Using self-generated identification codes to match anonymous longitudinal data in a sexual health study of secondary school students: a cohort study.

Publisher: BioMed Central Country of Publication: England NLM ID: 101088682 Publication Model: Electronic Cited Medium: Internet ISSN: 1472-6947 (Electronic) Linking ISSN: 14726947 NLM ISO Abbreviation: BMC Med Inform Decis Mak Subsets: MEDLINE

Original Publication: London : BioMed Central, [2001-

Sexual Health*/statistics & numerical data ; Students*/statistics & numerical data; Humans ; Male ; Female ; Longitudinal Studies ; Adolescent ; Hong Kong ; Prospective Studies ; Schools

Competing Interests: Declarations. Ethics approval and consent to participate: The study was reviewed and approved by the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (reference: UW 19–090). All methods were carried out in accordance with relevant guidelines and regulations. Informed consent to participate in the study was obtained from the parent or legal guardian of the study participants. The schools sent a consent form to all parents at the beginning of the school year, which allowed them to opt out of the evaluation process. Any students whose parents chose to opt out of the evaluation were excluded from this study. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.
Objective: This study aimed to (i) describe the procedures for generating self-generated identification codes (SGICs) in a prospective longitudinal evaluation of a sexual health program for secondary school students in Hong Kong; (ii) outline the matching strategies and processes; (iii) examine rates of successful matching and associated factors; and (iv) compare the responses of participants whose data could be matched to those whose data could not.
Methods: A prospective longitudinal cohort study was conducted. The SGIC comprised a 5-element code with 4 digits and 3 letters. A matching algorithm was developed to link baseline and follow-up data collected from students in Years 1 to 3 (n = 1,064) during the 2019-2020 school year. Matching success and associated factors were analyzed, and responses from matched and unmatched participants were compared.
Results: The rate of perfectly matched cases was 49.06%, while 23.59% were partially matched, and 27.35% were unmatched. Logistic regression analysis revealed that male students (adjusted odds ratio [aOR]: 0.63) and Year 1 students (vs. Year 3; aOR: 0.56) were less likely to be perfectly matched. Compared to unmatched cases, perfectly and partially matched cases were less likely to have missing values and more likely to exhibit positive attitudes toward the sexual health program and related topics, such as the importance of sexual health, equal relationships, and condom use.
Conclusion: The use of SGICs successfully matched approximately 72.65% of the study sample over a one-year period. These findings highlight the potential of SGICs as a tool for longitudinal data matching while underscoring the need for further refinement of code generation processes and matching algorithms to minimize data wastage and improve effectiveness.
(© 2025. The Author(s).)

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Keywords: Adolescents; Anonymity; Cohort studies; Longitudinal study; Self-generated identification codes; Sexual health

Date Created: 20250602 Date Completed: 20250603 Latest Revision: 20250605

20250605

PMC12131654

10.1186/s12911-025-03028-1

40457293