Clinical Study On Differential Diagnosis Of Crohn’s Disease From Intestinal Tuberculosis

Background:CD is a granulomatous inflammation generally seen in developed countries, ITBis an infectious disease generally seen in developing countries. With the continuousimprovement of living standards and the increase in resistance rates ofmycobacterium tuberculosis in China, the incidence CD and ITB in China showed arising trend. However, owing to very similar early clinical manifestations of these twodiseases and lacking of specific diagnostic indicators, these2diseases were veryeasily misdiagnosed, which is not conducive to the treatment of patients. Therefore, ifthese2diseases were able to be early and exactly diagnosed，it will be conducive tothe treatment of patients. However, there is still lacking of gold standard for earlydiagnosis of these2diseases.Objective:To investigate the value of clinic pathologic features for differential diagnosis ofCrohn’s disease (CD) from intestinal tuberculosis (ITB).Methods:From August2011to July2012，the patients who suffered from suspectedintestinal diseases at the gastroenterology outpatient clinic of First Affiliated Hospitalof Nanchang University were enrolled. The results of the general information, clinicalmanifestations, biochemical examinations, colonoscopy changes, pathologyexaminations and imaging examinations were collected for patients who diagnosedCD and ITB in clinical. The sensitivity, specificity, positive predictive value, negativepredictive value and the OR value of statistically significant indicators of these twodiseases were calculated. The diagnostic indicators with high specificity wereselected to establish a scoring system. Each indicator prompting CD scored+1, andeach indicator prompting ITB scored-1, and according to this principle, the totalscore for each patient was calculated, and then the best cutoff value for the diagnosisof these two diseases were calculated based on ROC curve, the patients whose totalscore was higher than this value were diagnosed as CD, otherwise as ITB, finally the accuracy rate and misdiagnosis rate of this scoring system for the diagnosis of thesetwo diseases were calculated.Results:1．50cases of patients were recruited, including21cases diagnosed with CD,29cases diagnosed as ITB. In CD patients, there were15males（73%）and6females（27%）with average onset age of29.57+11.703years and average duration of29.52+40.243months; In ITB patients, there were15males（52%）and14females（48%）with average onset age of38.69+14.193years and average duration of16.87+27.714months. The differences of the genders, ages and duration of disease between thesetwo diseases were not statistically significant (P>0.05). In the occupation of CDpatients,13cases were students and workers（62%）,4cases were farmers（19%）,4cases had other jobs（19%）; in that of ITB patients,7cases were students andworkers（24%）,12cases were farmers（41%）,10cases had other jobs（35%）. Afterpairwise statistical calculation, the occupation of students and workers between thesetwo diseases had significantly difference (P <0.05), their sensitivity, specificity,positive predictive value and negative predictive value were62%,76%,65%,73%;the occupation of farmers and other jobs between these two diseases had nosignificantly difference (P>0.05).2. In clinical manifestations, both CD and ITB patients had abdominal pain andweight loss. The number of cases of CD and ITB patients who had associated nightsweats were2cases （10%）and6cases （21%）.3cases （14%）of patients withperianal lesions had CD,4cases （14%）of patients with extrapulmonary tuberculosisinfection had ITB. The differences of all clinical manifestations between these twodiseases were not statistically significant (P>0.05).3. In PPD, T-SPOT.TB and biochemical tests, PPD and T-SPOT.TB positive ratewere higher in ITB patients than in CD patients. PPD and T-SPOT.TB were27cases（93%）and26cases（90%）in ITB patients, respectively, and4cases （19%）and0cases （0%）in CD patients, respectively. The patients with elevated high-sensitivityC-reactive protein elevation, erythrocyte sedimentation rate (ESR) elevation or serumalbumin decrease were more commonly seen in CD patients, they were17cases cases（81%）,18cases （86%）and16cases（76%）in CD patients,12cases（41%）, 13cases （45%）and13cases（45%）in ITB patients. The differences of all theseindicators between these two diseases were statistically significant (P <0.05). Theirsensitivity, specificity, positive predictive value and negative predictive value werePPD (93%,81%,87%,89%)、T–SPOT (90%,100%,100%,88%)、high-sensitivityC-reactive protein (81%,59%,59%,81%)、ESR (86%,55%,58%,84%) and serumalbumin (76%,55%,55%,76%).4. In Endoscopy, both CD and ITB patients had multiple irregular ulcers mainlyin the terminal ileum and ileocecal valve. In CD patients, there were patients withvisible longitudinal ulcers, aphthous ulcers, nodular hyperplasia or cobblestone-likemucosa, they were9cases（43%）,4cases（19%）,10cases （48%）and5cases（24%）; while in ITB patients, there were patients with visible ring ulcers or ulcerscars, they were10cases （34%）and8cases（28%）.The differences of aphthousulcers between these two diseases were not statistically significant (P>0.05), and thedifferences of the remaining indicators between these two diseases were statisticallysignificant (P <0.05). Their sensitivity, specificity, positive predictive value andnegative predictive value were longitudinal ulcers (43%,97%,90%,70%)、nodularhyperplasia (48%,90%,77%,70%)、cobblestone-like mucosa（24%、100%、100%、64%）、ring ulcers（34%、95%、91%、51%）and ulcer scars（28%、100%、100%、50%）.5. In pathological examination, no caseous granuloma was detected in ITBpatients (it is a gold standard for ITB diagnosis), the patients with granuloma in bothgroups were13cases（62%）and19case（s66%）, but they had no caseous granuloma.The patients whose granuloma grew from the lamina propria were6cases（26%）and12cases（41%）, the patients whose granuloma grew from the submucosa were4case（s19%）and10case（s34%）,4case（s19%）and7cases（24%）had accumulationof lymphocytes,16cases（76%）and18cases（62%）had the formation of lymphoidnodules,8cases（38%）and5cases（17%）had crypt abscess. The differences of allpathological indicators between these two diseases were not statistically significant(P>0.05).6. The CTE check showed the patients with CD or ITB had thickening bowelwalls. The patients with intestinal diseases, intestinal fistula, target sign or comb sign were more commonly seen in CD patients, they were15case（s71%）,8case（s38%）,8cases（38%） and9cases（43%）. They had significantly difference (P <0.05), Theirsensitivity, specificity, positive predictive value and negative predictive value wereintestinal diseases （71%、90%、83%、81%）、intestinal fistula（38%、97%、89%、68%）、target sign（38%、97%、89%、68%）and comb sign（43%、97%、90%、70%）. The6cases patients with lymph node strengthening had ITB, they were notstatistically significant (P>0.05).7. In15statistically significant indicators, the OR value of the students andworkers、high-sensitivity C-reactive protein、ESR、serum albumin、longitudinalulcers、nodular hyperplasia、cobblestone-like mucosa、intestinal diseases、intestinalfistula、target sign and comb sign were more than1, they were risk factors of CD andwere positively correlated to CD; the OR value of PPD、T-SPOT.TB、ring ulcers、ulcer scars were less than1, these indicators were protective factors of CD and werenegatively correlated to CD, but these indicators were positively correlated to ITB.8.In these15indicators,11diagnostic indicators with high specificity wereselected to establish the scoring system. The calculation results showed that theaverage number of the total score of the CD group was2.81±1.750, the averagenumber of the total score of the ITB was-2.10±0.976, the best cutoff value in ROCcurve was-0.5, the diagnostic area under the curve was0.995, it was statisticallysignificant (P <0.001), the diagnostic sensitivity and specificity of this point were100%and93.1%. The diagnostic accuracy rate and misdiagnosis rate of this scoringsystem was96%and4%.Conclusions:1. In positive indicators for the diagnosis of CD, the longitudinal ulcers、nodularhyperplasia、cobblestone-like mucosa、intestinal diseases、intestinal fistula、target signand comb sign have high specificity.2. In positive indicators for the diagnosis of ITB, the PPD and T-SPOT.TB havehigh sensitivity and specificity, the ring ulcers and ulcer scars have high specificity.