Diagnostic misclassification reduces the ability to detect linkage in inflammatory bowel disease genetic studies (original) (raw)
Inflammation and inflammatory bowel disease
Diagnostic misclassification reduces the ability to detect linkage in inflammatory bowel disease genetic studies
- M S Silverberga,
- M J Dalyc,
- D N Moskovitza,
- J D Riouxc,
- R S McLeodb,
- Z Cohenb,
- G R Greenberga,
- T J Hudsonc,d,
- K A Siminovitcha,
- A H Steinharta
- aDepartment of Medicine, Mount Sinai Hospital Inflammatory Bowel Disease Centre, University of Toronto, Toronto, Canada, bDepartment of Surgery, Mount Sinai Hospital Inflammatory Bowel Disease Centre, University of Toronto, Toronto, Canada, cWhitehead Institute/MIT Center for Genome Research, Cambridge, MA, USA, dMontreal Genome Centre, McGill University Health Centre, Montreal, Canada
- Dr A H Steinhart, Room 445, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario M5G 1X5, Canada. hsteinhart{at}mtsinai.on.ca
Abstract
BACKGROUND Linkage data have now identified several inflammatory bowel disease (IBD) susceptibility loci but these data have not been consistently replicated in independent studies. One potential explanation for this is the possibility that patients enrolled in such studies may have been erroneously classified with respect to their diagnosis.
AIMS To determine the rate and type of misclassification in a large population of individuals referred for participation in an IBD genetics study and to examine the effect of diagnostic misclassification on the power to detect linkage.
METHODS The medical records of 1096 patients entered into an IBD genetics programme were reviewed using standardised diagnostic criteria. The original patient reported diagnoses were changed, if necessary, based on review, and the reasons for the change in diagnosis were recorded. To evaluate the effect of misclassification on linkage results, simulations were created with Gensim and analysed using Genehunter to evaluate a model for IBD inheritance.
RESULTS Sixty eight of 1096 (6.2%) individuals had a change in diagnosis from that originally reported. The majority of changes were patients with either Crohn's disease or ulcerative colitis who were determined not to have IBD at all. The principal reasons for changes to the original diagnosis were discordance between the patients' subjective reports of diagnosis and actual clinical history, endoscopic, or pathological results; a change in disease pattern over time; and insufficient information available to confirm the original diagnosis. A 10% misclassification rate resulted in 28.4% and 40.2% loss of power to detect a true linkage when using a statistical model for a presumed IBD locus with λsvalues of 1.8 and 1.3, respectively.
CONCLUSIONS Diagnostic misclassification occurs in patients enrolled in IBD genetic studies and frequently involves assigning the diagnosis of IBD to non-affected individuals. Even low rates of diagnostic misclassification can lead to significant loss of power to detect a true linkage, particularly for loci with modest effects as are likely to be found in IBD.
inflammatory bowel disease
Crohn's disease
ulcerative colitis
genetics
linkage analysis
Abbreviations used in this paper
IBD
inflammatory bowel disease
CD
Crohn's disease
UC
ulcerative colitis
IDC
indeterminate colitis
ASP
affected sibling pair
LOD
logarithm of odds
MLS
multipoint LOD score
Statistics from Altmetric.com
Request Permissions
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.