According to findings from a recent 18-year retrospective study1 TNF inhibitor biologic medications help slow the progression of radiographic damage (damage in the spine visible on X-ray) in ankylosing spondylitis. TNF inhibitors have been widely used in patients with ankylosing spondylitis (AS) who do not respond sufficiently to non-steroidal anti-inflammatory drugs (NSAIDs). TNF inhibitors reduce inflammation by targeting an inflammation-causing substance called Tumor Necrosis Factor (TNF).
In this study medical records of 1,280 AS patients were reviewed, of whom 595 were prescribed a TNF inhibitor medication at least once. Of the 595, 338 people had gone off and then back on a TNF inhibitor at least once. A total of 2,364 intervals of going off and then back on a TNF inhibitor were calculated among the 338 patients.
Radiologists then used the Stoke Ankylosing Spondylitis Spinal Score (mSASSS) (a four-point scoring system measuring disease progression through scoring and tracking X-rays of the lower back and neck) to determine and compare the radiographic progression and change rate during times when patients were taking a TNF inhibitor, vs when they were off the TNF inhibitor.
The analysis revealed that the rate of progression of spinal damage while on TNF inhibitors was far less (average of 0.848) compared to when patients were off TNF inhibitors (average of 0.970 points).
Although, there were some limitations to this study2, the analysis did show that the rate of radiologic progression was lower when patients were being treated with these medications, compared with when they were not.
The authors concluded that, “The rate of radiographic progression was different between periods in which patients were exposed and not exposed to TNFi. Our study provided strong evidence that TNFi therapy slows the radiographic progression by overcoming the limitations of previous studies. Treatment using TNFis is among the modifiable factors for radiographic progression in patients with AS.”
 A retrospective study is an epidemiologic study that analyzes data collected before the study had begun, to determine if past events are related to the present distribution or severity of disease.
 Study limitations included:
– Not including smoking status, which is known to have a significant effect on radiographic progression in AS. (The authors note that there were too many missing values for smoking status in the data set.)
– Not including patients who had never taken a TNF inhibitor medication.
-The authors state that they, “imputed the mSASSS data with interpolation, because mSASSS tends to increase very slowly with radiological progression in the real world.”
Koo BS, Oh JS, Park SY, et al
Tumour necrosis factor inhibitors slow radiographic progression in patients with ankylosing spondylitis: 18-year real-world evidence
Annals of the Rheumatic Diseases 2020;79:1327-1332.