Table 1

Levels of CEBM modified for scientific papers investigating disease pathophysiology with bench research.

Level

Differential diagnosis/symptom prevalence study

Blinded

Controls

Remark/example


1a

Systematic review of prospective cohort studies

NR

NR

No systematic reviews available


1b

Prospective cohort study with good follow-up

NR

Implicit

An item is assessed (e.g. breast implant) and the occurrence of FMS is followed prospectively


1c

All or none case series

Test and assessment of results

Obligatory

All patients with low IL-4 have FMS, none has high IL-4


1d

1c

Test or assessment of results

Obligatory

1c


2a

Systematic review (with homogeneity) of

NR

NR

No systematic reviews available


2b and better studies


2b

Retrospective cohort study, or poor follow-up

NR

Implicit

FMS patients are investigated now, if they have had breast implants in the past; large size studies


2c

Ecological studies

Test and assessment of results

Implicit

FMS patients are investigated simultaneously, if they have FMS and if they have low IL-4 levels.


2d

2c

Test or assessment of results

Implicit

2c


3a

Systematic review (with homogeneity) of 3b and better studies

No systematic reviews available


3b

Non-consecutive cohort study, or very limited population

Test and assessment of results

Obligatory

FMS patients and controls (limited population) are now investigated if they have low IL-4


levels


3c

3b

Test or assessment of results

Obligatory

3b


3d

1c, 2c, 3b

Not blinded

Obligatory


4

Case series or superseded reference standards

All studies without control group

Case series with historical controls; case reports


5

Expert opinion without explicit critical appraisal, or based on physiology, bench research or "first principles"

NR


Abbreviations: CEMB: Oxford Center for Evidence-based Medicine FMS: fibromyalgia syndrome; NR: not relevant

Üçeyler et al. BMC Musculoskeletal Disorders 2011 12:245   doi:10.1186/1471-2474-12-245

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