Table 2

Associations of individual-level and country-level socioeconomic factors with disease activity (ASDAS) and physical function (BASFI)

Independent variablesASDAS 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 educationRefRefRef
 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 weightRefRefRef
 Underweight0.13 (−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
 AsiaRefRefRef
 Europe0.15 (−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 America0.08 (−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.