Diagnostic Evaluation and Management of Sacroiliitis

Introduction to Sacroiliitis

Sacroiliitis is a condition that may be associated with inflammatory bowel disease, occurring in 20-50% of patients with ulcerative colitis and Crohn's disease, and screening for extra-intestinal manifestations is recommended 1
Early diagnosis and treatment of sacroiliitis are crucial to prevent progression to ankylosing spondylitis, which occurs in only 1-10% of patients with sacroiliitis 1

Patients with inflammatory back pain lasting more than 3 months, particularly those under 40 years, should be evaluated for sacroiliitis, considering characteristics such as morning stiffness >30 minutes, pain at night/early morning, and improvement with exercise 1, 2
The American College of Radiology recommends radiographs of sacroiliac joints as the first-line imaging modality for evaluation of suspected sacroiliitis, including anteroposterior view of pelvis to evaluate sacroiliac joints and hips 3
Complementary radiographs of the spine are also recommended for evaluation of suspected sacroiliitis 4
MRI of sacroiliac joints should be considered when radiographs are negative but clinical suspicion remains high, or in patients with short duration of symptoms, using T1-weighted spin-echo, STIR, and fat-saturated T2-weighted sequences 3, 1
The American College of Rheumatology suggests considering HLA-B27 testing, which has 90% sensitivity and 90% specificity, in patients with suspected sacroiliitis 2

The American College of Rheumatology recommends starting treatment with NSAIDs for 2-4 weeks, with a trial of at least two different NSAIDs at maximal doses for at least 2-4 weeks each, before considering other options 5, 6, 7
NSAID failure should be considered after 1 month of continuous use, with at least two different NSAIDs for 15 days each, and treatment response should be assessed after 2-4 weeks of NSAID therapy, using standardized measures like ASDAS to monitor disease activity 5, 6, 7
Helps identify and reduce mechanical factors contributing to microtrauma and repetitive stress in patients with sacroiliitis, and should be initiated concurrently with pharmacological treatment, as recommended by the American College of Rheumatology 6, 8

The American College of Rheumatology strongly recommends TNF inhibitors as the next step after NSAID failure, with options including Etanercept, Adalimumab, Infliximab, and Golimumab, based on high-quality evidence 8, 6, 7, 9
No particular TNFi is recommended over others for typical sacroiliitis cases, with a conditional recommendation based on moderate-quality evidence from the American College of Rheumatology 7, 9
Selection considerations for TNFi include concomitant inflammatory bowel disease, recurrent uveitis, and higher risk of tuberculosis or recurrent infections, with a conditional recommendation based on low-quality evidence from the American College of Rheumatology 7
If TNF inhibitors fail or are contraindicated, IL-17 inhibitors (secukinumab or ixekizumab) are strongly recommended as alternatives, with a strong recommendation based on high-quality evidence from the American College of Rheumatology 5, 7, 9

Sulfasalazine is conditionally recommended only for patients who have contraindications to TNFi, have failed more than one TNFi, or have predominant peripheral arthritis, with a conditional recommendation based on moderate-quality evidence from the American College of Rheumatology 6, 7
JAK inhibitors are strongly recommended when biologics are contraindicated or unavailable 5
Biosimilars are strongly recommended as therapeutic options when biologics are indicated, and cost considerations should be weighed when choosing between equally effective treatments, with a recommendation to consider the cost-effectiveness of different treatment options 5, 10

Intra-articular injections may be conditionally recommended for isolated active sacroiliitis that fails to respond to NSAIDs, and may provide relief for up to 9 months, with the most appropriate candidates being those with pain present for more than one month and intensity greater than 4/10, and should be image-guided (preferably fluoroscopic) 11, 12
Repeat injection may be appropriate if there is ≥75% relief from diagnostic injection or ≥50% relief for at least 2 months after first injection 12
Radiofrequency ablation, specifically cooled radiofrequency ablation, may be considered after positive response to SI joint injection, targeting the SI joint, not the cluneal nerves, and may provide longer-lasting relief for patients who fail conservative management and injections 13, 10
SI joint fusion should be reserved for patients with positive response to SI injection with >75% relief, failure of all nonsurgical treatments, and continued or recurrent SIJ pain, with percutaneous SI arthrodesis preferred over open arthrodesis due to improved safety profile 11, 10

Treatment response should be assessed after 2-4 weeks of NSAID therapy and 6-12 weeks of TNFi therapy, using standardized measures like ASDAS to monitor disease activity, with a strong recommendation for the use of standardized measures to assess disease activity, as supported by the American College of Rheumatology 10, 7, 14, 6, 5
Patients should be screened for tuberculosis, hepatitis B, and other infections before initiating TNFi therapy, with a strong recommendation based on high-quality evidence from the American College of Rheumatology 7
Disease monitoring should include patient-reported outcomes, clinical findings, laboratory tests (including CRP), and imaging when appropriate 10, 7, 14
Regular monitoring of treatment response and adjustment of therapy as needed is recommended, with a strong recommendation for the use of standardized measures to assess disease activity, as supported by the American College of Rheumatology 7, 10

Patient education about the condition and self-management strategies is recommended, as supported by the European League Against Rheumatism and the American College of Rheumatology 14, 5, 7, 6
Paracetamol (acetaminophen) and opioid-like drugs might be considered for residual pain after previously recommended treatments have failed, according to the European League Against Rheumatism 15