Annular closure device for disc herniation: meta-analysis of clinical outcome and complications

Table 2 Quality Assessment of the Included Studies

	Bailey et al.	Klassen et al.	Parker et al.	Vukas et al.
Clear definition of study population	Yes	Yes	Yes	Yes
Clear description of outcomes and outcome assessments	Yes	Yes	Yes	Yes
Independent assessment of outcome parameters	No^a	No^a	No^a	No^a
Sufficient follow-up duration	Yes	No^b	Yes	Yes
No selective loss of follow-up	No^c	No^c	Yes	Yes
Identification of confounders and prognostic factors	Yes	Yes	No^d	No^d

^a, lack of blinding; ^b, 90 days ^c, patients fail to attend follow-up; ^d, limitations poorly reported

ISSN: 1471-2474