TNF and inflammatory bowel disease: Using similar inclusion periods of IBD diagnosis for both cases and controls (since 1991) almost abolished treatment differences (5-aminosalicylic acids (5-ASA), 89.6% (cases) versus 89.8% (controls), p = 0.954; thiopurines, 35.6% versus 40.2%, p = 0.432; methotrexate, 0.0% versus 5.3%, p = 0.049; cyclosporine, 4.1% versus 1.5%, p = 0.102; anti-TNFα therapy, 15.1% versus 19.7%, p = 0.326).