It is not clear if the downward trend in cardiovascular disease (CVD) observed for ages up to 85 years can be extended to the oldest old, those 85 years and above.
This nationwide cohort study presents age specific trends of CVD as well as for myocardial infarction (MI) and stroke separately for the period 1994 to 2010 for individuals 85 to 99 years old in Sweden. Data were extracted from national registries. All analyses were based on one-year age- and sex- specific figures. The risk for CVD increased with every age above 85 years although the rate of increase leveled off with age. Over time, the risk for CVD and MI decreased for all ages, and for stroke for ages up to 89 years. However, the risk of MI increased until around 2001 in all age groups and both sexes but decreased after that. The overall mortality improved for all outcomes over the period 1994 to 2010, so did the survival within 28 days from an event. The average annual decline in mortality over all ages, 85 and above was 3% for MI, 2% for stroke and for 2% CVD. Corresponding figures for ages 60-84 was 4% for each of MI, stroke and CVD. The results were similar for men and women.
Improvements in CVD risks observed among ages up to 85 years appear to have extended also to ages above 85 years, even if the rate of improvement plateaued with age. The improvements in survival for all ages up to 99 years give no support to the hypothesis that more fragile individuals reach higher ages. Additional research is needed to find out if improvement in survival can be seen also for the second and third event of CVD, stroke and MI.
It is often taken for granted that an ageing population will lead to an increased burden for the health care sector. However, for several diseases of big public health impact the rates have actually come down for a substantial period of time. In this study we investigate how much the incidence rates for myocardial infarction (MI), stroke, and cancer will have to decline in order to counterbalance future demographic changes (changes in population size and age structure) and compare these figures with observed historical trends. Information on incidence rates were obtained from the National Board of Health and Welfare and referred to the total Swedish population. Population projections were obtained from Statistics Sweden. We projected the number of MI events to increase 50-60% between 2010 and 2050. The decline in incidence rates that is required to keep the number of events constant over time is, on average, 1.2%/year for men and 0.9%/year for women, somewhat higher than the trend for the past 10 years. For stroke the corresponding figures were 1.3% (men) and 1% (women), well in line with historical trends. For cancer the results indicate an increasing number of events in the future. Population ageing is more important than population growth when projecting future number of MI, stroke and cancer events. The required changes in incidence rates in order to counterbalance the demographic changes are well in line with historical figures for stroke, almost in line regarding MI, but not in line regarding cancer. For diseases with age dependence similar to these diseases, a reduction of incidence rates in the order of 1-2% is sufficient to offset the challenges of the ageing population. These are changes that have been observed for several diseases indicating that the challenges posed by the ageing population may not be as severe as they may seem when considering the demographic component alone.
It has been suggested that certain health behaviours, such as smoking, may operate as mediators of the well-established inverse association between IQ and mortality risk. Previous research may be afflicted by unadjusted confounding by socioeconomic or psychosocial factors. Twin designs offer a unique possibility to take genetic and shared environmental factors into account. The aim of the present national twin study was to determine the interrelations between IQ at age 18, childhood and attained social factors and smoking status in young adulthood and mid-life. We studied the association between IQ at age 18 and smoking in later life in a population of 11 589 male Swedish twins. IQ was measured at military conscription, and data on smoking and zygosity was obtained from the Swedish Twin Register. Information on social factors was extracted from censuses. Data on smoking was self-reported by the twins at the age of 22-47 years. Logistic regression models estimated with generalised estimating equations were used to explore possible associations between IQ and smoking among the twins as individuals as well as between-and within twin-pairs. A strong inverse association between IQ and smoking status emerged in unmatched analyses over the entire range of IQ distribution. In within-pair and between-pair analyses it transpired that shared environmental factors explained most of the inverse IQ-smoking relationship. In addition, these analyses indicated that non-shared and genetic factors contributed only slightly (and non-significantly) to the IQ-smoking association. Analysis of twin pairs discordant for IQ and smoking status displayed no evidence that non-shared factors contribute substantially to the association. The question of which shared environmental factors might explain the IQ-smoking association is an intriguing one for future research.
Hip fracture is a common cause of disability and mortality among the elderly. Declining incidence trends have been observed in Sweden. Still, this condition remains a significant public health problem since Sweden has one of the highest incidences worldwide. Yet, no Swedish lifetime risk or survival trends have been presented. By examining how hip fracture incidence, post-fracture survival, as well as lifetime risk have developed between 1995 and 2010 in Sweden, this study aims to establish how the burden hip fractures pose on the elderly changed over time, in order to inform initiatives for improvements of their health.
The entire Swedish population 60 years-old and above was followed between 1987 and 2010 in the National Patient Register and the Cause of Death Register. Annual age-specific hip fracture cumulative incidence was estimated using hospital admissions for hip fractures. Three-month and one-year survival after the first hip fracture were also estimated. Period life table was used to assess lifetime risk of hip fractures occurring from age 60 and above, and the expected mean age of the first hip fracture.
The age-specific hip fracture incidence decreased between 1995 and 2010 in all ages up to 94 years, on average by 1% per year. The lifetime risk remained almost stable, between 9% and 11% for men, and between 18% and 20% for women. The expected mean age of a first hip fracture increased by 2.5 years for men and by 2.2 years for women. No improvements over time were observed for the 3-month survival for men, while for women a 1% decrease per year was observed. The 1-year survival slightly increased over time for men (0.4% per year) while no improvement was observed for women.
The age-specific hip fracture incidence has decreased over time. Yet the lifetime risk of a hip fracture has not decreased because life expectancy in the population has increased in parallel. Overall, survival after hip fracture has not improved.
Life expectancy and time to first hospitalization have been prolonged, indicating that people live longer without needing hospital care. Life expectancy increased partially due to improved survival from severe diseases, which, however, could lead to a more fragile population. If so, time to a subsequent hospitalization could decrease. Alternatively, the overall trend of improved health could continue after the first hospitalization, prolonging also the time to subsequent hospitalizations. This study analyzes trends in subsequent hospitalizations among Swedish men and women above the age of 60, relating them to first hospitalization. It also looks at trends in the proportion of never hospitalized.
Individuals were followed in national registers for hospital admissions and deaths between 1972 and 2010. The proportion of never hospitalized individuals at given ages and time points, and the annual change in the risks of first and subsequent hospitalizations, were calculated.
An increase in the proportion of never hospitalized was seen over time. The risks of first as well as subsequent hospitalizations were reduced by almost 10% per decade for both men and women. Improvements were observed mainly for individuals below the ages of 90 and up to the year 2000.
The reduction in annual risk of both first and subsequent hospitalizations up to 90 years of age speaks in favor of a postponement of the overall morbidity among the elderly and provides no support for the hypothesis that the population becomes more fragile due to increased survival from severe diseases.
Non-response to population surveys is a common problem in epidemiological and public health research. Systematic non-response threatens the validity of results. Researchers rarely evaluate the magnitude of systematic non-response because of limited access to population data. This study explores how well morbidity and mortality in postal survey respondents aged 65 years and older represented that of the target population.
The 2010 Stockholm Public Health Survey and the Swedish Population Register were linked to the Cause of Death Register and the National Patient Register in Sweden. Differences were analysed between the response group and the corresponding population in mortality, hospital admission, days spent in hospital and number of diagnoses. Finally, data were weighted for non-response to see if this improved generalizability.
Non-response increased with age, and this increase was more pronounced among women than men. Respondents were marginally less often admitted to hospital, hospitalized fewer days and had slightly fewer diagnoses than the population, in particular after age 80. Significantly fewer women died in the response group than in the population as a whole. In terms of mortality among men and in terms of hospitalizations for most age groups, the respondents represented the population fairly well. Non-response weighting adjustment did not improve generalizability.
Postal questionnaires are likely to capture morbidity (hospitalization) among women and men aged 65-80 years old and mortality among men, while morbidity after age 80 and mortality in women are likely to be underestimated.
To illustrate how the fundamental epidemiological measures, incidence rate and prevalence proportion, can be estimated based on Swedish population registers using acute myocardial infarction (MI) as an example, together with a discussion about the analytical decisions.
All individuals in Sweden aged 60-89 (born 1904-1954) during the study period 1994-2014 were identified through the Total Population Register. Cases of MI were defined and identified from information on hospital admissions and causes of death. Incidence rates of all, first, and recurrent MI were calculated together with prevalence proportions.
The incidence rate of all, first, and recurrent MI declined over the study period. While the incidence rates of first MI are lower for women than men, the incidence rates of recurrent MI are considerably higher but similar for men and women. The prevalence calculated with duration of disease set at 28 days also declined. This was despite improved survival from MI and increased life expectancy over the same period meaning that the decline in incidence was large enough to compensate for increased survival.
Calculating incidence and prevalence of diseases using population registers requires detailed and well-reasoned definitions. The definitions will affect both the study population and the number of disease events and it is essential that the cases and the study population are defined in a coherent way. Different measures of disease occurrence contribute with different aspects of the disease panorama and a joint interpretation contributes to a thorough understanding of the disease development in a population.
The inverse association between education and mortality has grown stronger the last decades in many countries. During the same period, gains in life expectancy have been concentrated to older ages; still, old-age mortality is seldom the focus of attention when analyzing trends in the education-mortality gradient. It is further unknown if increased educational inequalities in mortality are preceded by increased inequalities in morbidity of which hospitalization may be a proxy.
Using administrative population registers from 1971 and onwards, education-specific annual changes in the risk of death and hospital admission were estimated with complimentary log-log models. These risk changes were supplemented by estimations of the ages at which 25, 50, and 75% of the population had been hospitalized or died (after age 60).
The mortality decline among older people increasingly benefitted the well-educated over the less well-educated. This inequality increase was larger for the younger old, and among men. Educational inequalities in the age of a first hospital admission generally followed the development of growing gaps, but at a slower pace than mortality and inequalities did not increase among the oldest individuals.
Education continues to be a significant predictor of health and longevity into old age. That the increase in educational inequalities is greater for mortality than for hospital admissions (our proxy of overall morbidity) may reflect that well-educated individuals gradually have obtained more possibilities or resources to survive a disease than less well-educated individuals have the last four decades.
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Previous studies have found inverse associations between intelligence quotient (IQ) and cigarette smoking, but the causal pathways linking IQ with smoking status and nicotine dependence (ND) are not well understood. The aim of this study was to explore the associations between IQ and ND using a genetically informative twin design to detect whether any association is because of shared genetic or environmental factors.
A population-based twin cohort with IQ measured in adolescence and ND later in life, analysed by classical twin modeling based on linear structural equations.
Swedish national registry data.
A total of 5040 male twins born 1951-84.
IQ was measured at military conscription at a mean age of 18 years. ND was self-reported at the ages of 22-57 years using the Fagerström Test for ND scale (FTND). Both cigarette smoking and Swedish snus use were analysed.
Both IQ and ND showed moderate heritability (0.58 and 0.39, respectively). The heritability of ND was similar for cigarette smoking and snus use. The phenotypic correlation between IQ and ND was weak: -0.11 (-0.16, -0.06) for total ND. Bivariate analysis revealed that this correlation was mainly because of genetic factors, but still the genetic correlation between IQ and ND from cigarette smoking was only -0.24.
Nicotine dependence, as measured by the Fagerström Test for Nicotine Dependence, shows moderate heritability in both smokers and snus users but is only weakly associated with intelligence quotient; common genetic factors underlying nicotine dependence and intelligence quotient probably account for little of the observed association between smoking and intelligence quotient.
BACKGROUND: High premorbid IQ test scores are related to a reduced rate of later total mortality, although little is known about the shape of this association (ie, dose-response versus threshold), or the role of mediating and confounding factors in explaining it. Additionally, the link between IQ and cause-specific mortality has been little explored. METHODS: A cohort of over 1 million Swedish men who underwent IQ testing at military service conscription at about 18 years of age was followed for mortality experience until middle age. RESULTS: An average of 20 years of follow-up gave rise to 14,498 deaths in an analytical sample of 994,262. In basic analyses adjusting for age, year of birth, and conscription testing center, lower IQ scores were associated with an elevated risk of all-cause mortality (HRper 1-SD decrease in IQ; 1.32; 95% confidence interval = 1.30-1.34). This relation was incremental across the full IQ range, and was robust to adjustment for indicators of childhood social circumstances. The association did not appear to be mediated by factors measured concurrent with IQ (blood pressure, body mass index, or cigarette smoking), nor was it attributable to reverse causality. However, controlling for education (a close correlate of IQ) led to marked attenuation. IQ was also associated with mortality from accidents, coronary heart disease, and suicides, but not cancer. CONCLUSIONS: In this large cohort we found a robust stepwise relation between early adult IQ and risk of total and accident mortality in men.