The prevalence of inflammatory back pain, sacroiliitis and spondyloarthropathy in patients who underwent lumbar disc herniation surgery

Objective: There is considerable delay in the diagnosis of ankylosing spondylitis (AS) because of the late appearance of radiographic sacroiliitis. A previous multi-center study conducted in our country showed that approximately 1/3 of the AS patients had been diagnosed as lumbar disc herniation (LDH), and 7% of these patients had undergone operation for that disorder. In this study we aimed to evaluate the frequency of inflammatory back pain (IBP), and the clinical findings related with AS and other spondyloarthropathies (SpA) in patients who had been surgically treated for LDH.Methods: We retrieved the records of the patients who underwent LDH surgery between 2008 and 2010 in the neurosurgery clinic of our university hospital. Eligible patients were then invited to the rheumatology clinic for further evaluation. All patients were examined according to a standard protocol. A face to face interview by using a standardized questionnaire addressing all the components of IBP including Calin and Berlin criteria sets was performed. The antero-posterior plain pelvic radiographs were planned for determination of sacroiliitis. The modified New York criteria (mNY) was used for the diagnosis of AS, and Amor and/or the European Spondyloarthropathy Study Group (ESSG) criteria were used for the diagnosis of other SpAs. A telephone interview was used for patients who did/could not come to the outpatient clinic by using a standardized form.Results: There were 789 patients who underwent LDH surgery. 468 patients (59%) could not be contacted despite at least 2 attempts. We contacted 321 patients (142 Men [44.2%], mean age 49±10.8 years) face to face interview and telephone interview were conducted with 123 and 198 patients, respectively. Both groups showed similar age, sex distribution, symptom duration and age at diagnosis. However, patients who came to hospital for face to face interview reported a significantly higher number of years of education (9±4.4 vs. 7±4.1, p<0.001) and a higher frequency of continuing pain after surgery (68% vs. 51.7, p<0.001). The mean age of onset-of low back pain was 34 ± 12.5 years. The mean age of LDH diagnosis was 41 ± 12.4 years. IBP was diagnosed in 108 (33.6%). and 51 (16.4%) patients according to the Calin and Berlin criteria sets respectively. Plain pelvic radiographs were performed in 308 patients and sacroiliitis was found to be present in 5 patients (1.2%). All patients with sacroiliitis fulfilled the mNY criteria for AS. In the face to face interview group, we planned the visualization of sacroiliac joints by magnetic resonance imaging (MRI) in 34 patients, but were able to perform in only 12 patients. Of those, four had active sacroiliitis in accordance with the Assessement of Spondyloarthritis International Society (ASAS) definitions for positive MRI. The overall prevalence of radiographic sacroiliitis (MRI sacroiliitis + X-ray sacroiliitis) in the face to face interview group was 6.5% ((4+4)/123). Based on the above findings, the overall prevalence of SpA was estimated as 17.7% (57 patients) and 8.7% (28 patients) according to the ESSG and Amor criteria, respectively.Discussion: The increased prevalence of AS and SpA among patients who underwent LDH surgery is of note. Patients satisfying the SpA criteria, who had persistent back pain after the surgery, require careful evaluation by the physicians dealing with low back pain.