Table 2.

Factors associated with first acute diverticulitis incidence rate ratios (adjusted IRRs from Poisson regression 1988–2012)

	Male		Female
	IRR (CI)	p value	IRR (CI)	p value
Diverticulitis, all (n = 650)
Calendar year	1.040 (1.023 to 1.058)	<0.001	1.040 (1.025 to 1.055)	<0.001
Age (5-year intervals)	1.039 (1.032 to 1.046)	<0.001	1.051 (1.045 to 1.057)	<0.001
First perforation with peritonitis (n = 50)
Calendar year	1.013 (0.952 to 1.079)	0.67	1.077 (1.0203 to 1.137)	0.007
Age (5-year intervals)	1.026 (1.001 to 1.056)	0.045	1.065 (1.042 to 1.089)	<0.001
Diverticulitis, <50 years of age (n = 112)
Calendar year	1.061 (1.025 to 1.098)	0.001	1.040 (1.025 to 1.055)	<0.001
Age (5-year intervals)	1.083 (1.049 to 1.118)	<0.001	1.051 (1.045 to 1.057)	<0.001