Disheartening developments on the world stage.
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Cardiovascular Diseases↗
Biomedical subjects
A Chockalingam
Publications and source records attributed to A Chockalingam.
Awareness, treatment, and control of hypertension in Canada.
The Canadian Heart Health Surveys are cross-sectional, population-based cardiovascular disease risk factor surveys that took place in each of the 10 Canadian provinces between 1986 and 1992. Hypertension awareness, treatment, and control status are examined. Of 23,129 randomly selected, noninstitutionalized respondents aged 18 to 74 years, 85% had four blood pressure (BP) measurements taken under standardized conditions, two at home during a home interview and two at a following clinic visit. The mean of all available measurements was used to determine hypertension status. Estimates are weighted and represent population values. Only 2% of respondents had never had their BP checked, and 73% had had their BP checked in the last 12 months. A systolic or diastolic BP > or = 140/90 mm Hg was found in 22% of participants (26% of men, 18% of women), representing 4.1 million Canadians. Overall, 16% of participants were treated and controlled; 23% were treated and not controlled; 19% were not treated and not controlled; and 42% were unaware of their hypertension (47% of men and 35% of women). Among hypertensives 18 to 34 years old, 64% of men and 19% of women were unaware of their hypertension. Among treated and not controlled hypertensives 63% had a mean systolic BP > or = 150 mm Hg, and 29% a diastolic BP > or = 95 mm Hg, suggesting that an important number of Canadians treated for hypertension are still at increased risk. Despite frequent interactions with the health care system, too many Canadians are still not well controlled or are unaware of their hypertension.
Adolescent↗
The role of diltiazem in treating hypertension and coronary artery disease: new approaches to preventing first events.
OBJECTIVE: To review the role of diltiazem in treating and preventing a group of cardiovascular diseases, including painful and silent cardiac ischemia, stroke, nonfatal myocardial infarction and sudden cardiac death, by modulating certain physiological causes that they appear to share. DATA SOURCES: A MEDLINE search was conducted for all clinical articles on the use of diltiazem for hypertension and coronary artery disease. When clinical data were not available, basic research findings were reviewed. DATA EXTRACTION AND SYNTHESIS: Because many cardiovascular events show a marked daily periodicity--which appears to coincide with circadian peaks in the ability of platelets to aggregate, sympathetic activity, coronary tone, blood pressure, heart rate and hematocrit, and a trough in fibrinolytic activity--the impact of diltizazem on these physiological changes was assessed. CONCLUSIONS: Diltiazem influences many of these events by increasing myocardial bloodflow, and reducing myocardial oxygen demand and cardiac workload. However, it differs from other calcium antagonists in its mild negative inotropic and moderate negative dromotropic effects, without apparent stimulation of cardiac performance or contractility. In addition, it inhibits platelet aggregation, decreases catecholamine release, diminishes coronary tone and blocks the vasoconstrictive actions of endothelin-1. This appears to translate into a beneficial effect on ischemia, thrombolysis, arrhythmias, infarct parameters, atherosclerosis and hypertension. Diltiazem has a relatively favourable safety and tolerability profile, and is available in a once-daily dosage form. The most common adverse effects are related to vasodilation (eg, edema and headache), and the most frequent serious adverse event is atrioventricular block, which occurs rarely. In summary, diltiazem appears to be well suited to preventing the first occurrence of cardiovascular events and may even have a role in preventing certain types of secondary events. The data accumulated so far indicate the need for a large scale random clinical trial addressing these outcomes.
Arrhythmias, Cardiac↗
Pharmacoeconomics of hypertension control: basic principles of economic evaluation.
Pharmacoeconomics, the science of assigning costs and outcomes of drug therapy can be applied to antihypertensive drug therapy. There are five principle tools: cost identification, cost minimization, cost benefit, cost effectiveness and cost utility. If only drug aquisition costs are considered, there are marked differences among antihypertensive drug classes. These differences become less marked when the costs per quality adjusted life year are calculated. Often, differences among patients rather than differences among drug prices account for the bulk of variation.
Adult↗
Prevention and control of high blood pressure: challenges and opportunities.
Cardiovascular disease is still the leading cause of death in developed countries and is becoming more common in the developing world. The reduction in incidence of many cardiovascular diseases in the last few decades may be attributed in part to extensive programs to reduce and manage risk factors such as hypertension. Nevertheless, untreated, uncontrolled and undiagnosed hypertension remains a significant concern. Many nations have adopted policies and programs for hypertension control. An international sharing of knowledge and experience could lead to improvements in the prevention and treatment of hypertension and to lower rates of cardiovascular disease. In keeping with Canada's leadership in hypertension and cardiovascular disease prevention, Ottawa will host the World Conference on Hypertension Control from June 21 to 24, 1995. This conference will give participants the opportunity to review current programs and develop improved strategies for hypertension control and cardiovascular disease reduction.
Canada↗
Comparison of the efficacy and safety of once-daily versus twice-daily formulations of diltiazem in the treatment of systemic hypertension. The Canadian Multicenter Diltiazem-CD Hypertension Trial Group.
The efficacy and safety of optimally titrated once-daily (CD) and twice-daily (SR) diltiazem were compared in 111 patients with mild to moderate systemic hypertension [seated diastolic blood pressure (DBP) > or = 95 mmHg and < or = 114 mmHg] in a multicenter, randomized, double-blind, placebo run-in, parallel-group trial. Following a 4 week washout and placebo-controlled run-in period, patients were randomized to receive diltiazem CD 180 mg and matching placebo (n = 54), or diltiazem SR 90 mg bid (n = 57). Total daily doses were titrated from 180 mg to 360 mg to achieve a goal of seated DBP < 90 mmHg during a 6 week titration period. The patients continued to receive their optimal dose for a 6 week follow-up period. Ninety-six (96) patients (diltiazem CD: 47, diltiazem SR: 49) completed the study protocol, with 60% of the diltiazem CD and 55% of the diltiazem SR patients achieving the goal of seated DBP of < 90 mmHg (p = 0.685). Although significant decreases occurred in seated and standing measurements of diastolic and systolic BP and heart rate with treatment in both groups, there were no significant differences between treatment groups. Both medications were well tolerated, with a similar frequency of adverse effects [diltiazem CD: 24/54 (37%) patients; diltiazem SR: 24/57 (42.1%) patients] with the most frequently reported adverse effects being headache and edema.
Adolescent↗
24 hour blood pressure control with once-daily versus twice-daily formulations of diltiazem.
The antihypertensive effects of once-daily diltiazem CD over a 24 hour period were compared with twice-daily diltiazem SR in 95 patients with mild to moderate hypertension using ambulatory blood pressure monitoring. This trial was designed as a multicenter, double-blind, parallel-group study. Following a 2 to 4 week placebo run-in period, diltiazem was administered as once-daily CD or twice-daily SR, starting with 180 mg daily and increasing to a maximum of 360 mg daily, to achieve a seated diastolic blood pressure goal of < or = 90 mmHg as measured by cuff between 08:00 and 10:00 in the morning. Following drug titration, patients received a maintenance dose of diltiazem for an additional 6 week follow-up phase. Twenty-four hour ambulatory blood pressure monitoring recordings were obtained at the end of the placebo, titration, and maintenance phases. Both diltiazem CD and diltiazem SR significantly reduced both systolic and diastolic blood pressure over the 24 hour day and maintained a normal circadian pattern. As well, treatment with once-a-day diltiazem CD significantly decreased the slope of the early morning rise of diastolic and mean blood pressure. Thus, diltiazem CD is as effective as diltiazem SR in lowering diastolic blood pressure over a 24 hour period and has the advantage of a once-daily formulation.
Adolescent↗
Self-measurement of blood pressure: benefits, risks and interpretation of readings. The Canadian Coalition for High Blood Pressure Prevention and Control.
The literature on the benefits and risks of self-measurement of blood pressure and interpretation of the readings was reviewed. Self-measurement of blood pressure is useful in selected patients with high blood pressure, can be used to monitor blood pressure closely outside health care facilities, and can determine whether patients have white coat hypertension. The involvement of patients in their own blood pressure management is increased and self measurement may result in more rapid achievement of target blood pressure readings, improvement in adherence to antihypertensive therapy and decreased health care utilization. However, some patients may not be suited to monitor their own blood pressure and some may experience an increase in anxiety regarding their health. With careful training and selection of patients, most can accurately assess their blood pressure. Self-measured readings are generally lower than readings in a physician's clinic (or office) and this must be accounted for in assessing response to therapy and usual levels of blood pressure. Self-measured readings are a valuable supplement to clinic readings in many patients.
Anxiety↗
Self-measurement of blood pressure: issues related to the training of patients. Canadian Coalition for High Blood Pressure Prevention and Control.
For effective self-measurement of blood pressure, patients need to be able to obtain accurate and reproducible measurements. Criteria for measuring blood pressure have been well developed in research studies, and through the use of standardized training programs it has been established that nonmedically trained individuals can obtain valid measurements. These recommendations for blood pressure measurement were adapted to the self-measurement situation. Either manual sphygmomanometers or automated electronic devices can be used effectively. Although automated devices may be easier to use, the health care practitioner should ensure that any such device has been demonstrated to be accurate and reliable before its adoption. There are no reported programs available for training individuals in the use of self-measurement. A check-list has been developed for use by health care practitioners. It is estimated that proper training will usually take more than 20 mins. Since many health care practitioners do not use the recommended blood pressure measurement technique, there is also a need to develop programs to 'train the trainers'. Finally, individuals undertaking regular self-measurement should have their technique and the calibration of their instruments checked at regular intervals (six to 12 months).
Blood Pressure Determination↗
Self-measurement of blood pressure: assessment of equipment. Canadian Coalition for High Blood Pressure Prevention and Control.
Equipment for the self-measurement of blood pressure is readily available to consumers. These devices use one or more surrogate (indirect) measures of pressure to estimate systolic and diastolic blood pressure. Manual auscultatory devices using stethoscope and sphygmomanometer have been adapted for home use, but a variety of automated devices based on auscultation, oscillometry, and other techniques are available and may be more suitable for individuals who have limited vision, hearing or dexterity. Despite the existence of voluntary evaluation protocols and mandatory manufacturing standards, blood pressure readings from some automatic devices may not be accurate. Some devices are packaged with insufficient information to ensure proper use, and most individuals need some form of guidance in their use and calibration testing. If self-measurement of blood pressure is to be of benefit, the health care professional must recommend only those devices that are accurate and suitable to the patient or client. The Canadian Coalition for High Blood Pressure Prevention and Control will endeavour to develop a regular means by which health care professionals can keep informed of available devices for blood pressure self-measurement.
Blood Pressure Determination↗
Self-measurement of blood pressure: recommendations of the Canadian Coalition for High Blood Pressure Prevention and Control.
OBJECTIVE: To provide health care professionals with guidelines on the use of blood pressure self-measurement. METHODS: Recommendations were devised after consideration of expert reviews and guidelines, personal files, international standards documents, personal communication with investigators and the results of a MEDLINE search (1966-94) using the term 'blood pressure determination'. BENEFITS, HARMS, COSTS: Self-measurement of blood pressure can be used to detect white coat hypertension, monitor changes in blood pressure closely, more rapidly achieve desired blood pressure goals, increase adherence to antihypertensive therapy and improve patient self-reliance. However, self-measured blood pressure readings may be misleading because there is insufficient normative, prognostic and outcome data and because some patients may not take accurate measurements. The use of self-measurement of blood pressure has a relatively small direct cost and may result in an overall reduction in treatment costs. RECOMMENDATIONS: Self-measured blood pressure readings can be a valuable supplement to clinic (or office) blood pressure readings. However, self-measurement is appropriate neither for patients who are physically or mentally incapable of accurate assessment and interpretation of readings nor for those who do not want to participate. Patients who self-monitor blood pressure require careful training in blood pressure measurement and instruction on the recording and interpretation of blood pressure readings. Advice to patients using monitoring equipment must take into account the needs and abilities of the patient. Although only a few electronic devices for the self-measurement of blood pressure have met recommended performance standards, their use may be more appropriate for some patients and the training requirements fewer than if manual devices are used. VALIDATION: The guidelines of several expert groups were examined in the preparation of these recommendations. The recommendations were presented at the World Conference on Hypertension Control in 1995 and were reviewed by the parent societies of the Canadian Coalition for High Blood Pressure Prevention and Control.
Blood Pressure Determination↗
Workshop III: Communicating among health professionals--including health politicians.
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Communication↗
Stroke prevention: implications for health policy.
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Canada↗
Surveillance for stroke in Canada.
The goal of surveillance is to identify patterns of disease occurrence, detect disease outbreaks, develop clues about possible risk factors, find persons that need further investigation, and anticipate health service needs. Two sources of data are available for the purposes of surveillance: primary data, such as those arising from health surveys or local population-based registries; and secondary data, arising from large administrative databases. The effectiveness of any program to monitor the health of a community can be judged by the application of three "r's": right (accuracy), reasonable (cost) and rapid (speed). Programs using primary sources of data satisfy only one of the three "r's," that of accuracy. Programs using secondary sources sacrifice accuracy for speed and cost. The challenge for Canada in setting up surveillance for stroke is that there is a relatively small population unevenly distributed over a very large geographical area. To date, surveillance in Canada has consisted of a combination of individually initiated research projects and government sponsored programs. The main focus has been to tackle the issue of the accuracy of the large databases by validating the discharge codes listed in the provincial hospital discharge databases. Three provinces have carried out independent validation studies yielding remarkably similar results, and this lends confidence that hospital discharge databases will provide a means of carrying out surveillance for at least this one aspect of stroke. It is likely that any program for stroke surveillance in Canada will be multifaceted, involving the use of large computerized databases supplemented by hospital-based registries set up in a few highly motivated local centres. Stroke surveillance will best be accomplished by a joint effort between government and researchers to ensure that the end product is of high quality and will meet the needs of improving the health of Canadians.
Aged↗
Primary prevention of stroke.
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Cerebrovascular Disorders↗
Changes in the patterns of blood pressure treatment in North America from 1960-1990.
Seven North American surveys investigation a total of 241,725 hypertensives conducted between 1960-90 were reviewed with respect to their treatment status. In 1960 and 1970 nearly half of hypertensives were unaware of their condition and only 16% were treated and well-controlled. During the time period between 1970-1990 the proportion of the 'unaware' respondents declined to 16%, while the proportion of treated and well controlled patients increased to more than 40%. The proportion of those who are treated but the blood pressure fails to be controlled by the therapy to a satisfactory degree remained essentially unchanged, at around 16%. The proportion of those who are aware of their hypertension but are not treated shows a moderately decreasing trend, still representing 16% of all hypertensives in a recent Canadian survey. Although the handling of hypertension as a public health problem is largely successful, one third of patients still don't receive optimal therapy or is not treated at all.
Adolescent↗
The geography of the community sex ratios for young children in Newfoundland.
Abnormalities of the sex ratio of births may be linked with environmental factors, including diet and pollutants in the general or occupational environments, which in turn can cause ill-health. To examine this relationship in the Province of Newfoundland and Labrador, where a geographical imbalance of mortality has already been identified, we examined the geographical distribution of sex ratios (boys/girls x 100) of young children (0-4 years) in the communities of the Province during recent years. The individual communities of the 1976 and 1981 censuses were assigned to contiguous regions and their component districts. The numbers in the appropriate age-groups in the communities in these two census years were used to calculate a mean sex ratio for each community; each community was allocated, according to the value of its ratio, to one of four predefined categories of ratio. From the numbers of communities belonging to these various categories of sex ratio in the regions and districts, the community sex ratios of these areas (i.e. regions and districts) were derived. As a preliminary assessment of the relationship between sex ratios and mortality, a small group of communities with the highest sex ratios was selected, and the mean standardized mortality ratios (SMRs) for all deaths in those communities were calculated. The community sex ratios of regions and districts declined from east to west. The difference in the ratios between the Avalon region (in the most easterly part of the Province) and the southwest region was statistically significant. Districts with high ratios were frequent, particularly those on the Avalon peninsula in the south-east of the island, whereas low ratios were more frequent on the south-west coast of the island, and a low ratio was also found for the only inland district. Of the communities with statistically reliable numbers, the township of Makkovik in Labrador had the highest sex ratio (100 x 50/25 = 200). The SMR of that community during 1976-82 was statistically elevated at 218. In the small group of communities studied, however, high sex ratios from census data for individual communities were not reliable predictors of high SMRs. Further work is required to clarify the inter-relationships between the sex ratios of the census data, the sex ratios of births, the mortality rates and environmental factors.
Child, Preschool↗
Treatment of mild hypertension.
The mortality of males and females increases two-fold with increasing diastolic blood pressure (DBP) from 83 to 102 mm Hg. There is a corresponding significant increase in cardiovascular morbidity. While there is a general consensus about the need for drug treatment for those patients with DBP of 100 mm Hg or more, there is a controversy as to the justification of pharmacotherapy in the DBP range of 90-100 mm Hg. The arguments against drug treatment of patients with sustained mild hypertension with DBP less than 100 mm Hg rest on results of the large scale clinical trials, which have shown only modest benefit, not commensurate with the risks and inconveniences of pharmacotherapy. Critical appraisal of trials conducted in the past decade suggest a good efficacy of treatment of mild hypertension. Furthermore, recent studies indicate that hypertension is not a symptomless well-being. The inconveniences and side effects of treatment could be greatly reduced with lower doses and selective application of the most appropriate drugs. In a randomized, double-blind, parallel-group study of 80 patients with mild hypertension, 10-20 mg of nitrendipine once a day was an efficacious blood pressure lowering treatment with no significant difference in the incidence of side effects compared to a placebo-treated control group.
Adult↗