Post-Hoc Enthusiasm and Wariness (PHEW)

The post-hoc fallacy (also termed the post-hoc-ergo-propter-hoc fallacy) has been recognized for centuries with endless relevance. The general concept in medical care is that patients who improve after a treatment are not necessary patients who improve because of a treatment. Modern medicine provides multiple opportunities to examine such pitfalls of judgment due to the prevailing uncertainty, incompleteness of our understanding pathogenic mechanisms, and natural tendency to connect treatments to outcomes. In this study, we will investigate whether judgments about vitamin supplementation might demonstrate the post-hoc fallacy.

Study Overview

• Status: Not yet recruiting
• Conditions: Health Behavior
• Intervention / Treatment: Other: Patient self-report

Detailed Description

We plan to conduct a brief survey of pharmacies portraying a patient in two slightly different versions. One version will portray the patient who feels better after starting a vitamin supplement whereas another version will portray the patient who feels unchanged after starting a vitamin supplement. The patients will be randomly assigned to participants and otherwise contain identical information. Judgments will be measured by eliciting participants recommendation about continuing the vitamin (Appendix_Script).

• Study Type: Interventional
• Enrollment (Anticipated): 100
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Donald A Redelmeier, MD, MSc; Phone Number: 4164806999; Email: dar@ices.on.ca

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Community pharmacist

Exclusion Criteria:

• Outside Ontario

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Health Services Research
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Success; Symptomatic improvement present	Other: Patient self-report; Simulated patient following structured script
Experimental: Failure; Symptomatic improvement absent	Other: Patient self-report; Simulated patient following structured script

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Response variable in each survey is a binary recommendation whether to continue the vitamin supplement or discontinue the vitamin supplement	Health provider clinical recommendation	Short-term (less than 5 minutes)

Collaborators and Investigators

• Sponsor: Sunnybrook Health Sciences Centre
• Investigators: Principal Investigator: Donald A Redelmeier, MD, MSc, Sunnybrook Health Sciences Centre

Study record dates

Study Major Dates

• Study Start (Anticipated): May 1, 2023
• Primary Completion (Anticipated): September 1, 2023
• Study Completion (Anticipated): September 1, 2028

Study Registration Dates

• First Submitted: January 7, 2023
• First Submitted That Met QC Criteria: January 7, 2023
• First Posted (Estimate): January 16, 2023

Study Record Updates

• Last Update Posted (Estimate): January 16, 2023
• Last Update Submitted That Met QC Criteria: January 7, 2023
• Last Verified: January 1, 2023

More Information

Terms related to this study

• Other Study ID Numbers: 5692

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No