Table 3

Modified Downs and Black scale25

PaperProspective (P) or retrospective (R) study(1) Clear aim/hypothesis(2) Outcome measures clearly described(3) Patient characteristics clearly described(5) Confounding variables described(6) Main findings clearly described(7) Measures of random variability provided(10) Actual probability values reported(11) Participants asked to participate representative of entire population(12) Participants prepared to participate representative of entire population(15) Blinding of outcome measurer(16) Analysis completed was planned(18) Appropriate statistics(20) Valid and reliable outcome measures(21) Appropriate case–control matching(25) Adjustment made for confounding variablesTotal
Cowan et al32R1112111UU11111114
Earl et al33R11121101U011U1112
Boling et al34R11121110U011U1112
Aminaka et al36R11111101U011U1111
Souza and Powers35R11121100U011U1111
Willson et al31R11111110U01111U11
Nakagawa et al38R11111110U011U009
Brindle et al39R11101110U011U0U8
Ott et al40R1101011UU001UUU6
Saad et al37R10001100U011U005
  • (For items 1–3, 6, 7, 10–12, 15, 16, 18, 20, 21 and 25)—0, no; 1, yes; U, unable to determine. (For item 5)—0, no: 1; partially: 2, yes.