Racial Disparities in Antidepressant Treatment After a Psychiatric Consultation

Overall Design:

The research design of this study combines two online questionnaires, a semi-structured qualitative interview (for a subset of participants), and a structured chart review. All participants who provide consent to participate in the study will be emailed the first online questionnaire a few days later and then the second online questionnaire three months after they have completed their consult. Twenty-four of these participants will also be invited to participate in the semi-structured qualitative interview in addition to the online questionnaires. The participants will have to complete the second online questionnaire prior to the qualitative interview. Chart review will be performed in all participants. Chart review will occur in parallel with the online questionnaires and the interview.

Participants will be recruited from the Centre for Addiction and Mental Health (CAMH) among patients: (1) diagnosed with depression during a one-time psychiatric consultation; (2) who either assent to be contacted regarding potential participation in research during their CAMH consultation, or who have indicated their agreement to be contacted regarding potential participation in research during the CAMH registration process. Potential participants will also be referred to the study by psychiatrists at CAMH after the patient completes a one-time outpatient psychiatric consultation if they assent to be contacted by the research team. Psychiatrists at CAMH will also be provided with REB-approved recruitment pamphlets to give to patients who express an interest in participating in the study, after which the patients can contact the research team directly if they are interested using the contact information provided in the pamphlet.

Shortly after the consultation is completed, potential participants will be contacted to confirm their interest in participation and to obtain informed consent. Shortly after, the participants will be emailed a link to complete a baseline 20-40 minute REDCap online questionnaire. The first online questionnaire will have two parts, the first part including questions about demographic information and the second part including clinical status and previously validated scales. Also, using a structured form adapted from another study conducted at CAMH, the participants' electronic health records will be reviewed to determine the content, structure, and length of the consultation note, the diagnoses given during the consultation, and treatment recommendations, including pharmacological (i.e., names and dosages of psychotropic medications) and non-pharmacological recommendations. Three months after they complete the psychiatric consultation, the participants will be emailed a link to complete the second 10- 20 minute REDCap online questionnaire, assessing treatment processes and outcomes.

In addition, a subgroup of 24 participants will be invited complete a semi-structured qualitative interview after they complete the second survey (using Webex). The participants will have to complete the second online questionnaire prior to the interview. All participants will be invited to take part in both the online questionnaires and the interview at the beginning of the study. This will continue until 12 participants who self-identify as BIPOC and 12 participants who self-identify as White have completed the interview.

Participant Recruitment and Screening:

The target is to have 50 - 100 participants completing the questionnaires, of which half will be participants who self-report as being from BIPOC communities. Invitation to participate in the interview will be offered to all participants from the beginning until 12 participants who self-identify as BIPOC and 12 participants who self-identify as White have completed it.

All potential participants will be contacted by phone by an investigator or a Research Analyst (RA) to screen for eligibility criteria and engage them in a consent discussion.

Sample Size Determination:

Assuming that there will be a 20 - 40% difference between participants who are from BIPOC communities and participants who are White in treatment outcomes (Kales et al., 2013; Simon et al., 2015), α = 0.05, power = 80%, sample size between 46 - 186 participants is sufficient to detect a between-group difference.

A systematic review of qualitative studies reported that the average sample size to reach saturation is 12-13 for homogeneous populations (Hennink \& Kaiser, 2022). As the study will consist of at least 2 distinct populations (participants who are White vs. from BIPOC communities), 12 participants from each group is sufficient.

Statistical Methods:

Between-group analyses will be performed by comparing White participants vs. participants from BIPOC communities. If there is a sufficient number of participants from a specific race/ethnicity to perform between-group analyses, secondary analyses will be performed by treating them as a separate group (e.g., White vs. Asian-South vs. Others).

Logistic regression analyses will be used to examine if there is an interaction effect between race/ ethnicity and potential moderators on observed racial disparities in treatment processes. Self-reported gender, annual income, any experience of discrimination in medical settings (DMS scale answer rarely or higher in any of the items), and having a negative perception of antidepressant treatment (Brief IPQ item 4 score < 5) will be explored as potential moderators.

Control of Bias:

Interviewer bias may occur during the semi-structured qualitative interview if the interviewer becomes aware of the participant's race/ ethnicity. To minimize this, interviewers will be unaware of the results of the REDCap questionnaires containing the race/ ethnicity information. Furthermore, interviewers will have a script they have to adhere to.