[An epidemiological study of sacroiliitis among the native inhabitants of Chukotka].

For determination of sacroiliitis frequency among natives of Chukotka peninsula a cross-over epidemiological study was conducted. A total of 975 subjects aged 6 years and older were examined. 324 of them (33.2%) had low back pain. X-ray of the pelvis was made in 239 of 324 patients. It was found that sacroiliitis incidence in Chukotka natives makes up 11.3%. There were marked differences in sex distribution: in males 17.1%, in females 5.7%, RR = 3.9. Out of Chukotka natives with low back pain 2.5% had ankylosing spondylitis, of patients with sacroiliitis 30%. A prospective study of patients with sacroiliitis recorded development of ankylosing spondylitis in 17% of the cases 4 years after the disease onset.