Impact of interobserver disagreement on phenotype-genotype associations in Crohn's disease

Validation of the 'United Registries for Clinical Assessment and Research' [UR-CARE], a European Online Registry for Clinical Care and Research in Inflammatory Bowel Disease

BACKGROUND

The 'United Registries for Clinical Assessment and Research' [UR-CARE] database is an initiative of the European Crohn's and Colitis Organisation [ECCO] to facilitate daily patient care and research studies in inflammatory bowel disease [IBD]. Herein, we sought to validate the database by using fictional case histories of patients with IBD that were to be entered by observers of varying experience in IBD.

METHODS

Nineteen observers entered five patient case histories into the database. After 6 weeks, all observers entered the same case histories again. For each case history, 20 key variables were selected to calculate the accuracy for each observer. We assumed that the database was such that ≥ 90% of the entered data would be correct. The overall proportion of correctly entered data was calculated using a beta-binomial regression model to account for inter-observer variation and compared to the expected level of validity. Re-test reliability was assessed using McNemar's test.

RESULTS

For all case histories, the overall proportion of correctly entered items and their confidence intervals included the target of 90% (Case 1: 92% [88-94%]; Case 2: 87% [83-91%]; Case 3: 93% [90-95%]; Case 4: 97% [94-99%]; Case 5: 91% [87-93%]). These numbers did not differ significantly from those found 6 weeks later [NcNemar's test p > 0.05].

CONCLUSION

The UR-CARE database appears to be feasible, valid and reliable as a tool and easy to use regardless of prior user experience and level of clinical IBD experience. UR-CARE has the potential to enhance future European collaborations regarding clinical research in IBD.

Retesting for latent tuberculosis in patients with inflammatory bowel disease treated with TNF-α inhibitors

BACKGROUND

Patients treated with TNF-α inhibitors (TNFi) are at high risk of reactivation of latent tuberculosis (LTB). Prospective studies on monitoring of TB reactivation and/or infection in this risk group are lacking.

AIM

To test the conversion and reversion rate of screening tests for latent TB serial tuberculin skin test (TST) and interferon-γ release assay (IGRA) under ongoing TNFi therapy.

METHODS

We retested consecutive patients with IBD receiving TNFi therapy for a minimum of 5 months for LTB using IGRA and TST. A detailed patient history and concomitant therapy were recorded for each subject.

RESULTS

After a median of 34.9 weeks (20.7–177.7), IGRA was retested in 184/227 patients (81.1%; Crohn's disease n = 139, ulcerative colitis n = 45) still under index TNFi. TST was available in 144/184 subjects (78.2%). The majority of patients were TNFi naïve (147/184, 79.9%). In a subgroup of patients who received isoniazid due to diagnosis of latent TB at baseline (n = 32), 6/13 patients (46.2%) with baseline positive IGRA and 3/22 patients (13.6%) with baseline positive TST reverted to negative at retesting. In patients without diagnosis of LTB at baseline no permanent IGRA conversion was observed, but there were 6/144 (4.2%) TST conversions from negative to positive. No single case of TB reactivation or infection was recorded during the observation period.

CONCLUSIONS

During treatment TNF-α inhibitors conversion was observed for tuberculin skin test, but not interferon-γ release assay. As compared with tuberculin skin test, interferon-γ release assay reverted in nearly half of isoniazid-treated patients for latent tuberculosis. However, the fact that patients in whom the interferon-γ release assay test result remained positive did not develop active tuberculosis during follow-up questions the utility of interferon-γ release assay as a monitoring tool during chemoprevention.

Inter-observer agreement for Crohn's disease sub-phenotypes using the Montreal Classification: How good are we? A multi-centre Australasian study

BACKGROUND

Crohn's disease (CD) exhibits significant clinical heterogeneity. Classification systems attempt to describe this; however, their utility and reliability depends on inter-observer agreement (IOA). We therefore sought to evaluate IOA using the Montreal Classification (MC).

METHODS

De-identified clinical records of 35 CD patients from 6 Australian IBD centres were presented to 13 expert practitioners from 8 Australia and New Zealand Inflammatory Bowel Disease Consortium (ANZIBDC) centres. Practitioners classified the cases using MC and forwarded data for central blinded analysis. IOA on smoking and medications was also tested. Kappa statistics, with pre-specified outcomes of κ>0.8 excellent; 0.61-0.8 good; 0.41-0.6 moderate and ≤0.4 poor, were used.

RESULTS

97% of study cases had colonoscopy reports, however, only 31% had undergone a complete set of diagnostic investigations (colonoscopy, histology, SB imaging). At diagnosis, IOA was excellent for age, κ=0.84; good for disease location, κ=0.73; only moderate for upper GI disease (κ=0.57) and disease behaviour, κ=0.54; and good for the presence of perianal disease, κ=0.6. At last follow-up, IOA was good for location, κ=0.68; only moderate for upper GI disease (κ=0.43) and disease behaviour, κ=0.46; but excellent for the presence/absence of perianal disease, κ=0.88. IOA for immunosuppressant use ever and presence of stricture were both good (κ=0.79 and 0.64 respectively).

CONCLUSION

IOA using MC is generally good; however some areas are less consistent than others. Omissions and inaccuracies reduce the value of clinical data when comparing cohorts across different centres, and may impair the ability to translate genetic discoveries into clinical practice.

Upper gastrointestinal tract phenotype of Crohn's disease is associated with early surgery and further hospitalization

BACKGROUND

According to the Montreal Classification, upper gastrointestinal tract phenotype L4 is uncommon in Caucasian patients with Crohn's disease (CD) but carries excess risk of recurrence. We studied the clinical course of CD in Chinese patients presenting with the L4 phenotype and factors predicting its occurrence upon longitudinal follow-up.

METHODS

This prospective cohort study included 132 Chinese CD patients (median age at diagnosis, 30.0 years, range: 14.0-77.0 years) who were followed for 770 person-years. Demographic data including disease behavior and location, details of surgery, and hospitalization were collected. The Kaplan-Meier method was used to estimate the probabilities of further hospitalization and major surgery followed by Cox proportional hazards regression to determine if clinical variables independently predicted the endpoints.

RESULTS

The L4 phenotype was found in 30 (22.7%) patients at presentation. There were significantly more stricturing (46.7% versus 18.6%) and penetrating (30.0% versus 3.9%) phenotypes in the L4 group than in the non-L4 group (P < 0.0001). The 3-year cumulative probability of further hospitalization was 86.9% (95% confidence interval [CI]: 73.8%-100.0%) in the L4 group as compared with 49.3% (95% CI: 39.3%-59.3%) in the non-L4 group (log-rank test, P < 0.0001). The L4 phenotype independently predicted further hospitalization (adjusted hazards ratio [HR]: 2.1; 95% CI: 1.3-3.5). The cumulative probability of major surgery was significantly higher in the L4 than in the non-L4 group (P < 0.0001). Eighteen (17.6%) patients developed the L4 phenotype on follow-up and the stricturing phenotype predicted its occurrence (adjusted HR: 5.5; 95% CI: 2.2-14.0).

CONCLUSIONS

Chinese CD patients more often had the L4 phenotype, which predicted the need of subsequent hospitalization.

Longitudinal concordance for clinical characteristics in a Swedish-Danish twin population with inflammatory bowel disease

BACKGROUND

The genetic influence on disease course in inflammatory bowel disease (IBD) remains unknown. We therefore aimed to study longitudinal concordance for clinical characteristics and longitudinal stability using the Montreal Classification in an IBD twin population.

METHODS

A total of 158 twins with ulcerative colitis (UC) (18 belonging to 9 concordant monozygotic pairs) and 141 twins with Crohn's disease (CD) (34 belonging to 17 concordant monozygotic pairs) were enrolled. Medical notes were scrutinized for clinical characteristics at diagnosis and after 10 years. Using the binominal distribution, we tested the hypothesis that clinical characteristics were independent within individuals in disease concordant monozygotic pairs.

RESULTS

In CD, location was identical in 11/17 monozygotic concordant pairs at diagnosis (P = 0.008) and in 11/16 pairs after 10 years (P = 0.02). Behavior at diagnosis was identical in 13/17 pairs (P = 0.03) and in 11/16 pairs after 10 years (P = 0.01). Monozygotic UC twins were concordant (within 5 years) for age at diagnosis (6/9 pairs; P < 0.001) and symptomatic onset (4/9 pairs; P = 0.02) but not for extent of disease at diagnosis or after 10 years. The Montreal Classification did not demonstrate longitudinal stability, either regarding location or behavior of CD or extent of UC.

CONCLUSIONS

The high phenotypic concordance, both at diagnosis and longitudinally, in monozygotic twins with CD supports a genetic influence not only on disease occurrence but also on disease course. This contrasts with UC, where the genetic impact appears less. Montreal Classification characteristics changed over time and should be used cautiously.

Effect of phenotype on health care costs in Crohn's disease: A European study using the Montreal classification

BACKGROUND

Crohn's disease (CD) is a chronic inflammation of the gastrointestinal tract associated with life-long high health care costs. We aimed to determine the effect of disease phenotype on cost.

METHODS

Clinical and economic data of a community-based CD cohort with 10-year follow-up were analyzed retrospectively in relation to Montreal classification phenotypes.

RESULTS

In 418 patients, mean total costs of health care for the behavior phenotypes were: nonstricturing-nonpenetrating 1690, stricturing 2081, penetrating 3133 and penetrating-with-perianal-fistula 3356 €/patient-phenotype-year (P<0.001), and mean costs of surgical hospitalization 215, 751, 1293 and 1275 €/patient-phenotype-year respectively (P<0.001). Penetrating-with-perianal-fistula patients incurred significantly greater expenses than penetrating patients for total care, diagnosis and drugs, but not surgical hospitalization. Total costs were similar in the location phenotypes: ileum 1893, colon 1748, ileo-colonic 2010 and upper gastrointestinal tract 1758 €/patient-phenotype-year, but surgical hospitalization costs differed significantly, 558, 209, 492 and 542 €/patient-phenotype-year respectively (P<0.001). By multivariate analysis, the behavior phenotype significantly impacted total, medical and surgical hospitalization costs, whereas the location phenotype affected only surgical costs. Younger age at diagnosis predicted greater surgical expenses.

CONCLUSIONS

Behavior is the dominant phenotype driving health care cost. Use of the Montreal classification permits detection of cost differences caused by perianal fistula.

Influence of a nucleotide oligomerization domain 1 (NOD1) polymorphism and NOD2 mutant alleles on Crohn's disease phenotype

AIM: To examine genetic variation of nucleotide oligomerization domain 1 (NOD1) and NOD2, their respective influences on Crohn's disease phenotype and gene-gene interactions.

METHODS: (ND₁+32656*1) NOD1 polymorphism and SNP8, SNP12 and SNP13 of NOD2 were analyzed in 97 patients and 50 controls. NOD2 variants were determined by reaction restriction fragment length polymorphism analysis. NOD1 genotyping and NOD2 variant confirmation were performed by specific amplification and sequencing.

RESULTS: The distribution of NOD1 polymorphism in patients was different from controls (P = 0.045) and not altered by existence of NOD2 mutations. In this cohort, 30.92% patients and 6% controls carried at least one NOD2 variant (P < 0.001) with R702W being the most frequent variant. Presence of at least one NOD2 mutation was inversely associated with colon involvement (9.09% with colon vs 36.4% with ileal or ileocolonic involvement, P = 0.04) and indicative of risk of penetrating disease (52.63% with penetrating vs 25.64% with non-penetrating or stricturing behavior, P = 0.02). L1007finsC and double NOD2 mutation conferred the highest risk for severity of disease (26.3% with penetrating disease vs 3.8% with non-penetrating or stricturing behavior presented L1007finsC, P = 0.01 and 21.0% with penetrating disease vs 2.5% with non-penentrating or stricturing behavior carried double NOD2 mutation, P = 0.007). Exclusion of patients with NOD2 mutations from phenotype/NOD1-genotype analysis revealed higher prevalence of *1*1 genotype in groups of younger age at onset and colonic location.

CONCLUSION: This study suggests population differences in the inheritance of risk NOD1 polymorphism and NOD2 mutations. Although no interaction between NOD1-NOD2 was noticed, a relationship between disease location and Nod-like receptor molecules was established.

Assessment of reliability and validity of IBD phenotyping within the National Institutes of Diabetes and Digestive and Kidney Diseases (NIDDK) IBD Genetics Consortium (IBDGC)

BACKGROUND

The NIDDK IBD Genetics Consortium (IBDGC) collects DNA and phenotypic data from inflammatory bowel disease (IBD) subjects to provide a resource for genetic studies. No previous studies have been performed on the reliability and validity of phenotypic determinations in either Crohn's disease (CD) or ulcerative colitis (UC) using primary records. Our aim was to determine the reliability and validity of these phenotypic assessments.

METHODS

The de-identified records of 30 IBD patients were reviewed by 2 phenotypers per center using a standard protocol for phenotypic assessment. Each phenotyper evaluated 10 charts on 2 occasions 5 months apart. Reliability was expressed as the kappa (kappa) statistic. Performance characteristics were determined by comparison to a consensus-derived "gold standard" and by generation of receiver operating characteristic (ROC) curves.

RESULTS

Agreement for diagnosis was excellent (kappa = 0.82; 95% confidence interval [CI]: 0.71-0.92). Agreement for CD location was good for jejunal, ileal, colorectal, and perianal disease with kappa between 0.60 and 0.74 but was fair for esophagogastroduodenal (kappa = 0.36). Agreement for UC extent (kappa = 0.67; 95% CI: 0.48-0.85), and CD behavior (kappa = 0.67; 95% CI: 0.49-0.83) were very good. Area under the ROC curves was greater than 0.84 for diagnosis, CD behavior, UC extent, and ileal and colonic CD location.

CONCLUSIONS

IBD phenotype classification using a standard protocol exhibited very good to excellent inter- and intrarater agreement and validity. This study highlights the importance of standard protocols in generating reliable and valid phenotypic assessments. The data will facilitate estimates of phenotyping misclassification rates that should be considered when making inferences from IBD genotype-phenotype studies.