1. Summary of characteristics of included studies.
| Study ID | Number of participants (included in analysis/included in study) | Prevalence of PH (%) | Age | Sex, male (%) | Classification of PH defined by WHO | Threshold of index test (mmHg) | RAP estimation | The interval between the index test and reference standard | How to handle the uninterpretable results of the index test | Sensitivity | Specificity |
| Amsallem 2016 | 199/307 | 77 | 50 ± (13)* | 46 | NR | 40 | using the diameter of IVC | 2 days | excluded from analysis | 92% | 89% |
| Balci 2016 | 103/103 | 57 | 48 (18 to 70)*** | 65 | Group 3 | 35 | NR | 3 days | NA | 85% | 66% |
| Colle 2003 | 165/165 | 10 | 48 ± (8)* | 70 | Group 1 | 30 | using the diameter of IVC | 7 days | NA | 76% | 95% |
| Er 2010 | 50/50 | 86 | 66.9 ± (14.5)* | 28 | NR | 38 | using the diameter of IVC | 2 hours | NA | 98% | 100% |
| Greiner 2014 | 1695/3920 | 72 | 63 ± (15)* | 67 | NR | 36 | using the diameter of IVC | 5 days | excluded from analysis | 87% | 79% |
| Hellenkamp 2018 | 90/90 | 76 | 64.8 [55 to 79]**** | 48 | NR | 31 | using the diameter of IVC | 1 days | NA | 81% | 55% |
| Hsu 2008 | 49/55 | 33 | 55 (20 to 80)** | 18 | Group 1 | 47 | not using the diameter of IVC | 4 hours | excluded from analysis | 75% | 91% |
| Kyranis 2018 | 96/100 | 68 | 58 ± (14)* | 43 | NR | 31 | using the diameter of IVC | 1 days | excluded from analysis | 92% | 87% |
| Lafitte 2013 | 155/310 | 67 | 64.8 ± (15.9)* | 52 | NR | 38 | using the diameter of IVC | 5 days | excluded from analysis | 88% | 83% |
| Mazhar 2011 | 99/159 | 58 | NR | NR | NR | 31 | NR | 3 days | excluded from analysis | 67% | 83% |
| Mo 2015 | 24/30 | 88 | NR | NR | NR | 35 | NR | 7 days | excluded from analysis | 95% | 33% |
| Mo 2015a | 87/87 | 68 | NR | NR | NR | 45 | NR | 7 days | excluded from analysis | 81% | 86% |
| Nowak 2018 | 37/65 | 70 | 53.3 ± (9.5)* | 75 | NR | 43 | NR | 5 days | excluded from analysis | 92% | 82% |
| Sawada 2019 | 189 /189 | 26 | 58 ± (17)* | 56 | NR | 41 | using the diameter of IVC | 1 days | NA | 92% | 91% |
| Schneider 2017 | 65/65 | 83 | 67.2 (19 to 89)** | 43 | mixture of Group 1, 2, 3, and 4 | 34 | not using the diameter of IVC | 1 days | NA | 87% | 91% |
| Venkateshvaran 2021 | 419/480 | 62 | NR | NR | NR | 31 | using the diameter of IVC | 3 hours | excluded from analysis | 40% | 88% |
| Wainstein 2017 | 134/134 | 62 | 47 ± (14.7)* | 47 | Group 3 | 36 | NR | 3 days | NA | 89% | 60% |
* mean ± (SD), ** mean (range), *** median (range), **** mean [interquartile]
Abbreviations: IVC: inferior vena cava NA: not applicable NR: not reported PH: pulmonary hypertension RAP, right atrial pressure WHO: World Health Organization