Table 1

Baseline characteristics and serious adverse events during follow-up

Baseline characteristicsJIA (n=68)HC (n=55)
Mean (SD) age (years)*14.1 (±1.6)14.3 (±1.2)
Compliance with vaccination†
Received only one dose0 (0%)0 (0%)
Received only two doses1 (1%)1 (2%)
Received three doses66 (97%)50 (91%)
Third vaccine uncertain due to dropout1 (1%)4 (7%)
Study visit completion
Attended 3 months visit64 (94%)46 (84%)
Attended 7 months visit63 (93%)47 (85%)
Attended 12 months visit63 (93%)46 (84%)
Dropouts in total vaccinated cohort2 (3%)6 (11%)
(Serious) adverse events0 (0%)0 (0%)
Lost to follow-up0 (0%)2 (4%)
Withdrawn for personal reason2 (3%)3 (5%)
Venous punctures too demanding0 (0%)1 (2%)
Seropositivity at baseline
HPV162 (3%)0 (0%)
HPV181 (1%)1 (2%)
JIA subtype
Oligoarticular JIA, persistent‡23 (34%)
Oligoarticular JIA, extended‡13 (19%)
Polyarticular JIA, RF positive7 (10%)
Polyarticular JIA, RF negative12 (18%)ND
Systemic onset JIA6 (9%)
Enthesitis related JIA1 (2%)
Psoriatic arthritis2 (3%)
JIA not specified4 (6%)
Disease characteristics
ANA positive39/65
RF positive12/58
HLA-B27 positive4/25ND
Median (IQR) age at onset (years)9.4 (3.6–12.1)
Median (IQR) duration of JIA (years)4.6 (1.7–10.4)
Median (IQR) disease activity
JADAS-273.1 (1.2–6.8)
Joints with active arthritis0 (0–1)
Patient well-being assessment, 10 cm VAS§1.9 (0.3–4.6)ND
PGA of disease activity, 10 cm VAS§0.9 (0–1.5)
ESR, mm/h8 (5–12)
Medication use
MTX24 (36%)
Mean (SD) dose (mg/m2/week)10.2 (±3.1)
NSAIDS37 (54%)
Other DMARDS¶6 (9%)ND
Anti-TNFα treatment9 (13%)
Median (IQR) dose (mg/week)45 (25–50)
Anti-IL1 treatment1 (1%)
Oral steroids0 (0%)
Participants reporting SAE11 (16%)1 (2%)
Number of SAEs reported141
Surgery2 Preplanned surgeries
Perforated eardrum
Correction of cerebral AVM
1 Preplanned surgery
Hospital admission3× diagnostic endoscopy**
Analysis of gait abnormalities**
Transient lower back pain
Preplanned lasertherapy uveitis
Allergic reaction anti-TNFα
Epileptic insult: cerebral AVM
Severe pharyngitis
  • Unless otherwise indicated, frequencies (percentage) are depicted.

  • *p=0.36 (Student t test).

  • †The second HPV vaccination was postponed in three patients and the third HPV vaccination in four JIA patients.

  • ‡52% (12/23) of the patients with persistent oligoarticular JIA and 85% (11/13) of the patients with extended oligoarticular JIA were ANA positive.

  • §Well-being and disease activity were both measured on a 10 cm VAS in which 0 represented ‘very well’ overall well-being or no disease activity, and 10 represented ‘very poor’ overall well-being or maximum disease activity.

  • ¶Five patients used leflunomide (10–20 mg) and one oligoarticular JIA patient used mycophenolate mofetil for the treatment of severe uveitis.

  • **3 Patients underwent an endoscopy at which inflammatory bowel disease was diagnosed. In all 3 patients, abdominal pain, diarrhoea with the passage of mucus, periods of constipation and intermittent rectal bleeding were already present prior to the first HPV vaccine dose. Gait abnormalities in one patient had a psychosomatic cause.

  • ANA, antinuclear antibody; AVM, arteriovenous malformation; DMARDS, disease modifying antirheumatic drugs; ESR, erythrocyte sedimentation rate; HC, healthy control; HLA, human leucocyte antigen; HPV, human papillomavirus; IL, interleukin; JADAS-27, Juvenile Arthritis Disease Activity Score involving 27 joints; JIA, juvenile idiopathic arthritis; MTX, methotrexate; ND, not determined; NSAIDS, non-steroidal anti-inflammatory drugs; PGA, Physician Global Assessment of disease activity; RF, rheumatoid factor; SAE, serious adverse event; TNF, tumour necrosis factor; VAS, visual analogue scale.