Table 4

Comparison of demographic and smoking history between patients with rheumatoid arthritis with or without a family history of the disease

	Family history +ve (n=96)	Family history −ve (n=143)	Significance (p value)
Sex (No (%))
Male	23 (24)	29 (20)
Female	73 (76)	114 (80)	0.499^4-150
Age at onset (years)
Mean (SD)	44 (12.5)	49 (13.5)	0.003^4-151
Smoking at diagnosis (No (%))
Yes	37 (39)	83 (58)
No	59 (61)	60 (42)	0.003^4-150
Social class (No (%))
Classes I–II	11 (11)	19 (13)
Classes IIIN–IIIM	37 (39)	47 (33)
Classes IV–V	48 (50)	77 (54)	0.656^4-150
Number of pack years
Median (semi-IQR)^4-154	4.0 (13.5)	25.0 (21.5)	<0.001^4-152

↵4-150 Resulting from a χ² test.
↵4-151 Resulting from a two sample t test.
↵4-152 Resulting from a two sample Wilcoxon test.
↵4-154 Semi-IQR = semi-interquartile range.