Two apps battle to help smokers kick the habit

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age 18 or older * Currently smoke, averaging at least 5 cigarettes/day for the last 30 days * Interested in quitting smoking in the next 30 days * Experience downloading and using one or more apps on their smartphone * Either screens negative for depression (Patient Health Questionnaire - 9 item \[PHQ-9\] score 0-4; n = 906) or screens positive for mild to moderately severe current depressive symptoms (PHQ-9 score 5-19; n = 906) * Willing and able to complete all study activities and to receive compensation by mail * Comfortable reading and writing in English * Have a mobile data plan and/or access to WiFi to support the use of the assigned app * Reside in the United States (US) * Willing to provide information for an emergency contact in case of serious concerns about the participant's physical or mental health Exclusion Criteria: * Self-report of currently receiving behavioral treatment for depression (e.g., psychotherapy or counseling, web- or app-based interventions); current use of pharmacotherapy for depression or for other mental health conditions that are not otherwise excluded is allowable (e.g., benzodiazepines, anticonvulsants, opioid agonists, antipsychotics) * Severe depression (PHQ-9 ≥ 20) * Current suicidal ideation reported on the PHQ-9 * History of a suicide attempt * Self-reported lifetime diagnosis of bipolar disorder, schizophrenia, schizoaffective disorder, antisocial personality disorder, or borderline personality disorder; or self-reported lifetime diagnosis of an alcohol or drug use disorder with use of the substance(s) in the past 30 days * Currently receiving other smoking cessation treatments, including pharmacotherapies (nicotine replacement therapy, bupropion, or varenicline) and behavioral interventions (e.g. quitline counseling, other digital health programs), but excluding electronic (e)-cigarettes/vaping * Previous use of the QuitGuide program * Employees/family of investigator or study center * Member of the same household as another participant * Woman who is pregnant or breastfeeding, or planning to become pregnant * Having a Google voice number as their primary phone number (due to association with fraudulent study entry attempts in our previous work) * Currently incarcerated * Participated in earlier studies to develop the Actify! app