Risk factors of admission for acute colonic diverticulitis in a population-based cohort study: The North Trondelag Health Study, Norway

Table 1 Percentage missing values in different variables

Variable	Females	Males
Hard physical activity	39	28
Cigarette smoking	7	5
Breathlessness	16	10
Constipation	12	9
Type of bread	13	16
Highest educational level	6	5

Table 2 Baseline characteristics of the study population n (%)

Characteristic	Acute colonic diverticulitis 1998-2012
	Females		Males
	No	Yes	No	Yes
Study population	22203	233	20009	125
Age in years at inclusion
Mean ± SD	49.9 (17.2)	59.8 (13.8)	49.5 (16.7)	54.7 (14.4)
Age groups (yr)
< 50	11892 (99.5)	57 (0.5)	10787 (99.6)	45 (0.4)
50-70	6708 (98.4)	112 (1.6)	6307 (99.1)	58 (0.9)
> 70	3603 (98.3)	64 (1.7)	2915 (99.3)	22 (0.7)
BMI (kg/m2)
< 25	9987 (99.3)	68 (0.7)	6983 (99.6)	26 (0.4)
25-29.9	8206 (98.9)	89 (1.1)	10146 (99.4)	64 (0.6)
≥ 30	4010 (98.1)	76 (1.9)	2880 (98.8)	35 (1.2)
Hard physical activity (h/wk)
< 1	9346 (99.0)	91 (1.0)	8368 (99.3)	58 (0.7)
≥ 1	4286 (99.6)	19 (0.4)	6105 (99.4)	36 (0.6)
Missing	8571 (98.6)	123 (1.4)	5536 (99.4)	31 (0.6)
Smoking cigarettes
Never	10134 (99.2)	81 (0.8)	7337 (99.6)	31 (0.4)
Previous	4137 (98.8)	51 (1.2)	6175 (99.2)	52 (0.8)
Daily	6295 (98.8)	75 (1.2)	5491 (99.4)	33 (0.6)
Missing	1637 (98.4)	26 (1.6)	1006 (99.1)	9 (0.9)
Problems with breathlessness the last 12 mo
Not at all	17030 (99.1)	155 (0.9)	16585 (99.5)	87 (0.5)
Slightly	1434 (98.8)	17 (1.2)	1262 (98.5)	19 (1.5)
Very much	185 (98.4)	3 (1.6)	189 (98.4)	3 (1.6)
Missing	3554 (98.4)	58 (1.6)	1973 (99.2)	16 (0.8)
Problems with constipation the last 12 mo
Not at all	13664 (99.1)	125 (0.9)	15690 (99.4)	90 (0.6)
Slightly	4640 (99.0)	48 (1.0)	2201 (99.4)	14 (0.6)
Very much	1213 (98.3)	21 (1.7)	285 (99.0)	3 (1.0)
Missing	2686 (98.6)	39 (1.4)	1833 (99.0)	18 (1.0)
Type of bread
Only fine	2670 (99.0)	28 (1.0)	3798 (99.5)	20 (0.5)
Mixed	3158 (99.0)	33 (1.0)	4062 (99.4)	23 (0.6)
Only coarse	13440 (98.9)	147 (1.1)	9018 (99.3)	62 (0.7)
Missing	2935 (99.2)	25 (0.8)	3131 (99.4)	20 (0.6)
Highest educational level
Primary school	8146 (98.7)	110 (1.3)	5519 (99.2)	46 (0.8)
Above primary school	12687 (99.3)	95 (0.7)	13536 (99.5)	73 (0.5)
Missing	1370 (97.3)	28 (2.7)	954 (99.4)	6 (0.6)
Living area
Urban	18225 (98.9)	195 (1.1)	16425 (99.4)	91 (0.6)
Rural	3978 (99.1)	38 (0.9)	3584 (99.1)	34 (0.9)

Data given as n (%) unless otherwise stated.

Table 3 Univariable Cox regression analysis of risk factors relating to admission for acute diverticulitis, after multiple imputation for missing values

Characteristic	Females		Males
	HR (95%CI)	P value	HR (95%CI)	P value
Age in years (yr)
< 50	1 (ref)		1 (ref)
50-70	3.55 (2.58-4.89)	< 0.001	2.36 (1.60- 3.48)	< 0.001
> 70	5.88 (4.10-8.44)	< 0.001	3.46 (2.06-5.79)	< 0.001
BMI (kg/m2)
< 25	1 (ref)		1 (ref)
25-29.9	1.59 (1.16-2.18)	0.004	1.62 (1.03-2.56)	0.040
≥ 30	2.86 (2.06-3.97)	< 0.001	3.20 (1.93-5.31)	< 0.001
Hard physical activity (h/wk)
< 1	1 (ref)		1 (ref)
≥ 1	0.46 (0.27- 0.77)	0.003	0.85 (0.56-1.29)	0.45
Smoking cigarettes
Never daily	1 (ref)		1 (ref)
Formerly	1.45 (1.04-2.01)	0.027	2.12 (1.36- 3.13)	0.001
Present daily	1.36 (1.01-1.83)	0.043	1.49 (0.91- 2.44)	0.11
Problems with breathlessness the last 12 mo
Not at all	1 (ref)		1 (ref)
Slightly	1.44 (0.87-2.36)	0.15	3.09 (1.88- 5.08)	< 0.001
Very much	2.32 (0.76- 7.12)	0.14	3.54 (1.13-11.2)	0.031
Problems with constipation the last 12 mo
Not at all	1 (ref)		1 (ref)
Slightly	1.14 (0.82-1.60)	0.44	1.25 (0.72-1.19)	0.43
Very much	2.02 (1.29-3.18)	0.002	2.35 (0.76-7.24)	0.14
Type of bread
Only fine	1 (ref)		1 (ref)
Mixed	0.97 (0.58-1.61)	0.90	1.03 (0.57-1.86)	0.93
Only coarse	1.01 (0.67-1.51)	0.96	1.26 (0.76-1.08)	0.38
Highest educational level
Primary school	1 (ref)		1 (ref)
Higher than primary school	0.49 (0.37-0.64)	< 0.001	0.57 (0.39-0.82)	0.002
Living area
Urban	1 (ref)		1 (ref)
Rural	0.92 (0.65-1.30)	0.63	1.80 (1.21-2.67)	0.004

BMI: Body mass index.

Table 4 Multivariable Cox regression analysis of risk factors relating to admission for acute diverticulitis, after multiple imputation for missing values

Characteristic	Females		Males
	HR (95%CI)	P value	HR (95%CI)	P value
Age in years (yr)
< 50	1 (ref)		1 (ref)
50-70	3.42 (2.40-4.86)	< 0.001	1.85 (1.22-7.80)	0.004
> 70	6.19 (4.02-9.54)	< 0.001	2.56 (1.45-4.52)	0.001
BMI (kg/m2)
< 25	1 (ref)		1 (ref)
25-29.9	1.25 (0.90-1.73)	0.18	1.46 (0.92-2.32)	0.11
≥ 30	2.06 (1.46-2.91)	< 0.001	2.58 (1.53-4.34)	< 0.001
Hard physical activity (h/wk)
< 1	1 (ref)		1 (ref)
≥ 1	0.67 (0.39-1.15)	0.15	1.03 (0.67-1.57)	0.90
Smoking cigarettes
Never daily	1 (ref)		1 (ref)
Formerly	1.65 (1.15-2.36)	0.007	1.45 (0.91-2.31)	0.12
Present daily	2.11 (1.51-2.94)	< 0.001	1.38 (0.84-2.29)	0.21
Problems with breathlessness the last 12 mo
Not at all	1 (ref)		1 (ref)
Slightly	1.12 (0.68-1.86)	0.66	2.57 (1.55-4.28)	< 0.001
Very much	1.43 (0.45-4.59)	0.55	2.48 (0.74-8.39)	0.14
Problems with constipation the last 12 mo
Not at all	1 (ref)		1 (ref)
Slightly	1.05 (0.75-1.48)	0.77	0.94 (0.53-1.66)	0.82
Very much	1.54 (0.95-2.49)	0.078	1.41 (0.43-4.68)	0.57
Type of bread
Only fine	1 (ref)		1 (ref)
Mixed	1.08 (0.65-1.79)	0.77	1.06 (0.58-1.93)	0.85
Only coarse	0.93 (0.62-1.41)	0.74	1.24 (0.74-2.07)	0.41
Highest educational level
Primary school	1 (ref)		1 (ref)
Higher than primary school	1.13 (0.82-1.54)	0.46	0.90 (0.61-1.33)	0.60
Living area
Urban	1 (ref)		1 (ref)
Rural	0.92 (0.65-1.30)	0.63	1.80 (1.21-2.67)	0.004