Kokjohn 1992

Methods	Trial design: randomised clinical trial. Randomisation and allocation: no details on allocation concealment. Blinding: no details on blinding. Number of participants: 45 women randomised, 24 in treatment, 21 in control.
Participants	Inclusion: history of primary dysmenorrhoea beginning within 2 years of menarche; regular cycle; moderate, severe or disabling dysmenorrhoea in each cycle, beginning day before or at onset of flow. Exclusion: excluded if any pelvic abnormality, endometriosis, use of birth control pills or IUD, or contraindications to spinal manipulation. Women also asked not to use analgesics during study and to abstain from exercise or intercourse 24 hr prior to treatment. Age: 20‐40 (mean 30.3) years. Source: recruited from local community by advertisements or referrals from chiropractors or gynaecologists. Location: chiropractic clinic in Chicago, USA.
Interventions	Treatment: high velocity low amplitude manipulation to clinically relevant vertebral and sacroiliac joints. Control: sham manipulation to midline base of sacrum. Duration: one treatment only.
Outcomes	VAS for abdominal pain. VAS for back pain. MDQ for menstrual distress. All scales assessed 15 min before and 60 min after treatment. Blood samples for KD PGF2α.
Notes	Outcome measurement rather limited temporally. No information on whether effects lasted longer than 1 hr post‐treatment.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	No details
Allocation concealment?	Unclear risk	No details
Blinding? All outcomes	High risk	No details of blinding
Incomplete outcome data addressed? All outcomes	Low risk	All participants accounted for
Free of selective reporting?	High risk	Outcome measurement rather limited temporally. No info on whether effects lasted longer than 1 hr post‐treatment