Kristina Sundquist

Familial associations of rheumatoid arthritis with autoimmune diseases and related conditions

OBJECTIVE In the era of genome-wide association studies, familial risks are used to estimate disease heritability and the likelihood of candidate-gene identification. This study was undertaken to estimate associations of rheumatoid arthritis (RA) with any of 33 autoimmune diseases and related conditions among parents and offspring, singleton siblings, twins, and spouses. METHODS The Multigeneration Register in Sweden was used as a reliable source of information on Swedish families throughout the last century. Data on autoimmune diseases in individual family members were obtained through linkage to the Hospital Discharge Register. The standardized incidence ratio (SIR) was calculated as a measure of the relative risk of RA in family members of patients with RA or any of 33 other autoimmune diseases or related conditions, as compared with the relative risk of RA in those lacking an affected family member. RESULTS Among a total of 447,704 patients, 47,361 were diagnosed as having RA. The SIRs for RA were 3.02 in offspring of affected parents, 4.64 in siblings, 9.31 in multiplex families, 6.48 in twins, and 1.17 in spouses. Significant associations with the familial risk of RA in offspring according to parental proband were observed for ankylosing spondylitis (SIR 2.96), localized scleroderma (SIR 2.40), Sjögrens syndrome (SIR 2.25), systemic lupus erythematosus (SIR 2.13), systemic sclerosis (SIR 1.65), Hashimoto thyroiditis/hypothyroidism (SIR 1.54), pernicious anemia (SIR 1.53), sarcoidosis (SIR 1.40), psoriasis (SIR 1.36), Wegeners granulomatosis (SIR 1.34), and asthma or polymyalgia rheumatica (SIR 1.32). CONCLUSION This is the first study to compare the familial risks of RA in relation to a large number of autoimmune diseases and related conditions using data from a single population. The high discordant familial risks in this population suggest that there is extensive genetic sharing between RA and the associated diseases.

Risk of Cancer Following Hospitalization for Type 2 Diabetes

The present study assessed subsequent cancer risks in type 2 diabetes patients first hospitalized for this disease at age >39 years. Twenty-four cancer types showed an elevated risk when follow-up was started after the last hospitalization for type 2 diabetes. No additional risk was found in familial diabetics.

Familial risks for type 2 diabetes in Sweden

OBJECTIVE Our aim was to characterize familial risks for type 2 diabetes by the type and number of affected family members, including half-siblings, adoptees, and spouses, to quantify risks and estimate the contribution of environmental effect. RESEARCH DESIGN AND METHODS Families were identified from the Multigeneration Register, and type 2 diabetic patients were obtained from the Hospital Discharge Register. Standardized incidence ratios were calculated for offspring with type 2 diabetes whose family members were hospitalized for type 2 diabetes at ages >39 years compared with those lacking affected family members. RESULTS The number of hospitalized type 2 diabetic patients was 157,549. Among 27,895 offspring, 27.9% had a parent or sibling also hospitalized for type 2 diabetes. The familial relative risk (RR) ranged from 2.0 to >30, depending on the number and type of probands. The highest RRs of type 2 diabetes were found in individuals who had at least two siblings affected by type 2 diabetes, irrespective of the parental disease. Adoptees showed no risk from adopted parents. CONCLUSIONS The study, the largest yet published, showed that familial RRs varied by the number and type of affected family member. However, much of the familial clustering remains yet to be genetically explained. The high risk should be recognized in clinical genetic counseling. The data from adoptees confirmed the genetic basis of the familial associations, but those from half siblings and spouses suggested that a smaller part of familial clustering may be accounted for by environmental factors.

Physical activity, exercise and self-rated health: a population-based study from Sweden

BackgroundIn order to screen for the most inactive individuals in the population and target health-related interventions where they are most needed it is important to assess different forms of physical activity in population-based studies. The aims were (1) to identify the most inactive individuals in the population by assessing two dimensions of physical activity, (2) to investigate the correlation between exercise and total physical activity and (3) to investigate the association between exercise, total physical activity and good self-rated health.MethodsA simple random sample of the Swedish population aged 25–64 years were interviewed about their living conditions, health and lifestyle in a survey performed by Statitics Sweden. In total 1876 women and 1880 men completed the survey during 1999 (response rate 76.6%) when two different questions about physical activity assessed exercise and total physical activity in all domains (e.g. transportation, exercise, and at work). Logistic regression models were used to estimate odds ratios.ResultsThe most inactive individuals (no exercise and total physical activity ≤ 2 hours per week) constituted 4.3% of the sample. The correlation between exercise and total physical activity was low (gamma = 0.4, p = 0.02). There were significant associations between higher levels of exercise, total physical activity and good self-rated health after adjustment for age, gender, country of birth, education, employment, marital status, housing tenure, smoking and BMI.ConclusionBoth exercise and total physical activity were independently associated with good self-rated health. It seems to be advantageous to use more than one question in population based surveys in order to evaluate several dimensions of physical activity and identify the most inactive individuals.

Coronary heart disease risks in first- and second-generation immigrants in Sweden : a follow-up study

Objectives.  To analyse whether there is an association between country of birth in first‐generation immigrants and first hospitalization for or death from coronary heart disease (CHD) and to analyse whether this association remains in second‐generation immigrants.

The influence of age at migration and length of residence on self-rated health among Swedish immigrants: a cross-sectional study

Objective. Increasing global migration has led to profound demographic changes in most industrialised countries. A growing body of research has investigated various health aspects among immigrant groups and found that some immigrant groups have poorer health than the majority population. It has been suggested that poor acculturation in the host country could lie behind the increased risk of worsened health among certain immigrant groups. The aim was to investigate the cross-sectional association between acculturation, measured as age at migration or length of residence, and self-rated health among young immigrants. Design. The simple, random samples of 7137 women and 7415 men aged 16–34 years were based on pooled, independent data collected during the period 1992–1999 obtained from the Swedish Annual Level of Living Survey (SALLS). Logistic regression was applied in the estimation of odds ratios (OR) for poor self-rated health, after accounting for age, sex, socioeconomic status (SES) and social networks. The non-response rate varied between 23.6 and 28.3% in the different immigrant groups. Results. The odds of poor self-rated health increased with increasing age at migration to Sweden among first-generation immigrants. For those who had resided in Sweden less than 15 years the odds of poor self-rated health were significantly increased. In addition, most of the immigrant groups had higher odds of poor self-rated health than the reference group. Conclusions. Health care workers and policy makers need to be aware that immigrants who arrive in the host country at higher ages and/or have lived in the host country for a shorter period of time might need special attention as they are more likely to suffer from poor self-rated health, a valid health status indicator that can be used in population health monitoring.

Smokeless tobacco and coronary heart disease: a 12-year follow-up study.

Background Cigarette smoking has declined whereas the use of smokeless tobacco is increasing. There is an ongoing debate as to whether smokeless tobacco is a recommendable strategy to help smokers to quit. However, very few studies have examined the association between smokeless tobacco, namely snuff, and coronary heart disease, which implies that it has not been possible to provide scientific results for public health policies and clinical guidelines concerning the use of smokeless tobacco. Design A follow-up study. Methods A random sample of 3120 healthy men aged 30–74 years was interviewed in 1988 and 1989 and followed up to the year 2000 with regard to coronary heart disease. Cox regression was used to estimate the relative risk of coronary heart disease in six categories of smoking and snuffing habits, after adjustment for established risk factors for coronary heart disease. Results Smokers, former smokers, and those who combined smoking and snuffing had significantly higher hazard ratios than never-smokers. The very highest hazard ratio was found among individuals combining smoking and snuffing. Daily snuffers had a hazard ratio of 1.62 (95% confidence interval 0.70–3.03) after adjustment for age. Conclusions Even though the association between daily snuffing and coronary heart disease was non-significant, the hazard ratio was markedly increased. Therefore, smokers should not use smokeless tobacco in order to quit smoking, especially as safer alternatives are available. Further studies in different settings are required to provide scientific results for public health policies and clinical guidelines.

Levelling off of prevalence of obesity in the adult population of Sweden between 2000/01 and 2004/05.

BackgroundThe escalating global epidemic of obesity is of worldwide concern because of its association with several chronic diseases and premature mortality. Some subgroups seem to be more affected than others. The aim of this study was to examine whether the mean BMI (adjusted for age) and the prevalence of obesity (adjusted for all the explanatory variables) changed between 2000/01 and 2004/05 in different subgroups of the Swedish population.MethodsThis study compared two cross-sectional, nationwide random samples of persons aged 16 to 84 years: the first from 2000/01 (5515 men, 5838 women) and the second from 2004/05 (4681 men, 4821 women). After stratification by gender, a logistic regression model was applied to analyse possible changes in mean BMI and the prevalence of obesity between 2000/01 and 2004/05.ResultsTotal mean BMI remained almost unchanged between 2000/01 and 2004/05 for both men and women. The prevalence of obesity increased slightly in both men and women, but not significantly (from 9.7 to 10.8% and from 9.6 to 10.2%, respectively). The prevalence of obesity in 2004/05 was especially high in some subgroups: men aged 45-54 (14.3%) or 55-64 (16.5%), women aged 65-74 (15.9%) or 75-84 (16.8%), men and women of middle educational level (15.6% and 14.4%, respectively), male former smokers (13.4%), and men from small towns or rural areas (13.1%).ConclusionsAlthough the mean BMI and obesity were almost unchanged in the Swedish adult population between 2000/01 and 2004/05, obesity levels in Sweden remained unacceptably high, especially in certain subgroups. Primary and secondary intervention actions should strive to decrease the prevalence of obesity in Sweden.

Cancer risks in ulcerative colitis patients.

Patients diagnosed with ulcerative colitis (UC) are known to be at an increased risk of colorectal and liver cancers and leukemia. UC is an autoimmune disease, which may present a wider spectrum of cancers. We wanted to examine the risk of cancer in a large population of UC patients in order to reach high statistical power. A UC research database was constructed by identifying UC patients from the Swedish Hospital Discharge Register and cancer patients from the Cancer Registry. Follow‐up of 27,606 UC patients hospitalized for the first time during the years 1964–2004 identified 2,058 patients with cancer. Standardized incidence ratios were calculated for cancer in UC patients by comparing to subjects without hospitalization for UC. The novel tumor sites in UC patients included small intestinal (carcinoid), pancreatic, breast and prostate cancers, nonthyroid endocrine gland tumors, non‐Hodgkin lymphoma and multiple myeloma. A total of 11 sites showed an increased risk, which remained at 6 sites when tumors diagnosed in the year of UC hospitalization were excluded; even chronic myeloid leukemia was in excess. Cancer risks depended on the age at first hospitalization for UC. The SIRs for colon, rectal, liver and pancreatic cancers declined by age at hospitalization for UC, while for endocrine tumors the older patients were at higher risk. Our large study identified novel subsequent cancers in UC patients. However, some of these, including small intestinal carcinoids, prostate cancers and nonthyroid endocrine tumors, may be in excess because of intensified medical surveillance of the patients.

The impact of country of birth and time in Sweden on overweight and obesity: a population-based study.

Aims: A study was undertaken to investigate the relationship between country of birth, time in Sweden, and overweight and obesity. Methods: Approximately 4,000 people aged 20—80 participated in a cross-sectional survey in 1994. The ethnic differences in overweight and obesity were analysed in a multivariate logistic regression analysis adjusting for age and education. The effect of number of years spent in Sweden on overweight and obesity was assessed for some of the ethnic groups compared with the Swedish-born group. Results: Men from Yugoslavia and Arabic-speaking countries were overweight/obese (BMI 25.0—) and obese (BMI 30.0—) to a significantly higher extent than men born in Sweden. Women born in Poland, Arabic-speaking countries, and all other countries were overweight/obese and obese to a significantly higher extent than women born in Sweden. Both Arabic men and women who had immigrated to Sweden in 1989 or earlier had an increased risk of overweight/obesity and obesity compared with the participants born in Sweden, while no increased risk was observed for the Arabic group that immigrated after 1989. Conclusions: There were significant differences in overweight and obesity between the country of birth groups. The findings follow the patterns of low leisure time physical activity among certain ethnic groups reported in a previous study, which has implications for public health measures directed to decrease differences in overweight and obesity by country of birth.