Inflammatory bowel disease (IBD) encompasses two distinct entities: ulcerative colitis (UC) and Crohn’s disease (CD). They are chronic inflammatory pathologies of the gastrointestinal tract that are not very common and primarily affect the colon and small bowel. Their clinical course is characterized by multiple relapses, and in recent years, a worldwide increase has been detected in the frequency of their appearance.1,2 The cause of IBD is unknown, but it results from a complex interaction between the genotype of the host, the gut microbiota, and environmental factors that trigger an alteration in the intestinal immune response.3 Historically, studies with a greater prevalence of IBD come from the Scandinavian countries, the United Kingdom, and North America. IBD affects approximately five million persons worldwide, which includes 1.4 million in the United States and close to three million in Europe.4 A systematic review of epidemiologic studies on IBD found a prevalence of UC of 4.9-505 per 100,000 inhabitants in Europe, 37.5-248.6 per 100,000 in North America, and 4.9-168.3 per 100,000 inhabitants in Asia. The prevalence of CD was 0.6-322 per 100,000 in Europe, 16.7-318.5 per 100,000 in North America, and 0.88-67.9 per 100,000 inhabitants in Asia. An increase in incidence over time was demonstrated in 75% of the studies on CD and 60% of the studies on UC.5 A more recent systematic review with 147 studies reported high prevalence rates for UC and CD in Europe (505 per 100,000 inhabitants for UC in Norway) and North America (286 per 100,000 inhabitants for UC in the United States), which have remained stable.6 Nevertheless, since 1990, population studies have shown an increase in incidence and prevalence in developing countries in Asia and South America, including Brazil and Mexico.6–9 The prevalence and incidence of UC and CD in Colombia was recently determined through information obtained from data cubes from the Comprehensive Social Security Information System (SISPRO, Spanish acronym) of the Colombian Department of Health and Social Security. For 2017 in Colombia, the prevalence of UC and CD in the adult population was 58.1/100,000 inhabitants and 8.9/100,000 inhabitants, respectively, and the incidence of UC and CD was 6.3/100,000 person/years and 0.74/100,000 person/years, respectively.10

Colombia has epidemiologic data on the behavior of IBD from local referral centers. In 1991 a case series was published that included 108 cases of IBD (98 UC and 10 CD) that were diagnosed between 1968 and 1990 in Bogotá.11 In 2010, at the Hospital Pablo Tobón Uribe in Medellín, the epidemiologic characteristics of 202 patients with IBD diagnosed between 2001-2009 were reported, with a distribution of 80.7% of patients with UC, 15.8% with CD, and 3.5% with IBD unclassified (IBD-U), for a UC:CD ratio of 5.1:1.12 The experience at the Clínica Universitaria Colombia in Bogotá with 165 patients was recently published, showing that 75.8% of the patients presented with UC and 24.2% with CD, for a UC:CD ratio of 3.1:1.13 However, we know of no combined data covering several regions of the country. Therefore, we decided to merge experiences and conduct a multicenter study to determine the epidemiologic, phenotypic, clinical, and current treatment characteristics of our Colombian patients with IBD, taking into account the global increase in the frequency of the disease, the availability of new diagnostic methods (through endoscopy, radiology, serology, and fecal markers), and the possibility of using new medical treatments in our country.

The present national register was achieved, thanks to the work and motivation of the different hospital centers in Colombia interested in the diagnosis and management of patients with IBD, and is a giant step toward understanding the epidemiology, clinical behavior, and treatment of Colombian patients with IBD. In addition, it is the national register with the largest number of patients in Latin America. Compared with previous Colombian studies, (8-10) the UC:CD ratio in the present register of 3.9:1 indicates that a greater number of CD cases than UC cases have been detected over the past decade. The predominance of UC over CD is similar to that reported in other Asian and Latin American countries, with the exception of Brazil, where there is a predominance of CD over UC.6,7 A study on 716 patients with IBD in Chile found 71% of cases with UC, 27% with CD, and 2% with IBD-U, for a UC:CD ratio of 2.6:1.21 Other studies in regions with a higher prevalence of IBD, such as the analysis by the Norwegian IBSEN group, reported 61.5% of patients with UC, 28.1% with CD, and 10.5% with IBD-U.16,19 A multicenter European register (EC-IBD) found 62.6% cases with UC, 32.0% with CD, and 7.4% with IBD-U.22,23 A Dutch study described a lower number of UC cases (53.0%), compared with CD (40.1%), and 6.8% of cases with IBD-U.24 A recent article from Hong Kong, with a register of 2,575 patients with IBD, within the time frame of 1981-2014, reported 59.8% of patients with UC, 38.2% with CD, and 2.0% with IBD-U, finding a decrease from the UC:CD ratio of 8.9:1 in the 1980s to 1.03:1, in the past 30 years.25 The same phenomenon is occurring in Colombia, and can be explained by a higher diagnostic suspicion of CD, better ileal intubation rates in patients with chronic diarrhea and anemia, and greater access to diagnostic methods for the study of small bowel diseases in our medical environment, such as capsule endoscopy and magnetic resonance enterography (MRE).

In the present study, in patients with UC, anatomic location was proctitis in 30.7% of the cases, left colitis in 35.7%, and extensive colitis in 33.5%. Our data were similar to those of other case series, in which the average locations were distributed in thirds. The Chilean study on 508 patients with UC mentioned above, described proctitis in 28% of cases, left colitis in 22%, and extensive colitis in 50%.21 A Hungarian study on 220 patients with UC reported proctitis in 26.8% of patients, left colitis in 50.9%, and extensive colitis in 22.3%.26 The Norwegian study by the IBSEN group found proctitis in 32.9% of cases, left colitis in 35%, and extensive colitis in 32.1%.16 The Asian study conducted in Hong Kong reported proctitis in 34.5% of cases, left colitis in 32.0%, and extensive colitis in 33.5%.25

Anatomic location in CD in the present register (ileal 46.5%, colonic 20.0%, ileocolonic 22.0%) showed a high percentage of patients with ileal involvement, compared with other case series. The Hungarian study26 reported ileal (20.2%), colonic (35.6%), and ileocolonic (44.2%) location. The Hong Kong register reported location in the ileum (24.5%), colon (32.3%), and ileum and colon (43.1%).25 In the Chilean study, ileal (27%), colonic (44%), and ileocolonic (28%) location was found.21 Another Dutch study described involvement of the terminal ileum in 31%, the colon in 27%, and the ileum and colon in 31%.24 The Norwegian IBSEN group reported 27.0% of patients had location in the terminal ileum, 48.5% exclusively in the colon, and 22.7% in the ileum and colon.19

CD behavior in our environment was found to be inflammatory in 53.9% of patients, stricturing in 34.0%, and penetrating in 12.1%. A total of 9.8% of our patients had perianal fistulizing involvement. Those results are somewhat different from findings in developed countries. The Norwegian IBSEN group determined that, at diagnosis, behavior in 62.0% of their patients was inflammatory, stricturing in 27.0%, and penetrating in 11%.19 In the Dutch study, 76% of patients presented with inflammatory behavior, 14% with stricturing disease, and only 7% with penetrating behavior at diagnosis.24 In the Hong Kong study, behavior was inflammatory in 65.2% of patients, stricturing in 25.1%, penetrating in 16.1%, and perianal in 24.5%.25 The abovementioned Hungarian study described inflammatory behavior in 64.4% of patients, stricturing disease in 17.8%, penetrating disease in 17.8%, and perianal behavior in 11.1% at diagnosis.26 In the Chilean case series on 196 CD patients, 80% presented with inflammatory disease, 10% with stricturing behavior, 9% with penetrating behavior, and 28% with perianal involvement.21 Those results could be explained by a delay in CD diagnosis due to the prolonged period of time between symptom onset and diagnosis, favoring disease progression, as has been shown in previous local studies.10,12

The large majority of patients with UC received 5-ASAs (93.6%), but 60.5% of the patients with CD received accumulated treatment with 5-ASAs, despite little clinical evidence for their use in that entity, according to international recommendations.15 A Swiss study found that 59% of CD patients were treated with 5-ASAs.27 A survey among German gastroenterologists showed that 10-36% of them prescribed 5-ASAs as monotherapy for treating CD.28 Thus, the continued provision of medical education at all levels is important for the adequate treatment of patients with CD.

In the present national register, 18.5% of our patients with UC and 47.3% with CD received biologic therapy. Those percentages are high compared with figures from other hospital centers. In the Hong Kong study mentioned above, 15.3% of CD patients received biologic therapy, compared with 1.3% of UC patients.25 The Dutch COIN study reported the use of biologic therapy in 22.7% of patients with CD and 4% of patients with UC.29 In a study based on a national register in Hungary,30 stratified by pediatric, adult, and older adult populations, biologic therapy was used in 15%, 9%, and 2% of the patients with CD, respectively, and in 4%, 3%, and 1% of the patients with UC, respectively. In the previously described Chilean study, biologic therapy was used in 34% of CD patients and 7% of UC patients.21 In a Danish study on 48,967 patients with IBD diagnosed between 1979 and 2011, in the first 9 years, anti-tumor necrosis factor (anti-TNF) agents were used in 23% of patients with CD and in 9% of patients with UC.31 A recent study on a French national register of 201,001 IBD patients found that the probability of anti-TNF therapy use at five years in CD patients was 33.8%, as monotherapy, and 18% as therapy combined with an immunosuppressant. In UC patients, those figures were 12.9% and 7.4%, respectively.32 A possible explanation for the high percentage of biologic therapy use in our patients is that the majority of hospitals that participated in the national register and provided the highest number of patients are both local and national referral centers that receive conventional management-refractory patients with complicated UC and CD (with strictures and fistulas), whose next treatment option is often biologic therapy. Therefore, as stated above, the percentage of individuals with CD with inflammatory behavior (B1) was lower, compared with other case series.

The percentage of patients with CD that required surgical management in our study was 27.6%, and 6.7% of our UC patients underwent colectomy. The patients with extensive and severe UC were at greater risk for colectomy and individuals with inflammatory CD (B1) had a lower risk for surgery. Similar results were reported by the IBSEN group that found a 19% colectomy rate in UC patients with extensive colitis, compared with 8% for left colitis and 5% for proctitis, at follow-up year ten.16 In the Hungarian study, the probability of colectomy at five years in UC patients was 5%. In CD patients, the probability of surgery was 9.8%, 18.5%, and 21.3%, after one, three, and five years of follow-up.26 The multicenter European register (EC-IBD) reported an accumulated surgery rate of 31.6% in CD at ten years, 22 and the Norwegian IBSEN group found the surgery rates in CD of 13.6%, 27.0%, and 37.9% at years one, five, and ten of follow-up. Stricturing and penetrating behaviors were independent risk factors for surgery, similar to that found in our national register.19 A systematic review based on population studies reported that the risk for surgery in CD was 16.3%, 33.3%, and 46.6% at years one, five, and ten of follow-up, respectively. In UC, the risk for colectomy was 4.9%, 11.6%, and 15.6% at years one, five, and ten of follow-up, respectively.33

In UC, 38.2% of the patients were hospitalized, and a majority of those patients had extensive UC, were < 40 years of age, and presented with severe activity. A recent systematic review with 20 studies carried out to determine the risk factors for colectomy in UC found that extensive colitis (OR 3.68, 95% CI: 2.39-5.69) and a history of hospitalization (OR 4.13, 95% CI: 3.23- 5.27) were risk factors.34 For patients with CD, 59.3% were hospitalized, of whom a larger number were < 40 years of age and presented with noninflammatory disease (B2, B3). A review of cohorts of patients with CD reported hospitalization rates of 31.9% and 61.8%, at years one and ten of follow-up, respectively.35 Hospitalization frequency in the Chilean study was similar to that of our register, reporting 35% in UC and 55% in CD.21 Regarding IBD mortality in our environment, 0.71% of the patients with UC and 2.19% of the patients with CD died, which are low rates. The mortality rates in the Hong Kong study25 were 1.2% in UC and 0.7% in CD. In the Dutch study, the mortality rates were 4% for CD and 7% for UC during the follow-up.24

In conclusion, the present national register has the highest number of patients with IBD in Latin America and shows a predominance of UC over CD (3.9:1) in Colombia, as occurs in other Latin American countries.7 The clinical behavior of our patients with CD was more severe, compared with results from other hospital centers worldwide. The patients with CD had a higher surgery rate and mortality rate, compared with the UC patients. Despite the clinical evidence against it, there is still a high percentage of 5-ASA use in CD (60.5%) in Colombia. Biologic therapy is very widely used in Colombia, predominantly using anti-TNF drugs. In UC, patients < 40 years of age, with extensive and severe disease, have a poor prognosis. In CD, patients < 40 years of age, with noninflammatory disease (B2, B3, perianal), have a worse prognosis. Among the limitations of the present study was its retrospective design, which can produce selection bias in relation to the data collection, as well as the fact that it was conducted on patients from referral hospitals, which are centers that treat the more complex cases of IBD.

Juliao-Baños F: Study design, patient recruitment, data collection, document drafting. Puentes F: Patient recruitment and data collection. López R: Patient recruitment and data collection. Saffon MA: Patient recruitment and data collection. Reyes G: Patient recruitment and data collection. Parra V: Patient recruitment and data collection.

Galiano MT: Patient recruitment and data collection. Barraza M: Patient recruitment and data collection. Molano J: Patient recruitment and data collection. Álvarez E: Patient recruitment and data collection. Corrales R: Patient recruitment and data collection.

Vargas LE: Patient recruitment and data collection. Gil F: Patient recruitment and data collection. Álvarez P: Patient recruitment and data collection. Limas L: Patient recruitment and data collection. Prieto R: Patient recruitment and data collection. Yance P: Patient recruitment and data collection. Díaz F: Patient recruitment and data collection. Bareño J: Statistical analysis and document review.

The authors declare there was no financial support in relation to the development of the present study.

The authors declare that there is no conflict of interest.