Table 5

Quality assessment subscores*†

DesignPatient sampleOutcomePrevalenceIncidenceTotal score
Prevalence/incidence
Author (year)
Q1
Study design
Q2
Exclusion rate
Q3
Sampling method
Q4
Outcome measurement
Q5
Reporting of prevalence
Q6
Reporting of incidence
Chang et al14 (1995)0111104
Kirby et al15 (1981)0010102
DiFiori et al16 (1996)00111NA3
DiFiori et al17 (2002)01111NA4
Dixon and Fricker18 (1993)1110104
Purnell et al19 (2010)011NA103
O'Kane et al20 (2011)0011NA13
Smoljanovic et al21 (2009)0011NA13
Kirialanis et al22 (2002)1010NA13
Caine et al23 (1989)1011NA14
Lindner and Caine24 (1990)1011NA14
DesignOutcome(Risk) factorsConfoundingAnalysis 
Risk factors
Author (year)
Q1
Study design
Q2
Dropout or loss of follow-up
Q3
Outcome measure-ment
Q4
(Risk) factors
Q5
Confounding
Q6
Analysis
Total score
DiFiori et al16 (1996)0011013
  • *1, Criterion is sufficiently met; 0, criterion is unclear or insufficiently met; NA, item is not applicable.

  • †Low quality, ≤2×1; sufficient quality, ≤2×0 and 3×1; good quality, ≥4×1.