Table 5

 Relationship between knee synovitis or joint effusion on US and predictive features in subjects with painful knee OA. Summary of multivariate analyses—odds ratio estimates (adjusted by country)

Predictive factorUS knee synovitisp Value*OR (95% CI)†
AbsentPresent
No (%)No (%)
Radiological K&L grades‡
    3–4260 (77.8)74 (22.2)<0.00012.20 (1.33 to 3.64)
    0–2240 (90.2)26 (9.8)
Joint effusion at clinical examination§
    Moderate-important153 (75.0)51 (25.0)<0.00011.97 (1.19;3.23)
    Absent-minimal347 (87.6)49 (12.4)
US joint effusion
*p Value of univariate analysis; †OR: odds ratio, 95% CI: 95% confidence interval, OR and 95% CI are adjusted though a logistic regression model analysing the probability of the presence of knee synovitis or joint effusion at US; ‡K&L, Kellgren and Lawrence radiological grade ⩾3, or <3 observed in both femorotibial compartments of the studied knee; §joint effusion: absent or minimal versus moderate or important; ¶sex: female versus male; **sudden aggravation of knee pain in the previous 2 weeks: absent, minimal or moderate versus severe or very severe.
Sex¶
    Female262 (60.4)172 (39.6)0.00160.62 (0.41 to 0.94)
    Male76 (46.1)89 (53.9)
Radiological K&L grades‡
    3–4162 (48.6)171 (51.4)<0.00011.91 (1.32 to 2.77)
    0–2176 (66.2)90 (33.8)
Joint effusion at clinical examination§
    Moderate-important93 (45.6)111 (54.4)0.00012.70 (1.76 to 4.16)
    Absent-minimal245 (62.0)150 (38.0)
Sudden aggravation of knee pain**
    Severe-very severe143 (52.0)132 (48.0)0.04411.77 (1.16 to 2.71)
    Absent-minimal-moderate195 (60.2)129 (39.8)