Table 1.

Eligibility Screening in a study of patients with recurrent or persistent low back pain from a randomized clinical trial investigating the comparative effectiveness of chiropractic maintenance care

Time point	Inclusion criteria	Exclusion criteria
Baseline 1 (1st visit)	Age 18–65 years. LBP with or without leg pain for altogether more than 30 days during the previous year. Previous episodes. Access to a mobile phone. Ability to send and receive SMS (text messages).	Pregnancy. Chiropractic treatment less than 3 months previously. Completely subsidized treatment from 3rd party payer. Serious pathology (i.e. acute trauma, cancer, infection, cauda equina, osteoporosis, vertebral fractures) or other contraindications to manual therapy.
Baseline 2 (4th visit)	Self-rated “definitely improved”
Baseline 3 (Study start)	Interval between treatments (after the 4th visit) can be scheduled 1 month or more.

LBP non-specific low back pain (Table reproduced from study protocol, approved by authors [22])