Table 1.

The pooled data of included studies (PTED/MED).

Study (year)	Study type	Study quality	Patients	Average age (years old)	Follow-up time	Surgical level
Abudurexiti T (2018) [13]	Prospective cohort study	NOS 8 stars	82/134	38.2±9.2/ 36.3±8.6	6 months to 2 years	L2–S1 (mostly L4/L5, L5/S1)
Chen Z (2018) [14]	RCT	CONSORT 20/22 items	80/73	40.2±11.4/ 40.7±11.1	1 year	L3–S1 (mostly L4/L5, L5/S1)
Liu T (2012) [15]	Retrospective cohort study	NOS 6 stars	25/13	41.5 (21–67)	13.5 months	L2–S1 (mostly L4/L5, L5/S1)
Li H (2018) [16]	Case-control study	NOS 8 stars	48/30	19.0±2.0/ 19.4±1.5	5 years	L3–S1 (mostly L4/L5, L5/S1)
Liu X (2017) [17]	Retrospective cohort study	NOS 7 stars	60/63	36.2±5.9/ 33.1±6.7	2 years	L3–L5 (mostly L4/L5)
Song H (2017) [18]	Case-control study	NOS 8 stars	30/30	54.8±6.5/ 53.6±6.4	18 months	T12–S1
Sinkemani A (2015) [19]	Case-control study	NOS 7 stars	36/50	44.2±6.5/ 41.5±7.2	1 year	L3–S1 (mostly L4/L5, L5/S1)
Yoon S (2012) [20]	Retrospective cohort study	NOS 6 stars	25/26	45.9 (13–70)/ 56.5 (32–79)	6 months at least	L1–S1 (mostly L4/L5, L5/S1)

RCT – randomized controlled trial; NOS – Newcastle-Ottawa Scale; CONSORT – Consolidated Standards of Reporting Trials.