The SPLIT project evaluates the implementation of a stratified model of care for people with low back pain patients who consulted primary care.This involves evaluating the process of implementation as well as patient level outcomes.

The project consists of two phases: First, a before-after study comprising two sequential but independent cohort studies will be conducted to compare the outcomes and cost-effectiveness of current practice with the SPLIT stratified model of care. Second, an implementation strategy will be developed based on the results of a survey regarding determinants of current practice, and two focus groups concerning the barriers and facilitators for the implementation of the SPLIT stratified model of care.

A before after study consisting of two sequential but independent cohorts of LBP patients, separated by a 3 months interval will be conducted in 6 primary care units in Portugal. In both cohorts participants will be recruited during a 7 months period.

Recruitment and data collection procedures will be identical for both cohorts. Participants will be eligible if they consult one of the participating General Practitioner practices (GA) due to non-specific Low Back Pain (LBP), with or without leg pain (The International Classification for Primary Care-2 diagnostic codes L03, L84, and L86), if they are aged between 18 and 65 years and able to read and speak the Portuguese language. They will be excluded if they have clinical signs of infection, tumor, osteoporosis, fracture, structural deformity, inflammatory disorder, radicular syndrome, or cauda equine syndrome, if they have severe depression or other psychiatric condition, if they are pregnant, or if they have undergone back surgery or conservative treatment in the prior 6 and 3 months, respectively.

Patients will be recruited by their GP, who will briefly explain the study and obtain consent to pass the contact details to a research assistant (RA). The RA will inform the patients about the study and ask them if they are willing to participate and to be contacted for follow-up questionnaires (by phone), and whether they give permission for their LBP medical records to be reviewed. Patients who decline referral will not be eligible for the study and will follow the usual clinical care.

On the initial screening with the RA, eligible LBP patients who consent to participate in the study will fill a questionnaire booklet containing socio-demographic and clinical questions, the Start Back Screening Tool, and patient reported outcomes concerning back-related disability (Roland Morris Disability Questionnaire), pain intensity (Numeric Pain Rating Scale), and health related quality of life (EuroQuol, five dimensions, 3 levels). These outcomes will be reassessed at 2 and 6 months following the first medical consultation. A Global Perceived Effect Scale (GPES) to assess patient overall perception of improvement with treatment will be added in the follow-up reassessments.

In both cohorts no specific instruction will be given to GPs concerning their practice. They will be encouraged to assess and treat their patients as usually and make all the referrals they think are appropriate for their patients. At the end of each cohort the GPs medical records will be reviewed and data concerning the number of primary care consultations, prescribed medications, ordering of diagnostic tests, referrals to other professionals or services will be extracted.

The primary outcome is back-related disability measured by the Roland Morris Disability Questionnaire (RMDQ). This questionnaire consists of 24 items related to activities of daily living and was developed to measure self-rated disability due to LBP. Each answer can be scored "0" or "1," thus leaving a range of scores from 0 to 24, with higher scores indicating higher disability. The RMDQ has shown good reliability, construct validity and responsiveness in studies with LBP patients. Secondary outcomes include pain, health related quality of life (HRQoL), and patients' perception of overall change of their back condition. Pain intensity will be measured by the Numeric Pain Rating Scale (NPRS). This is an 11-point self-report measure (0 to 10) with the labels "no pain" and "worst imaginable pain" on the ends, that has proven to be valid and reliable with patients with musculoskeletal pain. The EuroQuol, five dimensions, 3 levels (EQ-5D-3L) is a generic measuring instrument developed to assess HRQoL. The weight applied to the states is based on the Portuguese valuation study of the EQ-5D-3L. GPES is a transition scale designed to assess the patients' perception of overall change in their back condition. All patient reported measures are cross-culturally validated into European Portuguese Language showing adequate psychometric properties.

Two criteria will be used to interpret the response to treatment: 1) the Minimal Clinically Important Difference established for the RMDQ and NPRS (reduction of ≥30% from baseline); the definition of persisting LBP disability (RMDQ score >7) at 2 and 6 months.

In parallel with the data collection of the first cohort, an implementation plan will be developed. Determinants of practice (change) will be identified through the results of a survey about the GPs and Physical Therapists (PTs) attitudes, beliefs and confidence in managing LBP patients, and their adherence to clinical guidelines. Behavioural change strategies will be selected and implemented. Based on the published results of the current practice in primary care, and on the effectiveness of knowledge transfer strategies in similar studies, it is very likely that the intervention program will include different strategies such as patient-mediated interventions, educational meetings and key practice enablers (e.g. a web platform with information for patients, mentoring program, audit and feedback) targeted to GPs, PTs and patients.

Inclusion Criteria:

• Clinical diagnosis of Low back Pain of any duration;
• Age between 18 and 65 years;
• Able to read and speak the Portuguese language.

Exclusion Criteria:

• Clinical signs of infection;
• Clinical signs of tumor;
• Clinical signs of osteoporosis;
• Clinical signs of fracture;
• Clinical signs of structural deformity;
• Clinical signs of inflammatory disorder;
• Clinical signs of radicular syndrome;
• Clinical signs of cauda equine syndrome;
• Clinical signs of severe depression or other psychiatric condition;
• Pregnant women;
• Patients that undergone a back surgery in the prior 6 months;
• Patients that received any type of conservative treatment in the prior 3 months.

There is a plan to make IPD and related data dictionaries available.

The data will became available after publication which is anticipated for no earlier than 30 of June 2020. From this date, data will remain available for a period of 3 years.

The data will be available on request.