Association between hypnotics use and increased mortality: causation or confounding?

PURPOSE: Many research studies have found associations between benzodiazepines and/or z-hypnotics (BZZ) and increasing mortality, leading to a discussion about causation or confounding. This study suggests a factor that could produce this association through confounding. METHODS: The Norwegian population in 2010 supplied 8862 deaths ages 41-80 and 898,289 controls. Index dates were added to control records which corresponded to death dates. BZZ use was recorded for 2 years before death/index date. RESULTS: Persons exposed to BZZ were more likely (OR = 2.3) to die than those who were not. With proximity of death, increasingly larger proportions of the prospective deaths received prescriptions for BZZ, until in the last 2 months 40-45% received BZZ. The frequency of BZZ use in controls increased with age as opposed to the death cohort where all ages showed similar rates of BZZ use. In the last few months before death, the youngest age group had an OR = 5.8 for BZZ use while the oldest age group an OR = 1.8, adjusted for age and sex. Opioid use showed a similar pattern of increasing use near death. CONCLUSIONS: The increased use of BZZ with approaching death is consistent with increasing symptomatic treatment in terminal illness. Thus, the association of BZZ and mortality is more likely to be due to confounding than to causality. Further evidence from this and other research includes similar use patterns for other drugs such as opioids, the lack of specificity in cause of death and the size of the association regarding age and time to death.

Comparison of diagnosed, self-reported, and physically-measured hypertension in Canada.

BACKGROUND: Hypertension is a substantial health concern because it poses significant risks for cardiovascular morbidity and mortality and is highly prevalent in the population. Tracking hypertension is important because it is a risk factor for other conditions, but prevalence estimates might vary depending on the data source used. METHODS: This report describes 3 national population-based data sources for estimating hypertension prevalence in Canada and discusses their strengths and weaknesses to aid in their use for policy and program planning. They are compared based on: sample coverage, case identification, and prevalence estimates. RESULTS: Each source produces a different measure of hypertension prevalence, as follows: (1) diagnosed hypertension from the Canadian Chronic Disease Surveillance System (CCDSS) (2007/2008); (2) self-reported diagnosed hypertension from the Canadian Community Health Survey (CCHS) (2007-2008); and, (3) physically-measured hypertension from the Canadian Health Measures Survey (CHMS) (2007-2009). Crude rates and counts of hypertension prevalence among individuals aged 20 to 79 years of age, excluding pregnant women, are compared, resulting in prevalence ranging from 18.2% in self-report data to 20.3% in diagnosed data. The data sources differ in terms of target population, case identification, and limitations, which affects the estimates. CONCLUSIONS: Each source has unique strengths and is best suited for addressing particular research questions. For example, diagnosed hypertension can be used to determine health care utilization patterns, self-reported to examine health determinants, and measured high blood pressure to improve awareness, treatment, and control. Combined, they can address multiple issues and increase our knowledge of hypertension in Canada.

Blood pressure in Canadian adults.

BACKGROUND: Hypertension is estimated to cause more than one-eighth of all deaths worldwide. In Canada, the last national surveys to include direct measures of blood pressure (BP) took place over the years 1985-1992; hypertension was estimated at 21%. DATA AND METHODS: Data are from cycle 1 of the Canadian Health Measures Survey, conducted from March 2007 through February 2009. The survey included direct BP measures using an automated device. Weighted frequencies, means and cross-tabulations were produced to estimate levels of hypertension awareness, treatment and control in the population aged 20 to 79 years. RESULTS: Among adults aged 20 to 79 years, hypertension (systolic BP higher than or equal to 140 or diastolic BP higher than or equal to 90 mm Hg, or self-reported recent medication use for high BP) was present in 19%. Another 20% had BP in the pre-hypertension range (systolic 120 to 139 or diastolic 80 to 89 mm Hg). Of those with hypertension, 83% were aware, 80% were taking antihypertensive drugs, and 66% were controlled. Uncontrolled hypertension was largely due to high systolic BP. INTERPRETATION: Hypertension prevalence is similar to that reported in 1992. Since then, the level of hypertension control has increased considerably.

Incidence, comorbidity, case fatality and readmission of hospitalized stroke patients in Canada.

BACKGROUND: Stroke is a leading cause of death and disability, and poses a significant burden of care for those who survive. OBJECTIVES: To estimate the incidence of hospitalization for stroke and describe the impact of age, sex and comorbidity on in-hospital mortality, length of stay and readmission rates. METHODS: Health insurance numbers were used to link acute care hospitalizations across Canada in 1999/2000 for stroke patients with no discharges for a stroke within the preceding five years. Patients were followed up for one year from the date of their initial admission. RESULTS: The numbers of men (15,367) and women (16,740) in the study were similar. The incidence of all types of stroke (International Classification of Diseases, ninth revision, codes 430, 431 and 434/436) for hospitalized men and women was 14.4 per 10,000, with a 15-fold rise from 8.7 for the age group of 45 to 64 years to 131.9 per 10,000 for the age group 80 years and older. For the index episode, stroke patients spent an average of 21.0 days in the hospital, and 18.2% died in the hospital within 28 days. Of those who survived the first episode, 10.3% were readmitted to the hospital within one year with a recurrent stroke, and overall 37.1% were readmitted for any cause (including stroke). Among these stroke patients, hypertension was codiagnosed in 35%; diabetes in 17%; arrhythmia in 15%; ischemic heart disease in 13.6%; and congestive heart failure in 5%. CONCLUSIONS: Hospital records linked by patient identification can produce more accurate national estimates of patients hospitalized with stroke than any current countrywide surveillance system.

Regional variations in cardiovascular mortality in Canada.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of death in Canada with wide, unexplained regional variations in heart disease mortality. However, no studies to date have explored the relationship between a number of health region characteristics and regional variation in heart disease mortality rates across Canada. INTRODUCTION: We studied the contribution of various traditional cardiac risk factors, social determinants of health and other community characteristics to regional variations in heart disease mortality rates across Canada. METHODS: Cardiovascular disease and ischemic heart disease (IHD) age-standardized mortality rates were obtained from Statistics Canada for three years - 1995 to 1997. Health region characteristics were taken from the 2000/2001 Canadian Community Health Survey, and the 1996 Canadian Census and the Labour Force Survey. Linear regression analyses and analyses of variance were employed to identify relationships between these health region characteristics and CVD and IHD mortality rates. RESULTS: Significant regional variations in CVD mortality rates per 100,000 population were observed. Newfoundland and Labrador had the highest CVD and IHD mortality rates, while Nunavut and the Northwest Territories had the lowest CVD and IHD mortality rates. Health region smoking and unemployment rates were identified as the most important factors associated with CVD and IHD mortality at the health region level. CONCLUSIONS: Significant regional variations in age-standardized CVD and IHD mortality were noted both at the provincial/territorial level and the health region level. Efforts to reduce CVD and IHD mortality in Canada require attention to both traditional risk factors (eg, smoking) and broader determinants of health (eg, unemployment rates).

Outcomes of acute myocardial infarction in Canada.

BACKGROUND: Little information is available on recent population-based trends in the outcomes of patients who have had an acute myocardial infarction (AMI) in Canada. METHODS: Data were analyzed from the Discharge Abstract Database and Hospital Morbidity Database of the Canadian Institute for Health Information. All new cases of AMI in Canada between fiscal 1997/98 and fiscal 1999/2000 of patients at least 20 years old were examined. Data were also analyzed from these databases for hospital readmissions for a second AMI, angina and congestive heart failure (CHF). RESULTS: There were 139,523 new AMI cases. The overall crude in-hospital AMI mortality rate in Canada was 12.3%. In-hospital mortality rate after an AMI was worse for women than for men in Canada (16.7% and 9.9%, respectively). The age- and sex-standardized in-hospital mortality rate varied from a low of 10.5% (95% CI 8.4% to 12.6%) in Prince Edward Island to a high of 13.1% (95% CI 12.8% to 13.5%) in Quebec. Among AMI survivors, 12.5% were readmitted within one year for angina, 7.7% for a second AMI and 7.5% for CHF. There were wide interregional differences in age- and sex-standardized mortality rates and one-year readmission rates. CONCLUSIONS: AMI is associated with a substantial acute mortality rate in Canada, especially in the elderly and female patients. Identifying the causes of interregional differences in patient outcomes should be a priority for future research.