Table 1.
Checklist of quality criteria used in the quality assessment
| Methodological issue | Questions addressed | Scoring |
|---|---|---|
| Theoretical background | 1. Is a theoretical background presented, to which the motivation for conducting the study and/or the hypotheses are linked? | Y = 3, NR = 2, N = 1 |
| Study participation | 2. Is the study population clearly described in terms of age, gender, and important HF characteristics? |
Y = 3, NR = 2, N = 1 Y = 3, NR = 1, N = 2 |
| 3. Is the percentage of eligible subjects who participated in the study (response rate) adequate? | ||
| Sampling | 4. Are patients who participated in the study similar to eligible non-participants, in terms of age, gender, and important disease characteristics? | Y = 3, NR = 1, N = 2 |
| Study attrition | 5. Is the percentage of subjects available for analysis adequate (i.e., >70 %)? |
Y = 3, NR = 1, N = 2 Y = 3, NR = 1, N = 2 |
| 6. Were reasons for loss to follow-up presented and assessed during the study for possible systematic attrition? | ||
| Determinant/correlate(s) measurement | 7. Are clear definitions of each determinant and/or correlate provided? |
Y = 3, NR = 2, N = 1 Y = 3, NR = 2, N = 1 Y = 3, NR = 1, N = 2 Y = 3, NR = 2, N = 1 |
| 8. Are clear operationalizations of each determinant and/or correlate provided? | ||
| 9. Are the measurement instruments used for the measurement of the determinants and correlates reliable and valid? | ||
| 10. Were the measurement approach, time and place of measurement of the determinants and/or correlates standardized or conducted in a way that limits systematically different measurement? | ||
| Outcome variable(s) measurement | 11. Are clear definitions of each outcome variable provided? |
Y = 3, NR = 2, N = 1 Y = 3, NR = 2, N = 1 |
| 12. Are clear operationalizations of each outcome variable provided? | ||
| 13. Are the measurement instruments used for the measurement of the outcome variable(s) reliable and valid? | Y = 3, NR = 2, N = 1 | |
| 14. Were the measurement approach, time and place of measurement of the outcome variable(s) standardized or conducted in a way that limits systematically different measurement? | Y = 3, NR = 2, N = 1 | |
| Statistical analyses | 15. Is the percentage of missing values adequate (i.e., <30 %)? | Y = 3, NR = 1, N = 2 |
| 16. Were multivariable analyses performed? If yes, was it clearly described which variables were included in the (multivariable) model(s)? | Y = 3, NR = 1, N = 2 | |
| General question | 17. Were there any other important flaws in the design or analyses of the study? | Y = 3, NR = 2, N = 1 |
Y yes, N no, NR not reported