Accepted for/Published in: Journal of Medical Internet Research
Date Submitted: Dec 22, 2025
Date Accepted: Jul 3, 2026
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Practical Fraud Detection and Prevention in Incentivized Online Surveys: Lessons from the ADOPT Study
ABSTRACT
Background:
Digital surveys are increasingly integrated into clinical and public health research to capture patient-reported outcomes. However, concerns about fraudulent or duplicate responses threaten data integrity. Most literature on survey fraud focuses on open-access online recruitment, where bot-generated or anonymous entries are common, but far less is known about fraud patterns in clinic-linked, incentive-based surveys. Evaluations of real-world implementation of fraud deterrence strategies remain limited.
Objective:
This study evaluated whether implementing enhanced fraud deterrence procedures in an incentive-based postoperative survey reduced the prevalence of potentially fraudulent responses. Secondarily, the study evaluated which indicators were most frequently triggered before and after implementation.
Methods:
This evaluation was conducted within the Alternatives to Dental Opioid after Tooth Extraction (ADOPT) study. Eligible patients aged 12-25 years were recruited through QR-coded, clinic-distributed flyers and invitation cards. Participants completed a screening survey followed by an incentivized postoperative survey between days 6-10 after tooth extraction. A mid-study protocol modification introduced enhanced fraud deterrence measures including required phone numbers, prohibiting email invitations, confirming date of birth across projects, and shifting to a manually reviewed participant list with SMS text message invitations. Responses were categorized into “control” (before modification) or intervention (after modification). An eight-item fraud scoring system assessing completion time outliers, late-night submissions, repeated screeners, unusual email formats, repeated phone numbers, impossible logic, blank recruitment source, and illogical response patterns was used to classify responses as potentially fraudulent (≥2 indicators). Sensitivity analyses evaluated thresholds from 1-3 indicators.
Results:
A total of 573 were included (control n=122; intervention n=451). The overall prevalence of potentially fraudulent responses was low (6.8%) and did not differ significantly between cohorts (7.4% vs. 6.7%, p=.778). Certain indicators shifted between cohorts: blank recruitment source declined (12.3% to 4.9%, p=.003), and repeated phone numbers increased (3.0% to 25.1%, p<.001), partly due to the phone number requirement in the intervention survey. No responses exhibited unusual email formats or impossible logic. Sensitivity analyses showed consistent patterns across alternative thresholds.
Conclusions:
Enhanced fraud deterrence procedures did not reduce overall fraud prevalence, but the low baseline rate suggest that clinic-linked, QR-based recruitment with modest incentives may be less susceptible to fraud than open-access online surveys. A transparent scoring system provides a replicable approach for assessing survey integrity and may be preferable to reliance on eligibility gating alone. Clinical Trial: NCT06275191
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