Risks of deep vein thrombosis, pulmonary embolism, and bleeding after covid-19: nationwide self-controlled cases series and matched cohort study.

OBJECTIVE: To quantify the risk of deep vein thrombosis, pulmonary embolism, and bleeding after covid-19. DESIGN: Self-controlled case series and matched cohort study. SETTING: National registries in Sweden. PARTICIPANTS: 1 057 174 people who tested positive for SARS-CoV-2 between 1 February 2020 and 25 May 2021 in Sweden, matched on age, sex, and county of residence to 4 076 342 control participants. MAIN OUTCOMES MEASURES: Self-controlled case series and conditional Poisson regression were used to determine the incidence rate ratio and risk ratio with corresponding 95% confidence intervals for a first deep vein thrombosis, pulmonary embolism, or bleeding event. In the self-controlled case series, the incidence rate ratios for first time outcomes after covid-19 were determined using set time intervals and the spline model. The risk ratios for first time and all events were determined during days 1-30 after covid-19 or index date using the matched cohort study, and adjusting for potential confounders (comorbidities, cancer, surgery, long term anticoagulation treatment, previous venous thromboembolism, or previous bleeding event). RESULTS: Compared with the control period, incidence rate ratios were significantly increased 70 days after covid-19 for deep vein thrombosis, 110 days for pulmonary embolism, and 60 days for bleeding. In particular, incidence rate ratios for a first pulmonary embolism were 36.17 (95% confidence interval 31.55 to 41.47) during the first week after covid-19 and 46.40 (40.61 to 53.02) during the second week. Incidence rate ratios during days 1-30 after covid-19 were 5.90 (5.12 to 6.80) for deep vein thrombosis, 31.59 (27.99 to 35.63) for pulmonary embolism, and 2.48 (2.30 to 2.68) for bleeding. Similarly, the risk ratios during days 1-30 after covid-19 were 4.98 (4.96 to 5.01) for deep vein thrombosis, 33.05 (32.8 to 33.3) for pulmonary embolism, and 1.88 (1.71 to 2.07) for bleeding, after adjusting for the effect of potential confounders. The rate ratios were highest in patients with critical covid-19 and highest during the first pandemic wave in Sweden compared with the second and third waves. In the same period, the absolute risk among patients with covid-19 was 0.039% (401 events) for deep vein thrombosis, 0.17% (1761 events) for pulmonary embolism, and 0.101% (1002 events) for bleeding. CONCLUSIONS: The findings of this study suggest that covid-19 is a risk factor for deep vein thrombosis, pulmonary embolism, and bleeding. These results could impact recommendations on diagnostic and prophylactic strategies against venous thromboembolism after covid-19.

Ambient temperature and stillbirth risks in northern Sweden, 1880-1950.

BACKGROUND: Climate vulnerability of the unborn can contribute to adverse birth outcomes, in particular, but it is still not well understood. We investigated the association between ambient temperature and stillbirth risk among a historical population in northern Sweden (1880-1950). METHODS: We used digitized parish records and daily temperature data from the study region covering coastal and inland communities some 600 km north of Stockholm, Sweden. The data included 141,880 births, and 3,217 stillbirths, corresponding to a stillbirth rate of 22.7 (1880-1950). The association between lagged temperature (0-7 days before birth) and stillbirths was estimated using a time-stratified case-crossover design. Incidence risk ratios (IRR) with 95% confidence intervals were computed, and stratified by season and sex. RESULTS: We observed that the stillbirth risk increased both at low and high temperatures during the extended summer season (April to September), at -10°C, and the IRR was 2.3 (CI 1.28, 4.00) compared to the minimum mortality temperature of +15°C. No clear effect of temperature during the extended winter season (October to March) was found. Climate vulnerability was greater among the male fetus compared to the female counterparts. CONCLUSION: In this subarctic setting before and during industrialization, both heat and cold during the warmer season increased the stillbirth risk. Urbanization and socio-economic development might have contributed to an uneven decline in climate vulnerability of the unborn.

The relationship between disability and parental status: a register study of the 1968 to 1970 birth cohorts.

BACKGROUND: Having children is a major life course event yet some disabilities could make it biologically challenging and some others could limit access to necessary socioeconomic resources. To date, there is relatively little data on disability and parental status and our study aimed to investigate this relationship. METHODS: This longitudinal cohort study was based on register data obtained from all people born in Sweden from 1968 to 1970 (n = 440220). We performed descriptive analyses, graphical plots, logistic regression, and Cox regression analyses. RESULTS: Our findings from both logistic regression and Cox regression indicated that individuals that started to receive disability benefits at an early age had reduced chances of having children during the follow-up duration. Men with disabilities were less likely to have children when compared to women with disabilities and to men and women without disabilities. CONCLUSIONS: We found evidence that disability during early adulthood was associated with reduced chances of having children. Findings support policies and programmes aimed at promoting optimal health during early adulthood, as this would promote continued labour force participation, reduce early use of disability benefits, and possibly improve chances of becoming a parent.

Climate vulnerability of Swedish newborns: Gender differences and time trends of temperature-related neonatal mortality, 1880-1950.

BACKGROUND: In resource-poor societies, neonatal mortality (death in the first 28 days of life) is usually very high. Young infants are particularly vulnerable to environmental health risks, which are modified by socioeconomic factors that change over time. We investigated the association between ambient temperature and neonatal mortality in northern Sweden during the demographic transition. METHODS: Parish register data and temperature data in coastal Västerbotten, Sweden, between 1880 and 1950 were used. Total and sex-specific neonatal mortality was modelled as a function of mean temperature, adjusting for age, seasonality and calendar time, using discrete-time survival analysis. A linear threshold function was applied with a cut point at 14.5 °C (the minimum mortality temperature). Odds ratios (ORs) with 95% confidence intervals (CIs) were computed. Further analyses were stratified by study period (1800-1899, 1900-1929, and 1930-1950). RESULTS: Neonatal mortality was 32.1 deaths/1000 live births, higher in boys than in girls, and decreased between 1880 and 1950, with high inter-annual variability. Mean daily temperature was +2.5 °C, ranging from -40.9 °C to +28.8 °C. At -20 °C, the OR of neonatal death was 1.56 (CI 1.30-1.87) compared to the reference at +14.5 °C. Among girls, the OR of mortality at -20 °C was 1.17 (0.88-1.54), and among boys, it was 1.94 (1.53-2.45). A temperature increase from +14.5 to +20 °C was associated with a 25% increase of neonatal mortality (OR 1.25, CI 1.04-1.50). Heat- and cold-related risks were lowest between 1900 and 1929. CONCLUSIONS: In this remote sub-Arctic region undergoing socio-economic changes, we found an increased mortality risk in neonates related to low but also to high temperature. Climate vulnerability varied across time and was particularly high among boys. This demonstrates that environmental impacts on human health are complex and highly dependent on the specific local context, with many, often unknown, contributing determinants of vulnerability.

Effect of extreme hot and cold weather on cause-specific hospitalizations in Sweden: A time series analysis.

Considering that several meteorological variables can contribute to weather vulnerability, the estimation of their synergetic effects on health is particularly useful. The spatial synoptic classification (SSC) has been used in biometeorological applications to estimate the effect of the entire suite of weather conditions on human morbidity and mortality. In this study, we assessed the relationships between extremely hot and dry (dry tropical plus, DT+) and hot and moist (moist tropical plus, MT+) weather types in summer and extremely cold and dry (dry polar plus, DP+) and cold and moist (moist polar, MP+) weather types in winter and cardiovascular and respiratory hospitalizations by age and sex. Time-series quasi-Poisson regression with distributed lags was used to assess the relationship between oppressive weather types and daily hospitalizations over 14 subsequent days in the extended summer (May to August) and 28 subsequent days during the extended winter (November to March) over 24 years in 4 Swedish locations from 1991 to 2014. In summer, exposure to hot weather types appeared to reduce cardiovascular hospitalizations while increased the risk of hospitalizations for respiratory diseases, mainly related to MT+. In winter, the effect of cold weather on both cause-specific hospitalizations was small; however, MP+ was related to a delayed increase in cardiovascular hospitalizations, whilst MP+ and DP + increased the risk of hospitalizations due to respiratory diseases. This study provides useful information for the staff of hospitals and elderly care centers who can help to implement protective measures for patients and residents. Also, our results could be helpful for vulnerable people who can adopt protective measures to reduce health risks.

Income inequality and old-age mortality in Sweden: do regional development and lagged effect matter?

We designed a retrospective cohort study for exploring the impact of municipality-level income inequality, based on the Gini 1986, 2004 indices, on all-cause old-age mortality among the older Swedish population during 2005-2009. We controlled for the confounding effects of individual and regional correlates and the lag effects of inequality by using multilevel logistic regression. The effects of income inequality were not consistent across age cohorts and, among the youngest cohorts, were negligible. This study reiterates that individual-level economics rather than the immediate or lagged effects of income inequality matter more for old-age mortality, even after controlling for individual and regional factors.

Hot and cold weather based on the spatial synoptic classification and cause-specific mortality in Sweden: a time-stratified case-crossover study.

The spatial synoptic classification (SSC) is a holistic categorical assessment of the daily weather conditions at specific locations; it is a useful tool for assessing weather effects on health. In this study, we assessed (a) the effect of hot weather types and the duration of heat events on cardiovascular and respiratory mortality in summer and (b) the effect of cold weather types and the duration of cold events on cardiovascular and respiratory mortality in winter. A time-stratified case-crossover design combined with a distributed lag nonlinear model was carried out to investigate the association of weather types with cause-specific mortality in two southern (Skåne and Stockholm) and two northern (Jämtland and Västerbotten) locations in Sweden. During summer, in the southern locations, the Moist Tropical (MT) and Dry Tropical (DT) weather types increased cardiovascular and respiratory mortality at shorter lags; both hot weather types substantially increased respiratory mortality mainly in Skåne. The impact of heat events on mortality by cardiovascular and respiratory diseases was more important in the southern than in the northern locations at lag 0. The cumulative effect of MT, DT and heat events lagged over 14 days was particularly high for respiratory mortality in all locations except in Jämtland, though these did not show a clear effect on cardiovascular mortality. During winter, the dry polar and moist polar weather types and cold events showed a negligible effect on cardiovascular and respiratory mortality. This study provides valuable information about the relationship between hot oppressive weather types with cause-specific mortality; however, the cold weather types may not capture sufficiently effects on cause-specific mortality in this sub-Arctic region.

Adverse perinatal conditions and receiving a disability pension early in life.

OBJECTIVE: The number of young adults on disability pension (DP) is increasing in European countries, creating a need to understand the related risk factors. This study aimed to determine whether adverse perinatal conditions are associated with receiving a DP early in life. METHODS: This longitudinal cohort study consisted of all persons (N = 453,223) born in Sweden during 1973-1977, observed from 1991 through 2010 when they were aged between 16 and 37 years. Statistics Sweden provided linked national data on the children and their parents. We used logistic regression to assess the association between perinatal health conditions (birth defect, Apgar score, and small for gestational age) and receiving a DP, adjusting for maternal education and the sex of the child. RESULTS: New recipients of DP were significantly more likely to have had a birth defect (adjusted odds ratio [AOR] 2.74, 95% CI: 2.49-3.00), to have had low Apgar score (AOR 2.12, 95% CI: 1.77-2.52), to have been small for gestational age (AOR 1.73, 95% CI: 1.54-1.94) and to be females (AOR 1.55, 95% CI: 1.46-1.64). Higher maternal education was associated with lower odds of receiving a DP (AOR 0.74, 95% CI: 0.69-0.79) for those with high school education and (AOR 0.67, 95% CI: 0.59-0.75) for those with university education. Age-stratified analysis confirmed increased odds of receiving a DP among those with birth defects and small for gestational age, but this effect reduced with increasing age. Apgar score was significantly associated with starting to receive a DP at ages 16-18 and 19-29, but not at ages 30-33. Women had lower odds of receiving a DP at ages 16-18 (AOR 0.73, 95% CI: 0.64-0.85); however, this reversed from age 19 and upwards (AOR 1.53, 95% CI: 1.41-1.67) and (AOR 2.16, 95% CI: 1.95-2.40) for the age groups of 19-29 and 30-33, respectively. Persons with high maternal education were less likely to receive a DP regardless of age at receiving a DP. CONCLUSION: Having a birth defect was the strongest indicator of receiving a DP during early adulthood, followed by small for gestational age and low Apgar score. Overall, the effects of the studied perinatal health conditions were pronounced in those who received a DP at 16-18 years, but this effect weakened with increasing age at receiving a DP. Our findings suggest that policies and programs geared at promoting optimal health at birth might contribute to a reduction in receiving a DP.

Neonatal Mortality and Temperature in Two Northern Swedish Rural Parishes, 1860-1899-The Significance of Ethnicity and Gender.

The aim of this study was to analyze the association between season of birth and daily temperature for neonatal mortality in two Swedish rural parishes between 1860 and 1899. Further, we aimed to study whether the association varied according to ethnicity (indigenous Sami reindeer herders and non-Sami settlers) and gender. The source material for this study comprised digitized parish records from the Demographic Data Base, Umeå University, combined with local weather data provided by the Swedish Meteorological and Hydrological Institute. Using a time event-history approach, we investigated the association between daily temperature (at birth and up to 28 days after birth) and the risk of neonatal death during the coldest months (November through March). The results showed that Sami neonatal mortality was highest during winter and that the Sami neonatal mortality risk decreased with higher temperatures on the day of birth. Male neonatal risk decreased with higher temperatures during the days following birth, while no effect of temperature was observed among female neonates. We conclude that weather vulnerability differed between genders and between the indigenous and non-indigenous populations.

Weather extremes and perinatal mortality - Seasonal and ethnic differences in northern Sweden, 1800-1895.

BACKGROUND: Many studies have shown the impact of heat and cold on total and age-specific mortality, but knowledge gaps remain regarding weather vulnerability of very young infants. This study assessed the association of temperature extremes with perinatal mortality (stillbirths and deaths in the first week of life), among two ethnic groups in pre-industrial northern Sweden. METHODS: We used population data of indigenous Sami and non-Sami in selected parishes of northern Sweden, 1800-1895, and monthly temperature data. Multiple logistic regression models were conducted to estimate the association of cold (<10th percentile of temperature) and warmth (>90th percentile) in the month of birth with perinatal mortality, adjusted for cold and warmth in the month prior birth and period, stratified by season and ethnicity. RESULTS: Perinatal mortality was slightly higher in Sami than in non-Sami (46 vs. 42 / 1000 live and stillbirths), but showed large variations across the region and over time. Both groups saw the highest perinatal mortality in autumn. For Sami, winter was a high-risk time as well, while for non-Sami, seasonality was less distinct. We found an association between exposure to cold and perinatal mortality among winter-born Sami [Odds ratio (OR) 1.91, 95% confidence interval (CI) 1.26-2.92, compared to moderate temperature], while there was little effect of cold or warmth during other seasons. Non-Sami, meanwhile, were affected in summer by warmth (OR 0.20, CI 0.05-0.81), and in autumn by cold (OR 0.39, CI 0.19-0.82). CONCLUSIONS: In this pre-industrial, subarctic setting, the indigenous Sami's perinatal mortality was influenced by extreme cold in winter, while non-Sami seemed to benefit from high temperature in summer and low temperature in autumn. Climate vulnerability of these two ethnic groups sharing the same environment was shaped by their specific lifestyles and living conditions.

The association between cold extremes and neonatal mortality in Swedish Sápmi from 1800 to 1895.

Background: Studies in which the association between temperature and neonatal mortality (deaths during the first 28 days of life) is tracked over extended periods that cover demographic, economic and epidemiological transitions are quite limited. From previous research about the demographic transition in Swedish Sápmi, we know that infant and child mortality was generally higher among the indigenous (Sami) population compared to non-indigenous populations. Objective: The aim of this study was to analyse the association between extreme temperatures and neonatal mortality among the Sami and non-Sami population in Swedish Sápmi (Lapland) during the nineteenth century. Methods: Data from the Demographic Data Base, Umeå University, were used to identify neonatal deaths. We used monthly mean temperature in Tornedalen and identified cold and warm month (5th and 95th) percentiles. Monthly death counts from extreme temperatures were modelled using negative binomial regression. We computed relative risks (RR) with 95% confidence intervals (CI), adjusting for time trends and seasonality. Results: Overall, the neonatal mortality rate was higher among Sami compared to non-Sami infants (62/1,000 vs 35/1,000 live births), although the differences between the two populations decreased after 1860. For the Sami population prior 1860, the results revealed a higher neonatal incidence rate during cold winter months (<-15.4°C, RR = 1.60, CI 1.14-2.23) compared to infants born during months of medium temperature. No association was found between extreme cold months and neonatal mortality for non-Sami populations. Warm months (+15.1°C) had no impact on Sami or non-Sami populations. Conclusions: This study revealed the role of environmental factors (temperature extremes) on infant health during the demographic transition where cold extremes mainly affected the Sami population. Ethnicity and living conditions contributed to differential weather vulnerability.

Season of birth, stillbirths, and neonatal mortality in Sweden: the Sami and non-Sami population, 1800-1899.

Seasonal patterns of neonatal mortality and stillbirths have been found around the world. However, little is known about the association between season of birth and infant mortality of pre-industrial societies in a subarctic environment. In this study, we compared how season of birth affected the neonatal and stillbirth risk among the Sami and non-Sami in Swedish Sápmi during the nineteenth century. Using digitised parish records from the Demographic Data Base at Umeå University, we applied logistic regression models for estimating the association of season of birth with stillbirths and neonatal mortality, respectively. Higher neonatal mortality was found among the winter- and autumn-born Sami, compared to summer-born infants. Stillbirth risk was higher during autumn compared to summer among the Sami, whereas we found no seasonal differences in mortality among the non-Sami population. We relate the higher neonatal mortality risk among winter-born Sami to differences in seasonality of living conditions associated with reindeer herding.

Association between Weather Types based on the Spatial Synoptic Classification and All-Cause Mortality in Sweden, 1991⁻2014.

Much is known about the adverse health impact of high and low temperatures. The Spatial Synoptic Classification is a useful tool for assessing weather effects on health because it considers the combined effect of meteorological factors rather than temperature only. The aim of this study was to assess the association between oppressive weather types and daily total mortality in Sweden. Time-series Poisson regression with distributed lags was used to assess the relationship between oppressive weather (Dry Polar, Dry Tropical, Moist Polar, and Moist Tropical) and daily deaths over 14 days in the extended summer (May to September), and 28 days during the extended winter (November to March), from 1991 to 2014. Days not classified as oppressive weather served as the reference category. We computed relative risks with 95% confidence intervals, adjusting for trends and seasonality. Results of the southern (Skåne and Stockholm) and northern (Jämtland and Västerbotten) locations were pooled using meta-analysis for regional-level estimates. Analyses were performed using the dlnm and mvmeta packages in R. During summer, in the South, the Moist Tropical and Dry Tropical weather types increased the mortality at lag 0 through lag 3 and lag 6, respectively. Moist Polar weather was associated with mortality at longer lags. In the North, Dry Tropical weather increased the mortality at shorter lags. During winter, in the South, Dry Polar and Moist Polar weather increased mortality from lag 6 to lag 10 and from lag 19 to lag 26, respectively. No effect of oppressive weather was found in the North. The effect of oppressive weather types in Sweden varies across seasons and regions. In the North, a small study sample reduces precision of estimates, while in the South, the effect of oppressive weather types is more evident in both seasons.

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.

The effect of Rh-negative disease on perinatal mortality: some evidence from the Skellefteå region, Sweden, 1860-1900.

The Rh-negative gene is a well-known cause of perinatal mortality. In this article, we analyze the possible role of Rh disease in perinatal mortality and stillbirths in a particular historical setting: the Skellefteå region in northern Sweden between 1860 and 1900. The data used for the study cover 23,067 children born to 4,943 women. The exact impact is not possible to establish using historical data, but the typical pattern of the disease allows us to make estimations. The expected levels based on knowledge of blood group distribution, the risk of sensitization from Rh incompatability, and the risk of perinatal mortality in births by sensitized mothers are compared with the observed levels. The results show that Rh disease was important for perinatal mortality and clustering of deaths within families.