Table 3.
Association between number of weeks of correct, under‐, and early dosing of MTX and baseline characteristics, showing odds ratios (95% CI) from longitudinal logistic GEE model and hazard ratios (95% CI) from Cox regression model for persistence, using backward selection from the full set of variables considereda
| Adherence (Overall) | Implementation | Persistence | |||||
|---|---|---|---|---|---|---|---|
| Correct dosing | Underdosing | Early dosing | Correct dosing | Underdosing | Early dosing | ||
| Age (years) | 1.10b (1.02‐1.20) | ||||||
| White ethnicity (1 white, 0 nonwhite) | 0.19b (0.10‐0.37) | 0.16b (0.07‐0.33) | |||||
| Education level (years) | 1.19b (1.00‐1.41) | ||||||
| Employed | 0.47 (0.22‐1.03) | 12.03b (2.45‐59.18) | |||||
| BMI (kg/m2) | 1.04 (0.99‐1.09) | 1.04 (1.00‐1.08) | |||||
| HAQ‐II (0‐3) | 0.47b (0.24‐0.94) | 2.63b (1.27‐5.44) | 0.37b (0.19‐0.73) | 0.50b (0.28‐0.89) | 2.48b (1.35‐4.57) | 0.34b (0.17‐0.69) | |
| Pain VAS (0‐10) | 1.24b (1.04‐1.47) | 1.21b (1.02‐1.43) | |||||
| PtGA VAS (0‐10) | 1.21b (1.03‐1.43) | 0.80b (0.68‐0.95) | 0.85b (0.73‐0.99) | 1.28b (1.10‐1.49) | 0.75b (0.63‐0.89) | 0.85 (0.71‐1.00) | |
| Prior csDMARD use (not MTX) | 2.01 (0.95‐4.25) | ||||||
| Prior bDMARD use | 0.42b (0.18‐0.98) | ||||||
| BMQ general harmc | 0.87 (0.74‐1.02) | ||||||
| BMQ‐specific necessityd | 0.89b (0.82‐0.95) | 0.85b (0.77‐0.93) | |||||
| Time (weeks) | 0.88b (0.79‐0.97) | 1.22b (1.10‐1.35) | 0.88b (0.78‐0.99) | 1.27b (1.18‐1.43) | |||
| Time2 (weeks2) | 1.00b (1.00‐1.01) | 0.99b (0.99‐1.00) | 1.00b (1.00‐1.01) | 0.99b (0.99‐1.00) | |||
Abbreviation: bDMARD, biologic DMARD; BMI, body mass index; BMQ, Beliefs about Medicines Questionnaire; CI, confidence interval; csDMARD, conventional synthetic DMARD; DMARD, disease‐modifying antirheumatic drug; GEE, Generalized Estimating Equations; HAQ, Health Assessment Questionnaire; MTX, methotrexate; PtGA, Patient Global Assessment of Disease Activity; VAS, visual analog scale.
aEach model represents a dimension. Correct dosing cannot be directly compared with under‐ or early dosing. See Online Supplementary Table 1 for correct dosing predictions. b P < 0.05. cBMQ general harm: higher score equals greater belief that medicines are harmful, addictive, poisons that should not be taken continuously. dBMQ‐specific necessity: higher score indicates greater belief in the necessity of the medication.