Objectives Patients with advanced ankylosing spondylitis (AS) experience disability because of reduced spinal mobility and pulmonary function impairment. This placebo-controlled study evaluated the effect of etanercept (ETN) in patients with advanced AS.

Methods A multicentre randomised double-blind placebo-controlled trial of 12 weeks' duration was performed. Patients had definite (modified New York criteria), active (Bath AS Disease Activity Index (BASDAI) ≥40), severe (radiological intervertebral bridges) AS refractory to non-steroidal anti-inflammatory drugs and were antitumour necrosis factor naive. They were treated with ETN 50 mg once weekly or identical placebo (PBO).

Results Of the 95 patients screened, 82 were randomised to receive ETN (n=39) or PBO (n=43). At baseline the disease was active (mean BASDAI 61.0±13.4, C reactive protein (CRP) 20.7±25.5 mg/l) and severe (mean Bath AS Metrology Index (BASMI) 5.7±1.3, mSASSS 36.5±20.5); forced pulmonary vital capacity (FVC) was 3.3±0.7 l. Improvement in BASDAI (normalised net incremental area under the curve between baseline and week 12, primary end point) was significantly greater in the ETN group than in the PBO group (−19.8±16.5 vs −11.0±16.4, p=0.019). Moreover, at week 12, ETN gave better results than PBO for the BASDAI (−26.4±19.7 vs −14.4±19.7; p=0.008), total back pain (−29.2±24.0 vs −14.9±24.0; p=0.010), BASFI (−21.7±17.6 vs −10.1±17.6; p=0.004), BASMI (−0.6±0.6 vs −0.2±0.6; p=0.011), CRP level (−15.7±14.2 vs −1.3±14.2; p<0.001) and FVC (+160±280 ml vs −20±280 ml; p=0.006).

Conclusions ETN has short-term efficacy for patients with advanced AS, as was previously reported for less advanced disease. The efficacy is observed for the main symptoms (pain) and on markers of inflammation (CRP), as well as disease severity in terms of spinal mobility and pulmonary function.