Table 2. Subgroup analyses results for association between serum levels of platelet to lymphocyte ratio and acute appendicitis.

Variable	SMD	95%CI	Degree heterogeneity (I2 statistics; %)	P value	No. of included Studies	P for interaction
Total	1.19	0.75 to 1.62	95.2	<0.001	11	NA
Sample size						0.149
<500	1.15	0.22 to 2.08	96.4	0.015	6
≥500	1.21	0.76 to 1.67	94.0	<0.001	5
Study region						<0.001
Europe	1.12	0.66 to 1.57	95.2	<0.001	10
Asia	1.90	1.54 to 2.25	-	0.003	1
Age (Mean/median)						0.001
Adult <30 years	0.58	0.12 to 1.04	61.7	0.472	3
Adult ≥30 years	1.46	0.89 to 2.02	96.8	0.004	7
Children	1.03	0.51 to 1.56	-	-	1
Appendicitis type						<0.001
Perforated AA	2.28	-1.72 to 6.28	98.9	0.263	2
Non-perforated AA	1.23	0.88 to 1.59	75.6	<0.001	2
AA during pregnancy	0.70	0.36 to 1.04	77.1	0.037	2
Study quality						<0.001
NOS score≥7	0.95	0.57 to 1.32	90.3	<0.001	8
NOS score <7	1.84	0.56 to 3.11	98.0	0.005	3
Control subject						<0.001
Healthy subjects	0.77	0.46 to 1.07	77.1	<0.001	3
Negative appendectomy	1.40	1.05 to 1.74	85.2	<0.001	4
Healthy pregnant women	0.66	-0.06 to 1.37	33.3	0.074	2
Non-AA outpatients or ED patients	1.90	-0.91 to 4.71	99.4	0.185	2

Abbreviations: AA, acute appendicitis; CI, confidence interval; ED, emergency department; NA, not available; SMD, standardized mean difference.