Doppler-ultralydsmåling af sygdomsaktivitet ved leddegigt
Introduction af Karen Ellegaard
Rheumatoid arthritis (RA) is a chronic autoimmune disease with a pathogenesis intimately associated with the synovial membrane. RA is characterized by pain on movement and most patients develop weakness and wasting of muscles. Also, RA often leads to irreversible cartilage and bone destruction, resulting in varying degrees of impairment of physical ability (1;2). No pathognomonic feature exists for the diagnosis of RA, which is therefore based on a set of classification criteria (3). No single measurement of disease activity exists thus the evaluation of disease activity is made by assessment of a combination of various measurements.
The use of ultrasound (US) imaging in the rheumatologic area has increased considerably within the last years and is becoming an integral part of the management of patients with RA in many rheumatologic settings (4). In an US examination, morphological changes are assessed by grey-scale US, and blood flow is investigated by US Doppler (4).
Despite increasing use of US Doppler in the assessment of synovial perfusion in RA, evidence of the validity of the measurement is sparse. Thus, the validity of Doppler US has to be further explored in order to optimise its use as a diagnostic tool for detection of inflammation and assessment of the degree of inflammation in RA (5).
Sufficient treatment in the initial stages of RA is crucial for the course of the disease and may prevent joint destruction (6-9). The early treatment of RA in combination with the introduction of new effective – and expensive - medications has increased the requirement for valid measurements for both diagnosis and monitoring of treatment in patients with RA. The use of Doppler US for these purposes has been demonstrated in several studies (6;10-15). Furthermore, recent studies have shown that patients in clinical remission may still display disease activity when assessed with Doppler US (16-18). In addition, one study showed that patients displaying subclinical Doppler activity were more likely to develop bone erosions (18) suggesting a superiority of US Doppler measurements to clinical assessment in the assessment of ongoing inflammation in patients with RA.
Thus, Doppler US is a promising measurement in the rheumatological area. However, before the full benefit of Doppler US measurements may be achieved, the validity has to be fully clarified.
The hypotheses of the thesis are
- US Doppler is a valid measurement of disease activity in RA
- US Doppler is applicable in assessment of disease activity in RA
The aim of this Ph.D. project was to investigate the accuracy of US Doppler as a measurement of inflammation/disease activity in patients with RA.
The accuracy was pursued by investigation of the:
- reliability of the US Doppler
- validity of the US Doppler
- learning experience of US Doppler examination