title: Requesting a unique personal identifier or providing a souvenir incentive did not affect overall consent to health record linkage: evidence from an RCT nested within a cohort.
abstract: OBJECTIVE
  It is unclear if unique personal identifiers should be requested from participants for health record linkage: this permits high-quality data linkage but at the potential cost of lower consent rates due to privacy concerns.
  
  
  METHODS
  Drawing from a sampling frame based on the FAMILY Cohort, using a 2 × 2 factorial design, we randomly assigned 1,200 participants to (1) request for Hong Kong Identity Card number (HKID) or no request and (2) receiving a souvenir incentive (valued at USD4) or no incentive. The primary outcome was consent to health record linkage. We also investigated associations between demographics, health status, and postal reminders with consent.
  
  
  RESULTS
  Overall, we received signed consent forms from 33.3% (95% confidence interval [CI] 30.6-36.0%) of respondents. We did not find an overall effect of requesting HKID (-4.3%, 95% CI -9.8% to 1.2%) or offering souvenir incentives (2.4%, 95% CI -3.1% to 7.9%) on consent to linkage. In subgroup analyses, requesting HKID significantly reduced consent among adults aged 18-44 years (odds ratio [OR] 0.53, 95% CI 0.30-0.94, compared to no request). Souvenir incentives increased consent among women (OR 1.55, 95% CI 1.13-2.11, compared to no souvenirs).
  
  
  CONCLUSIONS
  Requesting a unique personal identifier or providing a souvenir incentive did not affect overall consent to health record linkage.
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 7 Sassoon Road, Hong Kong, China. Electronic address: nimy@hku.hk.
authors.forename: Michael Y
authors.initials: MY
authors.lastname: Ni
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 7 Sassoon Road, Hong Kong, China.
authors.forename: Tom K
authors.initials: TK
authors.lastname: Li
authors.affiliation: Li Ka Shing Faculty of Medicine, The University of Hong Kong, 7 Sassoon Road, Hong Kong, China.
authors.forename: Rex W H
authors.initials: RWH
authors.lastname: Hui
authors.affiliation: School of Epidemiology, Public Health and Preventive Medicine, University of Ottawa, 600 Peter Morand Crescent, Ottawa, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: McDowell
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 7 Sassoon Road, Hong Kong, China.
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Leung
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007258:Informed Consent / Q000706:statistics & numerical data*; D008297:Male; D008498:Medical Record Linkage / Q000379:methods*; D016347:Medical Records Systems, Computerized / Q000706:statistics & numerical data*; D008875:Middle Aged; D009042:Motivation; D016032:Randomized Controlled Trials as Topic; D012737:Sex Factors; D055815:Young Adult
keywords: Consent; Data linkage; Health record linkage; Incentive; Randomized; Unique identifier