Retrospective evaluation of patients with inflammatory bowel diseases using anti-TNF agents

Objective: The primary aim of this retrospective study was to evaluate the efficacy of biological therapies in achieving remission in inflammatory bowel diseases (IBD), to compare their differences, relative advantages, and to identify factors that may affect treatment non-response. Materials and Methods: Our study included patients diagnosed with Ulcerative Colitis (UC) or Crohn's Disease (CD) and followed up in our clinic at Manisa Celal Bayar University Faculty of Medicine between the years 2014 and 2024. Among 2037 patients screened during this period, 100 patients who had used at least one biological agent and met the inclusion criteria were enrolled in the study. Patients' demographic and disease characteristics, use of immunomodulators, and extraintestinal complications were analyzed. Clinical and laboratory responses to biological treatments were recorded after treatment, and comparisons were made between the different therapies. Results: A total of 100 patients were included in the study, of whom 64% were diagnosed with Crohn's disease (CD) and 34% with ulcerative colitis (UC). In the CD group, 54.79% of the patients were male, while 56.25% of UC patients were male. The mean age at diagnosis was higher in UC patients (41.56 years) compared with CD patients (38.93 years), and the difference between the groups was statistically significant (p=0.000). Regarding clinical manifestations, perianal fistula was observed exclusively in CD patients (26.03%). Rectal bleeding was significantly more frequent in UC (34.38%) than in CD patients (5.48%). Abdominal pain was also more common in the CD group (52.05%) compared with the UC group (12.50%). Altered bowel habits (diarrhea/increased defecation frequency) were the most frequently reported symptoms in both CD (58.90%) and UC (50.00%) patients. Overall, 78% of the patients received adalimumab and 22% received infliximab. The median treatment duration was 11 months in the adalimumab group and 9 months in the infliximab group. The treatment discontinuation rate was significantly higher in the infliximab group (68.2%) compared with the adalimumab group (44.9%). Discontinuation due to patient preference was also notably higher in the infliximab group (22.7% vs. 5.1%). Loss of response/ineffectiveness was the most common reason for treatment cessation in both groups (adalimumab 16.7%; infliximab 22.7%). Discontinuation due to abscess/fistula formation was more frequent in the infliximab group (9.1%) than in the adalimumab group (5.1%). Baseline CRP levels were higher in the infliximab group. Following treatment, both anti-TNF agents resulted in a significant reduction in CRP levels. Infliximab demonstrated a greater absolute decrease (≈12.7 mg/L), while adalimumab showed a higher relative reduction percentage (59.0% vs. 54.5%). No statistically significant differences were found between anti-TNF treatment groups regarding the distribution of comorbidities, including cardiovascular, endocrine/metabolic, respiratory, neurological/psychiatric, and rheumatologic/autoimmune diseases (p>0.05). Conclusion: In this retrospective study, the demographic characteristics of IBD patients followed in our clinic and their responses to adalimumab and infliximab treatments were evaluated. The study found that Crohn's disease was more common (64%) and that male patients were dominant in both IBD subtypes. Mucosal bleeding in Ulcerative Colitis (UC) and abdominal pain and perianal fistula in Crohn's disease (CD) were found to be more prominent; these findings were consistent with the natural clinical differences of the diseases. The majority of patients used adalimumab (78%). Treatment persistence in this group was found to be higher compared to the infliximab group (11 months versus 9 months). The significantly higher treatment discontinuation rate (68.2%) in the infliximab group, particularly the four-fold higher rate of discontinuation due to patient request, suggests the impact of the intravenous route of administration on patient adherence. While the most common reason for discontinuation in both drugs was inefficacy/loss of response, discontinuation due to abscess/fistula development was more common in the infliximab group; this is consistent with infliximab initially being preferred in more severe disease phenotypes. When evaluating CRP changes, significant inflammation control was achieved with both treatments. Infliximab provided a greater absolute CRP reduction, while adalimumab showed a higher percentage reduction rate. These results indicate that both anti-TNF agents are effective; however, the route of administration plays an important role in treatment persistence and patient adherence.