Table 3.

Quality assessment^a of studies.

Study	Selection				Outcome			Other	Composite score
	Representative		Ascertainment of exposure	Outcome not present at start	Assessment of outcome		Follow-up
	>60% relapse	>60% MAT			Validated tool	Central review
Ashraf 2013 [16]	✓	✓	✓	✓	✓		✓	Retrospective single centre	6
Bagatell 2011 [17]	✓	NR	✓	✓	✓	✓	✓	Alternative definition of high risk	6
Di Giannatale 2014 [18]	✓	✓	✓	✓	✓	✓	✓		7
Garaventa 2003 [19]			✓	✓	✓	✓	✓		5
Kushner 2010 [20]	✓	✓	✓	✓	✓		✓	Retrospective single centre	6
Rubie 2006 [21]	✓	✓	✓	✓	✓	✓	✓		7
Simon 2007 [22]	✓		✓	✓	✓		✓	Alternative definition of high risk; Variation in treatment delivered	5
Simon 2007 [23]			✓	✓	✓		✓	Alternative definition of high risk	4
Mody 2017 [24]			✓	✓	✓	✓	✓	Randomised trial	5+

MAT, myeloablative therapy with autologous stem cell rescue.

✓ denotes study meets the criteria, NR, not reported.

Alternative definition of high risk refers to [1]: The US groups including children over 18 months with localised unresectable tumours & unfavourable histology group as high risk, whereas in the UK/rest of Europe, these groups are classed as intermediate risk [2]; The German studies include localised resectable tumours with MYCN amplification as high risk when others do not and exclude the 12–18 months with metastatic disease but no MYCN amplification from their high-risk group.

^aQuality assessed using modified Newcastle Ottawa Scale [13].