TNFI halts progression in ankylosing spondylitis via reducing disease activity
Tumour necrosis factor inhibitors (TNFIs) may inhibit spinal radiographic progression in patients with ankylosing spondylitis (AS) through the inhibiting effect of the drugs on disease activity, a study suggests.
A total of 432 AS patients (mean age 40.3 years; 65.7 percent male) participating in the Swiss Clinical Quality Management cohort were examined. Mean symptom duration was 13.8 years. Patients were followed up for up to 10 years and underwent radiographic assessments every 2 years, yielding data for 616 radiographic intervals.
Two readers scored radiographs according to the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) with known chronology. An increase in ≥2 mSASSS units in 2 years was defined as radiographic progression.
Results revealed a mean mSASSS increase of 0.9 units in 2 years. Prior use of TNFI halved the odds of progression (odds ratio [OR], 0.50; 95 percent CI, 0.28 to 0.88), as shown in binomial generalized estimating equation models with adjustment for potential confounding and multiple imputation of missing values.
TNFI appeared to have no direct effect on radiographic progression (OR, 0.61; 0.34 to 1.08; p=0.09). The reduced progression seen with prior TNFI use was rather mediated by an improvement in Ankylosing Spondylitis Disease Activity Score (OR, 0.75; 0.59 to 0.97; p=0.01).
“We present important clues concerning the period of time needed before the inhibitory effects can be objectified: around 2 years of continuous TNFI use, as there was no impact of TNFI treatment during a 2-year radiographic interval, while there was an effect if the treatment was started before this interval,” researchers said.
Researchers also pointed out that inflammation needs to be suppressed for at least 2 years in order to demonstrate an inhibition of radiographic progression, noting that three open-label extensions of randomized control trials have previously failed to demonstrate an inhibition of radiographic progression in AS patients treated with TNFI over 2 years during this period. [Arthritis Rheum 2008;58:3063–70; Arthritis Rheum 2008;58:1324–31; Arthritis Res Ther 2009;11:R127]