Risk factors in stroke: a clinical study in Mexican patients

Association Between Nitrogen Dioxide Pollution and Cause-Specific Mortality in China: Cross-Sectional Time Series Study

BACKGROUND

Nitrogen dioxide (NO2) has been frequently linked to a range of diseases and associated with high rates of mortality and morbidity worldwide. However, there is limited evidence regarding the risk of NO2 on a spectrum of causes of mortality. Moreover, adjustment for potential confounders in NO2 analysis has been insufficient, and the spatial resolution of exposure assessment has been limited.

OBJECTIVE

This study aimed to quantitatively assess the relationship between short-term NO2 exposure and death from a range of causes by adjusting for potential confounders in Guangzhou, China, and determine the modifying effect of gender and age.

METHODS

A time series study was conducted on 413,703 deaths that occurred in Guangzhou during the period of 2010 to 2018. The causes of death were classified into 10 categories and 26 subcategories. We utilized a generalized additive model with quasi-Poisson regression analysis using a natural cubic splines function with lag structure of 0 to 4 days to estimate the potential lag effect of NO2 on cause-specific mortality. We estimated the percentage change in cause-specific mortality rates per 10 μg/m3 increase in NO2 levels. We stratified meteorological factors such as temperature, humidity, wind speed, and air pressure into high and low levels with the median as the critical value and analyzed the effects of NO2 on various death-causing diseases at those high and low levels. To further identify potentially vulnerable subpopulations, we analyzed groups stratified by gender and age.

RESULTS

A significant association existed between NO2 exposure and deaths from multiple causes. Each 10 μg/m3 increment in NO2 density at a lag of 0 to 4 days increased the risks of all-cause mortality by 1.73% (95% CI 1.36%-2.09%) and mortality due to nonaccidental causes, cardiovascular disease, respiratory disease, endocrine disease, and neoplasms by 1.75% (95% CI 1.38%-2.12%), 2.06% (95% CI 1.54%-2.59%), 2.32% (95% CI 1.51%-3.13%), 2.40% (95% CI 0.84%-3.98%), and 1.18% (95% CI 0.59%-1.78%), respectively. Among the 26 subcategories, mortality risk was associated with 16, including intentional self-harm, hypertensive disease, and ischemic stroke disease. Relatively higher effect estimates of NO2 on mortality existed for low levels of temperature, relative humidity, wind speed, and air pressure than with high levels, except a relatively higher effect estimate was present for endocrine disease at a high air pressure level. Most of the differences between subgroups were not statistically significant. The effect estimates for NO2 were similar by gender. There were significant differences between the age groups for mortality due to all causes, nonaccidental causes, and cardiovascular disease.

CONCLUSIONS

Short-term NO2 exposure may increase the risk of mortality due to a spectrum of causes, especially in potentially vulnerable populations. These findings may be important for predicting and modifying guidelines for NO2 exposure in China.

Air Pressure, Humidity and Stroke Occurrence: A Systematic Review and Meta-Analysis

Background/Aims: An influence of climate upon stroke risk is biologically plausible and supported by epidemiological evidence. We aimed to determine whether air pressure (AP) and humidity are associated with hospital stroke admission. Methods: We searched MEDLINE, Embase, PsycINFO, CINAHL, Web of Science, and GEOBASE, from inception to 16 October 2015 to identify relevant population-based observational studies. Where possible, data were pooled for meta-analysis with odds ratios (OR) and corresponding 95% confidence intervals (CI) by means of the random-effect method. Results: We included 11 studies with a total of 314,385 patients. The effect of AP was varied across studies for ischemic stroke (IS) and subarachnoid haemorrhage (SAH). Pooled ORs (95%CI) associated with 1 hPa increase in AP for the risk of IS, intracerebral hemorrhage (ICH) and SAH were 1.00 (0.99–1.01), 1.01 (0.99–1.02) and 1.02 (0.97–1.07) respectively. The pooled ORs (95%CI) associated with 1 percent increase in humidity for the risk of IS and ICH were 1.00 (1.00–1.01) and 1.00 (0.99–1.01) respectively. Conclusion: This review shows that there is no evidence of a relationship between AP or humidity and the occurrence of hospital admission for stroke. Further research is needed to clarify the extent and nature of any relationship between AP, humidity and stroke in different geographical areas.

Environmental factors and stroke: A selective review

Despite numerous prior stroke risk factor investigations, much remains unknown about the effect of environmental factor changes on stroke incidence and mortality rates. Yet these data might be important for defining a number of measures to prevent stroke and for developing a greater understanding of the origin and incidence trends of stroke in different regions and populations. In this paper we review the current state of knowledge about certain environmental stroke risk factors.

Stroke program for India

India is silently witnessing a stroke epidemic. There is an urgent need to develop a national program towards "Fighting Stroke". This program should be specific to our national needs. In order to recommend on who should lead an Indian fight-stroke program, we examined the published opinions of stroke clinicians and the official documents on stroke care training abroad. We identified the resources that already exist in India and can be utilized to develop a national fight-stroke program. Through a review of published literature, we noted different opinions that exist on who would best manage stroke. We found that because stroke is a cardiovascular disorder of the central nervous system, its management requires a multi-disciplinary approach involving clinicians with background not limited to neurology. India has very few neurologists trained in stroke medicine and they cannot care for all stroke patients of the country. We propose a mechanism that would quickly put in place a stroke care model relevant in Indian context. We recommend for tapping the clinical expertise available from existing pool of non-neurologist physicians who can be trained and certified in stroke medicine (Strokology). We have discussed an approach towards developing a national network for training and research in Strokology hoping that our recommendations would initiate discussion amongst stroke academicians and motivate the national policy makers to quickly develop an "Indian Fight Stroke Program."

The related causes in very early morning onset of stroke

We investigated the influence of early awakening and related factors on onset of cerebrovascular disease (CVD). Totally 1199 stroke patients, in whom the onset time was known, at 3 reference hospitals were included in this study. The effects of demographic, medical, and pathophysiological factors on the circadian pattern of an unselected series of patients with ischemic stroke were analyzed. Nine-hundred seventeen CVD patients with cerebral infarction (CI), 240 patients with intracerebral hemorrhage (CH), and 42 patients with subarachnoid hemorrhage (SAH) were identified. The greatest portion of strokes (32.5%) occurred between 03:00 and 06:00 a.m. Nearly one half of the strokes in this series occurred in the very early- to mid-morning hours. This analysis of strokes provides strong evidence with a higher risk in the early morning hours (03:00 a.m. to 06:00 a.m.), and lower risk during the night time period (21:00 p.m. to midnight). Approximately 1 of every 3 strokes (1 of 3 ischemic strokes, 1 of 6 hemorrhagic strokes, and 1 of 8 subarachnoid hemorrhages) is attributable to the early morning excess. This difference tried to be explained by three ways: cold weather, religious factors, and physiological mechanisms.

Diurnal and seasonal variations in the onset of primary intracerebral hemorrhage in individuals living in Izumo City, Japan

OBJECT

Little is known about the temporal patterns of primary intracerebral hemorrhage (ICH) among the general population. The aim of this study was to examine diurnal and seasonal variations in the onset of ICH in a community-based series.

METHODS

The study population consisted of 350 patients who presented with primary ICH for the first time and were treated between 1991 and 1998 in Izumo City, Japan. Among the entire patient population, the onset of hemorrhage was rarely observed during the night and a peak was observed in the late afternoon. In men 69 years of age or younger, the onset of ICH exhibited a bimodal distribution, with an initial high peak between 8:00 and 10:00 a.m. and a second, lower peak between 6:00 and 8:00 p.m. In contrast, in men 70 years of age or older and in women regardless of age, only a single evening peak, between approximately 6:00 and 10:00 p.m., was found, and no morning peak was observed. For the entire patient population (for both sexes), and for men alone, seasonal variations--a peak in winter and a trough in summer-were significant for all age groups combined. This factor was significant for patients 69 years of age or younger, during the daytime hours (8:00 a.m.-8:00 p.m.), and for patients with untreated hypertension; however, it was not significant for patients 70 years of age or older, during nighttime hours (10:00 p.m.-8:00 a.m.), or for treated hypertensive and normotensive patients. In women, no significant seasonal patterns were found, regardless of patient age, time of day at onset of ICH, or the presence of risk factors. Seasonal variations were statistically significant for patients with hematomas larger than 5 ml, but not for those with hematomas 5 ml or smaller.

CONCLUSIONS

Temporal distributions in the onset of ICH seem to be influenced by patient sex and age. The seasonal patterns of ICH occurrence may result mainly from changes that occur during the daytime, and may also be modified by the presence of untreated hypertension and by the volume of the hematoma.

A population-based study of the associations of stroke occurrence with weather parameters in Siberia, Russia (1982-92)

Previous studies have established a seasonal variation in stroke occurrence, but none have assessed the influence of inclement weather conditions on stroke incidence in a general population of Russia. We performed a stroke population-based study in the Oktiabrsky District of Novosibirsk, Siberia, Russia. Included in the analysis were 1929 patients with their first occurrence of ischemic stroke (IS), 215 patients with their first occurrence of intracerebral hemorrhage (ICH) and 64 patients with their first occurrence of subarachnoid hemorrhage (SAH): all patients were aged between 25 and 74 years. The cumulative daily occurrence of total strokes and stroke subtypes was evaluated in relation to aggregated daily mean values of ambient temperature, relative humidity and air pressure by means of Poisson regression analysis to estimate the rate ratio (RR) with corresponding confidence interval (CI) and to identify the weather parameters of most importance. In a multivariate analysis, with adjustment for the effects of season, solar and geomagnetic activity, and age of the patients, low ambient temperature (RR 1.32; 95% CI 1.05-1.66) and mean value of air pressure (RR 0.986; 95% CI 0.972-0.999) were important predictors of IS occurrence, while mild ambient temperature (RR 1.52; 95% CI 1. 04-2.22) was an important predictor of ICH occurrence. No relationship between SAH occurrence and any one of the weather parameters studied was revealed. There was no interaction between any meteorological variables that was statistically significant. Inclement weather conditions are associated with the occurrence of IS and ICH in Siberia, Russia. Among the meteorological parameters studied, low ambient temperature and mean air pressure are the most important predictors of IS occurrence, whereas the occurrence of ICH is associated with mild ambient temperature. There is no association between any one of the weather parameters studied and the occurrence of SAH.

Chronobiological patterns of onset of acute cerebrovascular diseases

There is a considerable amount of data indicating that several major unfavorable cerebrovascular events are not randomly distributed over time, but show a peculiar distribution along the day, the week, and the months of the year. The authors review the available evidence on the chronobiological (circadian, weekly, and seasonal) patterns of onset of acute cerebrovascular diseases and variations in their possible triggering mechanisms. The existence of a peculiar chronobiological pattern in the onset of acute cerebrovascular disease, characterized by both circadian (morning and evening occurrence), circaseptan (last and first days of the week), and circannual (especially in winter) is confirmed, although differences depending on biological (gender, age), pathological (diabetes, hypertension, smoke, alcohol), cultural, social, and environmental factors exist. A deeper knowledge of the underlying pathophysiologic mechanisms could provide more effective insights for both preventive strategies and optimization of therapeutic approach.

Very early morning increase in onset of ischemic stoke

A study was conducted on 525 consecutive patients ranging in age from 36 years to 86 years to determine whether diurnal variation occurs in the onset of acute ischemic stroke. There was a clear (Dmax=0.19, P<0.01) diurnal variation with a significant (t=-4.96, P<0.001) peak between four a.m. and six a.m. Strokes occurred more often during the two hours following awakening than during any other time of the day. The peak time of ischemic stroke in our study was about two hours earlier than in previous reports, probably because of the different waking times of the studied populations. We concluded that the time of awakening influences the circadian distribution rather than the time of day itself.

Diurnal variation in incidence of stroke: Oxfordshire community stroke project

OBJECTIVE

To determine whether diurnal variation occurs in the onset of stroke.

DESIGN

Community based study over four years.

SETTING

Oxfordshire, United Kingdom.

SUBJECTS

105,000 people, of whom 675 had a first ever stroke. 545 had a cerebral infarction, 66 had primary intracerebral haemorrhage, 33 had subarachnoid haemorrhage, and in 31 the type of stroke was not known.

MAIN OUTCOME MEASURES

Time of stroke and degree of activity at onset.

RESULTS

In the 578 patients for whom it was known whether onset occurred while asleep or awake, the proportion with onset during sleep was 25% (135/545) for cerebral infarction, 17% (11/66) for primary intracerebral haemorrhage, and 0% (0/33) for subarachnoid haemorrhage. This difference persisted if patients in whom it was not known whether they were asleep or awake at onset were classed as asleep. For all stroke types together there was a significant (chi 2 = 218.7, p less than 0.001) diurnal variation with a morning peak between 0800 and 1000, which persisted even after allowing for strokes first noted on waking by redistributing the hour of onset through the preceding eight hours (chi 2 = 47, p less than 0.001). A significant diurnal variation was also found in the onset of cerebral infarction (peak 0800-1000, chi 2 = 208.4, p less than 0.001). Fewer patients had other forms of stroke and the diurnal variations for primary intracerebral haemorrhage (peak 1000-1200) and subarachnoid haemorrhage (peaks 0800-1000 and 1800-2000) were not significant. There seemed to be a second smaller peak for all types of stroke.

CONCLUSIONS

All types of stroke are most likely to occur after waking in the morning. The cause of the circadian variation requires further study.

[Diabetes mellitus as a prognostic factor in ischemic cerebrovascular diseases]

As part of a prospective study about 347 cases of ischemic cerebral vascular disease (DCVI) admitted to a general hospital 36 diabetic and 36 non-diabetic patients with similar sex, age and blood pressure were evaluated with the objective of assessing the effect of diabetes mellitus on prognosis in DCVI. All patients had various types of DCVI (thrombosis, thromboembolism or cardiac embolism). The diabetic patients had statistically longer admissions (p less than 0.05), more complications during admission (p less than 0.05), more infectious complications (p less than 0.01) and a greater number of deaths at the end of follow-up (p less than 0.05). After 377 +/- 429 (mean +/- standard deviation) days of follow-up, 50% of the diabetics had died while after 387 +/- 405 days 25% of the non-diabetics had died. Deaths in both groups occurred in average at the 8th month after the vascular event that led to the first admission. There were no differences with respect to the number of deaths during admission or to neurological conditions of the survivors at the end of the first admission or at the end of follow-up.

Do patients with sleep apnea die in their sleep?

Patients with sleep apnea syndrome (SAS) show cardiac dysrhythmias in association with cyclical nocturnal hypoxemia; are they at risk of dying during sleep? To assess this claim, we reviewed the clinical course of 91 patients with polysomnographically documented SAS between July 1978 and June 1986. A control group was comprised of 35 patients who were referred with symptoms suggestive of SAS but had negative sleep studies. Follow-up was obtained by survey questionnaire. Nine of 91 SAS and four of 35 control patients had died by completion of the study. There were no statistically significant differences in mortality between the two groups. None of the SAS patients died in their sleep, but they reported a higher incidence of disability and vehicular mishaps than did control subjects. The findings in this study do not support the hypothesis that SAS patients are at increased risk of dying in their sleep.

Wind-chill and the seasonal variation of cerebrovascular disease

The hospital admission rates for patients with specific types of stroke were examined for seasonal variation and correlation with meteorological factors. A seasonal variation in admission rates was found for subarachnoid haemorrhage, thrombo-embolic brain infarction and ill-defined cerebrovascular disease. Overall this seasonality was more strongly associated with the computed chilling effect of the atmosphere than with changes in temperature, humidity or wind speed alone. No seasonal variation was observed for admission rates of intracerebral haemorrhage, transient ischaemic attack or occlusion of precerebral arteries. Intracerebral haemorrhage admission rates exhibited a decrease with time. This evidence suggests that seasonal variation in admission rates exists only for certain pathological types of stroke and this is strongly associated with changes in the chilling effect of the atmosphere.

Italian multicenter study of reversible cerebral ischemic attacks. Part 5. Risk factors and cerebral atherosclerosis

As part of a prospective study, the influence of several premorbid and environmental factors on the presence, extent and severity of cerebral vessel atherosclerosis was studied in 462 patients with clinical diagnosis of RIA who underwent cerebral angiography. The extent and severity of atherosclerosis of the cerebral vessels was quantified using extracranial and intracranial cerebrovascular scores (ECS, ICS) based on the number and severity of the lesions in 11 extracranial and 21 intracranial arterial segments. Results of univariate and multivariate analyses indicate that the presence of atherosclerotic changes of cerebral vessels, as shown by angiography, was strongly related with age in both sexes. The lesions were more frequent in males, in particular under age 55. Elevated cholesterol was associated with a higher incidence of atherosclerotic lesions. Smoking was associated with a higher incidence of extracranial lesions. Age, smoking and history of hypertension were the best predictors of the extent and severity of cerebral vessel atherosclerosis.

When people die. Cause of death versus time of death

A sample of 4,920 disease-related deaths from New York City for 1979 (8.7 percent of all relevant data from New York City's files) showed a 60 percent rise in death rate beginning at 2 A.M. and reaching a peak at 8 A.M. A smaller peak was also noted at 6 P.M. The rise in human mortality beginning at 2 A.M. and peaking at 8 A.M. might be explained by: artifact of deaths occurring anytime during the night that are discovered after daybreak, effect of less efficient health care between 2 A.M. and 8 A.M., and disease processes that somehow increase risk of death between 2 A.M. and 8 A.M. An attempt was made to differentiate among these possibilities by comparing time of death for various subsamples. The bimodal pattern appeared only in the temporal distribution of deaths of persons over 65 years of age; deaths of persons under 65 did not show significant temporal concentration. There were also prominent differences in the distribution of deaths for different reported causes of death. Ischemic heart disease, which numerically accounted for over 50 percent of the sample, showed peak mortality at 8 A.M. for both males and females. Hypertensive disease showed a significant peak in mortality at 1 A.M. for females only. Cerebrovascular disease peaked significantly at 6 A.M. with a significant peak only for males. The age and disease specificity of the 2 A.M. to 8 A.M. rise in death is consistent with a disease-related explanation for the bimodal circadian pattern in mortality. The quality and efficiency of health care could be improved with more precise information on peak periods of risk for specific morbid conditions.