### INTRODUCTION

### DIAGNOSTIC TEST ACCURACY

^{*}index is another useful global estimate of test accuracy for comparing sROC curves and is defined at the point where sensitivity equals specificity on an sROC curve. A Q

^{*}value of 1.0 indicates 100% accuracy (i.e., sensitivity and specificity of 100%) [8].

### METHOD OF META-ANALYSIS OF DIAGNOSTIC TEST ACCURACY

### 1. Describing the results of individual studies

### 2. Searching for heterogeneity

*I*

^{2}value, which quantifies the effect of heterogeneity and does not depend on the number of studies or the type of outcome data.

*I*

^{2}values range from 0-100% and represent the proportion of inter-study variability that can be attributed to heterogeneity rather than chance (

*I*

^{2}=100%×(Q-df)/Q) [13].

*I*

^{2}values of 25%, 50%, and 75% are interpreted as low, moderate, and high estimates, respectively.

### 3. Testing for the threshold effect

### 4. Deciding on the model for statistical pooling

### 5. Dealing with heterogeneity

### 6. Interpreting meta-analysis results of diagnostic tests

### AN EXAMPLE OF A META-ANALYSIS OF DIAGNOSTIC TESTS

*I*

^{2}from 0-100%, which represents the proportion of inter-study variability attributable to heterogeneity rather than to chance [12]. We used a random effects model to combine the sensitivity, specificity, PLR, NLR, and DOR estimates due to heterogeneity, and analyzed the sROC curves. The Q

^{*}index is another useful global estimate of test accuracy for comparing sROC curves. Statistical manipulations for this meta-analysis were performed with Meta-DiSc, version 1.4 (Hospital Universitario Ramon y Cajal, Madrid, Spain) [17]. Inter-study heterogeneity observed in a meta-analysis indicates variability in results across studies. A threshold effect is the most important cause of heterogeneity. Different sensitivities and specificities due to various study conditions cause different threshold effects. We checked Spearman's correlation coefficient between the logit of sensitivity and the logit of 1-specificity to assess the presence of a threshold effect. To examine the potential sources of heterogeneity observed in the meta-analysis, meta-regression was performed with the following covariates: 1) study quality, 2) sample size, 3) study design, and 4) diagnostic criteria.

^{*}index was 0.833, indicating a high diagnostic accuracy. A Spearman's rank correlation test showed no evidence of a threshold effect (Spearman's correlation coefficient=0.2674; P=0.488). Meta-regression showed that study quality, sample size, study design, and diagnostic criteria were not significant sources of heterogeneity in the meta-analysis. The meta-analysis of diagnostic tests demonstrates that MSGB has a high diagnostic accuracy and plays an important role in the diagnosis of pSS [18].