Inclusion Criteria

Randomized controlled trials

Population, allocation, study design, and outcomes identified

Adult patients of >16 years with diagnosed CD

Compared placebo to anti-inflammatory agent 5-aminosalicylic acid (5-ASA, Mesalazine, or mesalamine) or placebo

Assessed relapse of disease activity in quiescent CD (surgically or medically induced) at last time point of assessment in the trial, endoscopic relapse, clinical relapse rate (CDAI), endoscopic assessment, severe endoscopic recurrence (Rutgeerts scoring system), clinical recurrence, and withdrawals due to relapse

Adverse events related to probiotics are considered as secondary outcomes.