Table 2.

Overview of included studies.

					Participants (n)		Gender (M/W)		Age (mean ± standard)
Author	Country	Years	Type of study	Recruitment period	D	D+F	D	D+F	D	D+F
Herkowitz et al	USA	1991	RCT	NA	25	25	1.50	0.25	65.0	63.5
Bridwell et al	USA	1993	RCT	1985.2–1990.3	9	34	0.28	0.31	72.3	64.6
Aihara et al	Japan	2012	RCT	2005.5–2008.8	33	17	1.36	0.55	63.0 ± 10.2	65.0 ± 9.2
Kleinstueck et al	Sweden	2012	RCT	2004.3–2008.5	56	157	0.70	0.29	73.0 ± 8.0	67.4 ± 9.4
Ghogawa et al	USA	2016	RCT	2002.3–2009.8	35	31	0.30	0.19	66.5 ± 8.0	66.7 ± 7.2
Forsth et al	Sweden	2016	RCT	2006.10–2012.6	117	111	0.41	0.61	67.0 ± 7.0	68.0 ± 7.0

D+F = decompression combined fusion, D = decompression, M/W = man/woman, NA = not available, RCT = randomized controlled trial.