Table 2.

Summary of study characteristics and population

References	Country	Study design	Study size	Age	Gender	Race	Education level
Briggs et al. [10] Briggs et al. [41]	Australia	Cross-sectional, mixed methods study	n = 117	Mean ages: 38.5 (No CL back pain), 37.4 (CL back pain-low disability), 43.2 (CL back pain-high disability)	Female (n = 71)	Unspecified	≤ Secondary school (n = 17), Trade certificate or diploma (n = 33), University degree (n = 30), No response (n = 37)
Devraj et al. [12]	USA	Cross-sectional	n = 139	≥ 18 years	Females (n = 105)	White (n = 98), African American (n = 24), Hispanic (n = 8), Asian or Pacific Islander (n = 4), Native American (n = 4)	≤ Secondary school (n = 37), Some college (n = 48), University degree (n = 54)
Farin et al. [11]	Germany	Cross-sectional	n = 577	17–85 years	Females (n ~ 317)	Unspecified	≥ Secondary school (77.9%), University-entrance diploma or technical college qualification (20.9%)
Camerini and Schulz [51]	Switzerland and Italy	Cross-sectional	n = 273	20–89 years	Female (n = 159)	Unspecified	≤ Secondary school (n = 90), Post-secondary non tertiary educational degree (n = 145), University degree (n = 38)
Burke et al. [53]	USA	Cross-sectional, retrospective	n = 23,393 (back pain sub-sample of 2580)	≥ 18 years	Unspecified	Included: White, Black, and Others	Included: ≤ High school, ≥ Some college
Al-Eisa et al. [48]	Saudi Arabia	Cross-sectional	n = 227	20–55 years	Female only	Unspecified	Unspecified
MacLeod et al. [54]	USA	Cross-sectional, retrospective	n = 7334	≥ 65 years	Females (n = 4384)	Sicker population (minority/non-white 7.3%, White 92.7%). Healthier population (minority/non-white 3.4%, White 96.6%)	Sicker population (≤ High school 41.8%, ≤ 2 year college 29.0%, ≥ 4 year college 29.2%). Healthier population (≤ High school 39.2%, ≤ 2 year college 28.9%, ≥ 4 year college 32.0%)
Köppen et al. [20]	Austria	Cross-sectional	n = 121	18–65 years	Female (n = 89)	Unspecified	Compulsory school (17%), School leaving examination/ apprenticeship (61%), University (22%)
Glassman et al. [47]	USA	Cross-sectional	n = 186	≥ 18 years	Females (n = 119)	Unspecified	≤ Secondary school (n = 108), University degree (n = 51), no data (n = 27)