Table 1. Standardized hospitalisation ratios (SHRs) and 95% confidence intervals (CIs) for migraine and vertigo among 420 095 subscribers to cellular telephones in Denmark, 1982–1995, followed up through 31 December 2003.

Condition	Latency (years)*	Observed	Expected	SHR	CI
Migraine	1	148	117.0	1.3	1.1–1.5
	1–4	611	503.6	1.2	1.2–1.3
	5–9	586	500.3	1.2	1.1–1.3
	≥10	56	53.3	1.1	0.8–1.4
	Total	1401	1174.2	1.2	1.1–1.3
Vertigo	1	137	126.3	1.1	0.9–1.3
	1–4	750	658.0	1.1	1.1–1.2
	5–9	1148	1023.2	1.1	1.1–1.2
	≥10	191	187.1	1.0	0.9–1.2
	Total	2226	1994.6	1.1	1.1–1.2

^*Time since first subscription to a cellular telephone.