The impact of pre-eclampsia definitions on the identification of adverse outcome risk in hypertensive pregnancy - analyses from the CHIPS trial (Control of Hypertension in Pregnancy Study).

OBJECTIVE: To examine the association between pre-eclampsia definition and pregnancy outcome. DESIGN: Secondary analysis of Control of Hypertension in Pregnancy Study (CHIPS) trial data. SETTING: International multicentre randomised controlled trial (RCT). POPULATION: In all, 987 women with non-severe non-proteinuric pregnancy hypertension. METHODS: We evaluated the association between pre-eclampsia definitions and adverse pregnancy outcomes, stratified by hypertension type and blood pressure control. MAIN OUTCOME MEASURES: Main CHIPS trial outcomes: primary (perinatal loss or high-level neonatal care for >48 hours), secondary (serious maternal complications), birthweight <10th centile, severe maternal hypertension, delivery at <34 or <37 weeks, and maternal hospitalisation before birth. RESULTS: Of 979/987 women with informative data, 280 (28.6%) progressed to pre-eclampsia defined restrictively by new proteinuria, and 471 (48.1%) to pre-eclampsia defined broadly as proteinuria or one/more maternal symptoms, signs or abnormal laboratory tests. The broad (versus restrictive) definition had significantly higher sensitivities (range 62-79% versus 36-50%), lower specificities (range 53-65% versus 72-82%), and similar or higher diagnostic odds ratios and 'true-positive' to 'false-positive' ratios. Stratified analyses showed similar results. Addition of available fetoplacental manifestations (stillbirth or birthweight <10th centile) to the broad pre-eclampsia definition improved sensitivity (74-87%). CONCLUSIONS: A broad (versus restrictive) pre-eclampsia definition better identifies women who develop adverse pregnancy outcomes. These findings should be replicated in a prospective study within routine healthcare to ensure that the anticipated increase in surveillance and intervention in a larger number of women with pre-eclampsia is associated with improved outcomes, reasonable costs and congruence with women's values. TWEETABLE ABSTRACT: A broad (versus restrictive) pre-eclampsia definition better identifies the risk of adverse pregnancy outcomes.

Survival Analysis in the Presence of Competing Risks: The Example of Waitlisted Kidney Transplant Candidates.

Competing events (or risks) preclude the observation of an event of interest or alter the probability of the event's occurrence and are commonly encountered in transplant outcomes research. Transplantation, for example, is a competing event for death on the waiting list because receiving a transplant may significantly decrease the risk of long-term mortality. In a typical analysis of time-to-event data, competing events may be censored or incorporated into composite end points; however, the presence of competing events violates the assumption of "independent censoring," which is the basis of standard survival analysis techniques. The use of composite end points disregards the possibility that competing events may be related to the exposure in a way that is different from the other components of the composite. Using data from the Scientific Registry of Transplant Recipients, this paper reviews the principles of competing risks analysis; outlines approaches for analyzing data with competing events (cause-specific and subdistribution hazards models); compares the estimates obtained from standard survival analysis, which handle competing events as censoring events; discusses the appropriate settings in which each of the two approaches could be used; and contrasts their interpretation.

Control of Hypertension In Pregnancy Study randomised controlled trial-are the results dependent on the choice of labetalol or methyldopa?

OBJECTIVE: To determine whether the difference in outcomes between 'less tight' (target diastolic blood pressure [dBP] of 100 mmHg) versus 'tight' control (target dBP of 85 mmHg) in the CHIPS Trial (ISRCTN 71416914, http://pre-empt.cfri.ca/;CHIPS) depended on the choice of labetalol or methyldopa, the two most commonly used antihypertensive agents in CHIPS. DESIGN: Secondary analysis of CHIPS Trial data. SETTING: International multicentre randomised controlled trial (94 sites, 15 countries). POPULATION OR SAMPLE: A total of 987 women with non-severe non-proteinuric pregnancy hypertension. METHODS: Logistic regression was used for comparisons of 'less tight' versus 'tight' control among women treated with labetalol (but not methydopa) versus methyldopa (but not labetalol). Analyses were adjusted for the influence of baseline factors, including use of any antihypertensive therapy at randomisation. MAIN OUTCOME MEASURES: Main CHIPS Trial outcomes: primary (perinatal loss or high-level neonatal care for > 48 hours), secondary (serious maternal complications), birthweight < 10th centile, severe maternal hypertension, pre-eclampsia, and delivery at < 34 or < 37 weeks. RESULTS: Of 987 women in CHIPS, antihypertensive therapy was taken by 566 women at randomisation (labetalol 111 ['less tight'] versus 127 ['tight'] or methyldopa 126 ['less tight'] versus 117 ['tight']) and 815 women after randomisation (labetalol 186 ['less tight'] versus 247 ['tight'] and methyldopa by 98 ['less tight'] versus 126 ['tight']). Following adjustment, odds ratios for outcomes in 'less tight' versus 'tight' control were similar between antihypertensive groups according to 'at randomisation' and 'after randomisation' therapy. CONCLUSION: Outcomes for 'less tight' versus 'tight' control were not dependent on use of methyldopa or labetalol. TWEETABLE ABSTRACT: In the CHIPS Trial, maternal and infant outcomes were not dependent on use of labetalol or methyldopa.

Do labetalol and methyldopa have different effects on pregnancy outcome? Analysis of data from the Control of Hypertension In Pregnancy Study (CHIPS) trial.

OBJECTIVE: To compare pregnancy outcomes, accounting for allocated group, between methyldopa-treated and labetalol-treated women in the CHIPS Trial (ISRCTN 71416914) of 'less tight' versus 'tight' control of pregnancy hypertension. DESIGN: Secondary analysis of CHIPS Trial cohort. SETTING: International randomised controlled trial (94 sites, 15 countries). POPULATION OR SAMPLE: Of 987 CHIPS recruits, 481/566 (85.0%) women treated with antihypertensive therapy at randomisation. Of 981 (99.4%) women followed to delivery, 656/745 (88.1%) treated postrandomisation. METHODS: Logistic regression to compare outcomes among women who took methyldopa or labetalol, adjusted for the influence of baseline factors. MAIN OUTCOME MEASURES: CHIPS primary (perinatal loss or high level neonatal care for >48 hours) and secondary (serious maternal complications) outcomes, birthweight <10th centile, severe maternal hypertension, pre-eclampsia and delivery at <34 or <37 weeks. RESULTS: Methyldopa and labetalol were used commonly at randomisation (243/987, 24.6% and 238/987, 24.6%, respectively) and post-randomisation (224/981, 22.8% and 433/981, 44.1%, respectively). Following adjusted analyses, methyldopa (versus labetalol) at randomisation was associated with fewer babies with birthweight <10th centile [adjusted odds ratio (aOR) 0.48; 95% CI 0.20-0.87]. Methyldopa (versus labetalol) postrandomisation was associated with fewer CHIPS primary outcomes (aOR 0.64; 95% CI 0.40-1.00), birthweight <10th centile (aOR 0.54; 95% CI 0.32-0.92), severe hypertension (aOR 0.51; 95% CI 0.31-0.83), pre-eclampsia (aOR 0.55; 95% CI 0.36-0.85), and delivery at <34 weeks (aOR 0.53; 95% CI 0.29-0.96) or <37 weeks (aOR 0.55; 95% CI 0.35-0.85). CONCLUSION: These nonrandomised comparisons are subject to residual confounding, but women treated with methyldopa (versus labetalol), particularly those with pre-existing hypertension, may have had better outcomes. TWEETABLE ABSTRACT: There was no evidence that women treated with methyldopa versus labetalol had worse outcomes.

Pathogenesis of obstructive sleep apnoea in hypertensive patients: role of fluid retention and nocturnal rostral fluid shift.

Obstructive sleep apnoea (OSA) is highly prevalent in hypertensive patients, particularly those with drug resistance. Evidence from animal experiments, epidemiologic studies and clinical trials strongly suggest a causal link. Mechanistic studies argue for increased sympathetic neural activity and endothelial dysfunction. However, disturbances in fluid volume regulation and distribution may also be involved in the pathogenesis of these two conditions. Several studies have shown a high prevalence of OSA in fluid-retaining states including hypertension, a direct relationship between the severity of OSA and the volume of fluid displaced from the legs to the neck during sleep, and a decrease in upper airway cross-sectional area in response to graded lower body positive pressure. Treatments targeting fluid retention and redistribution, including diuretics, mineralocorticoid antagonists, exercise, and possibly renal denervation lower blood pressure and reduce the apnoea-hypopnoea index, a measure of OSA severity. From these observations, it has been postulated that during the daytime, excess fluid collects in the lower extremities due to gravity, and on lying down overnight is redistributed rostrally to the neck, where it may narrow the upper airway and increase its collapsibility, predisposing to OSA when pharyngeal dilator muscle activity decreases during sleep. This article discusses the associations between OSA and hypertension and reviews the evidence for fluid accumulation and its nocturnal rostral redistribution in the pathogenesis of OSA in hypertensive patients.

HLA-DR and -DQ eplet mismatches and transplant glomerulopathy: a nested case-control study.

We conducted a nested case-control study from a cohort of adult kidney transplant recipients to assess the risk of transplant glomerulopathy (TG) as a function of donor and recipient HLA-DR and -DQ incompatibility at the eplet level. Cases (n = 52) were defined as patients diagnosed with transplant glomerulopathy based on biopsies showing glomerular basement membrane duplication without immune complex deposition. Controls (n = 104) with a similar follow-up from transplantation were randomly selected from the remaining cohort. HLAMatchmaker was used to ascertain the number of DRB1/3/4/5, DQA1 and DQB1 related eplet mismatches (eplet load). Multivariable conditional logistic regression models demonstrated an increase in the odds of TG (odds ratios [OR] of 2.84 [95% confidence interval (CI): 1.03, 7.84] and 4.62 [95% CI: 1.51, 14.14]) in the presence of 27-43 and >43 HLA-DR + DQ related eplet mismatches versus <27 eplet mismatches, respectively. When the eplet load was modeled as a continuous variable, the OR for TG was 1.25 (95% CI: 1.04, 1.50) for every 10 additional HLA-DR + DQ eplet mismatches. Our study suggests that minimization of HLA-DR + DQ eplet mismatches may decrease the incidence of transplant glomerulopathy diagnosed by indication biopsies. The role of eplet immunogenicity/antigenicity as determinants of allograft outcomes requires further study.

Shift in sleep apnoea type in heart failure patients in the CANPAP trial.

In patients with heart failure (HF), the predominant type of sleep apnoea can change over time in association with alterations in circulation time. The aim of this study was to determine whether, in some patients with HF, a spontaneous shift from mainly central (>50% central events) to mainly obstructive (>50% obstructive events) sleep apnoea (CSA and OSA, respectively) over time coincides with improvement in left ventricular ejection fraction (LVEF). Therefore, sleep studies and LVEFs of HF patients with CSA from the control arm of the Canadian Continuous Positive Airway Pressure for Patients with Central Sleep Apnea and Heart Failure (CANPAP) trial were examined to determine whether some converted to mainly OSA and, if so, whether this was associated with an increase in LVEF. Of 98 patients with follow-up sleep studies and LVEFs, 18 converted spontaneously to predominantly OSA. Compared with those in the nonconversion group, those in the conversion group had a significantly greater increase in the LVEF (2.8% versus -0.07%) and a significantly greater fall in the lung-to-ear circulation time (-7.6 s versus 0.6 s). In patients with HF, spontaneous conversion from predominantly CSA to OSA is associated with an improvement in left ventricular systolic function. Future studies will be necessary to further examine this relationship.

Women's views of their experiences in the CHIPS (Control of Hypertension in Pregnancy Study) Pilot Trial.

BACKGROUND: Satisfaction with maternity care is strongly related to the patient-caregiver relationship and involvement in the decision-making process. We sought to compare women's views about their care in a randomized trial of 'less tight' vs. 'tight' control of non-proteinuric pre-existing or gestational hypertension in pregnancy. METHODS: In the CHIPS Pilot Trial, women completed a postpartum questionnaire to assess their likes and dislikes about their blood pressure (BP) management and trial participation. Comparisons were descriptive. RESULTS: Baseline information was similar for the 'less tight' and 'tight' control groups. Of 132 women, 126 (95.5%) from 17 centers completed a postpartum questionnaire, usually within days of delivery. At least 90% of women in both groups were satisfied with their care, and would be willing to participate again or recommend participation to a friend. Women in both the 'less tight' and 'tight' groups were satisfied with BP management (98.4% vs. 95.1%), and the frequency of tests of maternal and fetal well being. Half of women in both groups perceived that their BP was too high and that caregivers thought that their BP was too high. More women in the 'less tight' (vs. the 'tight') control group took less medication than expected (71.7% vs. 38.2%). More women in the 'tight' (vs. the 'less tight') group took more medication than they expected (60.0% vs. 22.2%). At least 60% of all women used home BP monitoring. CONCLUSION: In the CHIPS Pilot Trial, while women stated that they were satisfied with their BP management and care, a surprising 50% in both groups thought that their BP was too high. The majority of women used home BP monitoring, the role of which must be further defined in hypertensive pregnancies.

The Control of Hypertension In Pregnancy Study pilot trial.

OBJECTIVE: To determine whether 'less tight' (versus 'tight') control of nonsevere hypertension results in a difference in diastolic blood pressure (dBP) between groups. DESIGN: Randomised controlled trial (ISRCTN#57277508). SETTING: Seventeen obstetric centres in Canada, Australia, New Zealand, and UK. POPULATION: Inclusion: pregnant women, dBP 90-109 mmHg, pre-existing/gestational hypertension; live fetus(es); and 20-33(+6) weeks. Exclusion: systolic blood pressure > or = 170 mmHg and proteinuria, contraindication, or major fetal anomaly. METHODS: Randomisation to less tight (target dBP, 100 mmHg) or tight (target dBP, 85 mmHg) blood pressure control. MAIN OUTCOME MEASURES: Primary: mean dBP at 28, 32 and 36 weeks. Secondary: clinician compliance and women's satisfaction. Other: serious perinatal and maternal complications. RESULTS: A total of 132 women were randomised to less tight (n = 66; seven had no study visit) or tight control (n= 66; one was lost to follow up; seven had no study visit). Mean dBP was significantly lower with tight control: -3.5 mmHg, 95% credible interval (-6.4, -0.6). Clinician compliance was 79% in both groups. Women were satisfied with their care. With less tight (versus tight) control, the rates of other treatments and outcomes were the following: post-randomisation antenatal antihypertensive medication use: 46 (69.7%) versus 58 (89.2%), severe hypertension: 38 (57.6%) versus 26 (40.0%), proteinuria: 16 (24.2%) versus 20 (30.8%), serious maternal complications: 3 (4.6%) versus 2 (3.1%), preterm birth: 24 (36.4%) versus 26 (40.0%), birthweight: 2675 +/- 858 versus 2501 +/- 855 g, neonatal intensive care unit (NICU) admission: 15 (22.7%) versus 22 (34.4%), and serious perinatal complications: 9 (13.6%) versus 14 (21.5%). CONCLUSION: The CHIPS pilot trial confirms the feasibility and importance of a large definitive trial to determine the effects of less tight control on serious perinatal and maternal complications.

A survey of canadian practitioners regarding diagnosis and evaluation of the hypertensive disorders of pregnancy.

BACKGROUND: How Canadian practitioners are diagnosing and managing the hypertensive disorders of pregnancy (HDP), particularly in relation to the 1997 recommendations published by the Canadian Hypertension Society (CHS), is not known. METHODS: A survey, with French and English versions (and covering diagnosis, evaluation, and management of pregnancy hypertension), was mailed to all members of the Society of Obstetricians and Gynaecologists of Canada (SOGC) (N = 1757, including obstetricians, family doctors practicing obstetrics, and midwives). Additionally, internists [i.e., all nephrologists (N = 191) and a random sample of 25% of general internists (N = 450)] registered with the Royal College of Physicians and Surgeons of Canada were sampled. The survey was distributed in two mailings and one reminder card. Data were entered into Microsoft Access, and Graph Pad Prism used to summarize responses [N (%)]. Differences in practice between specialties were examined, with a Bonferonni correction used to calculate a significant p value based on the number of comparisons and alpha of 0.05. RESULTS: Respondents numbered 1187 (49.5%), with 466 not informative for the purpose of the study (due to retirement, or practices that do not include pregnant women with hypertension). The final analysis included 721 completed surveys. Most (609, 84.5% of) respondents take blood pressure (BP) with women in the sitting position, and use a mercury sphygmomanometer (79%) and the 5th Korotkoff (61%) sound to designate diastolic BP (dBP). To monitor pregnancies complicated by preeclampsia, most clinicians use the proposed laboratory tests of maternal well-being (usually at least once/week), fetal well-being [nonstress test (NST, at least once/week), and ultrasonographic studies (once weekly to every two weeks)]. There is general agreement that women with preeclampsia should be delivered for uncontrolled hypertension, end-organ dysfunction, or fetal compromise (nonreassuring NST, severe oligohydramnios, biophysical profile < 4, estimated fetal weight < 5th centile, and reversed end-diastolic flow by umbilical artery Doppler velocimetry). Less consensus was seen for delivery for preeclampsia at > 34 weeks, mild asymptomatic HELLP syndrome, hyperreflexia, and absent end-diastolic flow by umbilical artery Doppler velocimetry. INTERPRETATION: This survey has clarified the current state of practice with respect to the diagnosis and evaluation of women with all types of HDP. In particular, we have identified areas of potential variability in BP measurement, and provided data on the feasibility of enrolling women with sub types of preeclampsia into intervention studies aimed at prolonging pregnancy.

A survey of Canadian practitioners regarding the management of the hypertensive disorders of pregnancy.

BACKGROUND: How Canadian practitioners are managing the hypertensive disorders of pregnancy (HDP) is not known, particularly in relation to the 1997 guidelines published by the Canadian Hypertension Society (CHS). METHODS: A survey, with French and English versions (and covering diagnosis, evaluation, and management of pregnancy hypertension), was mailed to all members of the Society of Obstetricians and Gynaecologists of Canada (SOGC) (N = 1757, including obstetricians, family doctors practicing obstetrics, and midwives). Additionally, internists [i.e., all nephrologists (N = 191) and a random sample of 25% of general internists (N = 450)] registered with the Royal College of Physicians and Surgeons of Canada were sampled. The survey was distributed in two mailings and one reminder card. Data were entered into Microsoft Access, and Graph Pad Prism used to summarize responses [N (%)]. Differences in practice between specialties were examined, with a Bonferroni correction used to calculate a significant p value based on the number of comparisons and alpha of 0.05. RESULTS: Respondents numbered 1187 (49.5%), with 466 not informative for the purpose of the study (due to retirement, or practices that do not include pregnant women with hypertension). The final analysis included 721 completed surveys. For all types of HDP, most internists, family doctors, and midwives initiate nonpharmacological therapy (most common advice to quit work) at dBP 80-89 mmHg (i.e., primary prevention). Only for preeclampsia do obstetricians most frequently use this threshold; otherwise, dBP 90-99 mmHg is usually chosen. For nonsevere hypertension, antihypertensive drug therapy (most commonly methyldopa or labetalol) is started by most practitioners at dBP 90-99 mmHg, although obstetricians are more likely to choose a higher threshold (p < 0.0001). There is little agreement about dBP treatment goal; most internists and family doctors normalize dBP, whereas obstetricians appear to be divided on dBP goals of 80-89 (46-51%) vs. 90-99 mmHg (41-44%) for all HDP (p = 0.66). Severe hypertension is commonly treated with parenteral hydralazine, labetalol, or magnesium sulphate. Short-acting or sustained release nifedipine is used rarely/never by most practitioners. Approximately one-third of obstetricians and family doctors use diazepam to treat eclampsia. The vast majority use MgSO4 prophylactically in women with preeclampsia. INTERPRETATION: This survey has clarified current stated management of women with HDP, and identified the need for both research into the dBP treatment goal that optimizes pregnancy outcomes among women with HDP, and translation of definitive studies into clinical practice.

Balloon angioplasty versus medical therapy for hypertensive patients with renal artery obstruction.

BACKGROUND: Atherosclerotic renal artery stenosis is the most common cause of secondary hypertension. Balloon angioplasty is widely used for the treatment of hypertensive patients with renal artery stenosis. OBJECTIVES: The objective of this systematic review was to compare the effectiveness of balloon angioplasty (with and without stenting) with medical therapy on blood pressure control, renal function, frequency of renovascular complications, and side effects in hypertensive patients with atherosclerotic renal artery stenosis. SEARCH STRATEGY: The reviewers performed a search of MEDLINE from 1966 to December 2002, EMBASE from 1980 to 2002, Science Citation Index from 1990 to 2002, the Cochrane Central Register of Controlled Trials and personal files to identify randomised controlled trials comparing balloon angioplasty with medical therapy in hypertensive patients with renal artery stenosis. In addition, reference lists of papers resulting from this search were hand-searched, and authors of published trials were contacted to enquire if they were aware of any eligible unpublished trials. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials comparing balloon angioplasty with medical therapy in hypertensive patients with haemodynamically significant renal artery stenosis (greater than 50 per cent reduction in luminal diameter and minimal follow-up of six months). DATA COLLECTION AND ANALYSIS: Two investigators independently extracted data on trial design, characteristics of trial participants, types of interventions, and outcome measures. The quality of the available data precluded a formal meta-analysis to assess the effect on blood pressure, renal function, and number and defined daily doses of antihypertensive drugs. Peto's odds ratios and corresponding 95% confidence intervals (CI) were calculated for dichotomous outcomes such as the presence or absence of patent vessels and renovascular complications. MAIN RESULTS: Three randomised controlled trials involving 210 patients met the inclusion criteria. In unselected patients there was a consistent, but statistically non significant trend towards lower blood pressure in the balloon angioplasty group. Patients treated with balloon angioplasty required less antihypertensive drugs in two of three trials, and were more likely to have patent renal arteries after 12 months (OR 4.2, 95% CI 1.8 to 9.8). There were no differences in renal function. There were significantly fewer cardiovascular and renovascular complications in patients treated with angioplasty (OR 0.32, 95% CI 0.15 to 0.70, test for heterogeneity p > 0.1). REVIEWER'S CONCLUSIONS: Available data are insufficient to conclude that balloon angioplasty is superior to medical therapy in lowering blood pressure of patients with renal artery stenosis in whom blood pressure can be controlled with medical therapy. In patients with hypertension refractory to medical therapy, there is some weak evidence that balloon angioplasty lowers blood pressure more effectively than medical therapy. Balloon angioplasty appears to be safe and leads to fewer cardiovascular and renovascular complications. There is a need for randomised controlled trials comparing the effect of balloon angioplasty and medical therapy on the preservation of renal function in the long term.

Serious perinatal complications of non-proteinuric hypertension: an international, multicentre, retrospective cohort study.

OBJECTIVE: To determine the proportion of births complicated by either a pre-existing or a gestational non-proteinuric hypertension, presenting at <34 weeks' gestation, and the associated incidence with 1 or more serious perinatal complications or birth weight <3rd centile for gestational age. METHODS: A retrospective chart review was conducted in 5 international centres, from 1998 to 2002, where "tight" control (normalization) of blood pressure (BP) is the norm. International Classification of Diseases (ICD) codes were used to identify women who delivered at > or =20 weeks' gestation, with any hypertensive disorder of pregnancy. Women were included if they had a diastolic blood pressure (dBP) of 90 to 109 mm Hg, due to either a pre-existing or a gestational non-proteinuric hypertension, presenting at <34 weeks' gestation. Women were excluded if they had ongoing severe hypertension, or if at presentation with dBP of 90 to 109 mm Hg, they had 1 or more of the following: proteinuria, an indication for "tight" control of BP or imminent delivery, or a known intrauterine fetal death or lethal fetal anomaly. Data were collected on paper forms, scanned into an electronic database, and summarized descriptively by type of hypertension. RESULTS: There were 305 eligible women (0.7% deliveries, 12.8% hypertensive deliveries) identified with non-proteinuric hypertension that was either pre-existing (133 [43.6%]) or gestational (172 [56.4%]). Regardless of hypertension type, 16.4% (n = 50) of pregnancies were complicated by birth weight <3rd centile or 1 or more serious perinatal complications, 34.3% (n = 100) by preterm birth, 30.8% (n = 94) by preeclampsia, and 2.0% (n = 6) by serious maternal complications. CONCLUSION: Non-proteinuric pre-existing or gestational hypertension, presenting before 34 weeks' gestation, identifies a subpopulation of hypertensive pregnant women at both substantial perinatal risk and maternal risk. The CHIPS (Control of Hypertension In Pregnancy Study) trial is designed to determine how best to manage the hypertension of such women in order to optimize perinatal outcome.

Refractory hypertension and sleep apnoea: effect of CPAP on blood pressure and baroreflex.

This study was undertaken to determine whether abolition of obstructive sleep apnoea (OSA) by continuous positive airway pressure (CPAP) could reduce blood pressure (BP) in patients with refractory hypertension. In 11 refractory hypertensive patients with OSA, the acute effects of CPAP on nocturnal BP were studied during sleep and its longer term effects on 24-h ambulatory BP after 2 months. During a single night's application, CPAP abolished OSA and reduced systolic BP in stage 2 sleep from 138.3 +/- 6.8 to 126.0 +/- 6.3 mmHg. There was also a trend towards a reduction in average diastolic BP (from 77.7 +/- 4.5 to 72.9 +/- 4.5). CPAP usage for 2 months was accompanied by an 11.0 +/- 4.4 mmHg reduction in 24-h systolic BP. In addition, both the nocturnal and daytime components of systolic BP fell significantly by 14.4 +/- 4.4 and 9.3 +/- 3.9 mmHg, respectively. Diastolic BP was reduced significantly at night by 7.8 +/- 3.0 mmHg. In patients with refractory hypertension, acute abolition of obstructive sleep apnoea by continuous positive airway pressure reduces nocturnal blood pressure. These data also suggest that continuous positive airway pressure may reduce nocturnal and daytime systolic blood pressure chronically. Randomised trials are needed to confirm the latter results.

High prevalence of unrecognized sleep apnoea in drug-resistant hypertension.

OBJECTIVES: To determine the prevalence of obstructive sleep apnoea (OSA) in adult patients with drug-resistant hypertension, a common problem in a tertiary care facility. DESIGN: Cross-sectional study. SETTING: University hypertension clinic. PATIENTS AND METHODS: Adults with drug-resistant hypertension, defined as a clinic blood pressure of > or = 140/90 mmHg, while taking a sensible combination of three or more antihypertensive drugs, titrated to maximally recommended doses. Each of the 41 participants completed an overnight polysomnographic study and all but two had a 24 h ambulatory blood pressure measurement. RESULTS: Prevalence of OSA, defined as an apnoea-hypopnoea index of > or = 10 obstructive events per hour of sleep, was 83% in the 24 men and 17 women studied. Patients were generally late middle-aged (57.2 +/- 1.6 years, mean +/- SE), predominantly white (85%), obese (body mass index, 34.0 +/- 0.9 kg/m2) and taking a mean of 3.6 +/- 0.1 different antihypertensive medications daily. OSA was more prevalent in men than in women (96 versus 65%, P = 0.014) and more severe (mean apnoea-hypopnoea index of 32.2 +/- 4.5 versus 14.0 +/- 3.1 events/h, P = 0.004). There was no gender difference in body mass index or age. Women with OSA were significantly older and had a higher systolic blood pressure, lower diastolic blood pressure, wider pulse pressure and slower heart rate than women without OSA. CONCLUSIONS: The extraordinarily high prevalence of OSA in these patients supports its potential role in the pathogenesis of drug-resistant hypertension, and justifies the undertaking of a randomized controlled trial to corroborate this hypothesis.

Rationale and design of the Canadian Continuous Positive Airway Pressure Trial for Congestive Heart Failure patients with Central Sleep Apnea--CANPAP.

BACKGROUND: Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) is commonly observed in patients with congestive heart failure (CHF), in which it is an independent risk factor for death. Treating CSR-CSA may, therefore, improve outcomes in patients with CHF. OBJECTIVE: The Canadian Continuous Positive Airway Pressure Trial for Congestive Heart Failure Patients with Central Sleep Apnea (CANPAP) is a multicentre, randomized, controlled clinical trial designed to test the hypothesis that treating CSR-CSA with continuous positive airway pressure (CPAP) will reduce the combined rate of all-cause mortality and cardiac transplantation in patients with CHF. Secondary outcomes include the severity of CSR-CSA, left ventricular volumes and function, submaximal exercise capacity, quality of life and hospital admissions. PATIENTS AND METHODS: The aim is to enroll 408 patients with CHF (New York Heart Association class II to IV and left ventricular ejection fraction of less than 40%) and CSR-CSA over a five-year period. Patients are randomly assigned to either standard medical therapy for CHF or standard medical therapy plus CPAP. The trial has 80% power to detect a 35% between-group treatment difference for the all-cause mortality-cardiac transplantation rate. Substudies will assess the role of oximetry as a screening tool for detecting CSR-CSA in patients with CHF, and the effects of CPAP on cardiac arrhythmias and plasma concentrations of natriuretic peptides and catecholamines. CONCLUSIONS: The CANPAP trial will help to define the role of CPAP better as a nonpharmacological intervention for the treatment of patients with CHF who have CSR-CSA.

Effects of continuous positive airway pressure on cardiovascular outcomes in heart failure patients with and without Cheyne-Stokes respiration.

BACKGROUND: Continuous positive airway pressure (CPAP) improves cardiac function in patients with congestive heart failure (CHF) who also have Cheyne-Stokes respiration and central sleep apnea (CSR-CSA). However, the effects of CPAP in CHF patients without CSR-CSA have not been tested, and the long-term effects of this treatment on clinical cardiovascular outcomes are unknown. METHODS AND RESULTS: We conducted a randomized, controlled trial in which 66 patients with CHF (29 with and 37 without CSR-CSA) were randomized to either a group that received CPAP nightly or to a control group. Change in left ventricular ejection fraction (LVEF) from baseline to 3 months and the combined mortality-cardiac transplantation rate over the median 2.2-year follow-up period were compared between the CPAP-treated and control groups. For the entire group of patients, CPAP had no significant effect on LVEF, but it was associated with a 60% relative risk reduction (95% confidence interval, 2% to 64%) in mortality-cardiac transplantation rate in patients who complied with CPAP therapy. Stratified analysis of patients with and without CSR-CSA revealed that those with CSR-CSA experienced both a significant improvement in LVEF at 3 months and a relative risk reduction of 81% (95% confidence interval, 26% to 95%) in the mortality-cardiac transplantation rate of those who used CPAP. CPAP had no significant effect on either of these outcomes in patients without CSR-CSA. CONCLUSIONS: CPAP improves cardiac function in CHF patients with CSR-CSA but not in those without it. Although not definitive, our findings also suggest that CPAP can reduce the combined mortality-cardiac transplantation rate in those CHF patients with CSR-CSA who comply with therapy.

Fall in mean arterial pressure and fetal growth restriction in pregnancy hypertension: a meta-analysis.

BACKGROUND: We investigated the relation between fetoplacental growth and the use of oral antihypertensive medication to treat mild-to-moderate pregnancy hypertension. METHODS: The study design was a metaregression analysis of published data from randomised controlled trials. Data from a paper that was regarded as an extreme statistical outliner were excluded from primary analyses. The change in (group) mean arterial pressure (MAP) from enrolment to delivery was compared with indicators of fetoplacental growth. FINDINGS: Greater mean difference in MAP with antihypertensive therapy was associated with the birth of a higher proportion of small-for-gestational-age (SGA) infants (slope: 0.09 [SD 0.03], r2=0.48, p=0.006, 14 trials) and lower mean birthweight significant after exclusion of data from another paper regarded as an extreme statistical outliner (slope: -14.49 [6.98] r=0.16, p=0.049, 27). No relation with mean placental weight was seen (slope -2.01 [1.62], r2=0.15, p=0.25, 11 trials). INTERPRETATION: Treatment-induced falls in maternal blood pressure may adversely affect fetal growth. Given the small maternal benefits that are likely to be derived from therapy, new data are urgently needed to elucidate the relative maternal and fetal benefits and risks of oral antihypertensive drug treatment of mild-to-moderate pregnancy hypertension.