2. Summary of investigations for heterogeneity.

Covariate	Subgroup	Number of studies	Number of participants	Number of cases	Sensitivity	Specificity
Overall		17	3656	1342	Median (range): 87% (40% to 98%)	Median (range): 86% (33% to 100%)
WHO Classification of PH	Not Group 3	3	279	87	Median (range): 76% (75% to 87%)	Median (range): 91% (91% to 95%)
	Group 3	2	237	142	Median (range): 63% (40% to 85%)	Median (range): 77% (66% to 88%)
	Not reported	12	3141	1113	Median (range): 92% (67% to 98%)	Median (range): 85% (33% to 100%)
The methods used to estimating RAP	Using the diameter of IVC	9	3057	967	Median (range): 92% (76% to 98%)	Median (range): 89% (55% to 100%)
	Not using the diameter of IVC	2	114	70	Median (range): 81% (75% to 87%)	Median (range): 91% (91% to 91%)
	Not reported	6	485	305	Median (range): 83% (40% to 95%)	Median (range): 83% (33% to 88%)
Threshold groups	< 36 mmHg	8	1061	711	Pooled sensitivity (95% CI): 89% (79% to 94%)	Pooled specificity (95% CI): 83% (70% to 91%)
	≥ 36 mmHg and < 40 mmHg	4	2034	328	Pooled sensitivity* (95% CI): 85% (57% to 96%)	Pooled specificity* (95% CI): 80% (76% to 84%)
	≥ 40 mmHg	5	561	303	Pooled sensitivity* (95% CI): 88% (83% to 92%)	Pooled specificity* (95% CI): 89% (85% to 93%)

* Pooled sensitivity and specificity estimated by the bivariate random effects model

Abbreviations:
CI: confidence interval
IVC: inferior vena cava
PH: pulmonary hypertension
RAP: right atrial pressure
WHO: World Health Organization