| External validity |
|
| 1) Was the study’s target
population a close representation of the national
population in relation to the relevant variables, for
example age, gender, and occupation? |
• Yes (LOW RISK): The study’s target population was a
close representation of the national population. |
| • No (HIGH RISK): The study’s target population was not
clearly representative of the national population. |
| 2) Was the sampling system a
true or close representation of the target
population? |
• Yes (LOW RISK): The sampling system was a true or
close representation of the target population. |
| • No (HIGH RISK): The sampling system was not a true or
close representation of the target population. |
| 3) Was some form of random
selection used to select the sample or was a census
performed? |
• Yes (LOW RISK): A census was performed or some form of
random selection was used to select the sample (for
example, simple random sampling, stratified random
sampling, cluster sampling, systematic sampling). |
| • No (HIGH RISK): No census was performed and no form of
random selection was used to select the sample. |
| 4) Was the probability of
non-response bias minimal? |
• Yes (LOW RISK): The response rate for the study was ≥
75%, that is, an analysis was performed that showed no
significant difference in relevant demographic
characteristics between responders and
non-responders. |
| • No (HIGH RISK): The response rate was < 75%, and if
any analysis was performed to compare responders and
non-responders, it showed a significant difference
between them in relevant demographic
characteristics. |
| Internal validity |
|
| 5) Were the data collected
directly from the individuals (rather than from a
proxy)? |
• Yes (LOW RISK): All the data were collected directly
from the individuals. |
| • No (HIGH RISK): In some cases the data were collected
from a proxy. |
| 6) Did the study use an
acceptable case definition? |
• Yes (LOW RISK): The study used an acceptable case
definition. |
| • No (HIGH RISK): The study did not use an acceptable
case definition. |
| 7) Did the study instrument
that measures the target parameter (for example,
prevalence of low back pain) demonstrate reliability and
validity (if necessary)? |
• Yes (LOW RISK): The study instrument demonstrated
reliability and validity (if necessary), for example,
test-retest, pilot, validation by a previous study,
etc. |
| • No (HIGH RISK): Reliability and validity were not
demonstrated for the instrument (if they were
necessary). |
| 8) Was the same data collection
model used for all the study subjects? |
• Yes (LOW RISK): The same data collection model was
used for all the individuals. |
| • No (HIGH RISK): The same data collection model was not
used for all the individuals. |
| 9) Was the duration of the
shortest prevalence period appropriate for the target
parameter? |
• Yes (LOW RISK): The duration of the shortest
prevalence period was appropriate for the target
parameter (for example, point prevalence, one week, one
year). |
| • No (HIGH RISK): The duration of the shortest
prevalence period was not appropriate for the target
parameter (for example, lifetime prevalence). |
| 10) Were the numerator and
denominator for the target parameter appropriate? |
• Yes (LOW RISK): The study used an appropriate
numerator and denominator for the target parameter (for
example, prevalence of low back pain). |
| • No (HIGH RISK): The study used a numerator and
denominator for the target parameter, but one or both of
them was inappropriate. |
| Internal validity |
|
| 11) Summary of overall risk of
bias in the study |
• LOW RISK OF BIAS: Further research is
highly unlikely to change our confidence in the
estimate. |
| • MODERATE RISK OF BIAS: Further research
is likely to have an imporant impact on our confidence
in the estimate and may change it. |
| • HIGH RISK OF BIAS: Further research is
highly likely to have an imporant impact on our
confidence in the estimate and is likely to change
it. |
