The majority of 1725 identified abstracts did not meet inclusion criteria as they were case reports/series, laboratory or genetic studies and were therefore excluded. This review was thus based on 24 articles (23 English and one Chinese language publication7) fulfilling criteria, with 18 studies reporting prevalence and six comparative studies reporting prevalence and/or clinical manifestations in adults aged 18 years or older.
SLE prevalence: community-based and hospital-based studies
Prevalence (per 100,000) of SLE in community-based studies ranged from 3.2–70.4 in studies in Asia (n = 10), and 46.7–161.0 in Asian migrant studies (n = 4) (Table 1). The majority of community-based studies in Asia were among subjects of Chinese or Japanese ethnicity, in which the prevalence ranged from 26.0–70.4 and 3.7–20.9, respectively. The 95% CI of point estimates of prevalence in these community-based studies generally overlapped. Of the four Asian migrant studies identified, two studies from the UK with multiple sources of ascertainment showed approximately double the prevalence of SLE in Indians as compared with Caucasians,15,16 which was statistically significant (i.e. non-overlapping 95% CI) in one study.16 Two studies comparing Caucasians with Chinese yielded differing results, with Chinese having the same prevalence (50.8, 95% CI 38.1–63.5) as Caucasians in one study among members of a Health Maintenance Organization in San Francisco,14 and more than twice the prevalence (161.0 vs. 71.0) in another study in Hawaii.17 The prevalence of SLE in the latter study was also higher among Filipinos (104.0) compared with Caucasians (71.0) but was similar among Japanese (81.0) and Caucasians.17
In five hospital-based studies, the prevalence of SLE (per 100 000) ranged from 12.0–1300.0 (Table 2). Two studies from Hong Kong reported differing prevalences of 58.8 (95% CI 54.9–62.7)18 and 250.0 (95% CI 207.2–292.8).19 This difference may be related to the use of different denominators for computing prevalence: the number of people living in the catchment area was used in the former, the number of medical referrals over a 2-year period in the latter.
Table 2. Prevalence of systemic lupus erythematosus among Asians (hospital-based studies)†
|Asian studies – Chinese|
|Hong Kong, China; retrospective chart review20||1.49 million (total adult population in the catchment areas of 2 hospitals under study)||58.8 (54.9, 62.7)|
|Hong Kong, China; retrospective chart review21||Medical referrals to two hospitals:|
Total = 52,323
|250.0 (207.2, 292.8)|
|Asian Studies – others|
|South India; retrospective chart review39||Not stated||1300.0|
|Malaysia; retrospective chart review22||Extrapolated from prevalence of amyotrophic lateral sclerosis which has a remarkably uniform rate throughout most parts of the world.||Overall: 43.0|
|Pakistan; retrospective chart review40||Not stated||Number of cases: 196 (49 cases < 3 ARC criteria)|
By way of comparison, in a recent review,21 worldwide prevalence of SLE ranged from 20.6–78.5 in the USA and Canada, 24.6–91.0 in Europe (including UK), 13.4–89.3 in Australia and 64.2 in Martinique.
SLE severity: clinical manifestations
We identified six comparative studies on clinical manifestations of SLE, with two studies comparing different ethnic groups living in the same Asian country, one study comparing Asians in Singapore with Caucasians in America, three studies comparing Asian migrants and Caucasians, and no studies comparing different ethnic groups in Asia living in their respective home countries. These studies found ethnic differences in severity of disease manifestations among ethnic groups in Asia and more severe disease manifestations among Asians than Caucasians. However, the results of these studies need to be interpreted in the light of the many factors influencing clinical manifestations of SLE, and the fact that these manifestations can develop at or after diagnosis. Some of these studies controlled for some but not all factors that could potentially influence disease manifestations.
Two comparative studies were performed among Chinese, Malay and Indian SLE patients living in the same Asian country.20,22 In a study in Malaysia among 539 SLE patients,20 Malays and Indians were less likely to present with a malar rash than Chinese (57%vs. 21%vs. 64%, P < 0.001, without adjustment for duration of symptoms or gender). In a study in Singapore among 472 SLE patients,22 after adjusting for age, gender and duration of symptoms prior to diagnosis, as compared with Chinese, Malays were more likely to present with renal (odds ratio [OR] 2.26, 95% CI 1.21–4.21) or central nervous system (CNS) (OR 3.97, 95% CI 1.01–9.34) involvement while Indians were less likely to present with malar rash (OR 0.30, 95% CI 0.13–0.68) but more likely to present with oral ulcers (OR 2.90, 95% CI 1.45–7.34) at diagnosis.
In the one study comparing Asian and Caucasian SLE patients both living in their respective home countries (Caucasians in Rochester, Minnesota [n = 46] and Chinese in Singapore [n = 175]),23 after controlling for subject- and SLE-related factors, Caucasians were more likely than Chinese to have serositis (OR 3.11, 95% CI 1.01–9.71) or a haematologic disorder (OR 6.95, 95% CI 2.20–21.97), but far less likely to have a malar rash (OR 0.19, 95% CI 0.07–0.54) or positive antinuclear antibodies (OR 0.11, 95% CI 0.03–0.52) at diagnosis. After diagnosis, Caucasians were less likely to develop proteinuria (relative risk [RR] 0.47, 95% CI 0.19–1.15) or other major organ involvement (RR 0.22, 95% CI 0.05–1.04), compared with Chinese.23
Three comparative studies among Asian migrants and Caucasians were identified. In a follow-up study among 80 SLE patients (9 Indians) performed in the UK,24 at 5 years after diagnosis, neuropsychiatric damage measured using the Systemic Lupus International Collaborative Clinics/American College of Rheumatology (SLICC/ACR) Damage Index in Indians was significantly higher than in Caucasians (0.22 vs. 0.12, P = 0.027). In the same study, at 10 years after diagnosis, a higher prevalence of renal damage was found among Indians compared with Caucasians (57.1 vs. 20.8%, P = 0.006). In a retrospective community-based study in Leicester (UK), in 50 SLE patients (19 Indians, 31 Caucasians), proteinuria and neuropsychiatric disease were significantly more common in Indians compared with Caucasians (58%vs. 35%, P < 0.02; 38%vs. 13%, P < 0.01, respectively).14 Indians were also more likely than Caucasians to be on immunosuppressive therapy (46%vs. 20%, P < 0.05) and had a higher mortality rate (27%vs. 8%, P = 0.04). However, socioeconomic status and other variables were not controlled for in this study. An Australian study compared SLE disease activity between Caucasians (n = 121) and South-East Asian/Chinese (n = 59) patients admitted to a tertiary healthcare facility due to active disease.25 Compared with Caucasians, South-East Asian/Chinese were more likely to be diagnosed with WHO class III/IV glomerulonephritis both at presentation (23%vs. 54%, P = 0.04) and during subsequent admissions (27%vs. 64%, P = 0.02), readmitted for flare (41%vs. 63%, P = 0.03), and to have higher rates of severe organ damage as measured by renal (OR 4.9, 95% CI 3.1–8.1) and central nervous system (CNS) (OR 2.4, 95% CI 1.2–4.8) involvement and higher rates of usage of cyclophosphamide (OR 7.5, 95% CI 4.2–13.8) after adjusting for age and gender, but not duration of symptoms, prior to presentation.