Table 3.

Adjusted incidence rate ratios (95% confidence intervals) for the association between immune-mediated inflammatory disease (IMID) and psychiatric disorders

Variable	Any psychiatric disorder	Depression	Anxiety disorder	Bipolar disorder
Combined IMID cohort
Year: cases pre-index	1.08 (1.03–1.13)	1.07 (1.02–1.12)	1.03 (0.98–1.07)	1.11 (0.99–1.24)
Year: cases post-index	0.93 (0.90–0.96)	0.95 (0.92–0.98)	0.89 (0.86–0.92)	0.98 (0.91–1.05)
Post-pre ratio: cases	0.86 (0.81–0.90)	0.89 (0.84–0.94)	0.87 (0.82–0.92)	0.88 (0.77–1.00)
Year: controls pre-index	1.03 (1.01–1.04)	1.01 (0.99–1.03)	1.00 (0.98–1.01)	1.04 (1.00–1.08)
Year: controls post-index	1.04 (1.03–1.06)	1.04 (1.02–1.06)	1.01 (0.98–1.03)	1.01 (0.97–1.05)
Post-pre ratio: controls	1.02 (0.99–1.05)	1.03 (1.00–1.07)	1.02 (0.99–1.04)	0.98 (0.91–1.05)

The year variable assesses whether there is an annual linear increase in incidence in the group (cases or controls) and period (pre-index or post-index) of interest. Post-pre ratio compares the year effect in the post-index v. pre-index periods. A ratio less than one indicates the yearly rise in incidence was greater in the pre-index than the post-index period. A ratio greater than one indicates the yearly rise in incidence was greater in the post-index than the pre-index period.