Comorbidities	Randomized controlled trials	Observational studies	Retrospective, insurance database studies	Registries	Mixed methods
Previous myocardial infarction	-	-	3.4 - 8.1 [60,78]	-	-
Aortic aneurysm	-	-	1.2 [103]	-	-
Stroke/cardiovascular disease (CVD)	2.1 [59]	-	7.5 - 48.2 [56,60,61,103,105]	-	-
Peripheral vascular disease (PVD)	6.0 - 6.1 [41,59]	-	5.9 - 11.3 [39,60,78,101]	-	2.1 [22]
Lung disease	7.6 - 7.7 [41,59]	5.6 - 15.7 [46,53,83]	1.7 - 26.1 [8,54,56,60,78,80,103,105]	-	3.9 [22]
Neurologic disease	2.1 [41,59]	-	-	2.4 [42]	8.0 [22]
Parkinson's disease (PD)/peripheral neuropathy	-	2.3 - 11.1 [46,53,83]	-	-	-
Dementia/hemi-/paraplegia	-	-	2.9 [60]	-	-
PD/Alzheimer disease /hearing loss	-	-	16.3 [54]	-	-
Rheumatologic disease
Musculoskeletal disorder, not specified	51.0 - 55.9 [41,59,[69], [70], [71]]	44.1 [27]	13.3 [60]	-	1.8 [22]
Osteoporosis	6.2 - 10.4 [59,[69], [70], [71]]	-	35.6 [60]	-	-
Osteoarthritis (OA)	-	-	6.8 - 20.2 [39,78,101]	-
Knee OA	-	4.9 - 15.8 [40,53,83]	-	-	4.8 [22]
Hip OA	-	2.0 - 13.7 [40,53,83]	-	-	2.7 [22]
Hip/knee OA	-	1.0 - 35.0 [40,46]	-	-	-
Rheumatoid arthritis	-	2.0 [40]	0.8 [78]	-	-
Pseudogout	-	-	0.8 [78]	-	-
Diffuse idiopathic skeletal hyperostosis (DISH)	-	-	0.8 [78]	-	-
Psychiatric disease		.
Depression	11.0 - 53.4 [41,59,[68], [69], [70], [71]]	17.9 - 27.3 [46,53,82]	5.7 – 7.3 [39,101]	-	2.7 [45]
Anxiety	4.8 - 38.1 [59,68]	17.1-17.6 [53,82]	-	-	-
Drug addiction	0.3 [59]	-	-	-	-
Cancer	7.7 [59]	-	4.6 - 9.3 [60,78,103,105]	1.3 [42]	-
Kidney disease	4.6 [41,59]	-	0.8 - 9.4 [56,60,61,103,105]	-	-
Urologic disease
Prostate hypertrophy	-	-	2.5 – 17.7 [54,103]	-	-
Gastrointestinal disease
Gastric disease	20.6 - 22.2 [41,59,[69], [70], [71]]	-	42.4 [60]	-	-
Intestinal disease	10.4 - 13.7 [41,59,[69], [70], [71]]	-	1.7 [78]	-	-
Liver disease	1.6 [41,59]	-	31.2 [60]	-	-
Endocrinologic disease
Hypothyroidism	-	-	0.8 [78]	-	-
Acquired immune deficiency syndrome (AIDS)	-	-	0.1 [60]	-	-
Ophthalmologic disease
Glaucoma	-	-	0.8 [78]
Other diseases	29.7 - 78.5g [41,[69], [70], [71]]	-	-	-	8.0h,22

Abbreviations: SD, standard deviation; IQR, interquartile range; n, number of patients

^aValue for back pain and leg pain respectively;

^bsymptom duration >5 years;

^csymptom duration >6 months;

^dsymptom duration >3 months;

^eduration of back pain >2 years;

^fduration of leg pain >2 years;

^gother diseases related to stroke, cancer, fibromyalgia, chronic fatigue syndrome, posttraumatic stress disorder, alcohol consumption, drug addiction, lung, liver, kidney, blood vessel, nervous system, migraine or anxiety;

^hother diseases than hip or knee joint arthrosis, peripheral vascular disease, diabetes, cardiovascular, pulmonary, neurologic or rheumatic disease