Sören Edvinsson

Acute fatal effects of short-lasting extreme temperatures in Stockholm, Sweden: evidence across a century of change.

Background: Climate change is projected to increase the frequency of extreme weather events. Short-term effects of extreme hot and cold weather and their effects on mortality have been thoroughly documented, as have epidemiologic and demographic changes throughout the 20th century. We investigated whether sensitivity to episodes of extreme heat and cold has changed in Stockholm, Sweden, from the beginning of the 20th century until the present. Methods: We collected daily mortality and temperature data for the period 1901–2009 for present-day Stockholm County, Sweden. Heat extremes were defined as days for which the 2-day moving average of mean temperature was above the 98th percentile; cold extremes were defined as days for which the 26-day moving average was below the 2nd percentile. The relationship between extreme hot/cold temperatures and all-cause mortality, stratified by decade, sex, and age, was investigated through time series modeling, adjusting for time trends. Results: Total daily mortality was higher during heat extremes in all decades, with a declining trend over time in the relative risk associated with heat extremes, leveling off during the last three decades. The relative risk of mortality was higher during cold extremes for the entire period, with a more dispersed pattern across decades. Unlike for heat extremes, there was no decline in the mortality with cold extremes over time. Conclusions: Although the relative risk of mortality during extreme temperature events appears to have fallen, such events still pose a threat to public health.

High-risk families: The unequal distribution of infant mortality in nineteenth-century Sweden

An analysis of infant mortality (based on 133,448 births) in two regions, Sundsvall and Skellefteå, in north-eastern Sweden during the nineteenth century shows that infant mortality was highly clustered with a relatively small number of families accounting for a large proportion of all infant deaths. Using logistic regression, two important factors were found to be associated with high-risk families: (i) a biological component evidenced by an over-representation of women who had experienced stillbirths, and (ii) a social component indicated by an increased risk among women who had remarried. The results strengthen the argument for using the family rather than the single child as the unit of analysis. The clustering of infant deaths points to the need to re-evaluate our interpretations of the causes of infant mortality in the past.

Change in food availability during pregnancy: Is it related to adult sudden death from cerebro- and cardiovascular disease in offspring?

Maternal access to food during pregnancy affects birth weight and other characteristics of offspring. It has been suggested that fluctuations in food availability during infancy, ranging from plentiful to starvation, may influence cerebro‐cardiovascular risk factors for the offspring during adult life. This study was designed to test the correlation between food availability changes during life before birth and adult sudden death from disease. This was a follow‐up study of ancient cohorts in the parish of Skellefteå, Sweden, comprising 7,572 individuals born between 1805 and 1849 and still alive at age 40. Food availability variations in the parish during their prenatal life were ascertained from historical sources, the main outcome measures being overall mortality and mortality from sudden death in the age range 40–70 years. The risk of sudden death was almost doubled for those whose mothers were struck by a poor harvest during the early stages of pregnancy, but who experienced a good harvest toward the end. Yet almost the same over‐risk was evident for the converse case: plentiful food supply in early pregnancy followed by a poor harvest toward the end. A stable maternal access to food during pregnancy is important for the offsprings risk of sudden death from cerebro‐ and cardiovascular disease as an adult. Am. J. Hum. Biol. 12:447–453, 2000.

Infant Mortality in the Nordic Countries 1780-1930

This article summarizes aspects of the decline in infant mortality in the five Nordic countries. During the nineteenth century, both the levels of infant mortality and its development differed among the Nordic countries. At an early date, Denmark, Norway and Sweden stood out as the countries with the lowest levels in Europe whereas levels of infant mortality in Iceland and Finland were comparatively high. Within the countries there were large regional differences that often crossed national borders. Artificial feeding characterized most of the areas with the highest infant mortality. Within the different countries the high infant mortality came to be seen as a problem during the eighteenth and nineteenth centuries. The spread of information, midwives as agents of change and high literacy are factors that have been proven important in explaining the subsequent decline.

Longitudinal databases - sources for analyzing the life-course: Characteristics, Difficulties and Possibilities

Longitudinal databases - sources for analyzing the life course : Characteristics, difficulties and possibilities

Testing Methods of Record Linkage on Swedish Censuses

Abstract. Research benefits a great deal when different kinds of registers can be combined. Record linkage is an important tool for connecting sources to create longitudinal databases of individual data. In this article, researchers test and evaluate different methods of record linkage used when linking two censuses. By comparing the results of the census linkage with other continuous Swedish parish registers, they find that applying constructed name variables and household links considerably increases the success rate without the risk of introducing bias. Missing links are mainly related to name problems, and appear most frequently among children and when the family structure has changed between the censuses. Faulty links are very few and must be regarded as only a marginal problem for analysis. The study underlines the importance of adapting the linkage process to the special characteristics of the sources.

The influence of seasonal climate variability on mortality in pre-industrial Sweden

Background Recent studies have shown an association between weather and climatic factors with mortality, cardiovascular and infectious diseases. We used historical data to investigate the impact of seasonal temperature and precipitation on total mortality in Uppsala, Sweden, during the first two stages of the demographic transition, 1749–1859. Design We retrieved mortality and population numbers of the Uppsala Domkyrka parish from digitised parish records and obtained monthly temperature and precipitation measures recorded in Uppsala during that time. Statistical models were established for year-to-year variability in deaths by annual and seasonal temperature and precipitation, adjusting for longer time trends. In a second step, a model was established for three different periods to study changes in the association of climate variability and mortality over time. Relative risks (RR) with 95% confidence intervals (CI) were calculated. Results Precipitation during spring and autumn was significantly associated with annual mortality (spring RR 0.982, CI 0.965–1.000; autumn RR 1.018, CI 1.004–1.032, respectively, per centimetre increase of precipitation). Higher springtime temperature decreased annual mortality, while higher summer temperature increased the death toll; however, both were only borderline significant (p=0.07). The significant effect of springtime precipitation for mortality was present only in the first two periods (1749–1785 and 1786–1824). On the contrary, the overall effect of autumn precipitation was mainly due to its relevance during the last period, 1825–1859 (RR 1.024, CI 0.997–1.052). At that time, higher winter precipitation was found to decrease mortality. Conclusions In urban Uppsala, during the 18th and 19th century, precipitation appeared to be a stronger predictor for mortality than temperature. Higher spring precipitation decreased and higher autumn precipitation increased the number of deaths. However, this association differed before and during the early stages of industrialisation. Further research shall take age-specific differences into account, as well as changes in socio-economic conditions during that time. This paper is part of the thematic cluster Global Health Beyond 2015 - more papers from this cluster can be found at http://www.globalhealthaction.netBackground Recent studies have shown an association between weather and climatic factors with mortality, cardiovascular and infectious diseases. We used historical data to investigate the impact of seasonal temperature and precipitation on total mortality in Uppsala, Sweden, during the first two stages of the demographic transition, 1749-1859. Design We retrieved mortality and population numbers of the Uppsala Domkyrka parish from digitised parish records and obtained monthly temperature and precipitation measures recorded in Uppsala during that time. Statistical models were established for year-to-year variability in deaths by annual and seasonal temperature and precipitation, adjusting for longer time trends. In a second step, a model was established for three different periods to study changes in the association of climate variability and mortality over time. Relative risks (RR) with 95% confidence intervals (CI) were calculated. Results Precipitation during spring and autumn was significantly associated with annual mortality (spring RR 0.982, CI 0.965-1.000; autumn RR 1.018, CI 1.004-1.032, respectively, per centimetre increase of precipitation). Higher springtime temperature decreased annual mortality, while higher summer temperature increased the death toll; however, both were only borderline significant (p=0.07). The significant effect of springtime precipitation for mortality was present only in the first two periods (1749-1785 and 1786-1824). On the contrary, the overall effect of autumn precipitation was mainly due to its relevance during the last period, 1825-1859 (RR 1.024, CI 0.997-1.052). At that time, higher winter precipitation was found to decrease mortality. Conclusions In urban Uppsala, during the 18th and 19th century, precipitation appeared to be a stronger predictor for mortality than temperature. Higher spring precipitation decreased and higher autumn precipitation increased the number of deaths. However, this association differed before and during the early stages of industrialisation. Further research shall take age-specific differences into account, as well as changes in socio-economic conditions during that time. This paper is part of the thematic cluster Global Health Beyond 2015 - more papers from this cluster can be found at http://www.globalhealthaction.net.

Do unequal societies cause death among the elderly? A study of the health effects of inequality in Swedish municipalities in 2006

Background : A lively public and academic debate has highlighted the potential health risks of living in regions characterized by inequality. Research provides an ambiguous picture, however, with positive association between income equality and health mainly being found on higher levels of geographical division, such as nations, but rarely at local level. Methods : We examined the association between income inequality (using the Gini coefficient) and all-cause mortality in Swedish municipalities in the 65–74 age group. A multi-level analysis was applied and controlled for by variables including individual income and average income level in the municipality. The analyses were based on individual register data on all residents born between 1932 and 1941, outcomes were measured for the year 2006. Results: Lower individual income and lower average income in the municipality of residence were associated with significantly increased mortality. We found an association between income inequality and mortality with excessive deaths in unequal municipalities after controlling for mean income level and personal income. The results from the analysis of individual data differed substantially from the analysis of aggregate data. Conclusions: Income inequality was significantly associated with mortality in the age group 65–74 at municipality level. The association is small compared to many other variables, but is not negligible. Even in a comparatively equal society like Sweden, the potential effects of income inequality on mortality at the local level warrant consideration.BACKGROUND A lively public and academic debate has highlighted the potential health risks of living in regions characterized by inequality. Research provides an ambiguous picture, however, with positive association between income equality and health mainly being found on higher levels of geographical division, such as nations, but rarely at local level. METHODS We examined the association between income inequality (using the Gini coefficient) and all-cause mortality in Swedish municipalities in the 65-74 age group. A multi-level analysis was applied and controlled for by variables including individual income and average income level in the municipality. The analyses were based on individual register data on all residents born between 1932 and 1941, outcomes were measured for the year 2006. RESULTS Lower individual income and lower average income in the municipality of residence were associated with significantly increased mortality. We found an association between income inequality and mortality with excessive deaths in unequal municipalities after controlling for mean income level and personal income. The results from the analysis of individual data differed substantially from the analysis of aggregate data. CONCLUSIONS Income inequality was significantly associated with mortality in the age group 65-74 at municipality level. The association is small compared to many other variables, but is not negligible. Even in a comparatively equal society like Sweden, the potential effects of income inequality on mortality at the local level warrant consideration.

Clustering of Deaths in Families: Infant and Child Mortality in Historical Perspective

This introduction surveys the field of family clustering of deaths and discusses the contributions in this special issue. The main focus is on mortality in historical contexts. Clustering of deaths in families has been found both in historical and contemporary populations, and we argue that the ‘family approach’ to infant and child mortality yields important and interesting insights for our understanding of different mortality patterns and the mortality transition. The articles in this issue, representing different but complementary approaches to the problem of death clustering, demonstrate that we should be aware of the strong family effects on child health, but also that we need to develop adequate methods for the analysis of this complex phenomenon. Here we discuss several explanations for death clustering, such as different biodemographic factors and those focusing on socioeconomic and cultural variables. We also discuss some of the methodological challenges in studying family clustering, and emphasize the need for comparison and the adoption of common measures.

Association of seasonal climate variability and age-specific mortality in northern Sweden before the onset of industrialization

Background and aims: Little is known about health impacts of climate in pre-industrial societies. We used historical data to investigate the association of temperature and precipitation with total and age-specific mortality in Skellefteå, northern Sweden, between 1749 and 1859. Methods: We retrieved digitized aggregated population data of the Skellefteå parish, and monthly temperature and precipitation measures. A generalized linear model was established for year to year variability in deaths by annual and seasonal average temperature and cumulative precipitation using a negative binomial function, accounting for long-term trends in population size. The final full model included temperature and precipitation of all four seasons simultaneously. Relative risks (RR) with 95% confidence intervals (CI) were calculated for total, sex- and age-specific mortality. Results: In the full model, only autumn precipitation proved statistically significant (RR 1.02; CI 1.00–1.03, per 1cm increase of autumn precipitation), while winter temperature (RR 0.98; CI 0.95–1.00, per 1 °C increase in temperature) and spring precipitation (RR 0.98; CI 0.97–1.00 per 1 cm increase in precipitation) approached significance. Similar effects were observed for men and women. The impact of climate variability on mortality was strongest in children aged 3–9, and partly also in older children. Infants, on the other hand, appeared to be less affected by unfavourable climate conditions. Conclusions: In this pre-industrial rural region in northern Sweden, higher levels of rain during the autumn increased the annual number of deaths. Harvest quality might be one critical factor in the causal pathway, affecting nutritional status and susceptibility to infectious diseases. Autumn rain probably also contributed to the spread of air-borne diseases in crowded living conditions. Children beyond infancy appeared most vulnerable to climate impacts.