Pivotal Test: WB001

The HAMD is a 17-item, clinician rated measure of depression. Each item is scored from 0 to 2 and assesses the following criteria: insomnia, somatic symptoms, genital symptoms, loss of weight, and insight. The total score is calculated as a sum and ranges from 0 to 52, with higher scores indicating a greater degree of depression. The HAMD is commonly used for diagnostic purposes in research; structured clinical interviews such as this are recommended to actually diagnose clinical depression. It will be the primary outcome measure.

Questions assessing current and previous therapy, medication and diagnoses.

The Edinburgh Postnatal Depression Scale (EPDS) is a validated screening for depressive symptomatology among women who have recently given birth. The instrument is recommended by the American College of Obstetricians and Gynecologists for postnatal depression screening for all postpartum individuals. It has 10 items that are scored on a 0-3 basis. For the purpose of this study item number 10 that inquires about suicidal ideation, was omitted. A total EPDS score will be utilized. A total score of 10 indicates possible depression and the maximum achievable is 30.

The 8-item PHQ is an abbreviated version of the PHQ-9, will be used to assess mood and anxiety symptoms respectively. The PHQ-9 is a widely used self-report measure, with demonstrated reliability and sensitivity to clinical change. The PHQ-8 excludes an item assessing suicidality.

The Generalized Anxiety Disorder 2-item scale (GAD-2) is a 2-item version of the GAD-7, a brief self-report tool to assess the frequency and severity of anxious thoughts and behaviors over the past 2 weeks. The correlation coefficient between the two measures was r=.75.

The MIB consists of 8 one-word items describing an emotional response, such as ''loving'' or ''disappointed." Mothers rate the degree they feel the emotional response with their infant using a 4-point Likert scale from very much=0 to not at all=3. Five items describe negative emotional responses and are reverse scored. Total scores can range from 0 to 24, with lower scores indicating good bonding. Mother-infant bonding has been shown to be positively correlated with postpartum depression scores, where lower MIB are associated with lower depression scores.

The PROMIS is a measure that evaluates and monitors physical, mental, and social health in adults and/or children. It can be used with the general population as well as with those living with chronic conditions. Each question has five response options ranging in value from 1-5. The total score is calculated by summing all items. Higher scores equal more of the concept being measured (e.g., more Fatigue, more Physical Function).

The MHSES was developed following Bandura's guidelines for constructing self-efficacy scales24. The six items assess confidence in managing stress, depression and anxiety, and are scored on a 10 point Likert scale (from 1, not at all confident to 10, very confident). Ratings across the 6 items are summed for an overall measure of MHSE (range 10 to 60), with higher scores indicating more self-efficacy. This measure is included as a way to capture an individual's confidence that they can successfully manage their mental health concerns.

The CSQ-8 is an 8-item measure used to assess client's satisfaction with treatment on a 4-point scale (1= "very dissatisfied" to 4= "very satisfied") [15, 22] will be utilized starting at week 2 and continuing biweekly thereafter. Example questions include, "how would you rate the quality of service you received?" and "did you get the kind of service you wanted?" Total sums range from 8-32, with high scores indicating greater satisfaction with Woebot. The CSQ-8 has been widely disseminated and considered both valid and reliable (α ranges= .83-.93).