Table 2 Potential barriers to general practitioners' adherence to clinical guidelines for ordering plain radiographs for back pain

1. Knowledge-related barriers

   a) Lack of awareness of the CG

See comment below.

   b) Lack of familiarity with the CG

Barrier may be less important, as GPs' own clinical ordering criteria seemed similar to current CG criteria (all studies). Some GPs were uncertain about criteria for ordering X-rays in addition to computed tomography/magnetic resonance imaging – unclear if this was due to lack of awareness of/familiarity with CG, as these GPs' knowledge of a specific CG was not examined (USA, Norway).

2. Attitude-related barriers

   a) Lack of agreement with the CG

GPs' clinical ordering criteria already seemed in line with current CG (all studies, but only the Dutch study reported on agreement with a specific CG). However, Dutch GPs disagreed with a CG presumption that ordering X-rays may elicit medical dependency, exemplifying that 2a) and 2c) may overlap.

   b) Lack of self-efficacy needed to follow the CG

GPs said they overused X-rays because they lacked clinical skills, suggesting that low self-efficacy may be a barrier (Norway).

   c) Lack of expectancy that following the CG will lead to desired patient outcomes

GPs might order X-rays not indicated by clinical criteria if this seemed more likely to lead to desired patient outcomes, e.g., reassurance (all studies), return to work (USA, Norway), economic support (Norway).

   d) Lack of motivation to follow the CG or inability to overcome the inertia of previous practice

Not reported.

3. Behaviour-related (i.e., external) barriers

   a) Guideline factors (e.g., inconvenient or confusing criteria)

Not examined (USA, Norway) or not reported (the Netherlands).

   b) Patient factors (e.g., preferences that conflicts with the CG)

Patients' wishes for X-rays seemed an important barrier (all studies).

   c) Environmental factors related to practice setting

c1) Lack of time

Included lack of time to negotiate or reassure patients (all studies).

c2) Lack of resources (e.g., lack of educational materials)

Not reported, but related barrier described below (4c).

c3) Organisational constraints (e.g., insufficient staff)

Not reported.

c4) Lack of reimbursement

Not reported.

c5) Increased malpractice liability

Not reported in the Dutch study.

4. Additional barriers not originally included in the framework

   a) Lack of expectancy that following the CG will lead to desired health care/consultation process

GPs might order 'non-indicated' X-rays to buy time (USA), negotiate (all studies), or build a good relationship with the patient (USA, The Netherlands).

   b) Feeling it emotionally difficult to follow the CG

GPs might order 'non-indicated' X-rays to maintain trust (USA) or limit conflict (USA, Norway), or to end a difficult consultation, reduce own anxiety, or protect own professional dignity (Norway).

   c) Improper access to actual/alternative health care services

Included easy access to actual X-ray services (Norway), and difficult access to physiotherapy (USA) or computed tomography (Norway).

   d) Pressure from other health care providers/organisations

GPs might order 'non-indicated' X-rays due to pressure from other health care providers (The Netherlands, Norway) or social security (Norway), or because the health maintenance organisation expected them to satisfy patients but limit use of (other) referral services (USA).