Table 3

OR of medication adherence (PDC)* by copay per covariable adjustment by models

Copayment ≥$10/month vs <$10
ORLower CIUpper CIP value
Model 1
 AZA (n=764)0.530.370.750.0004
 HCQ (n=9510)0.590.530.65<0.0001
 MMF (n=843)0.760.571.030.08
 MTX (n=552)1.030.661.610.90
 Combination therapy (n=1880)0.750.580.970.03
Model 2
 AZA (n=764)0.510.360.730.0002
 HCQ (n=9510)0.600.540.66<0.0001
 MMF (n=843)0.760.561.030.07
 MTX (n=552)1.080.691.700.73
 Combination therapy (n=1880)0.750.580.970.03
Model 3
 AZA (n=764)0.440.300.66<0.0001
 HCQ (n=9510)0.610.550.68<0.0001
 MMF (n=843)0.690.490.960.03
 MTX (n=552)0.950.571.590.85
 Combination therapy (n=1880)0.730.550.970.03

  • Model 1: adjusted by age, sex, and race or ethnicity.

  • Model 2: adjusted by model 1 variables, Elixhauser comorbidities, tobacco use, HLD and antiphospholipid syndrome.

  • Model 3: adjusted by model 2 variables, annual household income, educational attainment, insurance type, deductible contribution and geographical region.

  • *Medication adherence is defined as PDC ≥80%.

  • AZA, azathioprine; HCQ, hydroxychloroquine; HLD, hyperlipidaemia; MMF, mycophenolate mofetil; MTX, methotrexate; PDC, proportion of days covered.