An Efficacy and Safety Study of Tramadol/Acetaminophen Versus Diclofenac in the Treatment of Pain in Participants With Ankylosing Spondylitis Receiving Stable Treatment of Disease Modifying Anti-rheumatic Drugs (DMARDs)

Inclusion Criteria: * Diagnosis of ankylosing spondylitis (AS), as defined by Modified New York Criteria for ankylosing spondylitis: a) Low-back pain of at least 3 months duration improved by exercise and not relieved by rest b) Limitation of lumbar spine in sagittal and frontal planes c) Chest expansion decreased relative to normal values for age and sex d) Bilateral sacroiliitis, grade 2-4 or Unilateral sacroiliitis, grade 3-4 (Stoke) * Participants are suffering from pain, with visual analogue scale (VAS) pain score greater than or equal to (\>=) 40 millimeter (mm) * Participants are receiving disease modifying anti-rheumatic drugs (DMARDs), which have reached to the stable dosage within 4 weeks prior to the randomization visit - Serum creatinine less than or equal to (\<=) 1.2 milligram per deciliter (mg/dL) * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \<= 3 times the laboratory's upper limit of normal * Exclusion Criteria: * Had an inadequate response to tramadol hydrochloride (HCl) therapy, or have discontinued tramadol HCl therapy due to adverse events * Have taken tramadol HCl within 4 weeks prior to the entry of the study * Have taken other medications for pain relief within 4 weeks prior to the entry of the study, except rescue medications * Evidence of significant uncontrolled concomitant diseases such as cardiovascular disease, nervous system, pulmonary, renal, hepatic, endocrine or gastrointestinal disorders * Women with pregnancy or bre…