Study designs of evaluations included in the review
Controlled clinical trials and randomised controlled trials were included.
Specific interventions included in the review
Paracetamol in doses ranging from 400 to 1000 mg, and codeine in mainly 60 mg doses. One trial used suppositories, while the others used oral medication (tablets or capsules).
Participants included in the review
All but two trials examined pain in surgical patients; one trial examined pain in children.
Outcomes assessed in the review
Pain intensity and pain relief, as measured by visual analogue or other quantitative rating scales in the primary studies. Four measures of pain relief were used: sum pain intensity difference (sum of differences between treatment and control groups, as noted at all different time points in the post-drug observation period), peak pain intensity difference (maximum pain intensity difference at any time during the observation period), total pain relief (summed pain relief over all time points), and peak pain relief (maximum pain relief experienced at any time point during the observation period).
Side-effects were assessed in terms of patients reporting at least 1 event, and the number of patients with an adverse reaction. The numbers of individual events were also reported: dizziness, drowsiness, nausea, vomiting, constipation and 'other'.
How were decisions on the relevance of primary studies made?
The authors do not state how the papers were selected for the review, or how many of the authors performed the selection.