Table 2

Risks of asthma in the insomnia and control groups

Characteristics	Insomnia				Control				IRR (95% CI)	P*
	No	Asthma	PY	IR†	No	Asthma	PY	IR†
All	48 871	424	192623.41	22.01	97 742	409	387095.85	10.57	2.08 (1.82 to 2.39)	<0.001
Age group (years)
<34	9515	27	37 931.78	7.12	19 031	17	76 049.26	2.24	3.18 (1.74 to 5.84)	<0.001
35–49	16 269	82	64 569.83	12.70	32 541	32	129 858.42	2.46	5.15 (3.43 to 7.75)	<0.001
50–64	13 611	85	53 788.73	15.80	27 221	83	108 051.32	7.68	2.06 (1.52 to 2.78)	<0.001
≥65	9476	230	36 333.07	63.30	18 949	277	73 136.86	37.87	1.67 (1.40 to 1.99)	<0.001
Sex
Male	19 569	180	76 611.01	23.50	39 138	179	154 370.93	11.60	2.03 (1.65 to 2.49)	<0.001
Female	29 302	244	11 6012.41	21.03	58 604	230	232 724.93	9.88	2.13 (1.78 to 2.55)	<0.001
Comorbidity
Hypertension	10 616	180	41 264.43	43.62	14 781	167	57 535.99	29.03	1.50 (1.22 to 1.86)	<0.001
Anxiety/ depression	4961	59	19 475.68	30.29	1649	15	6417.10	23.38	1.30 (0.74 to 2.28)	0.37
Allergic rhinitis	1742	19	6881.46	27.61	1561	8	6157.11	12.99	2.13 (0.93 to 4.85)	0.07
Urticaria	949	6	3719.76	16.13	1158	6	4556.88	13.17	1.23 (0.40 to 3.80)	0.73
Atopic dermatitis	247	1	973.35	10.27	299	4	1152.70	34.70	0.30 (0.03 to 2.65)	0.28
Bronchiolitis	57	1	227.06	44.04	130	1	515.46	19.40	2.27 (0.14 to 6.29)	0.56
Sleep apnoea	87	1	344.54	29.02	21	1	80.21	124.70	0.23 (0.01 to 3.72)	0.30
CVD	4936	117	18 838.57	62.11	6187	114	23 618.24	48.27	1.29 (0.99 to 1.67)	0.06

*P values were determined using Poisson regression models.
†IR: per 10 000 person-years.
CVD, cardiovascular disease; IR, incidence rate; IRR, incidence rate ratio; PY, person-years.