Table 2

Secondary outcomes: improvements and differences between study groups

DoxycyclinePlaceboDifference
Outcome measurenMean (95% CI)nMean (95% CI)(95 % CI)
WOMAC pain
Baseline (SD)11652 (19)11546 (17)
Δ Week 12, baseline107−8 (−4 to −11)110−7 (−4 to −11)0 (−5 to 5)
Δ Week 24, baseline108−8 (−5 to −12)110−8 (−3 to −12)0 (−6 to 5)
WOMAC stiffness
Baseline (SD)11558 (22)11354 (19)
Δ Week 12, baseline106−7 (−3 to −11)110−9 (−5 to −13)2 (−4 to 7)
Δ Week 24, baseline108−5 (−1 to −8)107−7 (−3 to −12)3 (−3 to 8)
WOMAC function
Baseline (SD)11252 (18)11547 (17)
Δ Week 12, baseline104−7 (−4 to −10)109−7 (−3 to −10)−1 (−5 to 4)
Δ Week 24, baseline103−8 (−4 to −11)107−7 (−3 to −10)−1 (−6 to 4)
VAS–PGA
Baseline (SD)11252 (25)11553 (26)
Δ Week 12, baseline100−7 (−1 to −13)106−9 (−3 to −15)1 (−7 to 10)
Δ Week 24, baseline95−7 (−1 to −13)105−10 (−3 to −17)3 (−6 to 12)
PCS (possible range 4–71)*
Baseline (SD)11436 (8)11436 (7)
Δ Week 12, baseline1042 (0 to 3)1093 (1 to 4)−1 (−3 to 1)
Δ Week 24, baseline1052 (1 to 3)1082 (1 to 4)0 (−2 to 3)
MCS (possible range 2–74)*
Baseline (SD)11452 (11)11454 (11)
Δ Week 12, baseline1041 (−1 to 2)109−1 (−3 to 1)2 (0 to 4)
Δ Week 24, baseline1051 (−1 to 2)1080 (−1 to 2)0 (−2 to 3)
  • Negative signs indicate improvement within groups (unless stated otherwise) or improvement in favour of doxycycline (in case of differences in change between groups). Scores are normalised (0–100; 0 = no symptoms) unless stated otherwise.

  • * Norm-based scores, higher scores indicate better health, individual scores in the 45–55 range indicate average health.

  • Negative signs indicate deterioration within groups or improvement in favour of placebo (in case of differences in change between groups).

  • MCS, mental component score; PCS, physical component score, VAS–PGA, visual analogue scale–patient global assessment; WOMAC Western Ontario McMaster Universities.