The diagnostic accuracy of the NICE risk–stratification algorithm in predicting pre-eclampsia: A systematic review with meta-analysis

Pre-eclampsia is a hypertensive disorder of pregnancy which, left untreated, can cause significant foeto-maternal morbidity. Accordingly, the National Institution for Health and Care Excellence (NICE) recommends that high-risk women be prescribed daily prophylaxis with 75-150 mg aspirin from 12 weeks gestation until delivery. NICE stratifies risk using 11 maternal risk factors; however, to date, the diagnostic accuracy of this system has never been evaluated by meta-analytic review. Our systematic review and meta-analysis evaluates the sensitivity and specificity of the NICE risk-stratification algorithm in predicting pre-eclampsia in pregnant women ≥ 16 years. Systematic searches of PubMed, Cochrane Library and SCOPUS identified 894,527 pregnancies from 20 eligible studies with a CBEM Level of Evidence ≤ 4. The logit-transformed sensitivities and specificities from each study were modelled as a bivariate distribution with random effects to generate restricted maximum-likelihood estimates (MLEs) for the overall sensitivity and specificity of the algorithm in predicting pre-eclampsia. These estimates were 43.3 % (95 % CI 32.6-54.7) and 91.0 % (95 % CI 84.0-95.1), respectively. Significant heterogeneity was exhibited between the sensitivities (I² = 93.2 %) and specificities (I² = 98.0 %) calculated by each of the included studies and, consequently, there is a low degree of certainty in these estimates. Overall, the NICE risk-stratification algorithm performs remarkably poorly when used to predict pre-eclampsia in any of 3 gestational categories. Clinicians should advise women that the post-test probabilities of pre-eclampsia are 1 in 4 for high-risk patients and 1 in 25 for low-risk patients (assuming a moderate incidence of 6 %;¹ see Appendix S3), although future studies are likely to alter these statistics.