Prediction and benefits of minimal disease activity in patients with psoriatic arthritis and active skin disease in the ADEPT trial

Abstract

Objectives: To determine the proportion of patients with psoriatic arthritis in the Adalimumab Effectiveness in Psoriatic Arthritis trial achieving minimal disease activity (MDA) and its individual components at 1 or more visits over 144 weeks, identify baseline predictors of MDA achievement, and evaluate the association of MDA status with independent quality of life (QoL)-related patient-reported outcomes (PROs).

Methods: Univariate and multivariate analyses were used to identify the baseline characteristics that predicted achievement of MDA at individual time points (weeks 12 through 144) or sustained MDA (achievement of MDA at 2 consecutive time points 12 weeks apart). The association of independent QoL-related PROs with MDA achievement was evaluated at weeks 24 and 144.

Results: In univariate analyses, higher baseline patient assessment of pain, tender joint count (TJC), enthesitis and Health Assessment Questionnaire-Disability Index (HAQ-DI) score were significantly associated with lower likelihood of achieving MDA at later time points. Multivariate analyses confirmed higher baseline HAQ-DI as a significant predictor for failure to achieve MDA at later time points. Achievement of sustained MDA was associated with lower baseline TJC and HAQ-DI score. Achievement of different MDA components appeared to be treatment dependent. MDA achievers had significantly better QoL-related PROs and greater improvements in PROs from baseline to week 24 compared with non-achievers.

Conclusions: Higher HAQ-DI score was the most consistent baseline factor that decreased the likelihood of achieving MDA and sustained MDA at later time points. Achieving MDA was associated with better independent QoL-related PROs.

Keywords: Anti-TNF; Psoriatic Arthritis; TNF-alpha.

Figure 1

Achievement of MDA over 144 weeks in patients initially receiving adalimumab or placebo during the double-blind period. Data are presented as observed (solid lines) and using NRI (dashed lines). Patients who escalated to weekly dosing on or after week 36 were counted as non-responders. Numbers of patients at each study visit are presented below the graph. ADA, adalimumab; MDA, minimal disease activity; NRI, non-responder imputation; OBS, as observed; PBO, placebo.

Figure 2

OR for baseline predictors of MDA at weeks 12, 24, 48, 96 and 144 by univariate analysis of observed data. CRP, C-reactive protein; HAQ-DI, Health Assessment Questionnaire-Disability Index; MDA, minimal disease activity; mTSS, modified total Sharp score; PASI, Psoriasis Area and Severity Index; PhGA, Physician Global Assessment of disease activity; PhGA-P, Physician Global Assessment of psoriasis; Ps, psoriasis; PsA, psoriatic arthritis; PtGA, Patient Global Assessment of disease activity; SJC, swollen joint count of 76 joints; TJC, tender joint count of 78 joints. *Statistically significant predictor of MDA.

Figure 3

OR for selected baseline predictors of MDA at weeks 12, 24, 48, 96 and 144 by multivariate analysis of observed data. Statistically significant variables in the univariate analysis were further selected with LASSO to adjust for confounding factors and collinearity. HAQ-DI, Health Assessment Questionnaire-Disability Index; LASSO, least absolute shrinkage and selection operator method; MDA, minimal disease activity; PASI, Psoriasis Area and Severity Index; Ps, psoriasis; SJC, swollen joint count of 76 joints; TJC, tender joint count of 78 joints. *Statistically significant predictor of MDA.

Figure 4

Box plot of HAQ-DI scores at baseline, week 96 and week 144 categorised by baseline PsA duration. The horizontal lines indicate the median, boxes mark the interval between the 25th and 75th percentiles, vertical lines indicate the maximum and minimum values, and + represents the mean. The dashed line represents HAQ-DI=0.5, which is the cut-off point for the MDA component. HAQ-DI, Health Assessment Questionnaire-Disability Index; MDA, minimal disease activity; PsA, psoriatic arthritis.

Figure 5

Mean of SF-36 and FACIT-F (A) and DLQI (B) scores at week 24 and mean change from baseline to week 24 in SF-36 and FACIT-F (C) and DLQI (D) scores in MDA achievers and MDA non-achievers. Data are presented as observed. Dashed lines represent MCID. *p<0.01; **p<0.01; ***p<0.001. DLQI, Dermatology Life Quality Index; FACIT-F, Functional Assessment of Chronic Illness Therapy-Fatigue; MCID, minimal clinically important difference; MCS, mental component score; MDA, minimal disease activity; PCS, physical component score; SF-36, Short Form 36 Health Survey.