Controlled clinical studies that evaluated the effects of yoga interventions on pain symptoms were eligible for inclusion. The outcomes of interest were pain intensity/frequency and pain-induced disability. Outcomes had to be assessed with appropriate pain measurement tools. Studies with complex interventions which could have included yoga practice were excluded.
Where specified, yoga styles included hatha, Iyengar and viniyoga. Control groups included waiting list, physical activity and lectures, routine care and conversation or anti-inflammatory drugs. Participants included patients with back pain, rheumatoid arthritis, headache/migraine, irritable bowel syndrome, muscle soreness, carpal tunnel syndrome or labour pain or were on hemo-dialysis or were healthy computer users. Participant age ranged from 14 to 70 years old; most studies included participants under 50 years old. Studies evaluated treatment in the short term (up to four weeks), medium term (six to 10 weeks) and long term (12 to 24 weeks).
Two authors assessed studies for inclusion. It appeared that disagreements were resolved by consensus.