ASSOCIATION BETWEEN NOCTURNAL BACK PAIN AND FATIGUE IN ANKYLOSING SPONDYLITIS AND IMPROVEMENTS IN BOTH PATIENT-REPORTED OUTCOMES WITH ETANERCEPT THERAPY

Background: Among patients with ankylosing spondylitis (AS), back pain at night and fatigue are frequent complaints that are associated with reduced quality of life. Nocturnal back pain disrupts sleep in AS patients and may contribute to fatigue during their waking hours. These two symptoms have been studied independently, but the relationship between them has not been well studied. Etanercept (ETN), a fully human TNF soluble receptor, has been shown to improve signs and symptoms of AS (including nocturnal pain and fatigue) in controlled studies. Objectives: To use data from previously conducted controlled clinical trials of ETN to evaluate the relationship between nocturnal back pain and fatigue in subjects with active AS. Methods: Data were combined from 4 clinical trials for subjects with AS who received ≥1 dose of ETN, sulfasalazine (SSZ), or placebo (PBO) and had ≥1 post-baseline efficacy value (N=1,283). Linear regression was performed, controlling for site, protocol, and demographic characteristics, to explore the relationship between nocturnal back pain (scores 0–100 on visual analogue scale [VAS]) and fatigue (scores 0–100 on VAS for fatigue item of the Bath Ankylosing Spondylitis Disease Activity Index [BASDAI]). Descriptive statistics and the correlation (Pearson's r) between these variables were calculated. Data for ETN 50-mg weekly and 25-mg twice-weekly dosing groups were combined. Results: Linear regression showed that, even after controlling for subject age, gender, and disease duration, improvement in nocturnal back pain was a significant predictor of improvement in fatigue (estimate, 0.49; p<0.0001). Patient-reported nocturnal back pain was moderately correlated with fatigue at baseline (r=0.40; p<0.0001), as were the changes from baseline for the two variables (r=0.61; p<0.0001). ETN provided greater reductions in pain and fatigue than SSZ and PBO (table). Improvement in fatigue in the ETN group was significant after controlling for change in nocturnal back pain but was not significant in the SSZ group. Table 1. Effects of treatment on nocturnal back pain and fatigue (0–100 VAS) in subjects with AS Nocturnal Back PainFatigue TreatmentMean Score*Mean ChangeMean Score*Mean Change (SD) at Baseline(SD) at Wk 12(SD) at Baseline(SD) at Wk 12 ETN62.64 (22.23)-36.16*61.47 (21.05)-27.49* SSZ63.32 (23.26)-23.80*59.93 (20.79)-15.44* PBO60.54 (21.34)-9.41*62.24 (21.40)-8.04* *p<0.0001, baseline vs wk 12. p<0.0001, between-group comparisons at wk 12 for both pain and fatigue. Conclusions: Nocturnal back pain was a significant predictor of fatigue in this pooled population of subjects with AS. Etanercept was superior to sulfasalazine in reducing fatigue and provided improvement in fatigue beyond its effects on nocturnal back pain. Additional research is needed to further investigate the findings of these exploratory analyses. References: 1. Bodur H, et al. Qual Life Res 2010 Oct 27 [Epub ahead of print]. 2. Davis JC, Jr., et al. Arthritis Rheum 2003;48:3230-6. 3. Brandt J, et al. Arthritis Rheum 2003;48:1667-75. 4. Calin A, et al. Ann Rheum Dis 2004;63:1594-600. 5. Davis JC, Jr., et al. Ann Rheum Dis 2008;67:346-52. 6. Dijkmans B, et al. J Rheumatol 2009;36:1256-64. Disclosure of Interest: M. Hammoudeh Grant/Research support from: Pfizer, D. Zack Shareholder of: Amgen, Employee of: Amgen, W. Li Shareholder of: Pfizer, Employee of: Pfizer, A. Koenig Shareholder of: Pfizer, Employee of: Pfizer, M. Stewart Shareholder of: Pfizer, Employee of: PfizerCitation: Annals of the Rheumatic Diseases, volume 70, supplement 3, year 2011, page 342Session: Spondylarthritis – treatment (Poster Presentations )