Predictive accuracy of the shock index for severe postpartum hemorrhage in high‐income countries: A systematic review and meta‐analysis

Abstract

Aim: The shock index has been suggested as a screening tool for predicting postpartum hemorrhage (PPH); however, there is little comprehensive evidence regarding its predictive accuracy. This systematic review and meta-analysis aim to investigate the predictive accuracy of the shock index for severe PPH in highincome countries. Methods: A comprehensive search was conducted on MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science (from inception to June 2021). Studies assessing the predictive performance of the shock index for PPH in high-income countries were included. Two or more reviewers independently extracted the data and assessed the risk of bias and applicability concerns using the modified Quality Assessment of Diagnostic Accuracy Studies 2 tool. PPH requiring higher-level care, such as blood transfusions, were considered as primary analyses. We described the hierarchical summary receiver-operating characteristic curve for data synthesis. Results: Nine studies were included after the eligibility assessment. All studies were considered to either have a high risk of bias or high applicability concerns. The sensitivity of the four studies that defined severe PPH as PPH requiring blood transfusion ranged from 0.51 to 0.80, whereas their specificity ranged from 0.33 to 0.92. Conclusions: This review shows that the predictive performance of the shock index for severe PPH is inconsistent. Therefore, the evidence for using the shock index alone as a screening tool for PPH in high-income countries is insufficient. Study registration: This review was prospectively registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN000044230).

Shock index as a predictor of postpartum haemorrhage after vaginal delivery: Secondary analysis of a multicentre randomised controlled trial

“…a population substantially different from the one we studied. [18][19][20][21][22] Only a few studies have investigated the predictive performance of SI as an early predictor of PPH in a general population of women vaginal delivery including non-PPH women. 16,27,39 Most of these studies reported AUROC values for postpartum SI to discriminate blood loss ≥1000 ml higher than our findings, 16,27 with AUROC values of 0.70 or higher, a range considered acceptable by most authors.…”

“…SI has mainly been explored as a predictor of adverse outcomes (maternal death, near‐miss, severe morbidity, transfusion, intensive care unit admission) in women with ongoing PPH, i.e. a population substantially different from the one we studied 18–22 …”

“…Moreover, the SI has mainly been explored as a haemodynamic parameter associated with severity in women with ongoing PPH but rarely as a predictor of PPH in a general population of parturients 18–22 . However, haemodynamics may change before clinical recognition of the haemorrhage by enhanced uterine profusion, active bleeding not reaching the blood loss volume threshold for PPH, failure of clinical detection of abnormal vaginal bleeding or even unrecognised clot collected within the uterus 23–26 .…”

“…Moreover, the SI has mainly been explored as a haemodynamic parameter associated with severity in women with ongoing PPH but rarely as a predictor of PPH in a general population of parturients. [18][19][20][21][22] However, haemodynamics may change before clinical recognition of the haemorrhage by enhanced uterine profusion, active bleeding not reaching the blood loss volume threshold for PPH, failure of clinical detection of abnormal vaginal bleeding or even unrecognised clot collected within the uterus. [23][24][25][26] Studies in unselected populations of women after vaginal delivery have assessed the utility of SI with cut-offs between 0.9 and 1.0 as an early sign of PPH, 16,27,28 and have reported promising findings with area under the receiver operating characteristic curve (AUROC) >0.70, a range considered acceptable by most authors.…”