gms | German Medical Science

Background: Claims data of statutory health insurances (SHI) are a useful resource for real-world evidence, but clinical data are lacking to identify the severity of diseases. As a consequence, proxies are often applied. Since the severity of rheumatoid arthritis (RA), the most common inflammatory joint disease, cannot be derived from the available ICD-10 codes in SHI data, alternative approaches are needed. Treatment options for RA include 3 groups of disease-modifying antirheumatic drugs (DMARD): conventional synthetic (cs), biologic (b) or targeted synthetic (ts) DMARDs. The latter (b/tsDMARDs) are approved only for the treatment of moderate to severe RA.

Objective: Aim of the study was to determine the severity level of RA based on SHI claims data using drug prescriptions as a proxy.

Methods: A representative sample of the German SHI population, the ‘German Analysis Database for Evaluation and Health Services Research’ (DADB), covers around 3.5 million individuals. For 2019, patients with RA were identified using an adopted case definition of Zi (Zentralinstitut für die kassenärztliche Versorgung in Deutschland) [1]: ICD-10diagnosis codes (M05/M06) in at least one quarter of the year and in one of the three subsequent quarters (M2Q criterion), and additionally the measurement of inflammatory markers (C-reactive protein/erythrocyte sedimentation rate). A hierarchical classification of treatment groups was performed over a two-year period based on DGRh (Deutsche Gesellschaft für Rheumatologie) treatment guideline, with patients classified as either (I) untreated or treated with at least one (II) glucocorticoid, (III) csDMARD, or (IV) b/tsDMARD based on prescriptions [2]. The prescription of b/tsDMARD was used as a proxy for moderate to severe RA. The number of patients was extrapolated to the overall German SHI population.

Results: In 2019, for 1.27% of the German SHI population a diagnosis with RA was reported. For 614,686 patients with prevalent RA, treatment groups were analyzed. Overall, 23.8% of RA patients were untreated, while 19.1% received glucocorticoids only. Approximately 39.0% of the patients were prescribed csDMARDs. About a fifth (18.0%) of the population received b/tsDMARDs.

Discussion: This analysis identified patients with RA in German SHI claims data based on a valid case definition. Moderate to severe RA was assumed for at least one fifth of the patients using prescriptions and procedures. The estimated severity of disease in the RA population was within the range established by the German authorities such as the Federal Joint Committee (G-BA) [3]. Reasons for a switch in therapy from b/tsDMARD to csDMARD or for discontinuation of b/tsDMARD, e. g. because of adverse events/planned surgeries, cannot be traced in SHI data.

Implication for research: Even though disease severity levels are not available within claims data, they can be described using proxies such as prescriptions. The severity definition proposed here should be evaluated by investigating additional proxies such as contact to a rheumatologist, seropositive (M05)/seronegative (M06) RA and hospitalization rates.