PT - JOURNAL ARTICLE AU - Moe, Sigrid Reppe AU - Haukeland, Hilde AU - Brunborg, Cathrine AU - Garen, Torhild AU - Botea, Antonella AU - Damjanic, Nenad AU - Wivestad, Gro AU - Øvreås, Heidi Kverneggen AU - Bøe, Thea AU - Orre, Anniken AU - Provan, Sella Aarrestaad AU - Molberg, Øyvind AU - Lerang, Karoline TI - LP-071 Accuracy of disease-specific ICD-10 code for incident systemic lupus erythematosus; results from a population-based cohort study set in Norway AID - 10.1136/lupus-2023-KCR.182 DP - 2023 Jul 01 TA - Lupus Science & Medicine PG - A115--A115 VI - 10 IP - Suppl 1 4099 - http://lupus.bmj.com/content/10/Suppl_1/A115.3.short 4100 - http://lupus.bmj.com/content/10/Suppl_1/A115.3.full SO - Lupus Sci Med2023 Jul 01; 10 AB - 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.View this table:Abstract LP-071 Table 1 Relationship between clinical parameters and length of stay in SLE patients with serious infection