Table 3.

Associations (odds ratios) between early vs. late mental disorder onset and the subsequent onset of chronic back or neck pain.

	Bivariate Models¹				Multivariate Model²

	Early	Late	Test of the difference between early and late		Early	Late	Test of the difference between early and late

	OR (95% C.I)	OR (95% C.I)	χ₁²	[p]	OR (95% C.I)	OR (95% C.I)	χ₁²	[p]
I. Mood disorders
Major Depressive Episode/Dysthymia	2.2^* (2.0-2.4)	1.5^* (1.4-1.7)	31.8^*	[0.000]	1.5^* (1.3-1.6)	1.3^* (1.2-1.4)	4.6^*	[0.032]
Bipolar Disorder (Broad)	2.5^* (2.1-3.0)	1.5^* (1.2-2.0)	8.3^*	[0.004]	1.2 (1.0-1.5)	0.9 (0.7-1.2)	3.0	[0.085]
II. Anxiety disorders
Panic Disorder	2.4^* (2.0-2.8)	1.7^* (1.4-2.0)	7.2^*	[0.007]	1.3^* (1.1-1.6)	1.2 (0.9-1.4)	0.9	[0.358]
Generalized Anxiety Disorder	2.6^* (2.3-3.0)	1.8^* (1.6-2.1)	15.4^*	[0.000]	1.5^* (1.3-1.7)	1.3^* (1.2-1.5)	1.6	[0.213]
Social Phobia	1.9^* (1.8-2.1)	1.5^* (1.1-2.0)	2.9	[0.090]	1.3^* (1.1-1.4)	1.0 (0.7-1.4)	1.6	[0.203]
Specific Phobia	1.9^* (1.7-2.0)	1.4 (1.0-1.9)	3.2	[0.075]	1.5^* (1.4-1.7)	1.2 (0.8-1.7)	1.7	[0.197]
Agoraphobia Without Panic Disorder	1.9^* (1.5-2.4)	1.4 (1.0-2.0)	2.4	[0.125]	1.0 (0.8-1.3)	0.9 (0.6-1.3)	0.4	[0.544]
Post-Traumatic Stress Disorder	2.2^* (1.9-2.6)	1.6^* (1.3-2.1)	4.9^*	[0.028]	1.3^* (1.2-1.6)	1.2 (1.0-1.5)	0.8	[0.372]
Obsessive Compulsive Disorder	1.8^* (1.4-2.5)	2.3^* (1.3-4.3)	0.4	[0.549]	1.4^* (1.0-1.8)	1.6 (0.9-3.0)	0.2	[0.642]
III. Impulse-control disorders
Intermittent Explosive Disorder	2.3^* (2.0-2.6)	1.8^* (1.3-2.6)	1.6	[0.210]	1.5^* (1.3-1.8)	1.3 (0.9-1.9)	0.4	[0.525]
Binge Eating Disorder	1.9^* (1.4-2.7)	2.4^* (1.5-3.9)	0.5	[0.467]	1.4 (1.0-1.9)	1.6 (1.0-2.7)	0.3	[0.620]
Bulimia Nervosa	2.8^* (2.1-3.7)	3.2^* (2.0-5.1)	0.3	[0.598]	1.4^* (1.0-2.0)	2.0^* (1.2-3.3)	1.0	[0.317]
IV. Substance disorders
Alcohol Abuse	1.9^* (1.7-2.2)	1.5^* (1.3-1.7)	10.1^*	[0.002]	1.4^* (1.2-1.7)	1.2^* (1.0-1.4)	2.7	[0.102]
Alcohol Dependence with Abuse	2.3^* (1.9-2.7)	1.6^* (1.3-2.1)	5.1^*	[0.023]	1.1 (0.9-1.3)	1.0 (0.8-1.3)	0.3	[0.612]
Drug Abuse	2.1^* (1.8-2.5)	2.2^* (1.7-2.9)	0.0	[0.896]	1.3^* (1.0-1.6)	1.4^* (1.1-1.9)	0.4	[0.521]
Drug Dependence With Abuse	2.2^* (1.7-2.8)	2.0^* (1.3-3.0)	0.2	[0.660]	0.7 (0.5-1.0)	0.8 (0.5-1.3)	0.2	[0.651]
V. Joint Effect of all Early Onset Disorders, χ²₁₆					746.2^*
VI. Joint Effect of all Late Onset Disorders, χ²₁₆						122.3^*
VII. Joint Effect of Early Onset Disorders independent of joint effect of any disorders,χ²₁₆							30.8^*

Significant at the 0.05 level, two-tailed test.

Models include dummy variables for early onset mental disorders (= first onset < 21 years of age) and for late onset disorders, plus control variables (age-cohort, person years, gender and country). A second bivariate model was estimated to test the significance of the difference between early and late onset disorders. This model included the dummy variables for the early onset disorder and the dummy variable for the disorder itself (i.e, having it at all), plus controls.

Multivariate models paralleled the bivariate models in design but included dummy variables for all mental disorders entered simultaneously.