Volume 16 Supplement 1

Lupus 2014: New Targets, New Approaches

Open Access

Preliminary population-based incidence and prevalence estimates of systemic lupus erythematosus: the California Lupus Surveillance Project

  • Maria C Dall'Era1,
  • Kurt Snipes2,
  • Miriam Cisternas3,
  • Caroline Gordon4 and
  • Charles G Helmick5
Arthritis Research & Therapy201416(Suppl 1):A38

https://doi.org/10.1186/ar4654

Published: 18 September 2014

Background

Previous estimates of prevalence and incidence of systemic lupus erythematosus (SLE) in the United States have varied widely due to factors such as heterogeneous source populations, limitations with case ascertainment, and differing case definitions. The California Lupus Surveillance Project (CLSP) is part of a national effort funded by the Centers for Disease Control and Prevention to determine more credible estimates of incidence and prevalence of SLE, with a special focus on Hispanics and Asians.

Methods

The CLSP is a population-based registry designed to determine the incidence and prevalence of SLE in San Francisco County, CA, USA. Sources of cases included hospitals, rheumatologists, nephrologists, commercial laboratories, and state population databases. These sources were queried for the International Classification of Diseases, Ninth Revision (ICD-9-CM) codes of 710.0 (SLE), 695.4 (discoid lupus), 710.8 (other specified connective tissue disease), and 710.9 (unspecified connective tissue disease). Laboratories were queried for serologic tests including ANA, anti-dsDNA, anti-Smith, antiphospholipid antibodies, and low complement levels. Pathology laboratories were queried for renal and cutaneous biopsies consistent with lupus. Over 15,000 potential SLE patients were identified after the initial queries, and trained abstractors performed detailed medical chart reviews on the >5,500 patients who met the catchment criteria of residence in San Francisco County within the years 2007 to 2009. Cases were defined as patients with documentation of ≥4/11 of the ACR Classification Criteria for SLE. Using SAS 9.3, we calculated prevalence and incidence rates and associated 95% confidence intervals (CIs). Denominators for all rates were obtained from the US Census data (revised 2000 to 2009 intercensal population files) for San Francisco County.

Results

The preliminary overall crude prevalence and incidence of SLE in San Francisco County was 90.4/100,000 and 5.1/100,000 respectively. The highest prevalence of disease was observed in Black women (430.6/100,000), followed by Hispanic and Asian (163.8/100,000 and 158.9/100,000, respectively), and White (111.3/100,000) women (Table 1).
Table 1

Preliminary prevalence and incidence rates (per 100,000) of SLE in San Francisco County, CA, USA

 

Prevalence (2007)

Incidence (2007 to 2009)

Race/ethnicity, sex

Number of cases

Crude rate (95% CI)

Number of cases

Crude rate (95% CI)

Overall

704

90.4 (84.0 to 97.3)

121

5.1 (4.3 to 6.1)

  Women

623

162.0 (149.8 to 175.2)

112

9.6 (8.0 to 11.5)

  Men

81

20.6 (16.5 to 25.5)

9

0.7 (0.4 to 1.4)

Black

138

243.0 (205.7 to 287.0)

27

15.9 (10.9 to 23.1)

  Women

121

430.6 (360.5 to 514.2)

25

29.9 (20.3 to 44.2)

  Men

17

59.2 (37.0 to 94.9)

2

2.3 (0.6 to 8.4)

White

255

58.1 (51.4 to 65.7)

43

3.2 (2.4 to 4.3)

  Women

230

111.3 (97.8 to 126.6)

38

6.0 (4.4 to 8.3)

  Men

25

10.8 (7.3 to 15.9)

5

0.7 (0.3 to 1.7)

Asian

264

95.8 (84.9 to 108.1)

39

4.6 (3.4 to 6.3)

  Women

233

158.9 (139.8 to 180.7)

37

8.3 (6.0 to 11.4)

  Men

31

24.0 (16.9 to 34.1)

2

0.5 (0.1 to 1.9)

Hispanic

99

87.7 (72.1 to 106.8)

17

4.9 (3.1 to 7.8)

  Women

87

163.8 (132.9 to 202.0)

16

9.8 (6.0 to 15.9)

  Men

12

20.1 (11.5 to 35.1)

1

0.5 (0.1 to 3.1)

Conclusions

The CLSP uses more complete case finding methods to provide current estimates of prevalence and incidence in a racially and ethnically diverse population. Racial and ethnic disparities in SLE were confirmed with the highest burden of disease in Black women, followed by Hispanic and Asians, and, finally, White women.

Authors’ Affiliations

(1)
University of California
(2)
California Department of Public Health
(3)
MGC Data Services
(4)
University of Birmingham
(5)
Centers for Disease Control and Prevention

Copyright

© Dall'Era et al.; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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