Quality statement 2: Diagnosis of axial spondyloarthritis using imaging

Quality statement

Adults with suspected axial spondyloarthritis and an X‑ray that does not show sacroiliitis have an MRI using an inflammatory back pain protocol.

Rationale

No single test can diagnose axial spondyloarthritis. Blood tests for HLA‑B27 may be negative in some people and not all people have raised inflammatory markers. X‑rays can support a diagnosis of radiographic axial spondylitis, but in some cases it can take several years for changes to be detectable, and sometimes changes may never show on X‑ray. When plain film X‑ray does not show sacroiliitis, MRI using an inflammatory back pain protocol that is interpreted by a specialist with knowledge of spondyloarthritis can support the diagnosis of non-radiographic axial spondyloarthritis and enable effective treatment to start.

Quality measures

Structure

a) Evidence of local arrangements to ensure that rheumatologists and musculoskeletal interface services can access X‑ray and MRI diagnostic services for people with suspected axial spondyloarthritis.

Data source: Local data collection, for example, from referral pathways or service specifications.

b) Evidence of local arrangements to ensure that a musculoskeletal radiologist interprets imaging for people with suspected axial spondyloarthritis when appropriate.

Data source: Local data collection, for example, from service specifications.

c) Evidence of an inflammatory back pain protocol outlining how to perform MRI on adults with suspected axial spondyloarthritis.

Data source: Local data collection, for example, from service protocols.

Process

a) Proportion of adults with suspected axial spondyloarthritis and an X‑ray that does not show sacroiliitis that have an MRl.

Numerator – the number in the denominator that have an MRI.

Denominator – the number of adults with suspected axial spondyloarthritis who have had an X‑ray that does not show sacroiliitis.

Data source: Local data collection, for example, local audit of patient records.

b) Proportion of MRIs for suspected axial spondyloarthritis in adults performed using an inflammatory back pain protocol.

Numerator – the number in the denominator performed using an inflammatory back pain protocol.

Denominator – the number of MRIs performed to investigate suspected axial spondyloarthritis in adults.

Data source: Local data collection, for example, local audit of patient records.

Outcomes

a) Time from first presentation of symptoms to diagnosis for adults with axial spondyloarthritis.

Data source: Local data collection, for example, local audit of patient records.

b) Health-related quality-of-life score of adults with axial spondyloarthritis.

Data source: Local data collection, for example, survey of adults with axial spondyloarthritis using a quality-of-life questionnaire.

c) Functional ability score of adults with axial spondyloarthritis.

Data source: Local data collection, for example, survey of adults with axial spondyloarthritis using a questionnaire to assess functional ability (such as the Bath Ankylosing Spondylitis Functional Index).

What the quality statement means for different audiences

Service providers (such as rheumatology and diagnostic imaging services) have protocols in place to ensure that X‑ray is used for first-line imaging in people with suspected axial spondyloarthritis. They perform MRI only when there is no evidence of sacroiliitis meeting modified New York criteria on X‑ray, or an X‑ray is not appropriate because the person's skeleton is not fully mature. They ensure that MRI for suspected axial spondyloarthritis is performed using an inflammatory back pain protocol.

Healthcare professionals (such as rheumatologists and healthcare professionals in musculoskeletal interface services) request X‑ray for first-line imaging in people with suspected axial spondyloarthritis unless a person is likely to have an immature skeleton. They request MRI using an inflammatory back pain protocol if there is no evidence of sacroiliitis meeting modified New York criteria on X‑ray. Rheumatologists and radiologists use the Assessment of Spondyloarthritis International Society/Outcome Measures in Rheumatology MRI criteria to interpret the MRI.

Commissioners (clinical commissioning groups) have service specifications that require MRI using an inflammatory back pain protocol for people with suspected axial spondyloarthritis when there is no evidence of sacroiliitis meeting modified New York criteria on X‑ray, or when an X‑ray is not appropriate because the person's skeleton is not fully mature.

Adults with symptoms that suggest axial spondyloarthritis are offered an MRI scan to check for inflammation if an X‑ray has not shown the condition, or if an X‑ray is not appropriate because the person has not finished growing.

Source guidance

Spondyloarthritis in over 16s: diagnosis and management (2017) NICE guideline NG65, recommendation 1.2.6

Definitions of terms used in this quality statement

Sacroiliitis

Inflammation of the sacroiliac joint at the base of the spine that meets the modified New York criteria (bilateral grade 2–4 or unilateral grade 3–4 sacroiliitis).

[NICE's guideline on spondyloarthritis, recommendation 1.2.6 and glossary in the full guideline]

Inflammatory back pain protocol

An MRI performed using short T1 inversion recovery (STIR) and T1 weighted sequences of the whole spine (sagittal view), and sacroiliac joints (coronal oblique view).

[NICE's guideline on spondyloarthritis, recommendation 1.2.7]

Equality and diversity considerations

There is a common misconception that axial spondyloarthritis mainly affects men. Healthcare professionals should be aware that axial spondyloarthritis affects a similar number of women as men. Women are less likely to show sacroiliitis on X‑ray than men, but they should still be offered X‑ray for first-line imaging of suspected axial spondyloarthritis. If a person does not have an X‑ray they cannot be diagnosed with radiographic axial spondyloarthritis and so are not eligible for any treatments that are only available for that indication.

Young people (around 16 to 18 years of age) with an immature skeleton are unlikely to show radiographic signs and therefore an X‑ray would be inappropriate at initial presentation. It is likely that people in this group would be offered further opportunities for assessment by X‑ray at a later stage in disease management.