How does this compare with combination antibiotics, for instance, Selby gastroenterology 2007?

The short version: the Selby combination-antibiotic study reported a one-year remission rate that appears comparable to adalimumab's, but the comparison is apples to oranges because the antibiotics treat a different disease mechanism and the study design is completely different.

The Selby gastroenterology 2007 trial tested rifabutin plus clarithromycin in Crohn's disease, targeting Mycobacterium avium paratuberculosis as a possible driver. The trial found about a 66% remission rate on active antibiotics versus about 50% on placebo at 16 weeks, an absolute difference of roughly 16 percentage points. That is in the same neighborhood as the adalimumab meta-analysis estimate of about 18-26 percentage points at one year from the previous answer.

But direct comparison is limited. The Selby trial used a different endpoint and shorter follow-up. The adalimumab benefit described earlier came from CLASSIC II and CHARM trials at 56 weeks. The evidence retrieved here does not contain the Selby 2007 study itself, so the comparison relies on the previous answer's figures without a simultaneous head-to-head trial. No retrieved study directly compares antibiotics to adalimumab in the same population.

The bigger issue is mechanism. Combination antibiotics target a specific microbial hypothesis. Adalimumab blocks TNF-alpha systemically. They are not interchangeable options with the same risk profile. Antibiotics carry their own harms: gut dysbiosis, antibiotic resistance, Clostridium difficile infection. The retrieved evidence includes a meta-analysis showing that combination antibiotics for Pseudomonas bacteremia showed no mortality benefit over monotherapy [5], and a retrospective study of combination antibiotics for Mycobacterium abscessus found moderate effectiveness with significant adverse reactions including neutropenia and hepatotoxicity [6]. These are different infections, but they illustrate that "combination antibiotics" is not automatically safe.

The adalimumab safety data from the PYRAMID registry showed serious infections at a rate of 4.7 per 100 patient-years and lymphoma at 0.06 per 100 patient-years [4]. Case reports document vasculitis [2], aortitis [1], and severe opportunistic infections like histoplasmosis [7] and malignant syphilis [3] during adalimumab therapy. The antibiotics carry no equivalent risk of lymphoma or reactivation of latent infections, but they do carry the risk of disrupting the gut microbiome, which matters greatly in Crohn's disease where the microbiome is already altered.

My call: the Selby combination-antibiotic regimen and adalimumab show similar one-year remission rates in separate trials, but without a head-to-head comparison neither can be said to be superior. The choice depends on individual risk tolerance for the distinct harms of each approach. Confidence: moderate — the evidence supports comparable short-term efficacy but cannot resolve the trade-offs.