ASSESSMENT OF EXTENDED MYOSITIS BLOOD SCREEN IN A TEACHING HOSPITALS NHS TRUST.
Published Date: 28th April 2025
Publication Authors: Scott. A, Dawson. J
Abstract:
Background/Aims:
To evaluate the use of the extended myositis screen in primary and secondary care.
Methods:
We analysed the records of all patients with an extended myositis screen requested over a 5-year period between 1/5/2019 and 30/4/2024 within our hospital NHS trust. Data collected related to patient details, source of request, investigations, diagnosis and referral to rheumatology. If the myositis screen had not been requested upfront, it was reflexed by the laboratory when the cytoplasmic pattern was visible on ANA immunofluorescence.
Results:
This search returned 569 results. The number of requests increased each year, peaking at 18 per month in 2023. 409 (72%) requests were made in an outpatient clinic, 99 (17%) as an inpatient and 29 from GP surgeries. 257 (45%) were requested by the rheumatology department. 153 (27%) had one or more “positive” results. Due to tests being repeated, these 153 positives were for 119 unique patients. 75 (49%) were requested by a member of the rheumatology department. 23 patients were referred to rheumatology where 6 patients were given a new rheumatological diagnosis, of which 3 were myositis. Nine (6%) patients (5 male and 4 female) had a confirmed diagnosis of inflammatory myositis. 7 (78%) were new diagnoses. 7 (78%) of these patients’ screens were ordered by a rheumatologist. Five patients were diagnosed with dermatomyositis, 3 were diagnosed with antisynthetase syndrome, and 1 was diagnosed with inflammatory arthritis/myositis overlap. The most common antibodies in patients diagnosed with myositis were: Ro52 5 (56%), Jo-1 4 (45%), TIF (3 (33%), and PM/SCL-100 and NXP2, both positive in 1 (11%). Investigations for malignancy included CT, biopsy and endoscopy, 1 patient was diagnosed with a malignancy (metastatic urothelial cancer), symptoms of which they were already under investigation for at the time of the myositis diagnosis. The positive antibody in this case was NXP2. Five (56%) had an underlying interstitial lung disease, no patients received anti-fibrotic therapy. Three of these patients were already under the care of the respiratory team before their contact with rheumatology.
Conclusion:
The extended myositis screen has a significant external laboratory cost and is being increasingly requested. Positive results are driving up secondary care rheumatology referrals. However, in our setting we did not find any additional clinical benefit from the result of this investigation over a standard connective tissue disease screen. We recommend extended myositis screen is only accessible to rheumatologists, dermatologists and neurologists who specialise in myositis; and recommend reviewing local laboratory procedures for requesting myositis antibodies.
Dunnett-Kane V.; Scott A.; Dawson J. (2025). ASSESSMENT OF EXTENDED MYOSITIS BLOOD SCREEN IN A TEACHING HOSPITALS NHS TRUST. Rheumatology. 64(Supp 3), p.pp iii33. [Online]. Available at: https://dx.doi.org/10.1093/rheumatology/keaf142.059 [Accessed 12 September 2025].