Extended report formula 0.56*sqrt(TJC28) + 0.28*sqrt(SJC28) + 0.70*Ln(ESR) + 0.014*(GH). Gross domestic product The GDP of each country in 2005 was obtained from a database of the International Monetary Fund16 and is expressed as UD$1000 or Euros (J) per capita (with an exchange rate of US$1.25 = J1.0 in 2005). GDP ranged from 3.5 to 49, including 14 ‘‘high GDP’’ countries with GDP per capita greater than US$24 000 and 11 ‘‘low GDP’’ countries with GDP per capita less than US$11 000. Statistical methods Descriptive results for each country are presented as mean, median and percentages. Comparisons of demographic vari- ables, clinical characteristics, RA disease activity measures and treatment-related variables within and/or between ‘‘high GDP’’ and ‘‘low GDP’’ countries were performed using parametric and non-parametric tests for continuous variables and the x2 test for categorical variables. Linear regression models were applied to analyse possible associations between DAS28 and GDP. RESULTS Patients The 6004 patients in the QUEST–RA database, from 71 clinics in 25 countries, represent a typical RA cohort in demographic features, with a mean age of 56 years, 79% women, and a mean disease duration of 11 years (table 1). Patients were younger and more likely to be women in ‘‘low GDP’’ compared with ‘‘high GDP’’ countries, whereas years of formal education, BMI and disease duration were similar (table 1). Patient characteristics are presented for each European and non-European country, in descending order of GDP in table 2. Disease activity Patients in ‘‘low GDP’’ countries had statistically significantly higher disease activity levels in all individual disease activity measures, including physician-derived measures, patient self- report scores and laboratory measures, as well as the composite index DAS28 (table 1). The percentage of patients with positive RF varied between 61% and 90% between countries (table 3), although the overall difference was only 4% between ‘‘high GDP’’ and ‘‘low GDP’’ countries (table 1). Erosive disease was less prevalent in ‘‘high GDP’’ countries, with differences of 14%, although with differences of only 5% in patients with more than 10 years of disease (table 1). Drug therapies DMARD were taken by 88–100% of all patients in the 25 countries (table 4), with no differences between ‘‘high GDP’’ and ‘‘low GDP’’ countries (table 1); the mean number of DMARD was 2.7. The median delay between first symptoms and initiation of the first DMARD ranged from less than 6 months in three countries to one year or more in 10 countries (table 4), with no significant difference between ‘‘high GDP’’ and ‘‘low GDP’’ countries (table 1). Methotrexate was taken by 69–98%, prednisone by 30–97% and biological agents by 1–54% of patients. DMARD were taken for less than 50% of disease duration in the UK, Ireland, Hungary, Latvia, Lithuania and Argentina, and for more than 100% in Finland, Greece and Table 2 Patient characteristics in the QUEST–RA study in Europe and other countries, in descending order of GDP GDP 2005 per capita (US$1000) Sites Patients Women, % Education, Age, years, years, mean median Smoking now, % Disease duration, BMI, mean years, mean Country Europe Ireland Denmark Sweden The Netherlands Finland UK France Germany Italy Spain Greece Hungary Estonia Poland Lithuania Latvia Serbia Kosovo Non-Europe USA Canada UAE Russia Turkey Brazil Argentina Total 1668 BMI, body mass index; GDP, gross domestic product; UAE, United Arab Emirates. 48.7 47.9 39.6 38.9 37.3 37.3 35.0 33.9 30.5 26.1 25.6 10.9 10.3 8.0 7.5 7.0 3.5 3.5 41.9 35.2 32.4 5.3 5.0 4.8 4.7 3 3 3 3 3 3 4 2 4 3 3 3 3 7 2 1 1 1 3 1 2 3 3 5 2 71 240 301 260 317 304 145 389 225 336 302 300 153 168 642 300 79 100 100 301 100 199 73 309 115 246 6004 64 77 72 66 72 78 78 84 78 74 76 87 85 87 83 80 88 84 73 79 86 85 86 89 90 79 56 58 59 59 59 60 55 59 61 60 58 58 56 53 54 53 59 55 57 58 45 54 52 52 51 56 12 10 10 11 9 12 10 10 8 10 12 12 12 12 13 13 8 8 13 12 15 13 5 8 9 11 24 31 19 22 15 19 19 13 16 17 15 24 14 11 7 18 18 5 20 30 6 15 13 13 21 17 25 25 25 26 27 25 25 26 25 26 26 25 26 25 26 27 26 28 28 27 26 26 27 25 26 26 11 12 12 9 14 15 13 13 10 11 12 13 12 12 11 13 10 8 9 12 6 6 12 8 10 11 Ann Rheum Dis 2009;68:1666–1672. doi:10.1136/ard.2009.109983