Variable name	Variable description
id	patient ID code
age	Age
sex	sex; female (1) vs. male (0)
migraine	diagnosis ; migraine (1) vs. tension-type (0)
chronicity	number of years of headache disorder
acupuncturist	acupuncturist id code
practice_id	gp practice id
group	treatment group; acupuncture (1) vs. control (0)
pk1	headache severity score baseline
pk2	headache severity score 3 month
pk5	headache severity score 1 year
f1	headache frequency baseline
f2	headache frequency 3 month
f5	headache frequency 1 year

Analyses of study data focused on headache severity scores (pk1, pk2, pk5), each coded using the following likert scale. The primary outcome was headache score at the one-year follow up.