Table 1. 7-year prevalence of asthma according to self-report, the Danish National Patient Register and the Register of Medicinal Product Statistics.

Classification method	N cases/N non-cases	Prevalence %
Self-reports
‘Self-reported asthma’: diagnosis of asthma given by a doctor (n = 53,637)	6,424/47,213	12.0%
‘Self-reported current asthma’: doctor diagnosis + current wheezing (n = 19,146)	2,244/16,902	11.7%
Danish National Patient Register
Hospital cases (n = 93,616)	5,861/87,755	6.6%
Register of Medicinal Product Statistics
Prescription cases (n = 93,616)	30,099/63,517	32.2%
Combination of methods
Self-reported asthma + hospital cases + prescription cases (n = 53,637)	1,935/51,207	3.6%