Gastroenterol Res

Gastroenterology Research, ISSN 1918-2805 print, 1918-2813 online, Open Access

Article copyright, the authors; Journal compilation copyright, Gastroenterol Res and Elmer Press Inc

Journal website https://gr.elmerpub.com

Original Article

Volume 000, Number 000, March 2025, pages 000-000

Incidence of Inflammatory Bowel Disease in Children

Figure 2. Number of new cases of UC, CD, and IBD-U per year. CD: Crohn’s disease; IBD-U: unclassified inflammatory bowel disease; UC: ulcerative colitis.

Figure 3. Number of children with newly diagnosed IBD, UC, CD, and IBD-U (per 100,000 children) in the Kujawsko-Pomorskie voivodeship. CD: Crohn’s disease; IBD-U: unclassified inflammatory bowel disease; UC: ulcerative colitis.

Figure 4. Trend in IBD incidence in children by age subgroup. IBD: inflammatory bowel disease.

**Table 1.** Characteristics of the Study Group at the Time of Data Collection
Characteristic	IBD (n = 118) (100%)	IBD (n = 118) (100%)
^aRural: less than 2000 inhabitants. ^bUrban: more than 2000 inhabitants. CD: Crohn’s disease; IBD: inflammatory bowel disease; IBD-U: unclassified inflammatory bowel disease; SD: standard deviation; UC: ulcerative colitis.
Age at the time of diagnosis in years					0.066
Mean ± SD	11.67 ± 4.15	12.47 ± 3.52	11.38 ± 4.5	9.23 ± 4.59
Min - Max	2 - 18	4 - 17	2 - 18	3 - 17
Sex, n (%)					0.892
Girls	52 (44%)	25 (44%)	22 (46%)	5 (38%)
Boys	66 (56%)	32 (56%)	26 (54%)	8 (62%)
Place of residence, n (%)					0.379
Rural^a	36 (31%)	21 (37%)	12 (25%)	3 (23%)
Urban^b	82 (69%)	36 (63%)	36 (75%)	10 (77%)
First-degree relatives of IBD, n (%)	18 (15%)	7 (12%)	10 (21%)	1 (8%)	0.174
Mother	9 (8%)	2 (4%)	7 (15%)	0 (0%)
Father	5 (4%)	2 (4%)	2 (4%)	1 (8%)
Siblings	4 (3%)	3 (5%)	1 (2%)	0 (0%)

Table 1. Characteristics of the Study Group at the Time of Data Collection

Characteristic

IBD (n = 118) (100%)

UC (n = 57) (48.3%)

CD (n = 48) (40.68%)

IBD-U (n = 13) (11.02%)

^aRural: less than 2000 inhabitants. ^bUrban: more than 2000 inhabitants. CD: Crohn’s disease; IBD: inflammatory bowel disease; IBD-U: unclassified inflammatory bowel disease; SD: standard deviation; UC: ulcerative colitis.

Age at the time of diagnosis in years

0.066

Mean ± SD

11.67 ± 4.15

12.47 ± 3.52

11.38 ± 4.5

9.23 ± 4.59

Min - Max

2 - 18

4 - 17

2 - 18

3 - 17

Sex, n (%)

0.892

Girls

52 (44%)

25 (44%)

22 (46%)

5 (38%)

Boys

66 (56%)

32 (56%)

26 (54%)

8 (62%)

Place of residence, n (%)

0.379

Rural^a

36 (31%)

21 (37%)

12 (25%)

3 (23%)

Urban^b

82 (69%)

36 (63%)

36 (75%)

10 (77%)

First-degree relatives of IBD, n (%)

18 (15%)

7 (12%)

10 (21%)

1 (8%)

0.174

Mother

9 (8%)

2 (4%)

7 (15%)

0 (0%)

Father

5 (4%)

2 (4%)

1 (8%)

Siblings

4 (3%)

3 (5%)

1 (2%)

0 (0%)

**Table 2.** Children With IBD With Regard to Age at the Time of Diagnosis, Onset of the First Symptoms, Sex, the Severity of Course, and Place of Residence in the Period 2011 - 2022
Characteristic	2011 – 2022, n = 118 (100%)	2011 – 2016, n = 48 (100%)	2017 – 2022, n = 70 (100%)	P
CD: Crohn’s disease; IBD: inflammatory bowel disease; UC: ulcerative colitis.
Mean age of onset of the first symptoms in years
IBD	10.48 ± 4.57	9.33 ± 4.95	11.27 ± 4.41	0.023
UC	11.40 ± 4.25	10.26 ± 5.42	11.97 ± 3.47	0.363
CD	10.06 ± 4.74	9.81 ± 4.64	10.26 ± 4.9	0.594
Mean age of diagnosis in years
IBD	11.67 ± 4.15	10.75 ± 4.51	12.3 ± 3.79	0.046
UC	12.47 ± 3.52	12.11 ± 3.94	12.66 ± 3.32	0.734
CD	11.38 ± 4.5	10.71 ± 4.57	11.89 ± 4.47	0.296
Age at the time of diagnosis
IBD				0.013
< 6 years of age	15 (12.71%)	11 (22.92%)	4 (5.71%)
≥ 6 years of age	103 (87.29%)	37 (77.08%)	66 (94.29%)
UC				0.033
< 6 years of age	3 (2.54%)	3 (6.25%)	0 (0.00%)
≥ 6 years of age	54 (45.76%)	16 (33.33%)	38 (54.29%)
CD				0.715
< 6 years of age	8 (6.78%)	4 (8.33%)	4 (5.71%)
≥ 6 years of age	40 (33.90%)	17 (35.42%)	23 (32.86%)
Sex
IBD				0.896
Girls	52 (44.07%)	21 (43.75%)	31 (44.29%)
Boys	66 (55.93%)	27 (56.25%)	39 (55.71%)
UC				0.925
Girls	25 (21.19%)	8 (16.67%)	17 (24.29%)
Boys	32 (27.12%)	11 (22.92%)	21 (30.00%)
CD				0.942
Girls	22 (18.64%)	10 (20.83%)	12 (17.14%)
Boys	26 (22.03%)	11 (22.92%)	15 (21.43%)
Severity of course/number of patients on biological therapy				0.024
IBD	36 (30.5%)	17 (35.42%)	19 (27.14%)
UC	15 (12.71%)	4 (8.33%)	11 (15.71%)
CD	17 (14.41%)	9 (18.75%)	8 (11.43%)
Severity of course/number of patients without biological therapy				0.851
IBD	82 (69.49%)	31 (64.58%)	51 (72.86%)
UC	41 (34.75%)	15 (31.25%)	27 (38.57%)
CD	31 (26.27%)	12 (25%)	19 (27.14%)
Place of residence
IBD				0.641
Urban	82 (69.49%)	35 (72.92%)	47 (67.14%)
Rural	36 (30.51%)	13 (27.08%)	23 (32.86%)
UC				0.771
Urban	36 (30.51%)	11 (22.92%)	25 (35.71%)
Rural	21 (17.80%)	8 (16.67%)	13 (18.57%)
CD				0.867
Urban	36 (30.51%)	16 (33.33%)	20 (28.57%)
Rural	12 (10.17%)	5 (10.42%)	7 (10.00%)

Table 2. Children With IBD With Regard to Age at the Time of Diagnosis, Onset of the First Symptoms, Sex, the Severity of Course, and Place of Residence in the Period 2011 - 2022

Characteristic

2011 – 2022, n = 118 (100%)

2011 – 2016, n = 48 (100%)

2017 – 2022, n = 70 (100%)

CD: Crohn’s disease; IBD: inflammatory bowel disease; UC: ulcerative colitis.

Mean age of onset of the first symptoms in years

IBD

10.48 ± 4.57

9.33 ± 4.95

11.27 ± 4.41

0.023

11.40 ± 4.25

10.26 ± 5.42

11.97 ± 3.47

0.363

10.06 ± 4.74

9.81 ± 4.64

10.26 ± 4.9

0.594

Mean age of diagnosis in years

IBD

11.67 ± 4.15

10.75 ± 4.51

12.3 ± 3.79

0.046

12.47 ± 3.52

12.11 ± 3.94

12.66 ± 3.32

0.734

11.38 ± 4.5

10.71 ± 4.57

11.89 ± 4.47

0.296

Age at the time of diagnosis

IBD

0.013

< 6 years of age

15 (12.71%)

11 (22.92%)

4 (5.71%)

≥ 6 years of age

103 (87.29%)

37 (77.08%)

66 (94.29%)

0.033

< 6 years of age

3 (2.54%)

3 (6.25%)

0 (0.00%)

≥ 6 years of age

54 (45.76%)

16 (33.33%)

38 (54.29%)

0.715

< 6 years of age

8 (6.78%)

4 (8.33%)

4 (5.71%)

≥ 6 years of age

40 (33.90%)

17 (35.42%)

23 (32.86%)

Sex

IBD

0.896

Girls

52 (44.07%)

21 (43.75%)

31 (44.29%)

Boys

66 (55.93%)

27 (56.25%)

39 (55.71%)

0.925

Girls

25 (21.19%)

8 (16.67%)

17 (24.29%)

Boys

32 (27.12%)

11 (22.92%)

21 (30.00%)

0.942

Girls

22 (18.64%)

10 (20.83%)

12 (17.14%)

Boys

26 (22.03%)

11 (22.92%)

15 (21.43%)

Severity of course/number of patients on biological therapy

0.024

IBD

36 (30.5%)

17 (35.42%)

19 (27.14%)

15 (12.71%)

4 (8.33%)

11 (15.71%)

17 (14.41%)

9 (18.75%)

8 (11.43%)

Severity of course/number of patients without biological therapy

0.851

IBD

82 (69.49%)

31 (64.58%)

51 (72.86%)

41 (34.75%)

15 (31.25%)

27 (38.57%)

31 (26.27%)

12 (25%)

19 (27.14%)

Place of residence

IBD

0.641

Urban

82 (69.49%)

35 (72.92%)

47 (67.14%)

Rural

36 (30.51%)

13 (27.08%)

23 (32.86%)

0.771

Urban

36 (30.51%)

11 (22.92%)

25 (35.71%)

Rural

21 (17.80%)

8 (16.67%)

13 (18.57%)

0.867

Urban

36 (30.51%)

16 (33.33%)

20 (28.57%)

Rural

12 (10.17%)

5 (10.42%)

7 (10.00%)

**Table 3.** Number of Patients According to the Season of the First Symptoms
Seasons	2011 - 2022, n = 118 (100%)	2011 - 2016, n = 48 (100%)	2017 - 2022, n = 70 (100%)	P
CD: Crohn’s disease; IBD: inflammatory bowel disease; UC: ulcerative colitis.
Spring, n (%)				0.276
IBD	34 (28.8%)	16 (33.33%)	18 (24.71%)
UC	18 (15.25%)	6 (12.5%)	12 (17.14%)
CD	10 (8.47%)	6 (12.5%)	4 (5.71%)
Summer, n (%)				0.875
IBD	31 (26.27%)	14 (29.17%)	17 (24.29%)
UC	15 (12.71%)	6 (12.5%)	9 (12.86%)
CD	13 (11.01%)	7 (14.58%)	6 (8.57%)
Autumn, n (%)				0.479
IBD	33 (27.97%)	10 (20.83%)	23 (32.86%)
UC	16 (13.56%)	5 (10.42%)	11 (15.71%)
CD	16 (13.56%)	4 (8.33%)	12 (17.14%)
Winter, n (%)				0.580
IBD	20 (16.95%)	8 (16.67%)	12 (17.14%)
UC	8 (6.78%)	2 (41.17%)	6 (8.57%)
CD	9 (7.63%)	4 (8.33%)	5 (7.14%)

Table 3. Number of Patients According to the Season of the First Symptoms

Seasons

2011 - 2022, n = 118 (100%)

2011 - 2016, n = 48 (100%)

2017 - 2022, n = 70 (100%)

CD: Crohn’s disease; IBD: inflammatory bowel disease; UC: ulcerative colitis.

Spring, n (%)

0.276

IBD

34 (28.8%)

16 (33.33%)

18 (24.71%)

18 (15.25%)

6 (12.5%)

12 (17.14%)

10 (8.47%)

6 (12.5%)

4 (5.71%)

Summer, n (%)

0.875

IBD

31 (26.27%)

14 (29.17%)

17 (24.29%)

15 (12.71%)

6 (12.5%)

9 (12.86%)

13 (11.01%)

7 (14.58%)

6 (8.57%)

Autumn, n (%)

0.479

IBD

33 (27.97%)

10 (20.83%)

23 (32.86%)

16 (13.56%)

5 (10.42%)

11 (15.71%)

16 (13.56%)

4 (8.33%)

12 (17.14%)

Winter, n (%)

0.580

IBD

20 (16.95%)

8 (16.67%)

12 (17.14%)

8 (6.78%)

2 (41.17%)

6 (8.57%)

9 (7.63%)

4 (8.33%)

5 (7.14%)