MATERNAL SERUM URIC ACID AS A PROGNOSTIC FACTOR FOR PERINATAL OUTCOME IN HYPERTENSIVE DISORDERS OF PREGNANCY AT THE UNIVERSITY OF MAIDUGURI TEACHING HOSPITAL

Abstract

Background: Hypertension is a common medical disorder seen in pregnancy and
it is responsible for significant maternal and perinatal morbidity and mortality
especially in developing countries. Maternal serum uric acid correlates with both
severity of maternal disease and perinatal morbidity/mortality and may influence
timing of delivery of the fetus to avoid further intrauterine complications. This
would improve fetal survival, hence decreasing fetal morbidity and mortality.
Objective: To determine the prognostic value of maternal serum uric acid level in
determining perinatal outcome in hypertensive disorders in pregnancy, and to
determine its association with disease severity.
Study design: Hospital based cross-sectional study.
Study area: Department of Obstetrics and Gynaecology of the University of
Maiduguri Teaching Hospital, Maiduguri, Nigeria.
Methodology: Patients were recruited consecutively as they were admitted into
the labour ward with a hypertensive disorder in pregnancy. The next two
normotensive non proteinuric pregnant women matched for age group and parity
admitted into the labour ward were taken as control. Socio-demographic
variables and clinical characteristics such as age, parity, admitting blood pressure,
degree of proteinuria, mode of delivery, gestational age at delivery, birth weight, Apgar score at 1st and 5th minute and admission to special care baby unit were
noted. Levels of maternal serum uric acid, liver enzymes, urine creatinine, spot
urinary protein-creatinine ratio, packed cell volume and platelet count were
recorded.
Results: one hundred and sixty cases and 320 controls were recruited for the
study. Fifty two point nine percent (52.9%) of cases had eclampsia, 17.8%
gestational hypertension, 10.8% preeclampsia, 8.3% chronic hypertension and
7.7% chronic hypertension with superimposed preeclampsia. There is a rising
trend in serum uric acid level as the hypertensive disorder worsens: the levels rise
significantly from gestational hypertension through preeclampsia to eclampsia
(474.86±125.63; 489.53±117.33; 542.22±147.81 respectively; P <0.001). The
serum uric acid level in chronic hypertension with superimposed preeclampsia is
significantly higher than in chronic hypertension (538.50± 165.25 vs.
510.54±125.27; P<0.001). The mean serum uric acid was also significantly higher
in cases compared to controls (520.23±143.08 vs. 276.10±58.21; P <0.001).
Hyperuricaemia was significantly associated with higher blood pressure
(121.42±20.90 vs. 164.20±29.10 systolic and 78.27±15.49 vs. 109.07±17.78
diastolic; P<0.01), spot urinary protein creatinine ratio (41.46±105.89 vs.
105.42±186.97 P <0.001) and liver enzymes (ASAT: 12.26±7.76 vs. 16.50±10.70 P
0.020, ALAT: 22.05±15.01 vs. 33.90±25.40 P 0.005). Although, the mean platelet
count (173.60± 54.70 vs. 179.0± 65.90 P 0.607) and packed cell volume
(32.70±6.30 vs. 33.30± 5.30 P 0.533) are lower in the hyperuricaemic group, this
was not statistically significant.
The hypertensive group delivered earlier, with significantly more preterm
deliveries (37.10 vs. 38.60 weeks; P <0.001) and their babies weighed less, with
significantly more low birth weight babies (2.45 vs 3.15kg; P <0.001). Spontaneous
vaginal delivery was achieved in 28.7% of cases compared to 85.6% of controls
and 22.3% of cases were delivered by caesarean section compared to 10.3% of
controls (P <0.001). Hyperuricaemia was significantly associated with adverse
perinatal outcome with high sensitivity, specificity and negative predictive value
but low positive predictive value. After logistic regression, hyperuricaemia was
associated with low birth weight (sensitivity 72.8%, specificity 86.9%, negative
predictive value 93.04%, positive predictive value 57.27% P <0.001), fetal distress
(sensitivity 70.0%, specificity 77.24%, negative predictive value 98.33%, positive
predictive value 11.86% P 0.002), intrauterine growth restriction (sensitivity
85.19%, specificity 82.99%, negative predictive value 97.72%, positive predictive
value 38.98% P 0.029), intrauterine fetal death (sensitivity 63.89%, specificity
78.46%, negative predictive value 96.38%, positive predictive value 19.49% P
0.003) and neonatal death (sensitivity 81.82%, specificity 76.61%, negative
predictive value 99.44%, positive predictive value 7.63% P 0.005).
Conclusion: Maternal hyperuricaemia is significantly associated with poor
perinatal outcome with high sensitivity and specificity and may be used to identify
a group of women who will need close fetal surveillance to prevent adverse
perinatal outcome but not as an independent factor for deciding time of delivery
due to its poor positive predictive value. It is therefore of poor prognostic value in
determining perinatal outcome.

MATERNAL SERUM URIC ACID AS A PROGNOSTIC FACTOR FOR PERINATAL OUTCOME IN HYPERTENSIVE DISORDERS OF PREGNANCY AT THE UNIVERSITY OF MAIDUGURI TEACHING HOSPITAL