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Table 1 Characteristics of the Longitudinal Study Sample*

From: Do medical conditions predispose to the development of chronic back pain? A longitudinal co-twin control study of middle-aged males with 11-year follow-up

Characteristics Incident Chronic Back Pain Over 11-Year Follow-up
No (n = 2418) Yes (n = 502) p value*
Sociodemographics
 Age (mean ± standard deviation) 50.6 ± 3.0 50.0 ± 3.1 < 0.001
 Race (%)
  White 2322 (96.3%) 481 (96.0%) 0.75
  Non-white 90 (3.7%) 20 (4.0%)
 Educational attainment
 Did not graduate high school 55 (2.4%) 22 (4.6%) 0.01
  High school graduate 494 (21.4%) 110 (23.1%)
  Some college/vocational schoola 1016 (44.0%) 215 (45.2%)
  Completed college or further studyb 744 (32.2%) 129 (27.1%)
Medical Comorbidities
 Arthritis 331 (13.7%) 111 (22.2%) < 0.001
 Diabetes 112 (4.6%) 30 (6.0%) 0.22
 Hypertension 508 (21.1%) 127 (25.5%) 0.03
 Coronary Artery Disease (CAD) 95 (3.9%) 30 (6.0%) 0.03
Overall Comorbidity Burden
 Medical comorbidity score, range 0–18 (median [IQR]) 0 [0–2] 1 [0–2] < 0.001
  1. *p-values reflect clustering by twinship
  2. aIncluding some college without completion, or having completed vocational school, technical school, or a 2-year college degree
  3. battended and/or completed graduate school