Kendall association coefficients between Work Productivity Survey and clinical and health-related quality of life assessments at baseline (randomized set, observed cases). Selective results of Kendall association coefficients are presented. (A) Work Productivity Survey (WPS) Question (Q)2 (number of work days missed because of arthritis). (B) WPS Q4 (rate of arthritis interference with work productivity. (C) WPS Q5 (number of days with no household work because of arthritis). (D) WPS Q9 (rate of arthritis interference with household work productivity). WPS Q2 and Q4 were assessed in employed patients only, whereas Q5 and Q9 were assessed in all patients. Q4 and Q9 are scored on a scale of 0 to 10 points (0 = no interference and 10 = complete interference). Correlation level (absolute value): low correlation (<0.3); moderate correlation (≥0.3 to <0.5). Ankylosing Spondylitis Disease Activity Score (ASDAS), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Total/Nocturnal Spine Pain, Ankylosing Spondylitis Quality of Life Scale (ASQoL): lower score = better. Short Form 36 items (SF-36), EuroQoL 5 dimensions Visual Analogue Scale (EQ-5D VAS): higher score = better. WP: Work productivity.