[Prevalence of rheumatoid arthritis in Germany based on health insurance data : Regional differences and first results of the PROCLAIR study].
BACKGROUND
Rheumatoid arthritis (RA) is the most common chronic inflammatory joint disease with a prevalence of up to 1 % in the adult population.


OBJECTIVE
This study describes the prevalence of RA diagnoses in outpatient health insurance claims data, based on different case definitions and stratified by age, sex and region of residence.


METHODS
Based on data from a nationwide statutory health insurance fund (BARMER GEK) from the year 2013, a cross-sectional study of insurants aged 18 years or older was conducted. The following case definitions were applied: A) a diagnosis of seropositive rheumatoid arthritis (M05) or other rheumatoid arthritis (M06) according to the international classification of diseases 10 German modification (ICD-10-GM) in at least two quarterly periods of the year 2013, B) case definition A plus determination of C‑reactive protein (CRP) or erythrocyte sedimentation rate (ESR) at least once, C) case definition B plus specific drug therapy and D) case definition A plus treatment by a rheumatologist. Raw as well as age and sex-standardized prevalences were calculated and stratified according to the federal state.


RESULTS
The study population consisted of 7,155,315 insurants of whom 60.2 % were female. Overall, RA prevalences for the respective case definitions were 1.62 % (A), 1.11 % (B), 0.94 % (C) and 0.64 % (D). When standardized to the German population the prevalences were 1.38 % (A), 0.95 % (B), 0.81 % (C) and 0.55 % (D). The proportion of women was approximately 80 % for all case definitions. Prevalences increased with age, peaking in the age group 70-79 years old and showing the highest values in eastern and the lowest in southern Germany for raw as well as standardized measures.


CONCLUSIONS
Regional differences in the prevalence of RA diagnoses in health insurance claims data were observed independent of age, sex and case definition. The expected prevalence according to the results of international studies was best achieved when case definitions with CRP or ESR were considered.
Department für Versorgungsforschung, Fakultät für Medizin und Gesundheitswissenschaften, Carl von Ossietzky Universität Oldenburg, Ammerländer Heerstr. 140, 26111, Oldenburg, Deutschland.|Abteilung für Epidemiologie und Gesundheitsmonitoring, Robert Koch-Institut, Berlin, Deutschland.
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S
Hense
Department für Versorgungsforschung, Fakultät für Medizin und Gesundheitswissenschaften, Carl von Ossietzky Universität Oldenburg, Ammerländer Heerstr. 140, 26111, Oldenburg, Deutschland.
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A
Luque Ramos
Programmbereich Epidemiologie, Deutsches Rheumaforschungszentrum Berlin, Berlin, Deutschland.
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J
Callhoff
Programmbereich Epidemiologie, Deutsches Rheumaforschungszentrum Berlin, Berlin, Deutschland.
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K
Albrecht
Programmbereich Epidemiologie, Deutsches Rheumaforschungszentrum Berlin, Berlin, Deutschland.|Klinik mit Schwerpunkt Rheumatologie und Klinische Immunologie, Charité Universitätsmedizin Berlin, Berlin, Deutschland.
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A
Zink
Department für Versorgungsforschung, Fakultät für Medizin und Gesundheitswissenschaften, Carl von Ossietzky Universität Oldenburg, Ammerländer Heerstr. 140, 26111, Oldenburg, Deutschland. falk.hoffmann@uni-oldenburg.de.
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F
Hoffmann
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000553:Ambulatory Care / Q000706:statistics & numerical data*; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000191:economics / Q000453:epidemiology*; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009313:National Health Programs / Q000706:statistics & numerical data*; D011159:Population Surveillance / Q000379:methods*; D015995:Prevalence; D012307:Risk Factors; D017678:Sex Distribution; D055815:Young Adult
Epidemiology; Health services research; Healthcare insurance data; Rheumatoid arthritis; Secondary data