Randomised controlled trials (RCTs) comparing paracetamol alone or with another treatment, with placebo/no treatment or another treatment (not including paracetamol), in patients with acute (12 weeks or less) or chronic (more than 12 weeks) non-specific low back pain, were eligible for inclusion. Trial participants were required to be over 16 years of age. Trials of participants with specific conditions such as fracture, cancer, rheumatology, or osteoporosis were excluded. The primary outcomes of interest were pain and disability following treatment, with disability measured by a scale or through other functional outcomes such as ability to work.
Included trials compared paracetamol with no treatment, non-steroidal anti-inflammatory drugs (aspirin, diflunisal, ibuprofen, phenylbutazone), other drugs (amitriptyline, codeine, or oxycodone plus aspirin), or other treatments (electroacupuncture or heat wraps), administered two to four times per day over two days to five weeks. Some trials included army recruits. Trial participant ages ranged from 16 to 75 years (where reported). The majority of trials were of participants with acute low back pain.
Two reviewers independently screened studies for relevance, and discrepancies were resolved by consensus.