The pain relief, safety, and tolerability of valdecoxib 40 mg once daily compared with diclofenac 75 mg twice daily for acute low back pain was studied. The effect of valdecoxib on the patient's level of disability and quality of life was also studied.

Inclusion Criteria:

• Acute low back pain, defined as either class 1a or class 2a according to the Quebec Task Force Classification and categorized as moderate-severe in the Pain Intensity Categorical Scale and Visual analogue score (VAS) greater or equal to 50 mm
• Acute low back pain was to have started at least 72 hours prior to inclusion in the trial and more than 6 weeks after the last episode of acute low back pain
• History of at least 1 reported episode of acute low back pain in the last 5 years

Exclusion Criteria:

• History of inflammatory arthritis, chronic pain, metastasis, Paget's disease, or other diseases known to cause pain
• Moderate to severe scoliosis
• Back pain due to major trauma or visceral disorder
• Unwilling to refrain from commencing concomitant physiotherapy
• Active or suspected esophageal, gastric pyloric channel, or duodenal ulceration or bleeding within 30 days prior to the first dose of study medication
• Any known laboratory abnormality, which in the opinion of the investigator, would contraindicate study participation
• Subject was pregnant or lactating woman , or was a woman of childbearing potential not using an acceptable method of contraception