Recommendations for national and local regulatory authorities concerning research in genetic markers of disease.
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Clinical Trials as Topic↗
Biomedical subjects
S Yusuf
Publications and source records attributed to S Yusuf.
Lysozyme levels for the diagnosis of tuberculous effusions in children.
Lysozyme level was measured in the fluid and serum of 42 tuberculous (25 pleural, 11 ascites and 6 pericardial) and 29 non-tuberculous (5 malignant, 9 empyema thoracis, 10 transudative ascites and 5 pyopericardium) effusions. The mean fluid lysozyme level was significantly raised in tuberculous pleural, ascites, and pericardial effusions in comparison to malignant pleural (p <0.001), transudative ascites (p < 0.001), and pyopericardium (p < 0.02) cases, respectively. The mean fluid/serum lysozyme ratio did not differ significantly between tuberculous and their corresponding non-tuberculous effusions. The confirmed tuberculous pleural effusion patients had significantly higher mean fluid lysozyme level and fluid/serum lysozyme ratio when compared with clinical cases (p < 0.05). The cut-off fluid lysozyme level of > or = 50/UI(-1) and fluid/serum lysozyme ratio of > or = 1.1 were considered for the diagnosis of tuberculous effusions; the sensitivity and specificity of fluid lysozyme and fluid/serum lysozyme ratios were 100, 100 per cent, and 97.6, 33.3 per cent, respectively, on excluding the patients with purulent effusions. A significant correlation was observed between the fluid and serum lysozyme levels in tuberculous effusions (r = 0.39,p < 0.01). Thus, fluid lysozyme was found to be a better and reliable test than fluid/serum lysozyme ratio for the diagnosis of tuberculous effusions in children.
Adolescent↗
The impact of time to thrombolytic treatment on outcome in patients with acute myocardial infarction. For the CORE investigators (Collaborative Organisation for RheothRx Evaluation).
OBJECTIVES: To examine the impact of time to thrombolytic treatment on multiple acute outcome variables in a single trial of thrombolysis in acute myocardial infarction. DESIGN AND PATIENTS: Mortality and reinfarction rate were measured in 2770 patients with acute myocardial infarction who received thrombolysis within 12 hours in CORE, an international, dose ranging trial of poloxamer 188. Tc-99m sestamibi infarct size and radionuclide angiographic ejection fraction substudies included 1099 and 1074 patients, respectively. RESULTS: Time to thrombolysis, subgrouped by intervals (< 2, 2-4, > or = 4-6, and > or = 6 hours), was significantly associated with infarct size (median 15.0%, 18.5%, 22.0%, 18.5% of left ventricle; p = 0.033), mean (SD) ejection fraction (51.5 (12.0)%, 48. 3 (13.9)%, 48.2 (13.3)%, 48.2 (15.0)%; p = 0.006), 35 day mortality (5.7%, 7.1%, 7.9%, 12.5%; p = 0.0004), six month mortality (7.3%, 8. 6%, 10.4%, 15.5%; p < 0.0001), and 35 day reinfarction rate (6.1%, 3. 2%, 4.0%, 0.9%; p = 0.0001). CONCLUSIONS: In this single large trial, the beneficial effect of time to thrombolysis on infarct size and ejection fraction was restricted to treatment given within two hours of symptom onset, while the effect on mortality was evident over all time intervals. Reinfarction rate was higher in patients treated with earlier thrombolysis.
Humans↗
Incidence, predictive factors, and prognostic significance of supraventricular tachyarrhythmias in congestive heart failure.
BACKGROUND: The incidence, predictive factors, morbidity, and mortality associated with the development of supraventricular tachyarrhythmias (SVTs) in patients with congestive heart failure (CHF) are poorly defined. METHODS: In the Digitalis Investigation Group trial, patients with CHF who were in sinus rhythm were randomly assigned to digoxin (n = 3,889) or placebo (n = 3,899) and followed up for a mean of 37 months. Baseline factors that predicted the occurrence of SVT and the effects of SVT on total mortality, stroke, and hospitalization for worsening CHF were determined. RESULTS: Eight hundred sixty-six patients (11.1%) had SVT during the study period. Older age (odds ratio [OR], 1.029 for each year increase in age; p = 0.0001), male sex (OR, 1.270; p = 0.0075), increasing duration of CHF (OR, 1.003 for each month increase in duration of CHF; p = 0.0021), and a cardiothoracic ratio of > 0.50 (OR, 1.403; p = 0.0001) predicted an increased risk of experiencing SVT. Left ventricular ejection fraction, New York Heart Association functional class, and treatment with digoxin vs placebo were not related to the occurrence of SVT. After adjustment for other risk factors, development of SVT predicted a greater risk of subsequent total mortality (risk ratio [RR] = 2.451; p = 0.0001), stroke (RR = 2.352; p = 0.0001), and hospitalization for worsening CHF (RR = 3. 004; p = 0.0001). CONCLUSION: In CHF patients in sinus rhythm, older age, male sex, longer duration of CHF, and increased cardiothoracic ratio predict an increased risk for experiencing SVT. Development of SVT is a strong independent predictor of mortality, stroke, and hospitalization for CHF in this population. Prevention of SVT may prolong survival and reduce morbidity in CHF patients.
Age Factors↗
Enalapril prevents clinical proteinuria in diabetic patients with low ejection fraction.
OBJECTIVE: Clinical proteinuria is a risk factor for both end-stage renal disease and cardiovascular disease. The prevalence of clinical proteinuria, its correlates and predictive value, and the effect of ACE inhibitors in preventing clinical proteinuria in diabetic and nondiabetic patients with left ventricular (LV) dysfunction are unknown. RESEARCH DESIGN AND METHODS: The Studies of Left Ventricular Dysfunction (SOLVD) trials were analyzed to determine the baseline distribution of clinical proteinuria and related cardiovascular risk factors, the effect of baseline proteinuria on the risk of hospitalization for congestive heart failure (CHF) and mortality, and the effect of enalapril in preventing new clinical proteinuria. RESULTS: A total of 5,487 out of 6,797 SOLVD participants (81%) were assessed for proteinuria at baseline. A total of 177 patients (3.2%) had baseline proteinuria. These patients had significantly higher systolic (137 vs. 125 mmHg, P < or = 0.001) and diastolic (83 vs. 77 mmHg, P < or = 0.001) blood pressure levels, a higher prevalence of diabetes (41 vs. 18%, P < or = 0.001), a lower ejection fraction (26.2 vs. 27.3%, P < or = 0.05), and greater degree of CHF (New York Heart Association [NYHA] class III/IV in 22 vs. 10%, P < or = 0.001) than patients without baseline proteinuria. Patients with baseline proteinuria also had higher rates of hospitalization for CHF (relative risk 1.81 [95% CI 1.37-2.41], P = 0.0001) and mortality (1.73 [1.34-2.24], P = 0.0001). Enalapril prevented clinical proteinuria in diabetic patients (0.38 [0.17-0.81], P = 0.0123) but not in nondiabetic patients (1.43 [0.77-2.63], P = 0.2622) without baseline proteinuria. CONCLUSIONS: Clinical proteinuria is an independent predictor of hospitalization for CHF and mortality in diabetic and nondiabetic patients with LV dysfunction. Enalapril significantly reduces the risk of clinical proteinuria in diabetic patients with LV dysfunction.
Angiotensin-Converting Enzyme Inhibitors↗
Prevalence and determinants of microalbuminuria in high-risk diabetic and nondiabetic patients in the Heart Outcomes Prevention Evaluation Study. The HOPE Study Investigators.
OBJECTIVE: To describe the characteristics of diabetic and nondiabetic participants in the Heart Outcomes Prevention Evaluation (HOPE) Study who are at high risk of developing cardiovascular (CV) disease and who have microalbuminuria (MA), and to identify the key determinants of MA in these two groups. RESEARCH DESIGN AND METHODS: Albuminuria was measured in 97% of patients enrolled in the HOPE Study as part of the MICRO-HOPE (MA, CV, and Renal Outcomes in HOPE) substudy. Baseline clinical characteristics of diabetic and nondiabetic participants with MA were recorded, and the univariate and multivariate relationship between these characteristics and the presence of MA was estimated for both groups. RESULTS: Baseline urinary albumin determinations were available in 3,574 (97.8%) diabetic participants and 5,708 (97.0%) nondiabetic participants. MA was detected in 1,151 (32.2%) diabetic participants and 837 (14.7%) nondiabetic participants. Age, waist-to-hip ratio, diabetes, smoking, hypertension, vascular disease, and left ventricular hypertrophy were independent determinants of MA in all participants. In diabetic participants, the odds of MA increased 16% for every 10.4 years of diabetes duration, and increased 8% for every 0.9% increase in glycated hemoglobin (assuming a GHb assay with an upper limit of 6% in the nondiabetic range). CONCLUSIONS: MA is independently associated with several risk factors for CV and renal disease in both diabetic and nondiabetic individuals at high risk for CV disease.
Aged↗
Oral anticoagulant therapy in patients with coronary artery disease: a meta-analysis.
CONTEXT: Despite years of use in coronary artery disease (CAD) and several studies of its effectiveness, the role of oral anticoagulants (OAs) remains controversial. OBJECTIVE: To determine the effects of long-term OA therapy, stratified by the intensities of anticoagulation and aspirin therapy, on outcomes in patients with CAD. DATA SOURCES: Studies were identified by MEDLINE, EMBASE, and CURRENT CONTENTS searches (1960-July 1999) and by reviewing reference lists and inquiring with experts and pharmaceutical companies. STUDY SELECTION: Studies were included if they were published between 1960 and July 1999, were randomized, had recruited patients with CAD, who had used OA therapy for at least 3 months. Of 43 articles identified, 30 articles (31 trials) were analyzed. DATA EXTRACTION: Information on type, duration, and method of monitoring OA therapy, as well as rates of death, myocardial infarction (MI), thromboembolic complications, stroke, and bleeding were abstracted by 2 independent observers. DATA SYNTHESIS: With high-intensity (international normalized ratio [INR], 2.8-4.8) OAs vs control (16 trials, 10056 patients), clear reductions in mortality (odds reduction [ORed], 22%; 95% confidence interval [CI], 13%-31%), MIs (ORed, 42%; 95% CI, 34%-48%), and thromboembolic complications including stroke (ORed, 63%; 95% CI, 53-71%) were observed, but were associated with a 6.0-fold (95% CI, 4.4- to 8.2-fold) increase in major bleeding. For moderate OAs (INR, 2-3) vs control (4 trials, 1365 patients) the ORed for death was 18% (95% CI, -6% to 37%); for MI, 52% (95% CI, 37%-64%); and for stroke, 53% (95% CI, 19%-73%), but it increased bleeding by 7.7-fold (95% CI, 3.3- to 18-fold). For moderate- to high-intensity OAs (INR, > or =2) vs aspirin (7 trials, 3457 patients), no reduction in death, MI, or stroke was observed, and it was associated with a 2.4-fold (95% CI, 1.6- to 3.6-fold) increase in major bleeding. For moderate- to high-intensity OAs and aspirin vs aspirin alone (3 trials, 480 patients), the ORed for death, MI, or stroke was 56% (95% CI, 17%-77%) and major bleeding increased by 1.9-fold (0.6- to 6.0-fold). For low-intensity OAs (INR, <2.0) and aspirin vs aspirin alone (3 trials, 8435 patients), no significant reduction in death, MI, or stroke was observed, and major bleeding increased by 1.3-fold (95% CI, 1.0- to 1.8-fold). CONCLUSIONS: Among patients with CAD, high-intensity and moderate-intensity OA are effective in reducing MI and stroke but increase the risk of bleeding. In the presence of aspirin, low-intensity OA does not appear to be superior to aspirin alone, while moderate- to high-intensity OA and aspirin vs aspirin alone appears promising and the bleeding risk is modest, but this requires confirmation from ongoing trials.
Administration, Oral↗
ACC/AHA guidelines for coronary artery bypass graft surgery: executive summary and recommendations : A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to revise the 1991 guidelines for coronary artery bypass graft surgery).
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American Heart Association↗
Comparison of candesartan, enalapril, and their combination in congestive heart failure: randomized evaluation of strategies for left ventricular dysfunction (RESOLVD) pilot study. The RESOLVD Pilot Study Investigators.
BACKGROUND: We investigated the effects of candesartan (an angiotensin II antagonist) alone, enalapril alone, and their combination on exercise tolerance, ventricular function, quality of life (QOL), neurohormone levels, and tolerability in congestive heart failure (CHF). METHODS AND RESULTS: Seven hundred sixty-eight patients in New York Heart Association functional class (NYHA-FC) II to IV with ejection fraction (EF) <0.40 and a 6-minute walk distance (6MWD) <500 m received either candesartan (4, 8, or 16 mg), candesartan (4 or 8 mg) plus 20 mg of enalapril, or 20 mg of enalapril for 43 weeks. There were no differences among groups with regard to 6MWD, NYHA-FC, or QOL. EF increased (P=NS) more with candesartan-plus-enalapril therapy (0.025+/-0.004) than with candesartan alone (0.015+/-0.004) or enalapril alone(0.015+/-0.005). End-diastolic (EDV) and end-systolic (ESV) volumes increased less with combination therapy (EDV 8+/-4 mL; ESV 1+/-4 mL; P<0.01) than with candesartan alone (EDV 27+/-4 mL; ESV 18+/-3 mL) or enalapril alone (EDV 23+/-7 mL; ESV 14+/-6 mL). Blood pressure decreased with combination therapy (6+/-1/4+/-1 mm Hg) compared with candesartan or enalapril alone (P<0.05). Aldosterone decreased (P<0.05) with combination therapy (23.2+/-5.3 pg/mL) at 17 but not 43 weeks compared with candesartan (0.7+/-7.8 pg/mL) or enalapril (-0.8+/-11. 3 pg/mL). Brain natriuretic peptide decreased with combination therapy (5.8+/-2.7 pmol/L; P<0.01) compared with candesartan (4. 4+/-3.8 pmol/L) and enalapril alone (4.0+/-5.0 pmol/L). CONCLUSIONS: Candesartan alone was as effective, safe, and tolerable as enalapril. The combination of candesartan and enalapril was more beneficial for preventing left ventricular remodeling than either candesartan or enalapril alone.
Aged↗
Homocyst(e)ine and cardiovascular disease: a critical review of the epidemiologic evidence.
PURPOSE: To review epidemiologic studies on the association between homocyst(e)ine level and risk for cardiovascular disease and the potential benefits of homocysteine-decreasing therapies. DATA SOURCES: Computerized and manual searches of the literature on total homocysteine levels and cardiovascular disease. STUDY SELECTION: Prospective studies and major retrospective epidemiologic studies evaluating the association between homocyst(e)ine levels and cardiovascular disease and the association between blood levels or dietary intake of folate, vitamin B6, and vitamin B12 and cardiovascular disease. DATA EXTRACTION: Relevant data on patient population, plasma homocyst(e)ine levels, duration of follow-up, and main results were extracted from studies that met the inclusion criteria. DATA SYNTHESIS: The designs and results of studies included in this review are summarized. A formal meta-analysis was not performed because the studies were heterogeneous in method and design. CONCLUSIONS: Results of epidemiologic studies suggest that moderately elevated plasma or serum homocyst(e)ine levels are prevalent in the general population and are associated with an increased risk for cardiovascular disease, independent of classic cardiovascular risk factors. Simple, inexpensive, nontoxic therapy with folic acid, vitamin B6, and vitamin B12 reduces plasma homocyst(e)ine levels. Although the association between homocyst(e)ine levels and cardiovascular disease is generally strong and biologically plausible, the data from the prospective studies are less consistent. In addition, epidemiologic observations of an association between hyperhomocyst(e)inemia and cardiovascular risk do not prove the existence of a causal relation. Therefore, the effectiveness of folate, vitamin B6, and vitamin B12 in reducing cardiovascular morbidity and mortality requires rigorous testing in randomized clinical trials. Several such trials are under way; their results may greatly affect cardiovascular morbidity and mortality, given the simplicity and low cost of vitamin therapy.
Arteriosclerosis↗
Design, baseline characteristics, and preliminary clinical results of the Organization to Assess Strategies for Ischemic Syndromes-2 (OASIS-2) trial.
Despite use of heparin and aspirin, 5-10% of patients with unstable angina develop myocardial infarction (MI) or refractory angina in the hospital. We tested the hypothesis that recombinant hirudin (lepirudin), a direct thrombin inhibitor, is superior to heparin, an indirect thrombin inhibitor, in patients with acute ischemic syndromes who were receiving aspirin. Patients (n = 10,141) with unstable angina or suspected acute MI without ST-segment elevation were randomly assigned heparin (5,000-U bolus, then 15-U/kg per hour infusion; n = 5,058) or hirudin (0.4-mg/kg bolus, then 0.15-mg/kg per hour infusion; n = 5,083) for 72 hours in a double-blind trial. The primary outcome measure was cardiovascular death or new MI at 7 days. Analysis was by intention to treat. At 7 days, 213 patients (4.2%) in the heparin group and 182 (3.6%) in the hirudin group had experienced cardiovascular death or new MI (relative risk = 0.84; 95% CI = 0.69-1.02; p = 0.077). The number of patients with cardiovascular death, new MI, or refractory angina at 7 days was 340 (6.7%) with heparin and 284 (5.6%) with hirudin (relative risk = 0.82; 95% CI = 0.70-0.96; p = 0.0125). These differences were primarily observed during the 72-hour treatment period (cardiovascular death or MI relative risk = 0.76; 95% CI = 0.59-0.99; p = 0.039; cardiovascular death, MI, or refractory angina relative risk = 0.78; 95% CI = 0.63-0.96; p = 0.019). Although there was an excess of major bleeding with hirudin requiring transfusion (59 [1.2%] vs 34 [0.7%] with heparin; p = 0.01), there was no excess in life-threatening episodes (20 in each group) or strokes (14 in each group). Data from the Organization to Assess Strategies for Ischemic Syndromes (OASIS)-2 trial suggest that a direct thrombin inhibitor, recombinant hirudin, is more effective than an indirect thrombin inhibitor, heparin, in preventing cardiovascular death, MI, or refractory angina. Recombinant hirudin also has an acceptable safety profile in patients with unstable angina or acute MI without ST-segment elevation.
Adult↗
The Organization to Assess Strategies for Ischemic Syndromes (OASIS) registry in patients with unstable angina.
Clinical approaches to the prevention of the potentially catastrophic consequences of coronary ischemic phenomena such as unstable angina and suspected non-Q-wave myocardial infarction (MI) differ across the world. In addition to prevailing physician beliefs in different societies, the level of access to catheterization laboratories largely determines whether an interventionist or conservative strategy is adopted. The Organization to Assess Strategies for Ischemic Syndromes (OASIS)--a prospective registry of approximately 8,000 patients with acute myocardial ischemia with no ST elevation, treated in 95 hospitals across 6 countries--furnished a unique window into regional differences in clinical management and the frequency and timing of invasive procedures (i.e., angiography, percutaneous transluminal coronary angioplasty [PTCA], and coronary artery bypass graft [CABG] surgery), as well as the outcomes of these trends. At 6 months after symptom onset, patients in the United States and Brazil, where the catheterization laboratory facilities are more accessible, underwent significantly (p <0.001) more angiography (69.4%), PTCA (23.6%), and CABG (25.2%) than in Canada and Australia, where the corresponding rates were 48.4%, 17.0%, and 16.8% (p <0.001), respectively; and in Hungary and Poland, where the respective rates were 23.5%, 5.8%, and 10.9% (p <0.001). This relatively aggressive approach led at 6 months to a more substantial decrease in refractory angina in the United States and Brazil than in Canada and Australia (20.4% vs 13.9%; p <0.001), but no improvement in rates of cardiovascular mortality and MI (10.5% versus 10.5%; p = 0.36). There was a significant (p < or = 0.012) increase in stroke, (1.9% vs 1.3%; p = 0.010) and major bleeding (1.9% vs 1.1%; p = 0.009) events. Furthermore, an inverse correlation emerged between baseline cardiovascular risk status and frequency of angiography and PTCA interventions preferentially for low-risk compared with high-risk patients. In concert with findings from other recent randomized trials, the OASIS Registry data suggest that although there are fewer hospital readmissions for unstable angina, there is a trend toward increased rates of death, MI, and stroke. These data urge a cautious approach to the use of invasive procedures in patients with unstable angina unless future trials demonstrate a clear benefit with an aggressive approach.
Adrenergic beta-Antagonists↗
Randomised controlled trials in cardiovascular medicine: past achievements, future challenges.
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Cardiology↗
Cardiovascular and cancer mortality among Canadians of European, south Asian and Chinese origin from 1979 to 1993: an analysis of 1.2 million deaths.
BACKGROUND: Cardiovascular disease and cancer are important health problems worldwide, yet our knowledge of these conditions is derived principally from populations of European descent. To investigate ethnic variations in major causes of death in Canada, the authors examined total and cause-specific mortality among European, south Asian, and Chinese Canadians. METHODS: Canadians of European, south Asian and Chinese origin were identified in the Canadian Mortality Database by last name and country of birth and in the population census by self-reported ethnicity. Age-standardized death rates by cause, per 100,000 population, were calculated for ages 35 to 74 years from 1979 to 1993 and in 5-year intervals grouped around census years (1979/83, 1984/88 and 1989/93). RESULTS: Rates of death from ischemic heart disease were highest among Canadians of south Asian origin (men 320.2, women 144.5) and European origin (men 319.6, women 109.9) and were markedly lower among Canadians of Chinese origin (men 107.0, women 40.0); the rates declined significantly in all 3 groups over the study period. Rates of death from cerebrovascular disease were relatively low and showed less ethnic variation (Canadian men of European, south Asian and Chinese origin 49.5, 47.0 and 45.8 respectively; Canadian women of European, south Asian and Chinese origin 34.8, 39.0 and 42.2 respectively) and declined similarly in all groups over time. Rates of death from cancer were highest among Canadians of European origin (men 343.6, women 236.2), intermediate among those of Chinese origin (men 258.1, women 161.6) and lowest among those of south Asian origin (men 122.3, women 131.3). Over time, cancer mortality increased in Canadians of European origin but remained constant or declined in those of south Asian and Chinese origin. INTERPRETATION: Substantial differences exist in rates of death from ischemic heart disease and cancer among European, south Asian and Chinese Canadians.
Adult↗
Evidence based cardiology: prevention of congestive heart failure and management of asymptomatic left ventricular dysfunction.
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Adult↗
Evidence based cardiology: emerging approaches in preventing cardiovascular disease.
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Angiotensin-Converting Enzyme Inhibitors↗
Relationship of glucose and insulin levels to the risk of myocardial infarction: a case-control study.
OBJECTIVE: To assess the relationship between dysglycemia and myocardial infarction in nondiabetic individuals. BACKGROUND: Nondiabetic hyperglycemia may be an important cardiac risk factor. The relationship between myocardial infarction and glucose, insulin, abdominal obesity, lipids and hypertension was therefore studied in South Asians-a group at high risk for coronary heart disease and diabetes. METHODS: Demographics, waist/hip ratio, fasting blood glucose (FBG), insulin, lipids and glucose tolerance were measured in 300 consecutive patients with a first myocardial infarction and 300 matched controls. RESULTS: Cases were more likely to have diabetes (OR 5.49; 95% CI 3.34, 9.01), impaired glucose tolerance (OR 4.08; 95% CI 2.31, 7.20) or impaired fasting glucose (OR 3.22; 95% CI 1.51, 6.85) than controls. Cases were 3.4 (95% CI 1.9, 5.8) and 6.0 (95% CI 3.3, 10.9) times more likely to have an FBG in the third and fourth quartile (5.2-6.3 and >6.3 mmol/1); after removing subjects with diabetes, impaired glucose tolerance and impaired fasting glucose, cases were 2.7 times (95% CI 1.5-4.8) more likely to have an FBG >5.2 mmol/l. A fasting glucose of 4.9 mmol/l best distinguished cases from controls (OR 3.42; 95% CI 2.42, 4.83). Glucose, abdominal obesity, lipids, hypertension and smoking were independent multivariate risk factors for myocardial infarction. In subjects without glucose intolerance, a 1.2 mmol/l (21 mg/dl) increase in postprandial glucose was independently associated with an increase in the odds of a myocardial infarction of 1.58 (95% CI 1.18, 2.12). CONCLUSIONS: A moderately elevated glucose level is a continuous risk factor for MI in nondiabetic South Asians with either normal or impaired glucose tolerance.
Biomarkers↗
Increased winter mortality from acute myocardial infarction and stroke: the effect of age.
OBJECTIVES: We examined seasonal variations in mortality from acute myocardial infarction (AMI) and stroke by age using 300,000 deaths in the Canadian Mortality Database for the years 1980 to 1982 and 1990 to 1992. BACKGROUND: The effect of age on environmental determinants of AMI and stroke is not well understood. METHODS: Seasonal variations were analyzed by month and for the four seasons (winter beginning in December). A chi-square test was used to test for homogeneity at p < 0.01, and relative risk ratios (RRs) for high and low periods were determined in relation to the overall mean. For each of four age subgroups, the magnitude of the seasonal variation was reported as the difference in mortality between the highest and lowest frequency seasons. RESULTS: By month, AMI deaths were highest in January (RR = 1.090) and lowest in September (RR = 0.904), a relative risk difference of 18.6%. The seasonal mortality variation in AMI deaths (winter vs. summer) increased with increasing age: 5.8% for <65, 8.3% for 65 to 74, 13.4% for 75 to 84 and 15.8% for >85 years (p < 0.005 for trend). Stroke mortality peaked in January (RR = 1.113) and had a trough in September (RR = 0.914), a relative risk difference of 19.9%. The seasonal variation in stroke mortality also increased with age. Seasonal variations were not seen in those aged <65 years, compared with 11.6% for 65 to 74, 15.2% for 75 to 84 and 19.3% for >85 years (p < 0.005 for trend). CONCLUSIONS: The elderly demonstrate a greater winter increase in AMI and stroke mortality than younger individuals. An understanding of these seasonal patterns may provide novel avenues for research in cardiovascular disease prevention.
Age Factors↗