Here you can read a number of examples of research that has contributed to society by using Swedish register-based data.
EXAMPLE OF RESEARCH CONTRIBUTION
Most examples of how research based on Swedish register data can contribute to different parts of society are taken from the publication “Swedish registers: A unique resource for health and welfare” (pdf). Further examples are described there.
Increased risk of suicide or heart disease immediately after cancer diagnosis
Receiving a cancer diagnosis can have serious consequences for one’s health, in addition to the cancer itself. Researchers studied the risks of suicide and heart disease in patients who had recently received a cancer diagnosis. The cancer patients were compared to individuals who had never been diagnosed with cancer.
The study included register data from over 6 million Swedes, collected during the period of between 1991 and 2006, during which just over 500 000 people received their first cancer diagnosis. Register-based data were obtained from, for example, the Cancer Register, the Cause of Death Register and the National Patient Register at the National Board of Health and Welfare, and the Total Population Register at Statistics Sweden. To further investigate and adjust for common causes of suicide/cardiovascular disease and cancer (confounders), the researchers compared the probability of a cancer diagnosis immediately before the outcomes (suicide/cardiovascular disease) with earlier time periods in the individuals’ lives.
During the first week after the diagnosis, cancer patients had an almost six-fold higher risk of death of cardiovascular disease and an almost 13-fold higher risk of suicide. The increased risks were not due to pre-existing mental illness or cardiovascular disease. Neither could they be explained by any common cause of cancer, suicide and/or cardiovascular diseases – for example, smoking which is a risk factor for both lung cancer and cardiovascular disease. The results indicate that the stress and psychological strain that a cancer diagnosis brings with it can lead to serious consequences, in addition to the actual cancer itself, especially during the immediate period after the cancer diagnosis.
Understanding the consequences of a cancer diagnosis has significance for the support relatives and healthcare professionals can provide, for example through the national care programs that are being developed for cancer patients.
Fall K, Fang F, Mucci L, Ye W, Andrén O, Johansson JE, Andersson SO, Sparén P, Klein G, Stampfer MJ, Adami HO, Valdimarsdóttir U. Immediate risk for cardiovascular events and suicide following a prostate cancer diagnosis: prospective cohort study. PLoS Med. 2009; 6(12):e1000197.
Fang F, Fall K, Mittleman MA, Sparén P, Ye W, Adami HO, Valdimarsdóttir U. Suicide and cardiovascular death after a cancer diagnosis. New Engl J Med. 2012;366:1310-8.
Successful schooling can reduce the social disadvantage of children in foster homes
Young people who have been placed in foster homes have a significantly higher risk of suicide attempts, drug abuse, crime and dependence on social subsidies compared to other adolescents. Researchers have studied this relationship association with the help of national registers.
In order to study psychosocial problems in adolescents who have been placed in foster homes, researchers linked data from registers at Statistics Sweden, the National Board of Health and Welfare, and the Swedish National Council for Crime Prevention, concerning young people from ten annual birth cohorts in Sweden, born between 1972 and 1981. The young people were followed from the age of 16 until 2005. They were compared with the corresponding situation for the majority population, Swedish adopted children, and young people who instead experienced social care interventions in their parental homes. More than 5 000 adolescents from foster homes were compared with just over 900 000 other adolescents.
The results highlight weak school performance as an important risk factor for later psycho-social problems. Thus, the study indicates that efforts to strengthen the school performance of children in foster homes, especially in the last year of primary school, should be highly prioritised as a measure to reduce their social disadvantage later in life.
Adolescents who had been placed in foster homes showed a 6- to 11-fold higher risk of suicide attempts, drug abuse, crime, and dependency on social subsidies. Up to 55 per cent of this increased risk could be statistically explained by weak school performance in the last year of compulsory school.
Marie Berlin, Bo Vinnerljung, and Anders Hjern, 2011. School performance in primary school and psychosocial problems in young adulthood among care leavers from long term foster care. Children and Youth Services Review 33: 2489-2497.
Gender equality bonus in parental benefits had no effect on the distribution of parental leave
Since the introduction of parental benefits in 1974, the issue of the distribution of parental leave allowance between women and men has been discussed. Several reforms have been implemented to achieve a more equal distribution, and the effects of these have been evaluated.
In 1995, one month of the parental leave allowance was reserved for each parent. The first reserved month was followed by a second one in 2002. In 2008, a gender equality bonus was introduced, which gives tax credits to parents who share the of parental benefit equally.
The reforms were analysed by comparing the withdrawal of parental benefit for children born just before the reforms were introduced to children born just after. The study was based on data from administrative registers at the Swedish Social Insurance Agency, which covers all parents in Sweden for the period between 1974 and 2010. For each reform, the comparison was based on data for parents of between 11 000 and 15 000 children.
One interpretation of the results is that reserved time is a more effective policy instrument than a financial bonus. The results can certainly also be attributed to the fact that changes at lower levels are easier to achieve, and because reforms may be most impactful when they are first introduced.
The results show that the first reserved month led to a more even distribution of parental leave between the parents. The second reserved month also had a clear effect, while the gender equality bonus did not show any noticeable effect on the distribution of parental benefits.
Ann-Zofie Duvander och Mats Johansson, 2012. Ett jämställt uttag? Reformer inom föräldraförsäkringen. Inspektionen för socialförsäkringen, Rapport 2012:4 (”An equal withdrawal? Reforms in parental insurance. The Swedish Social Insurance Inspectorate, Repport 2012:4”).
Ann-Zofie Duvander and Mats Johansson, 2012. What are the effects of reforms promoting fathers’ parental leave use? Journal of European Social Policy 22(3): 319-330.
The school reform of the 1950s led to lower mortality after the age of 40
There is a clear association between education and health. However, it is unclear whether education itself leads to better health. Researchers have benefitted from data on the Swedish school reform in the 1950s in order to understand more about this phenomenon.
Education leads to more well-paid and less physically demanding jobs, which can affect the conditions for an individual’s health. Furthermore, one can get better at embracing a healthier lifestyle through education. However, individuals with different length of education differ in several additional ways. This complicates the issue of whether it is the education itself that is the cause of better health and lower mortality.
An extra year in elementary school introduced in the school reform of the 1950s was associated with lower mortality after age 40.
During the 1950s, nine years of elementary school were gradually introduced in Sweden, following the former eight-year compulsory schooling. The school reform can be likened to an experimental situation because the students did not themselves choose the length of their compulsory schooling. This was instead determined by their year of birth and the municipality in which their school was located. In this quasi-experimental situation, differences in average life expectancy probably do depend on differences in educational length, rather than on other differences.
With the help of register-based data from the National Board of Health and Welfare and Statistics Sweden, the researchers compared the mortality of those who had received eight years of compulsory schooling to the mortality of those who had had nine years of schooling. The study included 1.2 million individuals born between 1943 and 1955.
The results showed that an extra year of compulsory schooling was associated with lower mortality after the age of 40. The lower mortality was mainly related to overall cancer, lung cancer and accidents. However, the effects were small and were only observed after the age of 40.
Publikation: Lager, A. och Torssander, J. 2012. Causal effect of education on mortality in a quasi-experiment on 1.2 million Swedes. PNAS 109: 8461-8466.
Free choice of school led to increased differences in grades between schools
Increased freedom of choice and the introduction of independent schools have fundamentally changed the Swedish school system. Concurrent with this reform, differences in grades between schools have increased. Researchers have investigated the causes for this.
Previously, the uptake areas for schools were based mainly on the schools’ distance from the home, whereas currently the freedom of choice has led to students commuting longer distances. Proximity to school has been replaced by other criteria. The main research question in this study was whether the increased differences in grades between schools were due to the distribution of pupils owing to increased freedom to choose their school, or if they are a consequence of enhanced housing segregation.
The increased freedom to choose a school, rather than enhancing housing segregation, contributed to increased differences in average grades between schools in Sweden.
The study was based mainly on register data from Statistics Sweden (the PLACE database at Uppsala University). The study included all pupils who had completed elementary school in 2000, 2003 and 2006; a total of over 320 000 pupils. Differences in their final grades were studied, both between students’ actual schools, and between the schools the students would have gone to had proximity been the main criterion for school placement.
The results showed that increased freedom to choose a school is the main driving force of greater differences in grades between schools in Sweden, rather than rising housing segregation.
John Östh, Eva Andersson and Bo Malmberg, 2013. School choice and increasing performance difference: A counterfactual approach. Urban Studies 50(2): 407-425.
Radiation therapy for breast cancer increases risk of cardiovascular disease
Radiation therapy for breast cancer has been shown to increase the risk of cardiovascular disease, probably due to the fact that the heart also is subjected to radiation during treatment. In studies of Swedish and Danish women, researchers examined how great this increase in risk is in relation to the radiation dose the heart is exposed to.
The researchers used data from Swedish and Danish cancer registers as well as health care records. In an initial study of about 35 000 women undergoing radiotherapy for breast cancer, the researchers observed that women with tumours in their left breast were at greater risk of subsequent cardiovascular disease than women with tumours in their right breast. This was thought to be due to the fact that the heart was exposed to a higher radiation dose when treating the left breast.
The researchers argue that these results call for physicians taking into account the exposure of the heart to radiation, as well as the cancer patient’s existing risk factors for cardiovascular disease, in decisions concerning radiotherapy for breast cancer.
In a follow-up study of just over 2000 Swedish and Danish women, the researchers wanted to determine how the risk increase is associated with radiation dose. In Sweden, the researchers studied women from Stockholm who had received a breast cancer diagnosis between 1958 and 2001 below the age of 70, and had subsequently received radiotherapy. The Danish women had been diagnosed between 1977 and 2000 below the age of 75 years.
Cases of severe heart disease, such heart attacks, increased linearly with the radiation dose the heart had been exposed to. The average radiation dose for the heart was estimated to be 4.9 Gy (grey), and the increase in cases of cardiovascular disease was 7.4% per Gy. The increase in cases of cardiovascular disease started within five years after the radiation treatment and lasted for at least 20 years. In absolute terms, the increase was greater in women who already had a high risk of cardiovascular disease.
McGale P, Darby SC, Hall P, Adolfsson J, Bengtsson NO, Bennet AM, Fornander T, Gigante B, Jensen MB, Peto R, Rahimi K, Taylor CW, Ewertz M. Incidence of heart disease in 35,000 women treated with radiotherapy for breast cancer in Denmark and Sweden. Radiother Oncol. 2011 Aug;100(2):167-75.
Darby SC, Ewertz M, McGale P, Bennet AM, Blom-Goldman U, Brønnum D, Correa C, Cutter D, Gagliardi G, Gigante B, Jensen MB, Nisbet A, Peto R, Rahimi K, Taylor C, Hall P. Risk of ischemic heart disease in women after radiotherapy for breast cancer. N Engl J Med. 2013 Mar 14;368(11):987-98.