Twenty-one RCTs (n=1,909) were included in the review. Jadad scores ranged from 2 to 5 points
Seventeen of 20 studies that compared combined treatment with paracetamol alone found combined treatment to be more effective. The median Jadad score for studies that showed a positive result was 4; for those that showed a negative result it was 3. Mean reduction in pain intensity was 35.0% (standard deviation 10.9%) with a mean reduction in supplementary analgesia of 38.8% (standard deviation 13.1%). There was statistically significant heterogeneity (p=0.003), which was also apparent from visual inspection of the funnel plots.
Nine of 14 studies that compared combined treatment with an NSAID alone found combined treatment to be more effective. The median Jadad score for studies that showed a positive result was 5; for those that showed a negative result it was 4. Mean reduction in pain intensity with combined treatment was 37.7% (standard deviation 26.6%). There was a reduction in analgesic supplementation of 31.3% (standard deviation 13.4%). There was statistically significant heterogeneity (p=0.002), which was also apparent from visual inspection of the funnel plots.
Results of subgroup analyses were reported.
There was no evidence of an increased incidence of side effects with combined treatment compared to a single analgesic. Most studies reported no differences between the groups.