.)

Participants: The patients were not informed of other portal messages. The portal message they received (if it had a link to asynchronous care or not and if it was sent by physician or system) was determined by random assignment.

Care Providers: After reviewing patients for exclusion criteria, the physicians were not informed which intervention group patients were assigned. They knew who was selected for the study and then those patients were randomly assigned to intervention groups by computerized randomization system.

Investigators: The data was extracted from the EHR and de-identified prior to sharing it with the investigators. Therefore, the investigators were blind to patients and patient assignment.

Outcomes Assessor: Outcomes were assessed only from de-identified data.