Table 4 Results from multivariate analysis. Presenting the effect of difficulties initiating sleep, difficulties maintaining sleep, early morning awakening, non-restorative sleep and fatigue on the odds ratio (OR) for reporting CWP in the 5-year and 18-year follow-up respectively. The OR, 95% confidence intervals (95% CI) and p-value (p) are presented in model 1–3. N = 1249 entered the 5-year follow-up analyses; N = 791 entered in the 18-year follow-up analyses

 No Problem

1

1

1

1

1

1

 Problem

1.91 (1.16–3.14)*

1.93 (1.18–3.18)*

1.71 (1.03–2.85)*

1.68 (1.00–2.81)

1.37 (0.81–2.34)

1.51 (0.89–2.57)

 No problem

1

1

1

1

1

 Problem

1.85 (1.14–3.01)*

2.25 (1.40–3.61)*

1.60 (0.98–2.63)

1.88 (1.16–3.05)*

1.32 (0.79-2.21)

1.72 (1.05–2.84)*

 No problem

1

1

1

 Problem

2.00 (1.23–3.27)*

1.54 (0.94–2.54)

1.71 (1.04–2.83)*

1.32 (0.79–2.21)

1.45 (0.86–2.43)

1.18 (0.69–2.01)

 No problem

1

1

1

1

 Problem

2.27 (1.37–3.75)*

2.04 (1.26–3.29)*

1.90 (1.15–3.13)*

1.57 (0.97–2.56)

1.51 (0.88–2.58)

1.39 (0.83–2.34)

 Low

1

1

1

1

1

1

 Intermediate

1.75 (0.83–3.66)

1.09 (0.60–2.00)

1.71 (0.84–3.45)

1.05 (0.59–1.89)

1.48 (0.70–3.15)

0.97 (0.52–1.79)

 High

3.70 (1.76–7.84)*

2.36 (1.24–4.50)*

2.59 (1.34–3.47)*

1.62 (0.92–2.85)

1.93 (0.87–4.26)

1.34 (0.69–2.68)