Patterns of Consent in Epidemiologic Research: Evidence from Over 25,000 Responders

Abstract

Ethical guidelines in the United Kingdom require written consent from participants in epidemiologic studies for follow-up or review of medical records. This may cause bias in samples used for follow-up or medical record review. The authors analyzed data from seven general population surveys conducted in the United Kingdom (1996-2002), to which over 25,000 people responded. Associations of age, gender, and symptom under investigation with consent to follow-up and consent to review of medical records were examined. Consent to follow-up was approximately 75-95% among survey responders under age 50 years but fell among older people, particularly females. Consent to follow-up was also higher among responders who had the symptom under investigation (pooled odds ratio = 1.61, 95% confidence interval: 1.36, 1.92). Consent to review of medical records followed a similar pattern. Patterns of consent were relatively consistent and represented a high proportion of responders. Males, younger people, and subjects reporting the symptom under investigation were more likely to give consent, and these groups may be overrepresented in follow-up samples or reviews of medical records. Although consent is high among responders, the additive effect of nonresponse and nonconsent can substantially reduce sample size and should be taken into account in epidemiologic study planning.

Large panel-survey data demonstrated country-level and ethnic minority variation in consent for health record linkage

“…We found the highest consent rate in the 16-24 age range, with little difference across the rest of the age spectrum, and although the association between age and consent in other studies has been inconsistent [38], this may reflect a greater willingness to share information secondary to greater exposure to and use of social media among this age group. The study also confirms the positive association between poorer health and consent to record linkage [14,30], which may arise because individuals with poor health, who are utilising the health service, can readily appreciate the benefits of linkage or want to give something back to the service.…”

“…Participation bias has been reasonably well characterised, and studies have demonstrated that respondents participating in surveys are more likely to be female [14]; be of higher socioeconomic status and employed [15][16][17]; and to be educated [18] and married [15,18]. Some authors have found higher participation in older age groups whilst others did not (see [19] for review).…”

“…Although some studies have examined predictors of consent to record linkage, they are far fewer than those focused on survey response, and with a few exceptions [14,28] they are either among smaller, non-representative samples, or they are among samples that are larger but survey-specific (e.g., a female only sample).…”

“…For example, some studies show a gradient of increased likelihood of consent with increasing age [29,30], while others found that older respondents are less likely to consent [14,31]. Higher socioeconomic position (i.e., socioeconomic status, educational level, car ownership, having private health insurance) is generally associated with higher rates of consent to record linkage [32,33].…”

“…However, in a large, nationally representative general survey Knies et al [28] found no effects for income. There is also evidence that those with health problems and higher levels of primary health care utilisation have higher rates of consent [14,28,30,33]. Given the paucity of studies utilising large population-based samples, the limited numbers of factors considered within studies, and evidence of inconsistencies in the findings, there is a rationale for further research in this area.…”