Real life experience confirms sustained response to long-term biologics and switching in ankylosing spondylitis

To investigate the long-term response to biological therapies in AS in a real life clinical setting and to quantify non-response and response to 'switching' therapies in these cases.

All patients prescribed TNF-blocking therapies for AS between 1999 and 2006 were studied. Response was evaluated using Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI) and CRP results.

A total of 113 patients (84 males: 29 females, mean age 45 yrs, median disease duration 16 yrs, 87% HLA-B27 positive) were identified. At baseline they had a mean BASDAI of 6.57, BASFI 6.57 and CRP of 31 g/dl. At the end of follow-up, these values had reduced to mean BASDAI of 3.12, BASFI 4.16 and CRP of 7 g/dl. Improvements were sustained for 24 months and beyond with no loss of effect. Only nine patients (8%) suffered side-effects leading to cessation or switching of first-line therapy and non-response occurred in 15 patients (13%) in the long term. Fifteen patients (13%) switched to a second drug and 14 of these (93%) had a significant and sustained response. Outcomes were similar regardless of drug used, duration of disease and HLA-B27 status.

Treatment of active AS with TNF blockers according to the British Society of Rheumatology guidelines leads to a sustained response for over 2 yrs with most patients tolerating the drugs well. The rate of non-response is significantly lower than that seen in RA and nearly all of these patients respond well to a second-line agent.