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LP-071 Accuracy of disease-specific ICD-10 code for incident systemic lupus erythematosus; results from a population-based cohort study set in Norway
  1. Sigrid Reppe Moe1,
  2. Hilde Haukeland1,2,
  3. Cathrine Brunborg3,
  4. Torhild Garen1,
  5. Antonella Botea4,
  6. Nenad Damjanic2,
  7. Gro Wivestad5,
  8. Heidi Kverneggen Øvreås6,
  9. Thea Bøe7,
  10. Anniken Orre8,
  11. Sella Aarrestaad Provan9,
  12. Øyvind Molberg1,10 and
  13. Karoline Lerang1
  1. 1Department of Rheumatology, Oslo University Hospital, Norway
  2. 2Department of Rheumatology, Martina Hansen Hospital, Norway
  3. 3Oslo Centre for Biostatistics and Epidemiology, Oslo University Hospital, Norway
  4. 4Department of Rheumatology, Betanien Hospital, Norway
  5. 5Department of Rheumatology, Sørlandet Hospital, Norway
  6. 6Department of Rheumatology, Revmatismesykehuset, Norway
  7. 7Department of Internal Medicine, Vestfold Hospital, Norway
  8. 8Department of Rheumatology, Drammen Hospital, Norway
  9. 9REMEDY – Center for treatment of Rheumatic and Musculoskeletal Diseases, Diakonhjemmet Hospital, Norway
  10. 10Institute of Clinical Medicine, University of Oslo, Norway


Background It is not clear how well administrative data identify incident disease in complex chronic disorders like Systemic Lupus Erythematosus (SLE). We aimed to clarify accuracy of ICD-10-coding in incident SLE by comparing incidence-rates from code-based case-definitions and confirmed SLE diagnosis by expert clinical assessment in a defined population.

Methods From administrative data, we identified all individual cases registered with a SLE-specific ICD-10 code (M32) during 1999–2017 in three Southeast Norway counties(2.1 million). All cases were manually chart-reviewed to confirm SLE diagnosis. To prevent against admixture of prevalent cases, we defined incident by presence of M32 in 2004–2017, but not in 1999–2003. Incidence-rates were estimated from five case-definition; (a-c) first occurrence of one-, two- and three or more M32-codes 2004–2017, (d) SLE diagnosis confirmed by chart-review and (e) SLE classified by 1997 ACR classification criteria. To define accuracy, we applied incidence-rate ratios obtained from dividing M32-derived incidence-rates to those from SLE diagnosis.

Results Of 1975 unique cases registered with a M32-code 1999–2017, chart-review confirmed SLE diagnosis in 936 cases (45%), while 1033 (52%) had conditions other than SLE.

Of 936 cases with confirmed SLE diagnosis, 323 (34%) were incident 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).

Conclusions Case-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 no discrepancy before 25 years of age.

Abstract LP-071 Figure 1

a-c) Age-distribution of estimated incidence of Systemic Lupus Erythematous (SLE) in study area 2004–2017 by different case-definitions; for all (a), women (b), men (c). d) Age distribution of incidence rate-ratios comparing SLE defined by two or more ICD-codes of SLE to SLE diagnosis confirmed by individual chart-review (i.e. accuracy of ICD-code); stratified by sex.

Abstract LP-071 Table 1

Relationship between clinical parameters and length of stay in SLE patients with serious infection

  • Systemic Lupus Erythematosus
  • Epidemiology
  • Validation

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