PT  - JOURNAL ARTICLE
AU  - A Wanders
AU  - R Landewé
AU  - A Spoorenberg
AU  - K de Vlam
AU  - H Mielants
AU  - M Dougados
AU  - S van der Linden
AU  - D van der Heijde
TI  - Scoring of radiographic progression in randomised clinical trials in ankylosing spondylitis: a preference for paired reading order
AID  - 10.1136/ard.2004.022038
DP  - 2004 Dec 01
TA  - Annals of the Rheumatic Diseases
PG  - 1601--1604
VI  - 63
IP  - 12
4099  - http://ard.bmj.com/content/63/12/1601.short
4100  - http://ard.bmj.com/content/63/12/1601.full
SO  - Ann Rheum Dis2004 Dec 01; 63
AB  - Objectives: To describe the influence of the reading order (chronological v paired) on radiographic scoring results in ankylosing spondylitis. To investigate whether this method is sufficiently sensitive to change because paired reading is requested for establishing drug efficacy in clinical trials. Methods: Films obtained from 166 patients (at baseline, 1 year, and 2 years) were scored by one observer, using the modified Stoke Ankylosing Spondylitis Spinal Score. Films were first scored chronologically, and were scored paired 6 months later. Results: Chronological reading showed significantly more progression than paired reading both at 1 year (mean (SD) progression 1.3 (2.6) v 0.5 (2.4) units) and at 2 years (2.1 (3.9) v 1.0 (2.9) units); between-method difference: p<0.001 at 1 year, and p<0.001 at 2 years. After 1 year, progression (>0 units) was found in 35/166 (21%) patients after paired reading and in 55/166 (33%) after chronological reading. After 2 years, these figures were 50/166 (30%) and 68/166 (41%), respectively. Sample size calculations showed that 94 patients in each treatment arm are required in a randomised clinical trial (RCT) to provide sufficient statistical power to detect a difference in 2 year progression if films are scored paired. Conclusion: Reading with chronological time order is more sensitive to change than reading with paired time order, but paired reading is sufficiently sensitive to pick up change with a follow up of 2 years, resulting in an acceptable sample size for RCTs.