Summary of evidence for disease-related and psychological predictors of adherence to MTX
| Predictor | Study | N | Adherence outcome | Unadjusted effect size (95% CI)/univariate analyses | p Value | Adjusted effect size (95% CI) | p Value |
|---|---|---|---|---|---|---|---|
| RA duration | |||||||
| Years | Salt and Frazier29* | 108 | Non-adherent (MARS ≤38) | NP | NP | OR 1.00 (1.01 to 1.00) | 0.83 |
| Waimann et al30 | 107 | Adherence (MEMS) | r 0.08 | >0.20 | NP | NP | |
| 1–5 | de Thurah et al26† | 941 | Non-adherence (CMG) | β 0.03 (0.01 to 0.06) | Sig | β 0.01 (−0.01 to 0.04) | NS |
| >5 | de Thurah et al26† | 941 | Non-adherence (CMG) | β 0.02 (−0.01 to 0.04) | NS | β −0.04 (−0.07 to −0.02) | Sig |
| >5 | de Thurah et al27† | 85 | Non-adherence (CQR ≤25th centile) at BL | PR 1.7 (0.7 to 4.1) | NS | PR 1.5 (0.5 to 4.7) | NS |
| >5 | de Thurah et al27† | 65 | Non-adherence (CQR ≤25th centile) at 9 mo | PR 1.5 (0.6 to 3.6) | NS | PR 1.2 (0.4 to 3.1) | NS |
| Inflammatory biomarkers | |||||||
| CRP | Contreras-Yanez et al24* | 93 | Adherent (CQ ≥9) vs non-adherent (CQ ≤8) | 2.4±2.6 vs 2.6±2.4 | 0.68 | NP | NP |
| CRP 8–32 | de Thurah et al26† | 941 | Non-adherence (CMG) | β 0.00 (−0.02 to 0.02) | NS | β −0.02 (−0.04 to 0.01) | NS |
| CRP >32 | de Thurah et al26† | 941 | Non-adherence (CMG) | β −0.02 (−0.05 to 0.01) | NS | β −0.04 (−0.07 to −0.02) | Sig |
| Erythrocyte sedimentation rate | Contreras-Yanez et al24* | 93 | Adherent (CQ ≥9) vs non-adherent (CQ ≤8) | 24.1±17.4 37.5±23.8 | 0.003 | NP | NP |
| Disease Activity Score-28 | |||||||
| Contreras-Yanez et al24* | 93 | Adherent (CQ ≥9) vs non-adherent (CQ ≤8) | 3.6±1.3 vs 5.1±1.9 | ≤0.001 | NP | NP | |
| Waimann et al30 | 90 | Per cent of adherent (MEMS) | r −0.27 | 0.01 | NP | NP | |
| Sharp score | Waimann et al30 | 79 | Per cent of adherent (MEMS) | r −0.06 | >0.20 | NP | NP |
| Functional ability | |||||||
| HAQ | de Klerk et al22*,‡ | 127 | Per cent of adherence (MEMS) | ANOVA (no data) | NS | NP | NP |
| Contreras-Yanez et al24* | 93 | Adherent (CQ ≥9) vs non-adherent (CQ ≤8) | 0.2±0.4 vs 0.4±0.5 | 0.04 | NP | NP | |
| HAQ >1.75 | de Thurah et al27† | 85 | Nonadherence (CQR ≤25th centile) | PR 1.2 (0.5 to 2.5) | NS | PR 1.4 (0.6 to 3.1) | NS |
| 0.75–1.75 | de Thurah et al27† | 65 | Non-adherence (CQR ≤25th centile) at BL | PR 1.5 (0.5 to 4.9) | NS | PR 0.8 (0.2 to 3.3) | NS |
| HAQ >1.75 | de Thurah et al27† | 65 | Non-adherence (CQR ≤25th centile) at 9 mo | PR 0.8 (0.3 to 2.5) | NS | PR 1.0 (0.2 to 3.4) | NS |
| Modified—HAQ | Waimann et al30 | 107 | Per cent of adherence (MEMS) | r −0.20 | 0.04 | NP | NP |
| Comorbidity | |||||||
| Number of comorbidities | Waimann et al30 | 107 | Per cent of adherence (MEMS) | r −0.06 | >0.20 | NP | NP |
| Per cent with comorbidity | Contreras-Yanez et al 24* | 93 | Adherent (CQ ≥9) vs non-adherent (CQ ≤8) | 40% (85) vs 36% (78.3) | 0.43 | NP | NP |
| Any vs none | de Thurah et al27† | 85 | Non-adherence (CQR ≤25th centile) at BL | PR 1.3 (0.4 to 3.9) | NS | PR 1.1 (0.4 to 3.3) | NS |
| de Thurah et al27† | 65 | Non-adherence (CQR ≤25th centile) at 9 mo | PR 1.3 (0.4 to 3.8) | NS | PR 2.2 (0.5 to 9.7) | NS | |
| COPD | de Thurah et al26† | 941 | Non-adherence (CMG) | β 0.00 (−0.04 to 0.04) | NS | β 0.04 (0.00 to 0.07) | Sig |
| Diabetes | de Thurah et al26† | 941 | Non-adherence (CMG) | β −0.04 (−0.1 to 0.02) | NS | β 0.00 (−0.05 to 0.05) | NS |
| Liver disease | de Thurah et al26† | 941 | Non-adherence (CMG) | β 0.06 (0.02 to 0.10) | Sig | β 0.04 (0.00 to 0.08) | Sig |
| BMQ low concern about MTX | de Thurah et al27† | 85 | Non-adherence (CQR ≤25th centile) at BL | PR 0.8 (0.4 to 1.8) | NS | PR 0.7 (0.3 to 1.8) | NS |
| de Thurah et al27† | 65 | Non-adherence (CQR ≤25th centile) at 9 mo | PR 0.5 (0.2 to 1.2) | NS | PR 0.5 (0.2 to 1.3) | NS | |
| BMQ high perceptions of MTX necessity | de Thurah et al27† | 85 | Non-adherence (CQR ≤25th centile) at BL | PR 0.4 (0.1 to 0.8) | Sig | PR 0.3 (0.1 to 0.8) | Sig |
| de Thurah et al27† | 65 | Non-adherence (CQR ≤25th centile) at 9 mo | PR 0.2 (0.1 to 0.6) | Sig | PR 0.4 (0.1 to 1.1) | NS | |
| LTMBS (self-efficacy) | de Klerk et al22‡ | 127 | Per cent of adherence (MEMS) | F 5.9 | 0.02 | NP | NP |
| UCL avoidant coping | de Klerk et al22*,‡ | 127 | Per cent of adherence (MEMS) | NP | NS | β −0.41 | < 0.05 |
| Passive reactive coping | |||||||
| UCL passive coping | de Klerk et al22*,‡ | 127 | Per cent of adherence (MEMS) | NP | NS | β 0.79 | <0.05 |
| UCL reactive coping | de Klerk et al22*,‡ | 127 | Per cent of adherence (MEMS) | NP | NS | β 0.4 | <0.05 |
| UCL active coping | de Klerk et al22*,‡ | 127 | Per cent of adherence (MEMS) | NP | NS | NP | NP |
| UCL reassuring thoughts | de Klerk et al22*,‡ | 125 | Per cent of adherence (MEMS) | NP | NS | NP | NP |
| Mental health | |||||||
| CES-D10 | Waimann et al30 | 107 | Per cent of adherence (MEMS) | r −0.19 | 0.05 | NP | NP |
| MOS SF-12 MCS | Waimann et al30 | 107 | Per cent of adherence (MEMS) | r 0.34 | <0.01 | NP | NP |
| MOS social support | Waimann et al30 | 107 | Per cent of adherence (MEMS) | r 0.17 | 0.08 | NP | NP |
| Health-related quality of life | |||||||
| European Quality of Life Measure | de Klerk et al22*,‡ | 127 | Per cent of adherence (MEMS) | F 5.42 | <0.01 | NP | NP |
| RA Quality of Life Measure | de Klerk et al22*,‡ | 81 | Per cent of adherence (MEMS) | F 0.21 | 0.65 | NP | NP |
| Nottingham Health Profile | de Klerk et al22*,‡ | 127 | Per cent of adherence (MEMS) | NP | NS | β −0.62 | <0.05 |
| MOS SF-12 Physical Component Summary | Waimann et al30 | 107 | Per cent of adherence (MEMS) | r 0.07 | >0.20 | NP | NP |
*Studies judged low quality.
†MTX adherence.
‡Includes RA, PMR and gout.
9 mo, 9 months; ANOVA, analysis of variance; BL, baseline; BMQ, Beliefs in Medicines Questionnaire; CES-D10, Centre of Epidemiologic Studies Depression Scale; CMG, continuous medication gap; COPD, chronic obstructive pulmonary disease; CQ, Compliance Questionnaire; CQR, Compliance Questionnaire—Rheumatology; CRP, C reactive protein; F, ANOVA test statistic; HAQ, Health Assessment Questionnaire; MARS, Medication Adherence Revised Scale; MEMS, Medicine Event Monitoring System; MOS, Medical Outcomes Study; MTX, methotrexate; NP, not presented; NS, non-significant; PR, prevalence ratio; r, Pearson correlation coefficient; RA, rheumatoid arthritis; SF-12 MCS, Mood Component Summary of MOS 12-item Short Form Health Survey; Sig, significant; UCL, Utrecht Coping List; β, regression coefficient.