Accuracy of serum uric acid in predicting complications of pre-eclampsia: a systematic review.
BACKGROUND
Pre-eclampsia is one of the largest causes of maternal and fetal mortality and morbidity. Hyperuricemia is often associated with pre-eclampsia.


OBJECTIVE
To determine the accuracy with which serum uric acid predicts maternal and fetal complications in women with pre-eclampsia.


METHODS
Systematic quantitative review of test accuracy studies.


METHODS
We conducted electronic searches in MEDLINE (1951-2004), EMBASE (1980-2004), the Cochrane Library (2004:4) and the MEDION database to identify relevant articles. A hand-search of selected specialist journals and reference lists of articles obtained was then carried out. There were no language restrictions for any of these searches.


METHODS
Two reviewers independently selected the articles in which the accuracy of serum uric acid was evaluated to predict maternal and fetal complications of pre-eclampsia.


METHODS
Data were extracted on study characteristics, quality and accuracy to construct 2 x 2 tables with maternal and fetal complications as reference standard. Summary likelihood ratios for positive (LR+) and negative LR(-) test results are generated for various threshold levels of uric acid.


RESULTS
There were 18 primary articles that met the selection criteria, including a total of 3913 women and forty-one 2 x 2 tables. In women with pre-eclampsia, a positive test result of uric acid greater than or equal to a 350-micromol/l threshold predicted eclampsia with a pooled likelihood ratio (LR) of 2.1 (95% CI 1.4-3.5), while a negative test result had a pooled LR of 0.38 (95% CI 0.18-0.81). For severe hypertension as the outcome measure, the LRs were 1.7 (95% CI 1.3-2.2) and 0.49 (95% CI 0.38-0.64) for positive and negative test results, respectively, and for caesarean section the LRs were 2.4 (95% CI 1.3-4.7) and 0.39 (95% CI 0.20-0.76). For stillbirths and neonatal deaths the respective LRs were 1.5 (95% CI 0.91-2.6) and 0.51 (95% CI 0.20-1.3). For the prediction of small-for-gestational-age fetus, the pooled LRs were 1.3 (95% CI 1.1-1.7) and 0.60 (95% CI 0.43-0.83) for positive and negative results, respectively. AUTHOR'S CONCLUSION: Serum uric acid is a poor predictor of maternal and fetal complications in women with pre-eclampsia.
Thangaratinam
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S
Academic Unit of Obstetrics and Gynaecology, Maternity Block, University Hospital of North Staffordshire, Stoke-on-Trent, UK. shakila@doctors.org.uk
Ismail
K M K
KM
Sharp
S
S
Coomarasamy
A
A
Khan
K S
KS
D015415:Biomarkers / Q000097:blood; D002585:Cesarean Section; D005260:Female; D005317:Fetal Growth Retardation / Q000097:blood; D017359:HELLP Syndrome / Q000097:blood; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000097:blood; D011225:Pre-Eclampsia / Q000175:diagnosis*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011296:Prenatal Diagnosis / Q000592:standards*; D012680:Sensitivity and Specificity; D050497:Stillbirth; D014527:Uric Acid / Q000097:blood*
D015415:Biomarkers; D014527:Uric Acid