Table 2.

Prevalence estimates on January 1 2015 and January 1 2019

	Prevalence on January 1 2015	Prevalence on January 1 2019	Rate ratio (2019/2015) (95% confidence interval), p
Overall population
Study population (n)	963,329	928,460	1.20 (0.96–1.51), 0.11
Prevalent cases (n)	147	170
Prevalence rate (× 100,000 persons) [95% confidence interval]	15.26 (12.89–17.94)	18.31 (15.66–21.28)
People undergoing tracheostomy at prevalence date
Study population (n)	963,329	928,460	1.83 (1.11–3.09), 0.012
Prevalent cases (n)	26	46
Prevalence rate (× 100,000 persons) [95% confidence interval]	2.69 (1.76–3.95)	4.95 (3.63–6.61)
People who were not tracheostomized at prevalence date
Study population (n)	963,329	928,460	1.06 (0.82–1.38), 0.63
Prevalent cases (n)	121	124
Prevalence rate (× 100,000 persons) [95% confidence interval]	12.56 (10.42–15.01)	13.36 (11.11–15.92)