Inter-observer agreement of standard joint counts in early rheumatoid arthritis: a comparison with grey scale...

The aims of the present study were to assess the inter-observer agreement of standard joint count and to compare clinical examination with grey scale ultrasonography (US) findings in patients with early rheumatoid arthritis (RA).

The study was conducted on 44 RA patients with a disease duration of <2 yrs. Clinical evaluation was performed independently by two rheumatologists for detection of tenderness in 44 joints and swelling in 42 joints. All patients underwent US assessment by a rheumatologist experienced in this method and blinded to the clinical findings. Joint inflammation was detected by US when synovial fluid and/or synovial hypertrophy was identified using OMERACT preliminary definitions. The inter-observer reliability was calculated by overall agreement (percentage of observed exact agreement) and kappa (kappa)-statistics. The reliability of US was calculated in 12 RA patients.

There was fair to moderate inter-observer agreement on individual joint counts for either tenderness or joint swelling apart from the glenohumeral joint. US detected a higher number of inflamed joints than did clinical examination. The mean (+/-S.D.) US joint count for joint inflammation was 19.1 (+/-4.1), while the mean (+/-S.D.) number of swollen joints was 12.6 (+/-3.6), with a significant difference of P = 0.01.

Our results provide evidence in favour of the hypothesis that clinical examination is far from optimal for assessing joint inflammation in patients with early RA. Furthermore, this study suggests that US can considerably improve the detection of signs of joint inflammation both in terms of sensitivity and reliability.