We combined individual patient data from one prospective monocentric study, Reissig 2001 [16], and two prospective multicentric studies, Nazerian 2014 [12] and Nazerian 2017 [17], enrolling consecutive patients with suspected PE.

After analysis of the existing literature on the topic, we selected for convenience the only 3 studies that reported complete information about the presence or absence of pleuritic pain on presentation. The studies had the following characteristics: (a) original publication; (b) prospective cohort study of patients with an objectively confirmed diagnosis of symptomatic PE; (c) record of presence or absence of pleuritic chest pain at presentation; (d) LUS performed in all enrolled patients.

One investigator, who was not a co-author of the three original studies included in the analysis, used the Quality Assessment of Studies of Diagnostic Accuracy included in Systematic Reviews-2 (QUADAS-2) tool to assess the methodological quality [18]. This tool is composed of two parts: risks of bias and concerns regarding applicability. The former was assessed in four domains patient selection, index test, reference standard and flow and timing, and the latter was assessed in three domains patient selection, index test and reference standard.

A core group of investigators (PN, GV and AR) developed the process for obtaining patient level data and the planned analyses, and all the co-authors approved them before the data collection phase.

After the investigators agreed to share their data, the databases were anonymously transferred to a central location under the auspices of PN. Data were checked, explanations for coding and uncertain data were clarified and a single pooled database was developed.

Reissig 2001 and Nazerian 2017 enrolled patients suspected of PE without differentiating the risk score, whereas Nazerian 2014 enrolled patients with Wells score > 4 (likely) or a positive d-dimer that underwent MCTPA.

The Wells score included the following items: clinical signs and symptoms of deep vein thrombosis (DVT) (+ 3), PE is most likely diagnosis or equally likely (+ 3), heart rate > 100 bpm (+ 1.5), immobilization at least 3 days or surgery in the previous 4 weeks (+ 1.5), previous objectively diagnosed PE or DVT (+ 1.5), hemoptysis (+ 1), malignancy with treatment within 6 months or palliative care (+ 1) [19]. Patients were categorized as PE likely if Wells score was > 4 and PE unlikely if ≤ 4. Cut-off values for d-dimer was