Secondary amyloidosis in ankylosing spondylitis

We evaluated the frequency of secondary amyloidosis, associated clinical features, and outcomes in ankylosing spondylitis (AS) patients diagnosed in the last decade. The medical records of AS patients diagnosed at single academic medical center were reviewed for clinical evidence of amyloidosis. During routine follow-up, routine urinalysis was performed at each visit; patients with significant proteinuria underwent rectal biopsy. We diagnosed 8 clinically apparent amyloidosis patients (1.1 %) in our cohort of 730 AS patients (508 males, 222 females). Four patients undergoing hemodialysis were diagnosed secondary amyloidosis. Three patients had nephrotic syndrome and renal dysfunction and one patient had non-nephrotic proteinuria. When AS patients with amyloidosis were compared to AS controls, it was observed that the amyloidosis group was older, had longer disease duration, higher initial BASDAI scores, and ESR values, and more frequent peripheral arthritis (p < 0.05). Logistic regression analysis revealed that the initial BASDAI level was an independent predictor for the development of secondary amyloidosis (OR:2.36). Six patients were administered anti-TNF therapy. The clinical findings resolved in these. In 2 patients with nephrotic syndrome and renal dysfunction, in addition to clinical improvement, there was a decrement in proteinuria; renal function improved or remained stable. Anti-TNF therapy is safe and effective in patients with renal failure, and at an earlier stage, appears effective in improving renal function. The development of proteinuria in AS patients should occasion a search for underlying amyloidosis.