2. Outcome matrix per trial group comparison.

Diagnosis	Pain	Function	HRQoL	Treatment success	Withdrawals	Adverse events	Serious adverse events
1. CFO versus shoes
asymptomatic flat feet	Whitford 2007 – post hoc subgroup (% pain)	Whitford 2007 – VO² max, motor skills	NR	NR	Wenger 1989; Whitford 2007	NR	NR
JIA	Powell 2005 – VAS	Powell 2005 – timed walk	Powell 2005 – FFI	Powell 2005	Powell 2005	Powell 2005 – none	NR
DCD	NR	Morrison 2013 – 6MWT	NR	Morrison 2013	Morrison 2013	NR	NR
2. PFO versus shoes
asymptomatic flat feet	Whitford 2007 post hoc subgroup (% pain) Asgaonkar 2012 – VAS	Whitford 2007 – VO² max, motor skills Asgaonkar 2012 – HR, gait	NR	Asgaonkar 2012; Gould 1989;	Asgaonkar 2012; Gould 1989; Wenger 1989; Whitford 2007	NR	NR
symptomatic flat feet	NR	Hsieh 2018	Hsieh 2018 – PODCI	Hsieh 2018	Hsieh 2018	NR	NR
JIA	Powell 2005 – VAS	Powell 2005 – timed walk	Powell 2005 – FFI	Powell 2005	Powell 2005	Powell 2005 – none	NR
3. CFO versus PFO
asymptomatic flat feet	Whitford 2007 – post hoc subgroup (% pain)	Whitford 2007 – VO² max, motor skills	NR	NR	Wenger 1989; Whitford 2007	NR	NR
JIA	Coda 2014; Powell 2005 – VAS	Powell 2005 – timed walk	Coda 2014; Powell 2005 – PedsQL	Coda 2014; Powell 2005;	Coda 2014; Powell 2005;	Coda 2014 – NR Powell 2005 – none	NR

6MWT: 6‐minute walk test; CFO: custom foot orthoses; DCD: developmental co‐ordination disorder; HRQoL: health‐related quality of life; JIA: juvenile idiopathic arthritis; HR: heart rate; NR: not reported; PedsQL: Pediatric quality of life inventory; PFO: prefabricated foot orthoses; PODCI: Paediatric outcome data collection instrument; FFI: Foot Function index; VAS: visual analogue scale