Through a comprehensive epidemiological study, we determined Sjögren syndrome (SS) prevalence and examined the association between SS and ionising radiation dose.
A total of 1008 atomic bomb survivors in Nagasaki agreed to undergo the tests comprising a questionnaire for xerophthalmia and xerostomia, Schirmer-I test, Saxon test, and tests of anti-SS-A/Ro and anti-SS-B/La antibodies, and, if necessary, Rose Bengal stain test, salivary ultrasonographic and MRI examination from November 2002 through October 2004. Diagnosis of SS was based on the American-European Consensus Group criteria, or a modified version thereof.
Among the 1008 participants (male 398, female 610, average age 71.6 years), 154 participants (15.3%) complained of xerophthalmia, and 264 (26.2%) of xerostomia. Reduced tear flow as assessed by the Schirmer-I test was detected in 371 of 992 participants (37.4%) and reduced saliva flow as assessed by the Saxon test in 203 of 993 participants (20.4%). Among all participants, 38 (3.8%) and 10 (1.0%) participants tested positive for anti-SS-A/Ro and anti-SS-B/La antibodies, respectively. Taking into consideration all the results, 23 participants were diagnosed with SS (primary 20, secondary 3), yielding a prevalence of 2.3%. Although the association between SS and radiation dose was not significant, radiation dose was significantly associated with hyposalivation.
The present comprehensive epidemiological study reveals that the prevalence of SS was 2.3% among Nagasaki atomic bomb survivors and was not associated with radiation dose. The association between radiation dose and hyposalivation supported the possibility that radiation exposure damaged salivary gland function.