TABLE 5.

Percentage of subjects with occupational exposure (P), prevalence rate ratios (PRRs) and population attributable risk percentage (PAR%) for occupational exposures using three definitions of asthma in the study population (all ages), and excluding childhood asthmatic subjects, in models adjusted for sex, age and smoking

	Study population (all ages)			Study population (excluding childhood asthmatic subjects)
	Current wheeze (n=498)	Asthma symptoms and/or medicine (n=498)	AHR (n=368)	Current wheeze (n=458)	Asthma symptoms and/or medicine (n=458)	AHR (n=344)
Exposure (ever) to sensitizers
P	58.5	57.1	64.8	58.3	56.3	65.9
PRR	1.09	1.16	1.90	1.09	1.13	2.03
PAR% (95% CI)	4.83 (2.46, 7.13)	7.88 (3.89, 11.7)	30.7 (25.5, 35.5)	4.81 (1.85, 7.68)	6.47 (0.75, 11.9)	33.4 (26.9, 39.4)
Exposure (ever) to irritants
P	14.62	10.00	5.56	14.56	8.33	6.82
PRR	1.45	0.94	0.42	1.48	0.79	0.5
PAR% (95% CI)	4.54 (4.27, 4.80)	−0.64 (−0.29, −0.99)	−7.68 (−7.36, −8.00)	4.72 (4.39, 5.05)	−2.21 (−1.79, −2.64)	−6.82 (−6.35, −7.29)

Data are presented for the study population for all ages, and excluding childhood asthmatic subjects. For each definition of asthma used, the number of subjects in the analysis is indicated in brackets. Significant differences are shown in bold type. The negative association of exposure (ever) to irritants for asthma symptoms and/or medicine, and airway hyperresponsiveness (AHR), implies a ‘healthy’ worker survivor effect, ie, those ever exposed to irritants had quit the offending work-place or changed jobs within the same workplace. Definitions of asthma: current wheeze, wheezing or whistling in the chest in the past 12 months; asthma symptoms and/or medication, waking up with shortness of breath, having an asthmatic attack and/or using asthma medication; AHR: a 20% fall in forced expiratory volume in 1 s from the postdiluent level in the methacholine challenge test before the maximum cumulative dose of 2 mg was reached