Absenteeism, presented as the mean percentage of work time missed due to PsA (as reported on the WPAI), and calculated as: 100*number of hours of work missed due to PsA / (number of hours of work missed due to PsA + number of hours worked). WPAI is a questionnaire used to evaluate lost productivity; scores are presented as percentages (multiplying the scores by 100), with 0% representing no impact on productivity and 100% representing complete impact on productivity.

Participants with an assessment at given time point.

Presenteeism (the extent to which PsA decreased productivity) is presented as the mean percentage of impairment while working due to PsA, and calculated as: 100*scale value of question 5 on the WPAI (between 0 and 10) / 10. WPAI is a questionnaire used to evaluate lost productivity; scores are presented as percentages (multiplying the scores by 100), with 0% representing no impact on productivity and 100% representing complete impact on productivity.

Participants with an assessment at given time point.

The mean percentage of OWPI due to PsA (based on the WPAI questionnaire) is presented, calculated as: Absenteeism (%) +[1- Absenteeism(%)*Presenteeism(%)]. WPAI is a questionnaire used to evaluate lost productivity; scores are presented as percentages (multiplying the scores by 100), with 0% representing no impact on productivity and 100% representing complete impact on productivity.

Participants with an assessment at given time point.

Activity impairment due to PsA (the extent to which PsA affected the ability to perform usual daily activities) is presented as the mean percentage of activity impairment, calculated as 100*scale value of WPAI question 6 (between 0 and 10) / 10. WPAI is a questionnaire used to evaluate lost productivity; scores are presented as percentages (multiplying the scores by 100), with 0% representing no impact on productivity and 100% representing complete impact on productivity.

Participants with an assessment at given time point.

The HAQ-DI is a participant-reported questionnaire. It consists of 20 questions referring to 8 domains: dressing/grooming, arising, eating, walking, hygiene, reach, grip, and daily activities. Participants assessed their ability to do each task over the past week using the following response categories: without any difficulty (0); with some difficulty (1); with much difficulty (2); and unable to do (3). Scores on each task were summed and averaged to provide a total score ranging from 0 (no disability) to 3 (very severe, high-dependency disability).

Participants with an assessment at given time point.

A participant is an ACR20, ACR50, or ACR70 responder if the following 3 criteria for improvement from Baseline are met:

• ≥ 20%, ≥ 50%, or ≥ 70% improvement in tender joint count;

• ≥ 20%, ≥ 50%, or ≥ 70% improvement in swollen joint count; and

• ≥ 20%, ≥ 50%, or ≥ 70% improvement in at least 3 of the 5 following parameters:

  • Physician's global assessment of disease activity
  • Participant's global assessment of disease activity
  • Participant's assessment of pain
  • HAQ-DI
  • Acute phase reactant (erythrocyte sedimentation rate/C-reactive protein).

Participants with an assessment.

The DAS28 is a validated index of arthritis disease activity. Twenty-eight tender joint counts, 28 swollen joint counts, C-reactive protein, and general health are included in the DAS28 score. Scores on the DAS28 range from 0 to 10, with higher scores indicating higher disease activity. Participants were classified according to their scores as below:

• DAS28 > 5.1 = High disease activity
• DAS28 < 3.2 = Low disease activity
• DAS28 < 2.6 = Remission

All participants

For calculation of the enthesitis (tenderness) score, MASES was used in practice by the physicians. This scale takes into account the sites (first costochondral joint, seventh costochondral joint, posterior superior iliac spine, anterior superior iliac spine, iliac crest, fifth lumbar spinous process and proximal insertion of the Achilles tendon) and they scored from 0 to 13. Minimum tenderness score was 0; maximum tenderness score was 13.

Participants with an assessment at given time point.

A total of 20 digits were assessed as entire digits, looking for signs of tender dactylitis. Dactylitis is defined as a uniform swelling of the digits where the joints cannot be defined. Investigators entered scores between 0 (no swelling or pain) and 6 (most severe swelling and pain).

Participants with an assessment at given time point.

Twenty-eight joints were assessed and classified as swollen/not swollen by pressure and joint manipulation on physical examination. The presence of swelling is scored 1 and no swelling is 0; range of score is 0-28, with higher scores indicating more swollen joints.

Participants with an assessment at given time point.

Twenty-eight joints were assessed and classified as tender/not tender by pressure and joint manipulation on physical examination. The presence of tenderness is scored 1 and no tenderness is 0; range of score is 0-28, with higher scores indicating more tender joints.

Participants with an assessment at given time point.

Since sufficient data could not be collected, this analysis was not performed.

ESR values were measured as an inflammatory parameter. Low ESR values mean less inflammation.

Participants with an assessment at given time point.

CRP values were measured as an inflammatory parameter. Low CRP values mean less inflammation.

Participants with an assessment at given time point.

A VAS was used to measure the participant's assessment of disease activity. For this assessment a 10-point scale was used (0: very well; 10: very poor).

Participants with an assessment at given time point.

A VAS was used to measure the physician's assessment of disease activity. For this assessment a 10-point scale was used (0: very well; 10: very poor).

Participants with an assessment at given time point.

A VAS was used to measure the participant's assessment of nocturnal back pain and fatigue. For this assessment a 10-point scale was used (0: very well; 10: very poor).

Participants with an assessment at given time point.

A VAS was used to measure the participant's assessment of back pain. For this assessment a 10-point scale was used (0: very well; 10: very poor).

Participants with an assessment at given time point.

A VAS was used to measure the participant's assessment of pain and fatigue. For this assessment a 10-point scale was used (0: very well; 10: very poor).

Participants with an assessment at given time point.

Number of participants with any serious adverse event (SAE) occurring during treatment with anti-TNF agents and/or participants who discontinued treatment due to SAEs or AEs which were caused by the treatment with anti-TNF agents during the course of treatment. An SAE is defined as an event that: results in the death; is life-threatening; results in an admission to the hospital or prolongation of hospitalization; is a congenital anomaly; results in a condition that substantially interferes with the activities of daily living of a study subject; is an important medical event according to the Investigator.

All participants