Modelling decisions to undergo genetic testing for susceptibility to common health conditions: An ancillary study of the Multiplex Initiative

Abstract

New genetic tests reveal risks for multiple conditions simultaneously, although little is understood about the psychological factors that affect testing uptake. We assessed a conceptual model called the multiplex genetic testing model (MGTM) using structural equation modelling. The MGTM delineates worry, perceived severity, perceived risk, response efficacy and attitudes towards testing as predictors of intentions and behaviour. Participants were 270 healthy insured adults aged 25–40 from the Multiplex Initiative conducted within a health care system in Detroit, MI, USA. Participants were offered a genetic test that assessed risk for eight common health conditions. Confirmatory factor analysis revealed that worry, perceived risk and severity clustered into two disease domains: cancer or metabolic conditions. Only perceived severity of metabolic conditions was correlated with general response efficacy (β = 0.13, p<0.05), which predicted general attitudes towards testing (β = 0.24, p<0.01). Consistent with our hypothesised model, attitudes towards testing were the strongest predictors of intentions to undergo testing (β = 0.49, p<0.01), which in turn predicted testing uptake (OR 17.7, β = 0.97, p<0.01). The MGTM explained a striking 48% of the variance in intentions and 94% of the variation in uptake. These findings support use of the MGTM to explain psychological predictors of testing for multiple health conditions.

Keywords:

• genetic testing
• Multiplex Initiative
• health behaviour
• common disease
• structural equation modelling
• personalised medicine
• USA

Acknowledgements

This research was supported by the Intramural Research Program of the National Human Genome Research Institute, National Institutes of Health. The proposed research was made possible through a collaboration with the Cancer Research Network funded by the National Cancer Institute (no. U19CA 079689). Group Health Research Institute and Henry Ford Hospital provided additional resources. Genotyping services were provided by the Center for Inherited Disease Research (CIDR). CIDR is fully funded through a federal contract from the National Institutes of Health to The Johns Hopkins University (no. HHSN268200782096C). Additionally, this research was supported in part by an appointment to the Senior Fellowship Program at the National Institutes of Health, which is administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the US Department of Energy and the National Institutes of Health. The authors thank the study participants, members of the Henry Ford Health System and members of the Multiplex Initiative Steering Committee for their efforts in making the Multiplex Initiative Ancillary Studies possible. The authors also thank the anonymous reviewers for their very useful feedback on an earlier draft of this manuscript.

Notes

1. Combining uninterested and unsure participants may have inflated the intention-uptake link to some extent, but in view of the strong effect, even without dichotomising the link would still be high.