Reliability of immunomagnetic separation and enzyme-linked immunosorbent assay for detection of human leukocyte antigen-B27 in patients with ankylosing spondylitis,low back pain and other arthritis

Tianwang LI; Jieruo GU; Minjian LIANG; Qiujing WEI; Like ZHAO; Zetao LIAO; Yuqiong WU

ABSTRACT

BACKGROUND:

Human leukocyte antigen (HLA)-B27 is closely connected to the occurrence of some rheumatic diseases such as ankylosing spondylitis and can be used as an important factor for evaluating the diagnosis of ankylosing spondylitis. Immunomagnetic separation and enzymelinked immunosorbent assay (IMS-ELISA) has been applied to the detection of HLA-B27.

OBJECTIVE:

To explore the accuracy, sensitivity and specificity of IMSELISA for detecting HLA-B27 and its value in the auxiliary diagnosis of ankylosing spondylitis.

DESIGN:

A clinical trial in comparison with the gold standard.

SETTING:

Departments of Rheumatology and Clinical Laboratory, Third Affiliated Hospital of Sun Yat-sen University.

PARTICIPANTS:

Eighty-six patients suffering from low back pain and/or arthritis who were treated for the first time in Department of Rheumatology from December 2002 to April 2003. Inclusion criteria ① Presence of manifestations of low back pain and/or arthritis; ② Thorough documentation of clinical and other examinations; ③ Informed consent to HLA-B27 examination; ④ Treatment for the first time in the Third Affiliated Hospital of Sun Yet-sen University. Those with other serious diseases or with incomplete record of clinical and/or accessory examinations were excluded. The 86 patients included 56 male and 30 female patients aged from 12 to 65 years.

METHODS:

Blood sample was detected for HLA-B27 by both IMS-ELISA and microlymphocytotoxicity test, and the latter was selected as the gold standard. The coincidence rate of the results detected by the two methods as well as the sensitivity, specificity, positive and negative predictive values of IMS-ELISA were calculated.MAIN OUTCOME

MEASURES:

① The coincidence rate of the results of the two methods. ② The sensitivity and specificity of IMS-ELISA for detecting HLA-B27.

RESULTS:

None of the patients was lost. For the 33 patients with ankylosing spondylitis, the positivity rate of IMS-ELISA (90.9％) was higher than that of microlymphocytotoxicity test (87.9％), but the difference was not statistically significant (P＞0.05). The total coincidence rate of the two methods was 93.0％ in all the 86 patients. The sensitivity, specificity, positive and negative predictive values of IMS-ELISA were 90.0％, 95.7％,94.7％ and 91.7％ respectively.

CONCLUSION:

Both IMS-ELISA and microlymphocytotoxicity test are capable of reliable examination of HLA-B27 with high sensitivity and specificity.