Fifty-five studies (4,361 participants with syncope and 1,791 controls) were included in the review.
An inverse relationship between sensitivity and specificity was observed: as sensitivity increased, specificity decreased (p<0.001). There was evidence of statistical heterogeneity across the studies (p<0.001).
The SROC curve suggested that the head-up tilt test has good overall ability to differentiate between symptomatic and asymptomatic participants (0.84, 95% CI 0.81 to 0.87).
Summary estimates according to tilt phases and pharmacological agents ranged between 25% and 66% for sensitivity, between 86% and 99% for specificity and between 5.94 and 14.40 for diagnostic odds ratios. Regimens using nitroglycerine showed the highest DOR (14.40, 95% CI 11.50 to 18.05) and the greatest sensitivity (66%, 95% CI 60% to 72%).
Multivariate analyses indicated that increasing age and a tilt angle of 60° reduced sensitivity and increased specificity. Other results were reported in the review.