Table 2. Meta-analysis of PLR levels in SLE patients compared to that in controls.

Groups	Population	No. of studies	Test of association				Test of heterogeneity
			SMD*	95% CI		p-value	Model	p-value	I 2
All	Overall	15	0.604	0.299–0.909	< 0.001		R	< 0.001	93.4
Ethnicity	Asian	6	0.520	0.359–0.681	< 0.001		R	0.082	48.7
	Arab	6	0.782	0.039–1.525	0.039		R	< 0.001	96.9
	European	3	0.505	0.344–1.353	0.244		R	< 0.001	94.2
Sample size	Small (< 200)	9	0.684	0.215–1.153	0.004		R	< 0.001	92.8
	Large (≥ 200)	6	0.492	0.053–0.932	0.028		R	< 0.001	95.0
SLE activity	Active vs. Inactive	5	0.553	0.000–1.106	0.050		R	< 0.001	87.9
LN	LN (+) vs. LN (-)	4	0.356	-0.145–0.858	0.164		R	< 0.001	84.8

PLR: Platelet to lymphocyte ratio, SLE: Systemic lupus erythematosus, LN: Lupus nephritis, CI: Confidence interval, F: Fixed effects model, R: Random effects model, NA: Not applicable.

*: Magnitude of Cohen’s d effect size (SMD): 0.2–0.5, small effect; 0.5–0.8, medium effect; ≥ 0.8, large effect.