The reported incidence and prevalence of Sjogren syndrome vary widely, contingent upon classification criteria used, study design, geolocation, and population studied.[8]Qin B, Wang J, Yang Z, et al. Epidemiology of primary Sjögren's syndrome: a systematic review and meta-analysis. Ann Rheum Dis. 2015 Nov;74(11):1983-9.
http://www.ncbi.nlm.nih.gov/pubmed/24938285?tool=bestpractice.com
[9]Alani H, Henty JR, Thompson NL, et al. Systematic review and meta-analysis of the epidemiology of polyautoimmunity in Sjögren's syndrome (secondary Sjögren's syndrome) focusing on autoimmune rheumatic diseases. Scand J Rheumatol. 2018 Mar;47(2):141-54.
http://www.ncbi.nlm.nih.gov/pubmed/28927315?tool=bestpractice.com
[10]Brito-Zerón P, Acar-Denizli N, Zeher M, et al. Influence of geolocation and ethnicity on the phenotypic expression of primary Sjögren's syndrome at diagnosis in 8310 patients: a cross-sectional study from the Big Data Sjögren Project Consortium. Ann Rheum Dis. 2017 Jun;76(6):1042-50.
http://www.ncbi.nlm.nih.gov/pubmed/27899373?tool=bestpractice.com
One systematic review only including cases of primary Sjogren syndrome (pSS) estimated the rate of the global incidence of pSS at 6.92 (95% CI 4.98 to 8.86) per 100,000 person-years at risk; however, the study reported significant heterogeneity between included studies (P<0.001, I2=98.51%).[8]Qin B, Wang J, Yang Z, et al. Epidemiology of primary Sjögren's syndrome: a systematic review and meta-analysis. Ann Rheum Dis. 2015 Nov;74(11):1983-9.
http://www.ncbi.nlm.nih.gov/pubmed/24938285?tool=bestpractice.com
The incidence rate of pSS in women was far higher than that for men, with reported estimates of 12.30 (95% CI 9.07 to 15.53) and 1.47 (95% CI 0.81 to 2.12) per 100,000 person years, respectively, and a male-to-female incidence ratio estimated at 9.29 (95% 6.61 to 13.04).[8]Qin B, Wang J, Yang Z, et al. Epidemiology of primary Sjögren's syndrome: a systematic review and meta-analysis. Ann Rheum Dis. 2015 Nov;74(11):1983-9.
http://www.ncbi.nlm.nih.gov/pubmed/24938285?tool=bestpractice.com
The prevalence rate of pSS in the total population was 60.82 cases per 100 000 inhabitants; however, after stratifying by study design the estimated prevalence in population-based studies was estimated at 43.03, and 282.35 in sample survey studies, per 100,000 inhabitants.
There is evidence to suggest that pSS affects middle-aged women predominantly.[11]Fox RI. Sjogren's syndrome. Lancet. 2005 Jul 23-29;366(9482):321-31.
http://www.ncbi.nlm.nih.gov/pubmed/16039337?tool=bestpractice.com
[12]Mavragani CP, Moutsopoulos NM, Moutsopoulos HM. The management of Sjogren's syndrome. Nat Clin Pract Rheumatol. 2006 May;2(5):252-61.
http://www.ncbi.nlm.nih.gov/pubmed/16932698?tool=bestpractice.com
In a subsequent population-based cohort study in the US not included in the systematic review, the annual incidence of pSS was estimated at 5.8 per 100,000 person-years, with an estimated prevalence of 10.3 per 10,000 inhabitants.[13]Maciel G, Crowson CS, Matteson EL, et al. Incidence and mortality of physician-diagnosed primary Sjögren syndrome: time trends over a 40-year period in a population-based US cohort. Mayo Clin Proc. 2017 May;92(5):734-43.
http://www.ncbi.nlm.nih.gov/pubmed/28389066?tool=bestpractice.com
One cross-sectional study suggests that diagnosis of pSS is strongly influenced by geolocation and ethnicity.[10]Brito-Zerón P, Acar-Denizli N, Zeher M, et al. Influence of geolocation and ethnicity on the phenotypic expression of primary Sjögren's syndrome at diagnosis in 8310 patients: a cross-sectional study from the Big Data Sjögren Project Consortium. Ann Rheum Dis. 2017 Jun;76(6):1042-50.
http://www.ncbi.nlm.nih.gov/pubmed/27899373?tool=bestpractice.com
In an analysis of 8310 patients with pSS in an international, multicentre registry, pSS was diagnosed a mean of 7 years earlier in black/African-American patients compared with white patients; the female-to-male ratio was highest in Asian patients (27:1) and lowest in black/African-American patients (7:1). A north-south gradient was reported for some symptoms, with lower frequency of ocular involvement (dry eyes and abnormal ocular tests) in northern Europe compared with southern European countries. Higher frequencies of antinuclear antibodies (ANAs) were reported in northern America and Asia compared with northern Europe, which had lowest frequencies of ANAs.[10]Brito-Zerón P, Acar-Denizli N, Zeher M, et al. Influence of geolocation and ethnicity on the phenotypic expression of primary Sjögren's syndrome at diagnosis in 8310 patients: a cross-sectional study from the Big Data Sjögren Project Consortium. Ann Rheum Dis. 2017 Jun;76(6):1042-50.
http://www.ncbi.nlm.nih.gov/pubmed/27899373?tool=bestpractice.com
The prevalence rates for Sjogren syndrome associated rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) have been estimated at 19.5% (95% CI 11.2 to 27.8) and 13.96% (95% CI 8.88 to 19.04), respectively.[9]Alani H, Henty JR, Thompson NL, et al. Systematic review and meta-analysis of the epidemiology of polyautoimmunity in Sjögren's syndrome (secondary Sjögren's syndrome) focusing on autoimmune rheumatic diseases. Scand J Rheumatol. 2018 Mar;47(2):141-54.
http://www.ncbi.nlm.nih.gov/pubmed/28927315?tool=bestpractice.com
The female-to-male ratio of secondary Sjogren syndrome in the population with RA was 14.7 (95% CI 7.09 to 256) and in the population with SLE was 16.82 (95% CI 1.22 to 32.4).[9]Alani H, Henty JR, Thompson NL, et al. Systematic review and meta-analysis of the epidemiology of polyautoimmunity in Sjögren's syndrome (secondary Sjögren's syndrome) focusing on autoimmune rheumatic diseases. Scand J Rheumatol. 2018 Mar;47(2):141-54.
http://www.ncbi.nlm.nih.gov/pubmed/28927315?tool=bestpractice.com
Significant overlap of systemic sclerosis and Sjogren syndrome has been reported.[14]Baldini C, Mosca M, Della Rossa A, et al. Overlap of ACA-positive systemic sclerosis and Sjögren's syndrome: a distinct clinical entity with mild organ involvement but at high risk of lymphoma. Clin Exp Rheumatol. 2013 Mar-Apr;31(2):272-80.
http://www.ncbi.nlm.nih.gov/pubmed/23343785?tool=bestpractice.com
[15]Salliot C, Mouthon L, Ardizzone M, et al. Sjogren's syndrome is associated with and not secondary to systemic sclerosis. Rheumatology (Oxford). 2007 Feb;46(2):321-6.
https://www.doi.org/10.1093/rheumatology/kel252
http://www.ncbi.nlm.nih.gov/pubmed/16877466?tool=bestpractice.com