Background: Accurate knowledge of outcomes in Systemic Lupus Erythematosus (SLE) is crucial to understanding the true burden of the disease. The main objective of this systematic review was to gather all population-based studies on mortality, end-stage renal disease (ESRD) and cancer in SLE. Method: We performed a systematic literature search in two electronic databases (MEDLINE and Embase) to identify all population-based articles on SLE and survival, mortality, ESRD and cancer. The SLE diagnosis had to be verified. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA). Results: We included 40/1041 articles on mortality (27), ESRD (11) and cancer (3), of which six were defined as inception studies. In the total SLE cohort, the standardized mortality ratio ranged from 1.9 to 4.6. Cardiovascular disease was the most frequent cause of death in studies with follow-up times over 15 years. SLE progressed to ESRD in 5–11% of all SLE patients. There are no data supporting increased cancer incidence from population-based inception cohorts. Conclusion: There is a need for more population-based studies on outcomes of SLE, especially inception studies, with the use of control groups and follow-up times over 15 years.

BackgroundAccurate estimations of incidence rates are important in all epidemiological studies. Register derived International Classification of Disease (ICD) codes appear near ideal case defining items being seemingly specific and easy to access in large populations, but their applicability in complex clinical syndromes like SLE is still unclear.ObjectivesWe aimed to clarify accuracy of ICD-10 coding in incident SLE by directly comparing incidence rates from code-based case-definitions and verified SLE diagnosis by expert clinical assessment in a defined population.MethodsFrom administrative data, we identified all individual cases who were registered at least once with the SLE-specific ICD-10 code M32 (i.e M32.1, M32.8 or M32.9) during 1999-2017 in three Southeast Norway counties (including Oslo), with total population 2.1 million. We manually reviewed the chart of every M32 coded case to confirm or reject SLE diagnosis. In cases found not to have SLE, most likely cause of inaccurate ICD-code was recorded. For the analyses of incidence rates by ICD-code, we applied a five-year washout period (1999-2003) and included only cases with first time M32 code from 2004 and onwards. Incidence rates were estimated from five case-definition; (a-c) first occurrence of one or more, two or more and three or more M32 codes from 2004-2017, respectively, (d) SLE diagnosis confirmed by chart review and (e) SLE classified by 1997 American College of Rheumatology classification criteria of SLE. To define accuracy, we applied incidence rate ratios obtained from dividing M32-derived incidence rate to those from SLE diagnosis.ResultsWe identified 1975 unique cases registered with a M32 code from 1999-2017. Chart review confirmed SLE diagnosis in 936 of the 1975 cases (45 %), while 1033 (52%) were found to have conditions other than SLE (most frequently another systemic connective tissue disease or cutaneous lupus).Of the 936 cases with confirmed SLE diagnosis, 323 (34%) were incident in the years 2004-2017 (Table 1). Figure 1a-c shows the incidence curves by different SLE case-definitions. Overall, the incidence rate ratio from two or more M32 code divided by SLE diagnosis was 2.1 (95 % confidence interval 1.8-2.4). Accuracy of ICD-coding was low for incident SLE across all ages, except in those under 25 years were the incidence rate ratio was 1.0 (95 % confidence interval 0.8-1.4) (Figure 1d). When reducing washout period to two instead of five years, the incidence rate ratio from two or more M32 codes divided by SLE diagnosis increased to 4.4 (95% confidence interval 3.8-4.7).ConclusionCase definitions based solely on ICD-10 code gave incidence rates of SLE twice as high as when cases were defined by expert clinical assessment, with a maximum discrepancy of seven times more in elderly (70-79 years of age) to a minimum of no discrepancy before 25 years of age.Table 1.Number of incident cases 2004-2017 in study area by different case definition of SLETotal, nWomen, nMen, nFirst occurrence of ICD code 2004-2017¹ICD code of SLE≥ 1 in time period1035867168ICD code of SLE≥ 2 in time period67058288ICD code of SLE≥ 3 in time period54347865Verified SLE diagnosis by chart review32327944SLE by 1997 ACR criteria²28924940¹No ICD code of SLE 1999-2003 ²American College of Rheumatology classification criteria SLEAcknowledgementsThis work was funded by DAM Foundation, The Norwegian Council for Musculoskeletal Health, Norwegian Women’s Public Health Association, Vivi Irene Hansens fund for SLE research and Ragna and Egil Eiken’s grant to promote rheumatism research.Disclosure of InterestsSigrid Reppe Moe: None declared, Hilde Haukeland Consultant of: UCB advisory board. Have not recieved any personal payment. Payment to employer/organisation., Cathrine Brunborg: None declared, Torhild Garen: None declared, Antonella Botea: None declared, Nenad Damjanic: None declared, Gro Wivestad: None declared, Heidi Kverneggen Øvreas: None declared, Thea Bøe: None declared, Anniken Orre: None declared, Sella Aarrestad Provan: None declared, Øyvind Molberg: None declared, Karoline Lerang: None declared.

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BackgroundPopulation-based studies on Systemic Lupus Erythematosus (SLE) patients with a verified diagnosis is considered the gold standard to find true outcomes in SLE, but few population-based SLE cohorts have follow-up over 15 years [1]. Norway is among the few countries worldwide where social and structural factors facilitate the gathering of complete population-based cohorts in rare disease like SLE due to its healthcare organization.ObjectivesTo examine long-term outcome of SLE in a population-based setting and determine if immediate cause of death differs between SLE patients and the general population.MethodsThe study included all SLE patients who were resident in the Southeast region of Norway during 1999 - 2017 and met the 1997 American College of Rheumatology classification criteria for SLE. All SLE diagnosis was confirmed by chart review. SLE patients and 15 controls for each case (matched by age, gender and ethnicity) were linked to the Norwegian Cause of Death Registry. We examined survival by means of Kaplan-Meyer estimates and used log rank test to test for differences. To estimate risk of death, we performed calculations of standard mortality rate (SMR) by dividing the number of deaths on the number of years observed. The excepted number of deaths referred to the number of deaths for the matched control group. All SLE cases were included in SMR. The 95 % confidence interval (CI) of SMR was calculated with Mid-P exact test. We defined immediate cause of death as the final event directly leading to death. An International Classification of Diseases 10th revision code of I00-99 or R96 classified as death from cardiovascular disease (CVD) (except pulmonary embolism and cerebral bleeding) and of infections A00-B99, J10-18, N39, M86 or U07.ResultsWe identified 1298 SLE patients in the region, of whom 673 was incident cases; all captures within one year from diagnosis. Of the incident cases, 76 (11%) died during 8434 years of follow-up (Table 1). The five-, ten-, 15- and 20-year survival for incident SLE patients (controls) was respectively 98 (98), 94 (96), 87 (94) and 82 (88) % and differed significantly first after ten years of disease duration compared to controls. Figure 1 shows 20-year survival for incident SLE patients and matched controls; stratified by gender. SMR for all SLE cases was 2.3 (95 % CI 1.5. - 4.0); female SLE 2.5 (95 % CI 1.6 – 3.9) and male SLE 1.9 (95 % CI 1.3 – 2.2). The most common immediate cause of death in SLE patients was CVD; whereof myocardial infarction (21 %) was most frequent. SLE patients died more often of CVD than controls (29 % vs. 21 %, p = 0.01) and had a tendency to more infections (23 % vs. 18 %, p = 0.07), whereof pneumonia (58 %) was most frequent.Table 1.Patient demographics, follow-up time and number of deaths in the total Systemic Lupus Erythematosus (SLE) cohort and in incident SLE patients.Total SLE cohortIncident SLEFemaleMalen = 1298n = 577n = 96Of European descent, n (%)1140 (88)472 (82)86 (90)Juvenile onseta, n (%)93 (7)31 (5)6 (6)LNb, n (%)470 (36)177 (30)49 (51)Cumulative ACR criteriac, µ (SD)5.4 (1.2)5.3 (1.2)5.1(1.1)Follow-up years, total1925261601217Deaths, n (%)282 (23)54 (9)22 (23)Age at diagnosis, years µ (SD)35.5 (15.7)37.4 (15.6)44 (17.9)Disease duration at death, years µ (SD)20.4 (12.5)9.6 (5.8)10.6 (10.5)µ: mean, n: number, SD: standard deviationa Diagnosed before age of 16 b Lupus Nephritis defined by 1999 American College of Rheumatology classification criteria for Systemic Lupus Erythematosus c1997 American Collee of Rheumatology classification criteria for Systemic Lupus ErythematosusConclusionMortality in SLE is substantially increased. Differences in survival compared to the general population only appear after ten years of disease duration. CVD was the most common immediate cause of death and more frequent in SLE patients.References[1]Reppe Moe, S., Haukeland, H., Molberg, Ø., & Lerang, K. (2021). Long-Term Outcome in Systemic Lupus Erythematosus; Knowledge from Population-Based Cohorts. J Clin Med, 10(19). doi:10.3390/jcm10194306Disclosure of InterestsNone declared