Table 1 Number of incident cases of MS in female nurse anaesthetists, other female nurses, and female teachers, with cumulative incidence rate ratios (CIR) and 95% confidence intervals (95% CI).

Observation period		Teachers	Other nurses	Nurse anaesthetists (crude)	Nurse anaesthetists (adjusted)
1985–2000	No	50	113	5
	CIR	1.0*		2.2	2.3
	95% CI			(0.8–5.5)	(0.9–5.8)
	CIR		1.0*	1.9	1.7
	95% CI			(0.8–4.7)	(0.6–4.1)
1990–2000	No	34	80	4
	CIR	1.0*		2.6	2.8
	95% CI			(0.9–7.3)	(1.0–8.1)
	CIR		1.0*	2.2	1.8
	95% CI			(0.8–5.9)	(0.6–5.0)
1995–2000	No	17	38	3
	CIR	1.0*		3.9	4.1
	95% CI			(1.1–13.3)	(1.2–14.3)
	CIR		1.0*	3.5	2.9
	95% CI			(1.1–11.2)	(0.9–9.5)

*Reference.

Age of subjects restricted to 30–50 years in 1990.

Nurse anaesthetists (n = 907), other nurses (n = 39 703), teachers (n = 20 053) according to the census of 1985.

CIR presented as crude and adjusted by age standardisation.