Do interviewer attitudes to data linkage influence respondents' consent to linkage? Analysis of Understanding Society.

BACKGROUND Variable consent rates threaten the validity of linked datasets. One modifiable element is the interviewer-respondent relationship. We examine interviewer attitudes to consent to linkage and the effect on respondent consent. METHODS Subjects were 27 380 respondents from the Wave 1 Understanding Society (US) survey in Great Britain and 449 interviewers who completed the US Interviewer Survey. Two types of consent were considered: (i) whether the interviewer would hypothetically agree to having their data linked if he/she was an US respondent and (ii) whether the respondent consented to have their data linked. Factors influencing the interviewer's propensity to link data were examined using logistic regression. The association between interviewer consent and respondent consent to health record linkage was assessed using multi-level logistic regression models. RESULTS The interviewer's propensity to consent to data linkage was strongly positively associated with its perceived usefulness: those that found it somewhat useful were 57% less likely to consent [adjusted odds ratio (AOR) 0.43, 95% CI: 0.22-0.82] compared to those who thought it was very useful. Positive beliefs about data security and their ability to understand the data linkage information were also associated. Respondents were 17% less likely to consent when interviewed by an interviewer who would not consent to record linkage (AOR 0.83, 95% CI: 0.71-0.97). CONCLUSIONS The interviewer's propensity to consent was influenced by their beliefs about data linkage, which in turn influenced respondent consent. We recommend using interviewer training to emphasize the usefulness of data linkage and the measures around data security.