Increased incidence of late-onset inflammatory bowel disease and microscopic colitis after a Cryptosporidium hominis outbreak

Figures & data

Figure 1. Cohort selection process. Patients diagnosed with inflammatory bowel disease (IBD) or microscopic colitis (MC) (ICD K50.0–52.9) in Region Jämtland Härjedalen between 1 January 2006 and 31 December 2019. SWIBREG: Swedish IBD register.

Table 1. Mean annual incidence and demographic characteristics of the study population presented by diagnosis.

	All N (%)	Mean annual incidence, per 100,000 (CI)			Male, N (%)			Median age, years (IQR)
		2006–2010	2011–2019	p	2006–2010	2011–2019	p	2006–2010	2011–2019	p
IBD^a	410 (72.6)	24.15 (11.70–36.61)	30.90 (24.67–37.13)	.19	64 (52.0)	150 (52.3)	1.00	40.00 (25.00–57.00)	43.00 (27.00–61.00)	.20
Ulcerative colitis	287 (50.8)	18.07 (7.82–28.31)	21.00 (15.97–26.02)	1.48	53 (57.6)	101 (51.8)	.43	35.00 (24.25–54.00)	38.00 (25.00–59.00)	.36
Crohn’s disease	100 (17.7)	5.11 (2.93–7.29)	7.97 (5.22–10.71)	.12	9 (34.6)	41 (55.4)	.11	46.00 (29.25–63.00)	50.50 (30.75–62.50)	.52
IBD – unclassified	23 (4.1)	0.98 (–0.24–2.19)	1.94 (0.96–2.91)	.17	2 (40.0)	8 (44.4)	1.00	63.00 (44.50–74.00)	57.00 (42.00–68.25)	.64
Microscopic colitis	155 (27.4)	4.12 (–0.61–8.84)	14.40 (9.57–19.24)	.01	3 (14.3)	36 (26.9)	.34	64.00 (55.50–74.00)	68.00 (56.00–74.00)	.54

CI: 95% confidence interval; IQR: interquartile range.

^aUlcerative colitis, Crohn’s disease and IBD-unclassified.

Figure 2. Annual incidence of inflammatory bowel disease and microscopic colitis in individuals ≥40 years of age in Region Jämtland Härjedalen.

Table 2. Negative binomial regression analysis of inflammatory bowel disease.

	IBD – UC, Crohn, IBD-U		Ulcerative colitis		Crohn’s disease
	IRR	95% CI	IRR	95% CI	IRR	95% CI
2011–2019 (2006–2010)	1.39	0.99–1.94	1.20	0.84–1.72	1.61	0.95–2.71
Female (male)	1.31	0.95–1.80	1.31	0.93–1.85	1.55	0.96–2.48
Age 40+ years (18–39 years)	0.85	0.61–1.17	0.65	0.46–0.92	1.46	0.88–2.42

Offset variable: adult inhabitants Region Jämtland Härjedalen. Reference for variable within parentheses. UC: ulcerative colitis, IBD-U: IBD-unclassified; IRR: incidence risk ratio; CI: confidence interval.

Table 3. Negative binomial regression analysis of inflammatory bowel disease in the population ≥40 years of age.

	IBD – UC, Crohn, IBD-U		Ulcerative colitis		Crohn’s disease
	IRR	95% CI	IRR	95% CI	IRR	95% CI
2011–2019 (2006–2010)	1.69	1.13–2.51	1.49	0.96–2.31	2.23	1.08–4.62
Female (male)	1.18	0.81–1.73	1.07	0.70–1.62	1.75	0.90-3.39

Offset variable: adult inhabitants Region Jämtland Härjedalen. Reference for variable within parentheses. UC: ulcerative colitis; IBD-U: IBD-unclassified; IRR: incidence risk ratio; CI: confidence interval.

Table 4. Negative binomial regression analysis of microscopic colitis.

	Microscopic colitis
	IRR	95% CI
2011–2019 (2006–2010)	6.43	2.78–14.87
Female (male)	4.97	2.40–10.27
Age 40+ years (18–39 years)	21.13	7.91–56.48

Offset variable: adult inhabitants Region Jämtland Härjedalen. Reference for variable within parentheses. UC: ulcerative colitis; IBD-U: IBD-unclassified; IRR: incidence risk ratio; CI: confidence interval.

Data availability statement

The data underlying this article will be shared on reasonable request to the corresponding author.