Proteinuria in pre-eclampsia: how much matters?

OBJECTIVE

To determine, in women with proteinuric pre-eclampsia, whether a discriminant value of proteinuria at the time of diagnosis predicts the presence or absence of subsequent adverse maternal and fetal outcomes.

DESIGN

Retrospective cohort study.

SETTING

One teaching hospital and two primary referral hospitals in Sydney, Australia.

SAMPLE

Three hundred and twenty-one pregnant women with proteinuric pre-eclampsia, managed according to a uniform management protocol.

METHODS

All women with the diagnosis of proteinuric pre-eclampsia in the years 1998-2001 were studied. After exclusion of women with pre-eclampsia superimposed on pre-existing hypertension, a twin pair, unavailable spot urine results, 353 women were analysed using logistic regression to determine separately the predictors of any adverse maternal or fetal outcomes at the time of delivery. Receiver operating characteristic (ROC) curves, sensitivity and specificity were then calculated from the data.

MAIN OUTCOME MEASURES

Adverse maternal outcomes: severe maternal hypertension (BP > or = 170/110 mmHg), renal insufficiency, liver disease, cerebral irritation, haematological disturbances. Adverse fetal outcomes: small for gestational age, perinatal mortality.

RESULTS

There were 108 (34%) adverse maternal outcomes and 60 (19%) adverse fetal outcomes including two stillbirths. In multivariate analysis, an adverse maternal outcome was significantly associated with higher spot urine protein/creatinine ratio at diagnosis (P < 0.0001) with an odds ratio (OR) of 1.003 per mg/mmol (95% confidence interval [CI] 1.002-1.004) and with older maternal age (P= 0.014) with OR 1.06 per year (95% CI 1.01-1.11). An increased risk of adverse fetal outcome was associated with higher spot urine protein/creatinine (P= 0.013; OR 1.44 per log [mg/mmol], 95% CI 1.08-1.92), gestation at diagnosis <34 weeks (P < 0.0001; OR 3.60, 95% CI 1.90-6.82) and early pregnancy systolic blood pressure < or =115 mmHg (P= 0.0002; OR 3.41, 95% CI 1.77-6.57). The area under the receiver operating characteristic (ROC) curve was 0.67 for adverse maternal outcomes and 0.72 for adverse fetal outcomes.

CONCLUSIONS

With increasing proteinuria, there is increased risk of adverse maternal and fetal outcomes. Although we did not identify a specific spot protein/creatinine ratio that could be used as a definitive screening value for adverse outcomes, it is possible to utilise data from this study to predict the likelihood of adverse maternal and fetal outcomes. A high spot urine protein/creatinine ratio in pre-eclamptic women of greater than 900 mg/mmol ( approximately 9 g/day), or greater than 500 mg/mmol (approximately 5 g/day) in women over 35 years, is associated with a greatly increased likelihood of adverse maternal outcomes.

What's new in defining hypertension and classifying hypertensive disorders in pregnancy

Hypertensive disorders are the most common medical problems encountered by women during pregnancy and remain a major cause of maternal and fetal mortality and morbidity throughout the world. This article provides an update on the definition and classifications of hypertension in pregnancy and discusses the recent consensus statement from the Australasian Society into the Study of Hypertension in Pregnancy (ASSHP). A review of the relevance of the traditional triad of symptoms in the assessment of women for hypertensive disorders in pregnancy is also presented. An understanding of these issues will help midwives accurately assess women and ensure that appropriate management of pregnancies complicated by hypertensive disorders occurs.

Does gestational hypertension become pre-eclampsia?

OBJECTIVE

To determine the likelihood of progression from gestational hypertension (GH) to pre-eclampsia (PE) in hypertensive pregnant women and whether this change can be identified in advance by available clinical and laboratory measures.

DESIGN

A retrospective analysis and a prospective study.

SETTING

St George Hospital, Sydney, a teaching hospital of the University of New South Wales delivering 2500 women per year.

POPULATION

Eight hundred and forty-five women with new hypertension in the second half of pregnancy, managed by a uniform protocol (661 in the retrospective analysis, 184 in the prospective study).

METHODS

Clinical and laboratory data at initial presentation were compared among women with GH who developed PE and those who remained with a diagnosis of GH until delivery. Data predictive for progression from GH to PE were analysed by logistic regression analysis.

MAIN OUTCOME MEASURED

Progression from GH to PE.

RESULTS

In the retrospective analysis, 416 women initially presented as having GH and 62 (15%) progressed to PE. In the prospective study, 112 women initially presented with GH and 29 (26%) progressed to PE, giving an overall progression of 17%. In both studies, women who developed PE from GH presented earlier than those who remained with GH until delivery. In multiple logistic regression analyses prior miscarriage and early gestation at presentation were associated with increased likelihood of progressing from GH to PE.

CONCLUSION

Approximately 15-25% of women initially diagnosed with GH will develop PE and this is more likely with earlier presentation or if the woman has had a prior miscarriage. Women with gestational hypertension diagnosed after 36 weeks of gestation have only about 10% risk of developing PE. These data should help stratify the risks of mildly hypertensive pregnant women being managed as outpatients in their third trimester.

Urinary calcium/creatinine ratio as a predictor of preeclampsia

Hypocalciuria has been associated with preeclampsia (gestational hypertension with proteinuria or other maternal organ dysfunction) but not usually with pure gestational hypertension or normal pregnancy. We hypothesized that hypocalciuria would be a marker of emerging preeclampsia in women presenting with gestational hypertension who later developed preeclampsia. Eighty-one women with de novo hypertension in the second half of pregnancy (n = 81) were enrolled prospectively. At first assessment, calcium/creatinine ratio was determined in a spot urine. Patients were followed until delivery and were classified subsequently according to the occurrence of preeclampsia. Gestational hypertensive patients who became preeclamptic (n = 31) had lower urinary calcium/creatinine ratios at presentation (ratio = 0.07, interquartile range [IQR] = 0.04-0.11) than women who remained as gestational hypertensives (n = 50; ratio = 0.17, IQR = 0.08-0.21; P = .002). Intact plasma parathyroid hormone (PTH) concentrations were similar between groups. Using a receiver operator curve, the best threshold value for the development of preeclampsia was a calcium/creatinine ratio of 0.10, which yielded a sensitivity of only 68% and a specificity of 70%. A low calcium/creatinine ratio preceded the emergence of preeclampsia by 12 (7-24) (median [IQR]) days among a group of women with gestational hypertension. Though this implies primary or secondary disturbances of renal calcium handling even before preeclampsia is clinically apparent, this measurement does not have sufficient sensitivity to recommend its use as a screening test for the emergence of preeclampsia.