Diagnostic uncertainty and prescription practices among pharmacists

Last registered on May 17, 2025

View Trial History

Pre-Trial

Trial Information

General Information

Title

Diagnostic uncertainty and prescription practices among pharmacists

RCT ID

AEARCTR-0013910

Initial registration date

June 28, 2024

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published

July 01, 2024, 12:58 PM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Last updated

May 17, 2025, 9:05 AM EDT

Last updated is the most recent time when changes to the trial's registration were published.

Locations

Country

Ghana

Region

Greater Accra

Primary Investigator

Name

Jan Priebe

Affiliation

Bernhard Nocht Institute for Tropical Medicine (BNITM)

Contact Primary Investigator

Other Primary Investigator(s)

PI Name

Edward Asiedu

PI Affiliation

University of Ghana

Contact Investigator

PI Name

Christoph Strupat

PI Affiliation

German Institute of Development and Sustainability (IDOS)

Contact Investigator

PI Name

Matthias Rieger

PI Affiliation

Erasmus School of Health Policy & Management

Contact Investigator

Additional Trial Information

Status

In development

Start date

2024-07-02

End date

2025-08-01

Keywords

Health

Additional Keywords

health care, pharmacy, uncertainty, Africa

JEL code(s)

D81, D83, I12

Secondary IDs

Prior work

This trial does not extend or rely on any prior RCTs.

Abstract

Our study aims to explore to what extent diagnostic uncertainty influences treatment choices of pharmacists in urban Ghana. A focus of the study will be to explore how pharmacists’ knowledge and economic preferences (e.g. risk aversion) influence dispensing practices.

External Link(s)

Registration Citation

Citation

Asiedu, Edward et al. 2025. " Diagnostic uncertainty and prescription practices among pharmacists." AEA RCT Registry. May 17. https://doi.org/10.1257/rct.13910-1.1

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

• Vignettes: Individuals will receive 4 vignettes that aim to vary patients’ symptoms to signal more/less clear underlying medical conditions. The order of the vignettes is randomized.
• Audit study: We employ an audit study in which characters portray different systems with characters being linked to diagnostically more or less clear medical conditions. The order of characters visiting pharmacies is randomized.

Intervention (Hidden)

• Vignettes: Individuals will receive 4 vignettes that aim to vary patients’ symptoms to signal more/less clear underlying medical conditions. The order of the vignettes is randomized. Correct answers to the vignettes are financially incentivized.
• Audit study: We employ an audit study in which characters portray different systems with characters being linked to diagnostically more or less clear medical conditions. The order of characters visiting pharmacies is randomized.

Intervention Start Date

2024-08-01

Intervention End Date

2025-07-31

Primary Outcomes

Primary Outcomes (end points)

I) Decision to give and sell antibiotics to patient (binary indicator)
II) Quality of advice related to antibiotics and condition

Primary Outcomes (explanation)

Binary indicators related to (i) antibiotic dispensing practices

Secondary Outcomes

Secondary Outcomes (end points)

Secondary Outcomes (explanation)

Experimental Design

The study employs a within-pharmacists design. Pharmacists receive a set of vignettes and are visited by mystery shoppers. The order of vignettes and of the different mystery shopper characters is randomized. Furthermore, actor-roles are randomized.

Experimental Design Details

Randomization Method

The random assignment will be done by (i) survey software (REDCAP) and (ii) principal investigators (STATA).

Randomization Unit

Pharmacist

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

No clustering.

Sample size: planned number of observations

Original registration: 1,600 (4 observations per pharmacist (N=400). Revised registration: 3,325 (7 observations per pharmacist (N=475))

Sample size (or number of clusters) by treatment arms

Original registration: 800 (2 observations per pharmacist (N=400).
Revised registration: 1662 (2 observations per pharmacy (N=475)).

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Comparison across alternative diagnostic uncertainties: In a basic group means comparison with 80% power, a significance level of 0.05, and 0.8 unit standard deviations, the MDE is 18pp for the total sample of 1,600 observations (4 per pharmacy). (Assumption: Baseline mean of 0.3 & 1 treatment vs. 1 control group comparison). Revised registration: MDE is 7.8pp keeping all parameters as they were except for the newly registered changes in sample size

Supporting Documents and Materials

IRB