Table 5

Multivariable logistic and linear regression comparing proportions of SARS-CoV-2 seropositivity and IgG antibody titres between patients with rheumatic immune-mediated inflammatory diseases and controls

SeropositivityIgG antibody titre
OR95% CIP valueBetaRatio95% CIP value
Healthy controls*1.00N.A.0.001.00N.A.
Patients with rheumatic diseases0.88(0.42 to 1.83)0.730.491.59(0.88 to 3.02)0.12
Covariables
Age0.97(0.95 to 1.0)0.040−0.00830.99(0.97 to 1.01)0.43
Sex
 Male*1.00N.A.0.001.00N.A.
 Female0.83(0.41 to 1.66)0.590.301.35(0.75 to 2.43)0.32
COVID-19-related hospitalisation0.83(0.41 to 1.66)0.67−1.886.58(1.76 to 24.56)0.005†
Time since COVID-19 in months0.95(0.88 to 1.01)0.10−0.150.86(0.81 to 0.91)<0.0001†
  • Seropositivity data are adjusted ORs with 95% CIs in parentheses, and p values. IgG antibody titre data are adjusted β, back-transformed β (ratio) with corresponding 95% CI in parentheses, and p values. Data on IgG antibody titre were missing for 14 (4%) of 367 samples due to shortage of serum volume.

  • *Reference group.

  • †Below the Benjamini threshold.

  • N.A., not available.