Associations of individual-level and country-level socioeconomic factors with disease activity (ASDAS) and physical function (BASFI)
| Independent variables | ASDAS β (95% CI)* | OR of having ASDAS ≥2.1 (95% CI)* | BASFI β (95% CI)* |
| n=3085£ | n=3085£ | n=3075£ | |
| Age (years) | −0.01 (−0.01 to 0.00) | 0.99 (0.98 to 0.99) | 0.01 (0.01 to 0.02) |
| Gender (female vs male) | 0.21 (0.13 to 0.29) | 1.70 (1.43 to 2.01) | 0.42 (0.27 to 0.56) |
| Education | |||
| University education | Ref | Ref | Ref |
| Secondary education | 0.23 (0.15 to 0.31) | 1.52 (1.27 to 1.80) | 0.37 (0.23 to 0.52) |
| Low education | 0.32 (0.20 to 0.44) | 1.66 (1.29 to 2.20) | 0.55 (0.33 to 0.78) |
| Rheumatic Disease Comorbidity Index (0–8) | 0.17 (0.13 to 0.20) | 1.40 (1.29 to 1.52) | 0.36 (0.30 to 0.43) |
| Body mass index | |||
| Normal weight | Ref | Ref | Ref |
| Underweight | 0.13 (−0.09 to 0.35) | 1.38 (0.86 to 2.22) | 0.34 (−0.05 to 0.73) |
| Overweight | 0.10 (0.02 to 0.18) | 1.19 (0.99 to 1.43) | 0.06 (−0.08 to 0.22) |
| Obesity | 0.21 (0.11 to 0.32) | 1.66 (1.33 to 2.08) | 0.30 (0.11 to 0.49) |
| Axial involvement (vs peripheral only) | 0.03 (−0.08 to 0.15) | 1.28 (0.99 to 1.65) | 0.56 (0.35 to 0.76) |
| Bamboo spine (yes vs no) | – | – | 0.97 (0.73 to 1.22) |
| ASDAS | – | – | 1.51 (1.44 to 1.57) |
| Smoking (now or ever vs never smoked) | 0.10 (0.03 to 0.18) | 1.21 (1.02 to 1.42) | 0.14 (0.01 to 0.27) |
| GDP (low vs medium and high) | 0.22 (−0.07 to 0.51) | 1.49 (0.91 to 2.45) | 0.25 (−0.25 to 0.75) |
| Alternative macroeconomic indicators and region† | |||
| HDI (high and medium vs very high) | 0.35 (0.07 to 0.64) | 1.84 (1.13 to 3.00) | 0.24 (−0.32 to 0.79) |
| Region | |||
| Asia | Ref | Ref | Ref |
| Europe | 0.15 (−0.18 to 0.47) | 1.30 (0.73 to 2.32) | 0.73 (0.28 to 1.18) |
| Africa | 0.62 (0.12 to 1.12) | 2.91 (1.21 to 7.03) | 1.07 (0.38 to 1.76) |
| North America | −0.17 (−0.70 to 0.36) | 1.02 (0.39 to 2.64) | 1.01 (0.26 to 1.75) |
| South America | 0.08 (−0.36 to 0.53) | 1.50 (0.68 to 3.33) | 1.31 (0.69 to 1.94) |
| Healthcare expenditure (low vs medium and high) | 0.19 (−0.11 to 0.49) | 1.44 (0.87 to 2.39) | 0.18 (−0.35 to 0.71) |
| Gini index (medium and high vs low) | −0.07 (−0.49 to 0.26) | 0.91 (0.53 to 1.57) | 0.10 (−0.47 to 0.67) |
Results from multilevel multivariable linear and logistic regression analyses. £Approximately 8% of cases had missing on one or more variables and thus not included in the model.
*Estimates with p<0.05 are highlighted in bold.
†GDP, HDI, region, HCE and Gini index estimates are derived from three separate models. Coefficients for individual covariates are derived from a model with GDP; only minor differences were observed in individual covariates between the three models.
ASDAS, Ankylosing Spondylitis Disease Activity Score; BASFI, Bath Ankylosing Spondylitis Functional Index; GDP, gross domestic product; HCE, healthcare expenditure; HDI, Human Development Index; Ref, reference.