A Cochrane review included 9 studies with a total of 636 subjects. Participants who were randomised to electromagnetic field treatment rated their pain relief 15.10 points more on a scale of 0 to 100 (MD 15.10, 95% CI 9.08 to 21.13; absolute improvement 15%) after 4 to 26 weeks' treatment compared with placebo. Electromagnetic field treatment had no statistically significant effect on physical function (MD 4.55, 95% CI -2.23 to 11.32; absolute improvement 4.55%) based on the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) scale from 0 to 100 after 12 to 26 weeks' treatment. No statistically significant difference in quality of life was found on a scale from 0 to 100 (SMD 0.09, 95% CI -0.36 to 0.54; absolute improvement 0.09%) after four to six weeks' treatment, based on the SF-36.
Comment: The quality of evidence is downgraded by study quality (inadequate reporting of study design and conduct, and there was high risk of bias for incomplete outcome data in three studies).