| Crude | Adjusted sex, age and education | All significant variables in same model | Co-twin analyses of discordant twin pairs (n = 93 pairs) |
---|---|---|---|---|
Sex | ||||
 Male | 0.84 (0.71–1.00) |  |  |  |
 Female | ref |  |  |  |
Age | ||||
 19–28 | 1.57 (1.27–1.94) |  | 1.38 (1.09–1.74) |  |
 29–37 | 1.14 (0.95–1.38) |  | 1.09 (0.89–1.35) |  |
 38–47 | ref |  | ref |  |
Education | ||||
 Primary | 1.90 (1.45–2.48) |  | 1.91 (1.44–2.52) | 2.55 (0.76–8.59) |
 Secondary | ref |  | ref |  |
 Higher education | 0.87 (0.73–1.05) |  | 0.95 (0.78–1.16) | 1.05 (0.46–2.39) |
Back pain | ||||
 LBP | 0.68 (0.55–0.85) | 0.74 (0.59–0.93) | 0.80 (0.63–1.02) | 0.38 (0.17–0.87) |
 NSP | 0.83 (0.69–1.00) | 0.85 (0.70–1.04) | 0.90 (0.73–1.11) | 0.92 (0.50–1.72) |
 LBP & NSP | ref | ref | ref | ref |
MDD/GAD | ||||
 No | 0.59 (0.47–0.73) | 0.62 (0.49–0.78) | 0.68 (0.55–0.83) | 0.55 (0.27–1.10) |
 Yes | ref | ref | ref | ref |
Self-rated health | ||||
 Excellent | 0.61 (0.42–0.88) | 0.66 (0.45–0.97) | 0.88 (0.58–1.34) | 0.96 (0.22–4.25) |
 Good | 0.56 (0.40–0.80) | 0.60 (0.41–0.86) | 0.76 (0.51–1.13) | 1.38 (0.35–5.44) |
 Moderate | 0.91 (0.63–1.30) | 0.91 (0.62–1.32) | 1.01 (0.67–1.50) | 1.24 (0.33–4.74) |
 Not good/Poor | ref | ref | ref | ref |
Physical activity | ||||
 None/low | 1.09 (0.84–1.41) | 1.08 (0.82–1.41) |  | 0.72 (0.31–1.69) |
 Moderate | ref | ref |  | ref |
 High | 1.08 (0.86–1.36) | 1.06 (0.83–1.35) |  | 1.17 (0.53–2.55) |
 Vigourous | 0.85 (0.63–1.14) | 0.91 (0.67–1.23) |  | 0.84 (0.31–2.25) |
Regular analgesia | ||||
 No | 0.96 (0.82–1.13) | 0.99 (0.83–1.18) |  | 0.82 (0.47–1.43) |
 Yes | ref | ref |  | ref |
Work variables | ||||
 Job demands 1–4 | 0.95 (0.81–1.10) | 0.91 (0.77–1.07) |  | 0.87 (0.53–1.44) |
 Job control 1–4 | 0.55 (0.48–0.63) | 0.60 (0.52–0.69) | 0.62 (0.52–0.72) | 0.59 (0.34–1.02) |
 Job support 1–4 | 0.70 (0.59–0.84) | 0.69 (0.57–0.82) | 0.85 (0.70–1.03) | 0.88 (0.53–1.45) |
 Low strain | 0.50 (0.38–0.66) | 0.52 (0.39–0.69) | 0.58 (0.43–0.77) | 0.47 (0.18–1.22) |
 Passive | 0.90 (0.70–1.17) | 0.87 (0.66–1.14) | 0.95 (0.72–1.25) | 0.95 (0.32–2.87) |
 Active | 0.56 (0.44–0.71) | 0.61 (0.47–0.79) | 0.64 (0.49–0.84) | 0.68 (0.28–1.67) |
 Strain | 0.71 (0.51–1.00) | 0.68 (0.48–0.97) | 0.75 (0.53–1.06) | 0.91 (0.30–2.72) |
 Iso-strain | ref | ref | ref | ref |