IL1β genotypes in patients who had undergone surgery (n=31) and those who had not (n=44) who do not carry two disease associated alleles. Significantly more patients who had undergone surgery were homozygous for allele 2 than those who had not, 22% v 4% respectively, 2 df, χ2=5.902, p=0.05. Results are shown as number (%)
| 1*1 | 1*2 | 2*2 | |
| Surgery | 12 (39) | 12 (39) | 7 (22) |
| No surgery | 24 (55) | 18 (41) | 2 (4) |