Do patients with inflammatory bowel disease want genetic testing?

Abstract

Inflammatory bowel disease (IBD) is a complex genetic disorder characterized by nonmendelian inheritance, incomplete penetrance, and disease susceptibility but not disease certainty. Genotype and phenotype associations are described, but the level of interest of patients with IBD in genetic testing for themselves or at-risk family members remains unknown. Thus, the goal of this study was to assess the interest of patients with IBD in genetic testing and their willingness to accept the uncertainty inherent in complex genetics. Consecutive outpatients with IBD were recruited to complete a 57-item self-administered survey. The survey included a layperson explanation of the limits of IBD genetics. A 5-point Likert scale was used to determine willingness to undergo genetic testing to determine diagnosis, prognosis, and treatment; to help their family; and to advance medical knowledge. The IBD Questionnaire, a validated measure of the health status attitudes of patients with IBD, was used. To determine limits of patient interest in testing family members, the standard reference gamble paradigm was used. Patients were presented with situations for the genetic test with various levels of certainty in 10% decrements starting with 100%. They indicated the lowest degree of certainty that they would accept to test their family member. One hundred fourteen patients (mean age 38.4 years; 48.2% women) completed the survey. Of these 114, 71.9% (82) had Crohn's disease. Among the patients who answered questions on self-willingness, 76.8% (86 of 112) would undergo testing for diagnostic confirmation, 81.3% (91 of 112) for prognostic value, 88.4% (99 of 112) for therapeutic decision making, and 85.0% (96 of 113) for advancement of medical knowledge. We found that 28.1% of patients (32 of 114) had a first-degree relative with IBD. Those patients with a first-degree relative with IBD were more willing to undergo genetic testing than those without a first-degree relative with IBD (raw score on self-willingness 4.62 vs 4.36; P=0.026). There was no significant association between patients' health status and their willingness to undergo genetic testing (IBD Questionnaire score and raw score on self-willingness; Spearman's correlation coefficient -0.06; P=0.51). We also found that 88.6% of patients (93 of 105) indicated an interest in testing family members if the test provided absolute certainty of future disease. The average lowest level of certainty these patients were willing to accept was 42.2%. Despite the complexity of IBD genetics, most patients with IBD are interested in testing and willing to accept a variable degree of uncertainty about the results. An important minority of patients does not wish to be tested. Future work should better identify the reasons for these different attitudes. This information should be factored into plans for widespread clinical testing.