Table 1.

Quitline treatment as usual (TAU) and enhanced E-cigarette coaching (EEC) treatment elements.

Call Number	Quitline TAU (control)	Enhanced E-cigarette Coaching (EEC) Intervention
Every call	Intervention grounded in social cognitive theory and US PHS clinical guidelines. Assessment of current status and challenges. Modify medications or set new quit date if needed.	Quitline TAU components PLUS behavioral support and education regarding e-cigarette use, EEC educational booklets referenced.
Call 1: Assessment & Planning	Program overview, assessment and planning with focus on setting a quit date, cessation medications, urge management, tobacco proofing and support. Quit Guide mailed.	(1) Assessment of e-cigarette use and intentions for use, (2) Education on relative harms of e-cigarettes, NRT and cigarettes, and (3) shared decision making (SDM) on use of e-cigarettes and FDA-approved cessation medications in quit plan. Tailored EEC educational booklet #1 mailed to participant.
Call 2: Quit date	Discuss quit date preparation, reinforce quit plan, set new quit date if needed.	Reinforce QP including use of e-cigarettes and/or medications. Tailored EEC educational booklet #2 mailed to participant.
Calls 3–5: Quit date follow-up	ACE model of relapse prevention (avoid, cope, escape), social support, tobacco proofing.	If currently using e-cigarettes: (1) behavioral coaching to use e-cigarettes/NRT to prevent relapse to smoking, (2) address intentions for long-term use of e-cigarettes.
NRT provision	Same for both groups. All are eligible for 2–8 weeks of NRT (depending on insurance status)
NRT dosing	Typically based on CPD prior to start of dual use, but also utilizes quit coach judgement guided by an established dosing protocol. Strongly encourages stopping all non-NRT forms of nicotine (including e-cigarettes) on quit date.	Participants will work with coaches using SDM to determine plans for e-cigarettes and NRT use while quitting. NRT dosing will be adjusted if participants plan to continue e-cigarette use. Coaches will assess potential side effects and quit plan adherence on every call and make needed adjustments to the QP or NRT dosing.