Hypertension in Pregnancy and Obstetric Acute Renal Failure
Hypertension in Pregnancy and Obstetric Acute Renal Failure
Objective To examine whether changes in postpartum haemorrhage, hypertensive disorders of pregnancy, or other risk factors explain the increase in obstetric acute renal failure in Canada.
Design Retrospective cohort study.
Setting Canada (excluding the province of Quebec).
Participants All hospital deliveries from 2003 to 2010 (n=2 193 425).
Main outcome measures Obstetric acute renal failure identified by ICD-10 diagnostic codes.
Methods Information on all hospital deliveries in Canada (excluding Quebec) between 2003 and 2010 (n=2?193?425) was obtained from the Canadian Institute for Health Information. Temporal trends in obstetric acute renal failure were assessed among women with and without postpartum haemorrhage, hypertensive disorders of pregnancy, or other risk factors. Logistic regression was used to determine if changes in risk factors explained the temporal increase in obstetric acute renal failure.
Results Rates of obstetric acute renal failure rose from 1.66 to 2.68 per 10 000 deliveries between 2003-04 and 2009-10 (61% increase, 95% confidence interval 24% to 110%). Adjustment for postpartum haemorrhage, hypertensive disorders, and other factors did not attenuate the increase. The temporal increase in acute renal failure was restricted to deliveries with hypertensive disorders (adjusted increase 95%, 95% confidence interval 38% to 176%), and was especially pronounced among women with gestational hypertension with significant proteinuria (adjusted increase 171%, 71% to 329%). No significant increase occurred among women without hypertensive disorders (adjusted increase 12%, -28 to 72%).
Conclusions The increase in obstetric acute renal failure in Canada between 2003 and 2010 was restricted to women with hypertensive disorders and was especially pronounced among women with pre-eclampsia. Further study is required to determine the cause of the increase among women with pre-eclampsia.
Obstetric acute renal failure, also referred to as pregnancy related acute kidney injury, is a serious and potentially life threatening complication of pregnancy. During the past 50 years, substantial declines in obstetric acute renal failure occurred in high income countries, owing to improvements in obstetric care and to the legalisation of pregnancy terminations and an associated decrease in infections. In recent years, however, rates have increased in both Canada and the United States. In Canada, obstetric acute renal failure increased significantly, from 1.6 per 10 000 deliveries in 2003 to 2.3 per 10 000 deliveries in 2007, whereas the rate in the United States increased from 2.3 in 1998 to 4.5 per 10 000 deliveries in 2008. These increases are of concern because obstetric acute renal failure is associated with high rates of maternal morbidity and a case fatality rate of 2.9%. Major risk factors for obstetric acute renal failure include chronic hypertensive disease, pre-eclampsia, postpartum haemorrhage, antepartum haemorrhage, sepsis, and other infections.
Since rates of postpartum haemorrhage have increased in several high income countries, we hypothesised that the hypovolaemia and related organ failure associated with postpartum haemorrhage may have been responsible for the observed increase in obstetric acute renal failure. An alternative hypothesis was related to hypertensive disorders of pregnancy, which represents the most important risk factor for obstetric acute renal failure. Although the rate of hypertensive disorders of pregnancy has not changed substantially in recent years in Canada, there have been considerable changes in the management of hypertension in pregnancy. In particular, guidelines promoting fluid restriction to prevent pulmonary oedema or changes in drugs for control of hypertension in combination with changes in pain management may have had the secondary effect of increasing acute renal failure through hypovolaemia, renal hypoperfusion, or nephrotoxicity.
We aimed to determine whether the temporal increase in postpartum haemorrhage in Canada explained the concurrent increase in obstetric acute renal failure. A secondary objective was to examine whether changes in hypertensive disorders of pregnancy (particularly pre-eclampsia) or other risk factors explained the increase in obstetric acute renal failure.
Abstract and Introduction
Abstract
Objective To examine whether changes in postpartum haemorrhage, hypertensive disorders of pregnancy, or other risk factors explain the increase in obstetric acute renal failure in Canada.
Design Retrospective cohort study.
Setting Canada (excluding the province of Quebec).
Participants All hospital deliveries from 2003 to 2010 (n=2 193 425).
Main outcome measures Obstetric acute renal failure identified by ICD-10 diagnostic codes.
Methods Information on all hospital deliveries in Canada (excluding Quebec) between 2003 and 2010 (n=2?193?425) was obtained from the Canadian Institute for Health Information. Temporal trends in obstetric acute renal failure were assessed among women with and without postpartum haemorrhage, hypertensive disorders of pregnancy, or other risk factors. Logistic regression was used to determine if changes in risk factors explained the temporal increase in obstetric acute renal failure.
Results Rates of obstetric acute renal failure rose from 1.66 to 2.68 per 10 000 deliveries between 2003-04 and 2009-10 (61% increase, 95% confidence interval 24% to 110%). Adjustment for postpartum haemorrhage, hypertensive disorders, and other factors did not attenuate the increase. The temporal increase in acute renal failure was restricted to deliveries with hypertensive disorders (adjusted increase 95%, 95% confidence interval 38% to 176%), and was especially pronounced among women with gestational hypertension with significant proteinuria (adjusted increase 171%, 71% to 329%). No significant increase occurred among women without hypertensive disorders (adjusted increase 12%, -28 to 72%).
Conclusions The increase in obstetric acute renal failure in Canada between 2003 and 2010 was restricted to women with hypertensive disorders and was especially pronounced among women with pre-eclampsia. Further study is required to determine the cause of the increase among women with pre-eclampsia.
Introduction
Obstetric acute renal failure, also referred to as pregnancy related acute kidney injury, is a serious and potentially life threatening complication of pregnancy. During the past 50 years, substantial declines in obstetric acute renal failure occurred in high income countries, owing to improvements in obstetric care and to the legalisation of pregnancy terminations and an associated decrease in infections. In recent years, however, rates have increased in both Canada and the United States. In Canada, obstetric acute renal failure increased significantly, from 1.6 per 10 000 deliveries in 2003 to 2.3 per 10 000 deliveries in 2007, whereas the rate in the United States increased from 2.3 in 1998 to 4.5 per 10 000 deliveries in 2008. These increases are of concern because obstetric acute renal failure is associated with high rates of maternal morbidity and a case fatality rate of 2.9%. Major risk factors for obstetric acute renal failure include chronic hypertensive disease, pre-eclampsia, postpartum haemorrhage, antepartum haemorrhage, sepsis, and other infections.
Since rates of postpartum haemorrhage have increased in several high income countries, we hypothesised that the hypovolaemia and related organ failure associated with postpartum haemorrhage may have been responsible for the observed increase in obstetric acute renal failure. An alternative hypothesis was related to hypertensive disorders of pregnancy, which represents the most important risk factor for obstetric acute renal failure. Although the rate of hypertensive disorders of pregnancy has not changed substantially in recent years in Canada, there have been considerable changes in the management of hypertension in pregnancy. In particular, guidelines promoting fluid restriction to prevent pulmonary oedema or changes in drugs for control of hypertension in combination with changes in pain management may have had the secondary effect of increasing acute renal failure through hypovolaemia, renal hypoperfusion, or nephrotoxicity.
We aimed to determine whether the temporal increase in postpartum haemorrhage in Canada explained the concurrent increase in obstetric acute renal failure. A secondary objective was to examine whether changes in hypertensive disorders of pregnancy (particularly pre-eclampsia) or other risk factors explained the increase in obstetric acute renal failure.
