OBJECTIVE: To discuss and improve the clinical diagnostic criteria of ankylosing spondylitis in order to improve the diagnosis rate and early diagnosis rate.
METHODS: From October 2005 to June 2009, 410 patients with unexplained lumbar and skeletal pain were selected and diagnosed by two diagnostic criteria, and the sensitivity and specificity of the revised diagnostic criteria were statistically analyzed. The sensitivity and specificity of the revised diagnostic criteria were 94.29% and 83.33%, respectively. 4-character test and sacroiliac joint percussion pain were more typical in early stage patients. Conclusion: The revised diagnostic criteria are simple and easy to use, have better sensitivity and specificity, and are more suitable for detecting patients with early-stage ankylosing spondylitis.
Ankylosing spondylitis is a chronic nonspecific connective tissue disease involving mainly the medial joints and bilateral sacroiliac joints, most commonly seen in young adults aged 10 to 40 years, and is one of the most difficult diseases in rehabilitation medicine [1-3]. There is no effective cure for AS, but early diagnosis and reasonable treatment can help to control symptoms and improve prognosis. Therefore, early diagnosis of AS and early intervention are necessary to improve the prognosis [6-7]. At present, the diagnosis of AS is mostly based on the New York criteria revised in 1984, which require the presence of a clear examination of sacroiliac arthritis on X-ray. However, patients who meet this criterion are mostly in the middle and late stages and have lost the good time for treatment, often leaving behind changes such as spinal ankylosis and joint deformity, and the disease is irreversible [8-9]. Therefore, the diagnostic criteria for AS are not satisfactory in terms of sensitivity or specificity, especially for early diagnosis [5]; in addition, the more insidious onset of AS makes the early diagnosis of AS more difficult. For this reason, based on the previous reports in the literature, we conducted clinical practice and research [l0] to grasp the pathological features of the sacroiliac joint, which involves 100% of the sacroiliac joints in the early stage of the disease, and performed a targeted physical examination of the sacroiliac joint, aiming to improve the clinical diagnostic criteria of AS and to study its sensitivity and specificity, in order to provide a basis for the diagnosis of AS.
1. Materials and methods
1.l Clinical data
From October 2005 to June 2009, 410 patients, including 264 males and 146 females, aged 12-45 years, with unexplained lumbar and skeletal pain from the Department of Orthopedics of Southern Hospital and the Department of Orthopedics of Dongguan Shigou Hospital were examined. The mean age of men was 21.5 (3.5) years and that of women was 24.5 (5.0) years; the mean time of onset was 10.09 (14.26) months for men and 721 (12.66) months for women. All samples were examined and registered according to the AS questionnaire, such as the “4” test, sacroiliac joint (sacrum) percussion pain test, morning stiffness and relief after activity, and the revised clinical diagnostic criteria were applied for sensitivity and specificity of the diagnosis. All patients underwent imaging examinations of the sacroiliac joint, and CT examinations were performed for those with sacroiliac joint changes of grade O on X-ray plain film and some of grade work. 1.2 Diagnostic criteria
1.2.1 New York criteria revised in 1984: ① low back pain and stiffness for more than 3 months with improvement in activity and no improvement at rest; ② restricted movement in the frontal and sagittal planes of the lumbar spine; ③ thoracic mobility lower than that of normal people of corresponding age and sex. Radiological criteria: bilateral sacroiliac arthritis at or above level 11 or unilateral sacroiliac arthritis at level 111 a W. The diagnosis of AS can be confirmed by meeting the radiological criteria and more than 1 clinical criteria [11].
1.2.2 Revised diagnostic criteria: ① unexplained low back pain/discomfort occurring before the age of 40; ② insidious onset; ③ duration of disease >l week; ④ morning stiffness, resting or nocturnal pain, relieved by activity; ⑤ positive “4” test and percussion pain in the sacroiliac joint and skeleton; ⑥ inflammatory changes on imaging of the sacroiliac joint. As was considered to be AS if 1 of the clinical criteria in ①-④ was met on the basis of ⑤; AS was diagnosed if 1 of the clinical criteria in ⑥ was met on the basis of ⑤.
1.3 Inclusion criteria
The patients complained of lumbar and skeletal pain or heel pain, morning stiffness, pain at night or resting pain. The pain was relieved after activity, the pain lasted for more than 1 week, and the bending activity was limited, accompanied by iritis, urethritis or diarrhea. 1.4 Exclusion criteria
Patients with clearly diagnosed rheumatoid arthritis, lumbar dorsal myofasciitis, lumbar spinal stenosis, lumbar disc herniation, degenerative changes of bone and joint, trauma, malignant tumor and psychological diseases were excluded, as well as patients who had been diagnosed with AS before the consultation.
2. Results
2.1 Clinical characteristics
Of the 410 patients, 330 were diagnosed with ankylosing spondylitis using the revised New York criteria, as shown in Table 1. 330 patients with AS had chronic onset in 318 cases and acute onset in 12 cases. Of the 330 patients with AS, 318 had chronic onset and 12 had acute onset. 31 had onset of <1 week, and all had sacroiliac joint changes of grade 11 or less; 86 had onset of >1 week and <3 months. There were 213 cases with onset time >3 months, and the most sacroiliac joint changes were grade I, 107 cases (32.42%). The number of sacroiliac joint changes was the highest in 107 cases (32.42%) and 179 cases (57.58%) in grades III and IV. (57.58%). Early stage patients (grade 0CII) were 107 (32.42%), and late stage patients were 179 (57.58%). 42%) and 223 cases (6.58%) in the late stage (grade III and II/grade). Morning stiffness or pain was relieved by activity in 313 patients (94.85%); resting or nocturnal pain in 268 patients (81.21%). 265 patients (80.30%) had positive 4-character test or sacroiliac joint percussion pain. The positive rate of pelvic orthopantomogram or sacroiliac joint CT examination was 100% in 330 patients with confirmed AS, while the imaging of sacroiliac joint was negative in all non-AS patients.
Table 1 Medical history and imaging classification of 330 patients with ankylosing spondylitis (cases)
Disease duration
Grading
0
I
II
II
IV
3 months
0
18
16
107
72
2.2 Sensitivity and specificity of the revised diagnostic criteria Among 410 patients, 330 were diagnosed with AS by applying the revised diagnostic criteria, with sensitivity (Sn) = screen (a + c), i.e., 330/(330 + 20) = 94.29%, and specificity (Sp) = d(b + d), i.e., 50/(10 + 50) = 83.33%, Table 2. Of the 107 early stage patients, all met clinical criteria in ⑤ and 1 of ①-④, of which ⑤ 86 (80.37%) were strongly positive. Among these early stage patients, 48 patients with sacroiliac joint X-ray changes were grade O and I, accounting for 44.86% of all early stage AS patients. After CT scan, there was no O-level change in any of them, and all of them were grade I and 11.
3, Discussion
AS is an inflammatory disease of the spinal joints of unknown etiology, mainly involving the sacroiliac and spinal joints. It is characterized by joint stiffness and loss of labor force, and its disability rate is high. However, if the lesion is detected early and certain treatment measures are taken in time, the deformity and disability can be prevented or delayed more effectively [l2 l3], and the key to reducing the disability rate is early detection, diagnosis and treatment.
Table 2 Relationship between the results of the revised AS diagnostic criteria and those of the revised New York criteria (cases)
Revised diagnostic criteria
Revised New York criteria 1984
Total
AS
Non-AS
AS positive
a (330)
b (10)
340
AS Negative
e (20)
d (50)
70
Total
350
60
410
AS has an insidious onset, long duration, and diverse onset, causing difficulties in diagnosis, and some patients are referred to various clinical departments and are easily misdiagnosed as other diseases, with a misdiagnosis rate of 65%-76% reported in the literature [l4]. In addition, over-reliance on imaging and overly strict criteria are among the most important causes of misdiagnosis. To date, common diagnostic criteria for AS, such as the New York criteria revised in 1984, emphasize radiological manifestations and one of three clinical indicators. The presence of sacroiliac arthritis on X-ray is required, such as bilateral sacroiliac arthritis > grade II or unilateral sacroiliac arthritis grade III-IV, and AS cannot be diagnosed on the basis of symptoms alone [ll]. Low back pain and morning stiffness for more than 3 months that improves with activity but not with rest; limited anterior-posterior and lateral movement of the low back; and decreased thoracic mobility. In fact, patients who meet these criteria are mostly in the middle to late stage of AS and have lost a good time for treatment, often leaving behind spinal ankylosis and joint deformity, and the condition is irreversible with further treatment. It has been reported in the literature that AS often takes 4-10 years from initial onset to definitive diagnosis [l5], and those with X-ray changes have been affected for many years and are in the middle to late stages [l5].
However, it ignores the early signs and symptoms of AS, especially the physical examination of the sacroiliac joint to detect sacroiliac arthritis. Early AS is mostly characterized by pain in the lumbar region, limited mobility, and 100% involvement, while the sacroiliac joint may not have abnormal changes on X-ray. In this study, we found that all patients with early AS met one of the clinical criteria in the revised criteria ⑤ and ① I ④, with a strong positive result in ⑤ of 80.37%. This provides important clues for the early diagnosis of AS and further imaging examinations. Among these early patients, 44.86% of the sacroiliac joint X-ray changes were grade O and I. None of the CT scans showed grade 0 changes, and all of them were grade I and II. If the diagnosis was made according to the revised New York criteria, none of these patients could be diagnosed as having AS, which could be considered “normal” and misdiagnosed and mistreated. The previous clinical screening criteria for AS: (1) low back discomfort occurring before age 40; (2) insidious onset; (3) persistence for more than 3 months; (4) morning stiffness; and (5) improvement with activity. The clinical diagnosis of AS is 95% sensitive and 85% specific if four or more of the above five criteria are met [l6]. In our group, 117 patients (35.46%) had a medical history of less than 3 months. Among them, 31 cases (9.39%) were <1 week. Among them, 31 (9.39%) were <1 week. Due to the insidious nature of the symptoms and signs, many patients are not aware of these atypical clinical manifestations and only seek medical attention when symptoms become apparent, which is one of the reasons for the short duration of the disease. Therefore, it is inappropriate to set the medical history of AS as >3 months in the diagnostic criteria. Most soft tissue strains or painful injuries have a duration of less than 1 week, while connective tissue diseases have a duration of more than 1 week, so the history of AS in this study was set at >1 week. Therefore, the early detection of sacroiliac arthritis, such as the 4-character test and sacroiliac joint percussion pain, can be faster and earlier than the thoracic mobility examination. Therefore, these sacroiliac joint examination methods are used instead of thoracic mobility examination.
In view of this, it is necessary to correctly understand and evaluate the scope of use and diagnostic methods of traditional diagnostic criteria for AS, including the New York criteria revised in 1984, the European criteria and other commonly used criteria. Therefore, there is a clinical need for a highly sensitive, simple, practical, and inexpensive screening method or diagnostic criteria to detect early AS patients. Through the study, it was found that the revised clinical screening criteria can make up for the above deficiencies, with easy operation, high sensitivity, and good help for the early diagnosis and screening of AS. For patients who meet the revised diagnostic criteria, especially those who meet one of the clinical criteria in ⑤ and ①-④ and have no obvious changes on x-ray, CT examination should be performed to clarify the diagnosis.