Table 5 Multivariate Coefficients for loss of Best FEV1 (after allowance for regression to the mean)

Gender (male v female)

11.3 (5.1)

0.03

11.9 (5.4)

0.02

Asthma since childhood

5.1⁺ (5.3)

0.34

1.1⁺ (6.0)

0.86

Social Classes 1 & 2 (v. classes 4 & 5)

13. (5.7)

0.05

10.7 (5.6)

0.11

Social Class 3 (v. classes 4 & 5)

2.9 (5.3)

1.4 (5.2)

Amount smoked (per 10 pack years)

0.7 (1.3)

0.60

0.5 (1.3)

0.71

Best PEF(per 10% deficit)

3.4 ⁺ (1.3)

0.008

3.1 ⁺ (1,2)

0.01

Actual/Best PEF(10% deficit)

0.7⁺ (1.8)

0.71

1.4⁺ (1.8)

0.44

Age at entry (per decade) (difference from age 50)

Linear

8.4⁺(3.2)

quadratic

5.1⁺ (0.9)

cubic

1.8 (0.5)

0.0003

Duration of asthma at entry (per decade) (difference from duration 20 yrs)

Linear

3.1 (2.4)

0.2 (2.4)

quadratic

2.5 (1.6)

0.4 (1.6)

cubic

0.91 ⁺ (0.39)

0.02

0.29⁺ (0.40)

0.46