Appendix 1. Electronic search strategies

Database: Ovid MEDLINE(R)

1 exp Infant, Newborn/

2 Premature Birth/

3 (neonat$ or neo nat$).ti,ab.

4 (newborn$ or new born$ or newly born$).ti,ab.

5 (preterm or preterms or pre term or pre terms).ti,ab.

6 (preemie$ or premie or premies).ti,ab.

7 (prematur$ adj3 (birth$ or born or deliver$)).ti,ab.

8 (low adj3 (birthweight$ or birth weight$)).ti,ab.

9 (lbw or vlbw or elbw).ti,ab.

10 infan$.ti,ab.

11 (baby or babies).ti,ab.

12 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11

13 exp Catheterization, Central Venous/ (13775)

14 catheters/ or catheters, indwelling/ or central venous catheters/

15 (central adj3 line$).ti,ab.

16 peripherally‐inserted.ti,ab.

17 CVC.ti,ab.

18 CVL.ti,ab.

19 PCVC.ti,ab.

20 PICC.ti,ab.

21 Umbilical Veins/

22 UVC.ti,ab.

23 UAC.ti,ab.

24 (umbilical adj3 cathet$).ti,ab.

25 (umbilical adj3 cannul$).ti,ab.

26 (umbilical adj3 line$).ti,ab.

27 Broviac.ti,ab.

28 Hickman.ti,ab.

29 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28

30 12 and 29

31 randomized controlled trial.pt.

32 controlled clinical trial.pt.

33 randomized.ab.

34 placebo.ab.

35 drug therapy.fs.

36 randomly.ab.

37 trial.ab.

38 groups.ab.

39 31 or 32 or 33 or 34 or 35 or 36 or 37 or 38

40 exp animals/ not humans.sh.

41 39 not 40

42 30 and 41

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

Database:Embase Via OVID

1 newborn/

2 prematurity/

3 (neonat$ or neo nat$).ti,ab.

4 (newborn$ or new born$ or newly born$).ti,ab.

5 (preterm or preterms or pre term or pre terms).ti,ab.

6 (preemie$ or premie or premies).ti,ab.

7 (prematur$ adj3 (birth$ or born or deliver$)).ti,ab.

8 (low adj3 (birthweight$ or birth weight$)).ti,ab.

9 (lbw or vlbw or elbw).ti,ab.

10 infan$.ti,ab.

11 (baby or babies).ti,ab.

12 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11

13 exp central venous catheterization/

14 catheter/

15 exp indwelling catheter/

16 exp central venous catheter/ or hickman catheter/ or peripherally inserted central venous catheter/ or subclavian vein catheter/

17 (central adj3 line$).ti,ab.

18 peripherally‐inserted.ti,ab.

19 CVC.ti,ab.

20 CVL.ti,ab.

21 PCVC.ti,ab.

22 PICC.ti,ab.

23 umbilical vein/

24 UVC.ti,ab.

25 UAC.ti,ab.

26 (umbilical adj3 cathet$).ti,ab.

27 (umbilical adj3 cannul$).ti,ab.

28 (umbilical adj3 line$).ti,ab.

29 Broviac.ti,ab.

30 Hickman.ti,ab.

31 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29 or 30

32 12 and 31

33 clinical trial/

34 randomized controlled trial/

35 randomization/

36 single blind procedure/

37 double blind procedure/

38 crossover procedure/

39 placebo/

40 randomi?ed controlled trial$.tw.

41 rct.tw.

42 random allocation.tw.

43 randomly allocated.tw.

44 allocated randomly.tw.

45 (allocated adj2 random).tw.

46 single blind$.tw.

47 double blind$.tw.

48 ((treble or triple) adj blind$).tw.

49 placebo$.tw.

50 prospective study/

51 33 or 34 or 35 or 36 or 37 or 38 or 39 or 40 or 41 or 42 or 43 or 44 or 45 or 46 or 47 or 48 or 49 or 50

52 case study/

53 case report.tw.

54 abstract report/ or letter/

55 52 or 53 or 54

56 51 not 55

57 32 and 56

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

Database: Maternity & Infant Care Database (MIDIRS) Via OVID

1 (neonat$ or neo nat$).ti,ab.

2 (newborn$ or new born$ or newly born$).ti,ab.

3 (preterm or preterms or pre term or pre terms).ti,ab.

4 (preemie$ or premie or premies).ti,ab.

5 (prematur$ adj3 (birth$ or born or deliver$)).ti,ab.

6 (low adj3 (birthweight$ or birth weight$)).ti,ab.

7 (lbw or vlbw or elbw).ti,ab.

8 infan$.ti,ab.

9 (baby or babies).ti,ab.

10 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9

11 Catheterization.de.

12 Catheters.de.

13 catheter$.ti,ab.

14 (central adj3 line$).ti,ab.

15 catheter$.ti,ab.

16 peripherally‐inserted.ti,ab.

17 CVC.ti,ab.

18 CVL.ti,ab.

19 PCVC.ti,ab.

20 PICC.ti,ab.

21 Umbilical veins.de.

22 UVC.ti,ab.

23 UAC.ti,ab.

24 (umbilical adj3 cathet$).ti,ab.

25 (umbilical adj3 cannul$).ti,ab.

26 (umbilical adj3 line$).ti,ab.

27 Broviac.ti,ab.

28 Hickman.ti,ab.

29 11 or 12 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28

30 10 and 29

31 limit 30 to randomised controlled trial

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

Database: CENTRAL Via John Wiley’s Cochrane Library Interface

#1 MeSH descriptor: [Infant, Newborn] explode all trees

#2 MeSH descriptor: [Premature Birth] explode all trees

#3 neonat*:ti,ab,kw (Word variations have been searched)

#4 neo‐nat*:ti,ab,kw (Word variations have been searched)

#5 newborn or new born* or newly born*:ti,ab,kw (Word variations have been searched)

#6 preterm or preterms or (pre term) or (pre terms):ti,ab,kw (Word variations have been searched)

#7 preemie* or premie or premies:ti,ab,kw (Word variations have been searched)

#8 prematur* near/3 (birth* or born or deliver*):ti,ab,kw (Word variations have been searched)

#9 low near/3 (birthweight* or birth weight*):ti,ab,kw (Word variations have been searched)

#10 lbw or vlbw or elbw:ti,ab,kw (Word variations have been searched)

#11 infan* or baby or babies:ti,ab,kw (Word variations have been searched)

#12 #1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10 or #11

#13 MeSH descriptor: [Catheterization, Central Venous] explode all trees

#14 MeSH descriptor: [Catheters] explode all trees

#15 MeSH descriptor: [Catheters, Indwelling] explode all trees

#16 MeSH descriptor: [Central Venous Catheters] explode all trees

#17 central near/3 line*:ti,ab,kw (Word variations have been searched)

#18 peripherally‐inserted:ti,ab,kw (Word variations have been searched)

#19 CVC or CVL or PCVC or PICC:ti,ab,kw (Word variations have been searched)

#20 MeSH descriptor: [Umbilical Veins] explode all trees

#21 UVC or UAC:ti,ab,kw (Word variations have been searched)

#22 (umbilical near/3 (cathet* or cannul* or line*)):ti,ab,kw (Word variations have been searched)

#23 Broviac or hickman:ti,ab,kw (Word variations have been searched)

#24 #13 or #14 or #15 or #16 or #17 or #18 or #19 or #20 or #21 or #22 or #23

#25 #12 and #24

Appendix 2. GRADE

GRADE considers that evidence from randomised controlled trials is "high" quality but that assessment may be downgraded based on consideration of any of five areas (Schünemann 2013):

• design (risk of bias) (Guyatt 2011b);

• consistency across studies (Guyatt 2011c);

• precision of estimates (Guyatt 2011d);

• directness of the evidence (Guyatt 2011e);

• presence of publication bias.

This results in an assessment of the quality of a body of evidence in one of four grades.

• High: we are very confident that the true effect lies close to that of the estimate of the effect.

• Moderate: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different.

• Low: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect.

• Very low: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.