Item plus signalling questions

Criteria for scoring 'yes', 'no' and 'unclear'

1

PATIENT SELECTION

Was a consecutive or random sample of patients enrolled?

Was a case‐control design avoided?

Did the study avoid inappropriate exclusions?

We will score this item 'yes' when patients were consecutively or randomly selected; 90% or more were evaluated at the hospital; 5% or less of had received anticoagulant therapy within 24 hours before testing; 30% or less were given a diagnosis of comorbidity such as chronic obstructive pulmonary disease or other pulmonary disease, malignancy or pregnancy complications (preeclampsia, syndrome of haemolysis, elevated liver enzymes and low platelets or eclampsia); and 10% or less had undergone prior testing for this episode of suspected PE. We will score 'no' if one of these criteria was not met.

2

INDEX TEST

Were index test results interpreted without knowledge of results of the reference standard?

We will score this item 'yes' in the following cases: if study authors state that the index test interpreter was unaware of the result of the reference test; or if the order of testing was index test before reference test for every patient. Even if clinical follow‐up was the reference test, the order of testing has to be stated for the item to be scored 'yes'. We will score the item ‘no’ for studies in which it is stated that the interpreter of the index test was aware of the result of the reference test. In other cases, we will score this as 'unclear'.

In cases of studies directly comparing the diagnostic accuracy of 2 index tests against the reference standard, these test results had to be interpreted without knowledge of the results of the comparator index test, and we will score this item similarly to the approach described above.

3

REFERENCE STANDARD

Is the reference standard likely to correctly classify the target condition?

Were reference standard results interpreted without knowledge of results of the index test?

We considered both PA and clinical follow‐up of at least 6 weeks as useful for correct classification of the target condition, the latter only if objective diagnostic tests are used in cases of suspected venous thromboembolism. We will score this item 'yes' if study authors state that reference tests were interpreted without knowledge of results of the index test. Furthermore, in cases of clinical follow‐up as a reference standard, any clinical suspicion of venous thrombosis during follow‐up needs to be followed by objective diagnostic testing (i.e. CUS or venography for suspicion of DVT, and scintigraphy, CTPA or pulmonary angiography for clinical suspicion of PE). If a patient died during follow‐up, we classified death as caused by PE in cases of confirmation by autopsy, in cases of an objective test positive for PE before death or if PE could not be confidently excluded as the cause of death.

4

FLOW AND TIMING

Was an appropriate interval between index test(s) and reference standard provided?

Did all patients receive a reference standard?

Did all patients receive the same reference standard?

Were all patients included in the analysis?

With PA, we will consider a time period of less than 24 hours between index and reference tests as short enough to ensure that the target condition did not change between tests, either because of natural progression of the disease or because of therapeutic intervention. For studies using pulmonary angiography as the reference test, we will score this item 'yes' if the time between index and reference tests was less than 24 hours.

Similarly, for studies directly comparing diagnostic accuracy of index tests, we will consider a time period of less than 24 hours between index tests and the reference test as short enough.

During clinical follow‐up, the disease may diminish through natural progression or through intervention. Or the condition may arise during follow‐up if it was not present at the time of the index test. Therefore, we will score studies using clinical follow‐up 'no' for this item.

We will score this item 'no' if less than 90% or a non‐random selection of patients underwent the reference test.

We will score this item 'no' if less than 90% of patients who had an index test result underwent pulmonary angiography or had clinical follow‐up as the reference test.