{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T10:17:10Z","timestamp":1777457830358,"version":"3.51.4"},"reference-count":23,"publisher":"Wiley","issue":"7","license":[{"start":{"date-parts":[[2002,7,11]],"date-time":"2002-07-11T00:00:00Z","timestamp":1026345600000},"content-version":"vor","delay-in-days":10,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Arthritis &amp; Rheumatism"],"published-print":{"date-parts":[[2002,7]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>Previous population studies have suggested that both rheumatoid factor (RF) production and rheumatoid arthritis (RA) may be declining in occurrence, and both secular and birth\u2010cohort influences have been implicated. Since Pima Indians have a very high incidence of RA and also have shown recent evidence of a decline in RA, this study evaluated the relative contributions of age, secular, and birth\u2010cohort influences on RF seropositivity in the Pima Indian population.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>RF data, as assayed by both the bentonite flocculation test (BFT) and the sheep cell agglutination test (SCAT), were available on 5,345 Pima Indians born between 1886 and 1975, who were surveyed at biennial intervals between 1966 and 1995. An age\u2013period\u2013cohort analysis was conducted using data on 18,295 examinations undertaken during the period of study.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>There was a decline in the proportion of positive test results for RF (titer \u22651:32) by both BFT and SCAT, in both male and female subjects from 1966\u20131975 to the later decades of the study (1976\u20131985 and 1986\u20131995). Across all periods, by both assays, the crude proportion of positive titers increased with increasing age of the subjects. There was a very clear birth\u2010cohort effect: the highest likelihood of seropositivity was in those individuals born around the end of the nineteenth century, with continuing decline in seropositivity up to the most recent birth cohort. A logistic regression analysis, adjusting for Pima heritage and sex, demonstrated a substantially greater influence of birth cohort than of calendar year on the frequency of RF positivity.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>In the Pima Indian population, environmental influences in early life are important predictors of the lifelong likelihood of RF positivity. This may have implications for understanding the epidemiology and etiology of RA.<\/jats:p><\/jats:sec>","DOI":"10.1002\/art.10360","type":"journal-article","created":{"date-parts":[[2002,9,11]],"date-time":"2002-09-11T02:05:28Z","timestamp":1031709928000},"page":"1729-1734","source":"Crossref","is-referenced-by-count":31,"title":["An epidemiologic study of trends in prevalence of rheumatoid factor seropositivity in Pima Indians: Evidence of a decline due to both secular and birth\u2010cohort influences"],"prefix":"10.1002","volume":"46","author":[{"given":"Ian","family":"Enzer","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Graham","family":"Dunn","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lennart","family":"Jacobsson","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peter H.","family":"Bennett","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"William C.","family":"Knowler","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alan","family":"Silman","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2002,7,11]]},"reference":[{"key":"e_1_2_6_2_2","doi-asserted-by":"publisher","DOI":"10.1002\/art.1780280503"},{"key":"e_1_2_6_3_2","doi-asserted-by":"publisher","DOI":"10.1093\/rheumatology\/31.6.365"},{"key":"e_1_2_6_4_2","first-page":"1282","article-title":"Rheumatoid factors antedating clinical rheumatoid arthritis","volume":"18","author":"Aho K","year":"1991","journal-title":"J Rheumatol"},{"key":"e_1_2_6_5_2","first-page":"1792","article-title":"Radiographic progression on radiographs of hands and feet during the first three years of rheumatoid arthritis measured according to Sharp's method (van der Heijde modification)","volume":"22","author":"Van der Heijde D","year":"1995","journal-title":"J Rheumatol"},{"key":"e_1_2_6_6_2","first-page":"5","article-title":"Prognostic factors and diagnostic criteria in early rheumatoid arthritis","volume":"57","author":"Kaarela K","year":"1985","journal-title":"Scand J Rheumatol"},{"key":"e_1_2_6_7_2","first-page":"427","article-title":"Time lag between active joint inflammation and radiological progression in patients with early rheumatoid arthritis","volume":"25","author":"Matsuda Y","year":"1998","journal-title":"J Rheumatol"},{"key":"e_1_2_6_8_2","first-page":"1189","article-title":"HLA linkage with rheumatoid arthritis or seropositivity","volume":"15","author":"Silman AJ","year":"1988","journal-title":"J Rheumatol"},{"key":"e_1_2_6_9_2","first-page":"512","article-title":"Rheumatoid factor detection in the unaffected first degree relatives in families with multicase rheumatoid arthritis","volume":"18","author":"Silman AJ","year":"1991","journal-title":"J Rheumatol"},{"key":"e_1_2_6_10_2","first-page":"2203","article-title":"Rheumatoid factor isotypes in monozygotic and dizygotic twins discordant for rheumatoid arthritis","volume":"22","author":"MacGregor AJ","year":"1995","journal-title":"J Rheumatol"},{"key":"e_1_2_6_11_2","volume-title":"Rheumatism in populations","author":"Lawrence JS","year":"1977"},{"key":"e_1_2_6_12_2","doi-asserted-by":"publisher","DOI":"10.1136\/ard.52.4.254"},{"key":"e_1_2_6_13_2","doi-asserted-by":"publisher","DOI":"10.1080\/030097400750001996"},{"key":"e_1_2_6_14_2","doi-asserted-by":"publisher","DOI":"10.1136\/ard.56.5.313"},{"key":"e_1_2_6_15_2","first-page":"537","article-title":"Shift in the incidence of rheumatoid arthritis toward elderly patients in Finland during 1975\u20131990","volume":"14","author":"Kaipianen\u2010Sepp\u0103nen O","year":"1996","journal-title":"Clin Exp Rheumatol"},{"key":"e_1_2_6_16_2","doi-asserted-by":"publisher","DOI":"10.1093\/oxfordjournals.aje.a115238"},{"key":"e_1_2_6_17_2","doi-asserted-by":"publisher","DOI":"10.1002\/art.1780370808"},{"key":"e_1_2_6_18_2","first-page":"1179","article-title":"What can we learn about rheumatic diseases by studying Pima Indians?","volume":"21","author":"Jacobsson LTH","year":"1994","journal-title":"J Rheumatol"},{"key":"e_1_2_6_19_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(50)91500-5"},{"key":"e_1_2_6_20_2","doi-asserted-by":"crossref","unstructured":"BozicevitchJ BunimJJ FreundJ WardSB.Bentonite flocculation test for rheumatoid arthritis. Proceedings of the Society for Experimental and Biological Medicine1958;97:180\u20134.","DOI":"10.3181\/00379727-97-23681"},{"key":"e_1_2_6_21_2","first-page":"191","volume-title":"Population studies of the rheumatic diseases exerpta medica","author":"Bennett PH","year":"1968"},{"key":"e_1_2_6_22_2","doi-asserted-by":"publisher","DOI":"10.1002\/art.1780110404"},{"key":"e_1_2_6_23_2","doi-asserted-by":"publisher","DOI":"10.1136\/ard.49.10.753"},{"key":"e_1_2_6_24_2","first-page":"1830","article-title":"Smoking and risk of rheumatoid arthritis","volume":"20","author":"Heliovaara M","year":"1993","journal-title":"J Rheumatol"}],"container-title":["Arthritis &amp; Rheumatism"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fart.10360","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/art.10360","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,10,10]],"date-time":"2023-10-10T21:36:23Z","timestamp":1696973783000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/art.10360"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2002,7]]},"references-count":23,"journal-issue":{"issue":"7","published-print":{"date-parts":[[2002,7]]}},"alternative-id":["10.1002\/art.10360"],"URL":"https:\/\/doi.org\/10.1002\/art.10360","archive":["Portico"],"relation":{},"ISSN":["0004-3591","1529-0131"],"issn-type":[{"value":"0004-3591","type":"print"},{"value":"1529-0131","type":"electronic"}],"subject":[],"published":{"date-parts":[[2002,7]]}}}