Is birthweight associated with risk of rheumatoid arthritis? Data from a large cohort study

Causal effects of time-varying body size on selected autoimmune disorders: a life course Mendelian randomisation study

BACKGROUND

Based on Barker's hypothesis, some studies investigated the associations between birth weight and several disorders. Apart from issues with statistical power and well-known shortcomings of the observational study design, there are no studies accounting for changes in weight-related body size over the life course regarding rheumatoid arthritis, psoriasis, psoriatic arthritis and multiple sclerosis.

METHODS

Using genetic information of up to 806 834 participants, this study investigated the associations between time-varying weight-related body size from birth to adulthood and the mentioned autoimmune diseases. Performing Mendelian randomisation (MR), the radial inverse-variance weighted approach was used iteratively in primary analyses. Robustness of the results was confirmed in several sensitivity analyses. Potential time-dependent mediation mechanisms were identified through network-clustering and assessed using multivariable MR.

RESULTS

Genetically predicted birth weight (fetal effect) was positively associated with rheumatoid arthritis (OR 1.44; 95% CI 1.17 to 1.77; Padj =0.005) but not with psoriasis, psoriatic arthritis or multiple sclerosis. This association was found to be mediated by body mass index (BMI) in adulthood (OR 1.45; 95% CI 1.14 to 1.84; Padj =0.019) rather than childhood. The direct effect of birth weight attenuated (OR 1.19; 95% CI 0.88 to 1.62); Padj =1) after adjustment for time-varying BMI.

CONCLUSION

Increased birth weight appears to be a risk factor for later manifestation of rheumatoid arthritis due to both fetal genetic components and high BMI persisting into adulthood. Approaches to prevent and minimise the risk of rheumatoid arthritis could include preventing obesity in adults with high birth weight.

Association of childhood infections and perinatal factors with ankylosing spondylitis: a Swedish nationwide case-control and sibling study

OBJECTIVES

To identify perinatal and early-life risk factors for ankylosing spondylitis (AS), controlling for family-shared confounding with a sibling comparison design.

METHODS

In this nationwide, register-based case-control study, we identified 5612 AS cases from the Swedish National Patient Register, and matched them with 22 042 individuals without inflammatory arthritis from the general population. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of AS in relation to childhood infections and a broad range of perinatal factors including fetal growth. Significant associations were further tested in a sibling comparison analysis, including 3965 patients with AS and their 6070 siblings without a diagnosis of spondyloarthritis.

RESULTS

We found no statistically significant associations between any studied fetal growth-related factor or other perinatal factors and the risk of developing AS. In contrast, having older siblings (adjusted OR 1.12; 95% CI 1.04 to 1.22 for one vs no older sibling) and history of a childhood tonsillectomy (adjusted OR 1.30; 95% CI 1.13 to 1.49) were associated with AS in the case-control analysis, results that also held in the sibling comparison. Serious childhood infection and multiple birth were significantly associated with AS in the case-control sample, but estimates were attenuated in the sibling comparison.

CONCLUSIONS

Having older siblings and a history of tonsillectomy in childhood were independently associated with development of AS, even after adjustment for family-shared factors in a sibling comparison analysis. This strengthens the hypothesis that childhood infections play a role in the aetiology of AS.

Pre- and Perinatal Factors Predicting Inflammatory Bowel Disease: A Population-Based Study with Fifty Years of Follow-Up

BACKGROUND

Pre- and perinatal events may be associated with an increased risk of inflammatory bowel disease [IBD]. We aimed to investigate the role of pre- and perinatal factors as potential risk factors for the development of IBD in a population with a follow-up of 50 years.

METHODS

We conducted a nested case-control study, reporting IBD incidence among individuals born in 1964-76, for whom pre- and perinatal exposures were reported as part of the Jerusalem Perinatal Study [JPS], by linking them to the database of the epidemiology group of the Israeli IBD Research Nucleus [epi-IIRN], including all IBD patients in Israel since 2005 and their matched controls.

RESULTS

We identified 2789 individuals within the epi-IIRN cohort who were also included in the JPS cohort [n = 90 079]: 746 IBD patients (405 with Crohn's disease [CD] and 341 with ulcerative colitis [UC]) and 2043 non-IBD controls. Those with a 'Non-western' family origin had decreased odds of developing CD and UC. High socioeconomic status was associated with CD but not UC. Low birth weight [≤2500 g] occurred less frequently in IBD cases compared to controls, especially in UC patients, showing a protective effect. Being the first born was associated with CD, and having older siblings lowered the odds of developing CD, decreasing 7% with each additional sibling. Smoking and breastfeeding data were available for a subset of individuals, but neither was associated with IBD development.

CONCLUSION

This population-based study identifies several pre- and perinatal variables as predictors of IBD development. This information may be helpful to facilitate implementation of early diagnosis interventions and family follow-up protocols.

Birthweight and subsequent risk for thyroid and autoimmune conditions in postmenopausal women

The objective of this study was to determine the association between birthweight and risk of thyroid and autoimmune conditions in a large sample of postmenopausal women. Baseline data from the Women's Health Initiative (n = 80,806) were used to examine the associations between birthweight category (<6 lbs., 6-7 lbs. 15 oz, 8-9 lbs. 15 oz, and ≥10 lbs.) and prevalent thyroid (underactive and overactive thyroid and goiter) and autoimmune (lupus, rheumatoid arthritis (RA), multiple sclerosis, ulcerative colitis/Crohn's disease) conditions. Follow-up questionnaire data were used to examine the associations between birthweight and incident underactive and overactive thyroid, lupus, and RA. Logistic and Cox proportional hazards regression models were used to estimate crude and adjusted odds (OR) and hazards ratios (HR), respectively. Overall, women born weighing ≥10 lbs. had an increased risk for underactive thyroid [OR 1.14 (95% CI 1.02, 1.28)] and incident lupus [HR 1.51 (95% CI 1.12, 2.03)] and a decreased risk for overactive thyroid [OR 0.67 (95% CI 0.50, 0.92)] compared to women born weighing 6-7.99 lbs., after adjustment for adult BMI, demographic variables, and lifestyle factors. Further, women born weighing <6 lbs. were at increased risk for underactive thyroid [OR 1.13 (95% CI 1.04, 1.22)]. Birthweight was not associated with other thyroid or autoimmune disorders. High birthweight was associated with later-life thyroid and autoimmune conditions while low birthweight was associated with underactive thyroid. Preconception and prenatal interventions aimed at reducing the risk of both high and low birthweights may reduce the burden of later-life thyroid and autoimmune conditions.

Phytochemicals from medicinal plants from African forests with potentials in rheumatoid arthritis management

OBJECTIVES

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by inflammation, pain, and cartilage and bone damage. There is currently no cure for RA. It is however managed using nonsteroidal anti-inflammatory drugs, corticosteroids and disease-modifying anti-rheumatic drugs, often with severe side effects. Hidden within Africa's lush vegetation are plants with diverse medicinal properties including anti-RA potentials. This paper reviews the scientific literature for medicinal plants, growing in Africa, with reported anti-RA activities and identifies the most abundant phytochemicals deserving research attention. A search of relevant published scientific literature, using the major search engines, such as Pubmed/Medline, Scopus, Google Scholar, etc. was conducted to identify medicinal plants, growing in Africa, with anti-RA potentials.

KEY FINDINGS

Twenty plants belonging to 17 families were identified. The plants are rich in phytochemicals, predominantly quercetin, rutin, catechin, kaempferol, etc., known to affect some pathways relevant in RA initiation and progression, and therefore useful in its management.

SUMMARY

Targeted research is needed to unlock the potentials of medicinal plants by developing easy-to-use technologies for preparing medicines from them. Research attention should focus on how best to exploit the major phytochemicals identified in this review for the development of anti-RA 'green pharmaceuticals'.

Preclinical Autoimmune Disease: a Comparison of Rheumatoid Arthritis, Systemic Lupus Erythematosus, Multiple Sclerosis and Type 1 Diabetes

The preclinical phase of autoimmune disorders is characterized by an initial asymptomatic phase of varying length followed by nonspecific signs and symptoms. A variety of autoimmune and inflammatory manifestations can be present and tend to increase in the last months to years before a clinical diagnosis can be made. The phenotype of an autoimmune disease depends on the involved organs, the underlying genetic susceptibility and pathophysiological processes. There are different as well as shared genetic or environmental risk factors and pathophysiological mechanisms between separate diseases. To shed more light on this, in this narrative review we compare the preclinical disease course of four important autoimmune diseases with distinct phenotypes: rheumatoid arthritis (RA), Systemic Lupus Erythematosus (SLE), multiple sclerosis (MS) and type 1 diabetes (T1D). In general, we observed some notable similarities such as a North-South gradient of decreasing prevalence, a female preponderance (except for T1D), major genetic risk factors at the HLA level, partly overlapping cytokine profiles and lifestyle risk factors such as obesity, smoking and stress. The latter risk factors are known to produce a state of chronic systemic low grade inflammation. A central characteristic of all four diseases is an on average lengthy prodromal phase with no or minor symptoms which can last many years, suggesting a gradually evolving interaction between the genetic profile and the environment. Part of the abnormalities may be present in unaffected family members, and autoimmune diseases can also cluster in families. In conclusion, a promising strategy for prevention of autoimmune diseases might be to address adverse life style factors by public health measures at the population level.

Birthweight, body size, and growth during childhood and risks of rheumatoid arthritis: a large Danish cohort study

Objectives: Adult obesity may be positively associated with risks of rheumatoid arthritis (RA), but associations with early life body size are unknown. We examined whether birthweight, childhood body mass index (BMI), height, and changes in BMI and height were associated with risks of adult RA.Method: A cohort of 346 602 children (171 127 girls) from the Copenhagen School Health Records Register, born in 1930-1996, with measured weights and heights from 7 to 13 years of age, were included. Information on RA, including serological status, came from national registers from 1977 to 2017. Cox regressions were performed.Results: During a median of 35.1 years of observation time per person, 4991 individuals (3565 women) were registered with RA. Among girls, per BMI z-score, risks of RA and seropositive RA increased by 4-9% and 6-10%, respectively. Girls with overweight had higher risks of RA than girls without overweight. Girls who became overweight by 13 years of age had increased risks of RA compared to girls without overweight at 7 or 13 years (hazard ratio = 1.40, 95% confidence interval 1.19-1.66). For boys, associations between BMI and RA (including seropositive RA) were not statistically significant. Height was not associated with RA (any type) in girls. Taller boys had higher risks of RA, especially seropositive RA. Birthweight was not associated with RA.Conclusions: Among women, childhood adiposity was associated with increased risks of RA. Among men, childhood height was positively associated with risks of RA. These findings support the hypothesis that early life factors may be important in the aetiology of RA.

The pre-clinical phase of rheumatoid arthritis: From risk factors to prevention of arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease considered as a multistep process spanning from the interaction of genetic (e.g., shared epitope or non-HLA loci), environmental and behavioral risk factors (e.g., smoking) leading to breaking immune tolerance and autoimmune processes such as the production of autoantibodies (e.g., antibodies against citrullinated proteins ACPA or rheumatoid factors, RF), development of the first symptoms without clinical arthritis, and, finally, the manifestation of arthritis. Despite the typical joint involvement in established RA, the pathogenesis of the disease likely begins far from joint structures: in the lungs or periodontium in association with citrullination, intestinal microbiome, or adipose tissue, which supports normal findings in synovial tissue in ACPA+ patients with arthralgia. The presence of ACPA is detectable even years before the first manifestation of RA. The pre-clinical phase of RA is the period preceding clinically apparent RA with ACPA contributing to the symptoms without subclinical inflammation. While the combination of ACPA and RF increases the risk of progression to RA by up to 10 times, increasing numbers of novel autoantibodies are to be investigated to contribute to the increased risk and pathogenesis of RA. With growing knowledge about the course of RA, new aspiration emerges to cure and even prevent RA, shifting the "window of opportunity" to the pre-clinical phases of RA. The clinical definition of individuals at risk of developing RA (clinically suspect arthralgia, CSA) makes it possible to unify these at-risk individuals' clinical characteristics for "preventive" treatment in ongoing clinical trials using mostly biological or conventional synthetic disease-modifying drugs. However, the combination of symptoms, laboratory, and imaging biomarkers may be the best approach to select the correct target at-risk population. The current review aims to explore different phases of RA and discuss the potential of (non)pharmacological intervention aiming to prevent RA.

In Utero and Early Life Exposure to the Great Chinese Famine and Risk of Rheumatoid Arthritis in Adulthood

OBJECTIVE

To investigate whether early life exposure to the Great Chinese Famine of 1959-1961 is associated with the risk of RA development in adulthood.

METHODS

This study included 101,510 participants who were enrolled in the Kailuan Study in 2006. RA cases were confirmed by medical record review. Logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (95% CI) for RA according to famine exposure status (exposed in utero or between ages 0 and 3 years, between ages 3 and 6 years, or at age 6 years or older), in comparison to participants born after 1961 who were not exposed to famine.

RESULTS

During 12 years of follow-up (2006-2018), we identified 187 RA cases. Individuals exposed to famine in utero or between ages 0 and 3 years had a higher prevalence of RA relative to other groups (0.2-0.35% versus 0.08-0.20%). After adjustment for potential confounders, the OR for RA was 2.95 (95% CI 1.55-5.59) for individuals exposed in utero, 4.53 (95% CI 2.72-7.54) for those exposed between ages 0 and 3 years, 2.55 (95% CI 1.43-4.57) for those exposed between ages 3 and 6 years, and 2.72 (95% CI 1.70-4.36) for those exposed at age 6 years or older versus individuals born after 1961. Similar associations with the risk of RA were observed for men and women when subjects were stratified by sex (P for interaction = 0.89).

CONCLUSION

Individuals exposed to famine in utero or in early childhood (between ages 0 and 3 years) were more likely to develop RA in adulthood, highlighting the importance of early life as a vulnerable developmental period.

Adiposity and the risk of rheumatoid arthritis: a systematic review and meta-analysis of cohort studies

Several studies have investigated associations between overweight/obesity and risk of developing rheumatoid arthritis, however, the evidence is not entirely consistent, and previous meta-analyses mainly included case–control studies, which can be affected by various biases. We therefore conducted a systematic review and meta-analysis of cohort studies on adiposity and risk of rheumatoid arthritis. Relevant studies were identified by searching PubMed and Embase databases. Random effects models were used to estimate summary relative risks (RRs) and 95% confidence intervals (CIs) for rheumatoid arthritis in relation to different measures of adiposity. Thirteen cohort studies (10 publications) were included. The summary RR per 5 kg/m² increase in body mass index (BMI) was 1.11 (95% CI 1.05–1.18, I² = 50%), but the association was restricted to women (1.15, 95% CI 1.08–1.21, I² = 17%) and not observed in men (0.89, 95% CI 0.73–1.09, I² = 58%). The summary RR per 5 kg/m² increment in BMI at age 18 years was 1.17 (95% CI 1.01–1.36, I² = 26%, n = 3), and per 10 cm increase in waist circumference was 1.13 (95% CI 1.02–1.25, I² = 44%, n = 2). Higher BMI in middle age, BMI at age 18 years, and waist circumference were associated with increased rheumatoid arthritis risk, suggesting adiposity could be targeted for primary prevention.

Childhood growth and risk of inflammatory bowel disease: a population-based study of 317,030 children

Background: Growth in childhood is associated with later development of autoimmune diseases and cancer, but the impact of growth on risk of inflammatory bowel disease (IBD) remains unknown. We conducted a population-based cohort study to examine whether birth weight, childhood height, or changes in height associated with later risk of IBD. Methods: Our cohort consisted of 317,030 children from the Copenhagen School Health Records Register (born 1930-1989) with height repeatedly measured from age 7 to 13 and with data on birth weight on a subset. Through linkage to the Danish National Patients Register, cases of IBD were identified. Cox proportional hazard regression was used to examine associations between measures of childhood growth and risk of IBD. Results: During more than 9 million years of follow-up, 1612 individuals were diagnosed with Crohn's disease (CD) and 2,640 with ulcerative colitis (UC). Birth weight and childhood heights were not associated with subsequent risk of CD or UC (HRs close to 1.00). Childhood growth from 7 to 10 years (CD: HR, 1.00; 95% CI, 0.85-1.18; UC: HR, 0.92; 95% CI, 0.81-1.05) and 10 to 13 years (CD: HR, 1.02; 95% CI, 0.89-1.17; UC: HR, 0.95; 0.85-1.05) did not associate with risk of IBD either. Conclusion: In this large population-based cohort study, birth weight and childhood growth did not influence risk of IBD, which contrasts with observations in other chronic diseases. Thereby, the study also suggests that pre-clinical effects of adult IBD are not measurable in childhood and that childhood risk factors for IBD do not influence growth.

Associations between Adipokines in Arthritic Disease and Implications for Obesity

Secretion from adipose tissue of adipokines or adipocytokines, comprising of bioactive peptides or proteins, immune molecules and inflammatory mediators, exert critical roles in inflammatory arthritis and obesity. This review considers the evidence generated over the last decade regarding the effects of several adipokines including leptin, adiponectin, visfatin, resistin, chemerin and apelin, in cartilage and bone homeostasis in the pathogenesis of rheumatoid arthritis and osteoarthritis, which has important implications for obesity.

Sex differences in adult mortality rate mediated by early-life environmental conditions

Variation in sex differences is affected by both genetic and environmental variation, with rapid change in sex differences being more likely due to environmental change. One case of rapid change in sex differences is human lifespan, which has become increasingly female-biased in recent centuries. Long-term consequences of variation in the early-life environment may, in part, explain such variation in sex differences, but whether the early-life environment mediates sex differences in life-history traits is poorly understood in animals. Combining longitudinal data on 60 cohorts of pre-industrial Finns with environmental data, we show that the early-life environment is associated with sex differences in adult mortality and expected lifespan. Specifically, low infant survival rates and high rye yields (an important food source) in early-life are associated with female-bias in adult lifespan. These results support the hypothesis that environmental change has the potential to affect sex differences in life-history traits in natural populations of long-lived mammals.

Presence of anticitrullinated protein antibodies in a large population-based cohort from the Netherlands

OBJECTIVES

To determine the prevalence of anticitrullinated protein antibodies (ACPAs) and their association with known rheumatoid arthritis (RA) risk factors in the general population.

METHODS

Lifelines is a multidisciplinary prospective population-based cohort study in the Netherlands. Cross-sectional data from 40 136 participants were used. The detection of ACPA was performed by measuring anti-CCP2 on the Phadia-250 analyser with levels ≥6.2 U/mL considered positive. An extensive questionnaire was taken on demographic and clinical information, including smoking, periodontal health and early symptoms of musculoskeletal disorders. RA was defined by a combination of self-reported RA, medication use for the indication of rheumatism and visiting a medical specialist within the last year.

RESULTS

Of the total 40 136 unselected individuals, 401 (1.0%) had ACPA level ≥6.2 U/mL. ACPA positivity was significantly associated with older age, female gender, smoking, joint complaints, RA and first degree relatives with rheumatism. Of the ACPA-positive participants, 22.4% had RA (15.2% had defined RA according to our criteria and 7.2% self-reported RA only). In participants without RA, 311 (0.8%) were ACPA-positive. In the non-RA group, older age, smoking and joint complaints remained significantly more frequently present in ACPA-positive compared with ACPA-negative participants.

CONCLUSIONS

In this large population-based study, the prevalence of ACPA levels ≥6.2 U/mL was 1.0% for the total group and 0.8% when excluding patients with RA. Older age, smoking and joint complaints were more frequently present in ACPA-positive Lifelines participants. To our knowledge, this study is the largest study to date on ACPA positivity in the general, mostly Caucasian population.

Post-Traumatic Stress Disorder and Risk for Incident Rheumatoid Arthritis

OBJECTIVE

To examine the association between symptoms of post-traumatic stress disorder (PTSD) and rheumatoid arthritis (RA) risk in a prospective cohort and to characterize the role of smoking in this relationship.

METHODS

A subset (n = 54,224) of the Nurses' Health Study II, a prospective cohort of female nurses, completed the Brief Trauma Questionnaire and a screen for PTSD symptoms. Participants were categorized based on trauma exposure and number of PTSD symptoms. Incident RA cases (n = 239) from 1989 to 2011 were identified. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs) between PTSD symptoms and incident RA. To identify the impact of smoking, secondary and subgroup analyses were performed. In all analyses, PTSD and smoking were lagged 2 years before the development of RA.

RESULTS

Compared to no history of trauma/PTSD symptoms, the HR for ≥4 PTSD symptoms and incident RA was 1.76 (95% CI 1.16-2.67) in models adjusted for age, race, and socioeconomic status. The risk for RA increased with an increasing number of PTSD symptoms (P = 0.01). When smoking was added to the model, the HR for RA remained elevated (HR 1.60 [95% CI 1.05-2.43]). In a subgroup analysis, excluding women who smoked before PTSD onset, results were unchanged (HR 1.68 [95% CI 1.04-2.70]).

CONCLUSION

This study suggests that women with high PTSD symptomatology have an elevated risk for RA, independent of smoking, adding to emerging evidence that stress is an important determinant of physical health.

Perinatal characteristics, older siblings, and risk of ankylosing spondylitis: a case-control study based on national registers

Background

The effect of circumstances and exposures early in life on the risk of developing ankylosing spondylitis (AS) is largely unknown. The purpose of this study was to determine whether perinatal characteristics predict development of AS.

Methods

AS cases (n = 1960; 59 % men) were defined as listed with a diagnosis of AS at least once in the Swedish National Patient Register and registered in the Swedish Medical Birth Register (born ≥1973). Population controls were retrieved from the Swedish Population Register (n = 8378; mean 4.3 controls/case), matched on birth year, sex and county. Odds ratios (OR) for developing AS were determined through conditional logistic regression, with regard to: birth weight, birth order, season of birth, maternal age, gestational length, size for gestational age, type of birth, mode of delivery, congenital malformations, mothers’ country of birth, mothers’ civil status and size of delivery unit.

Results

In the univariate analyses statistically significant increases in risk for developing AS were observed for having older siblings (OR 1.18; 95 % Cl 1.06–1.30). No association was observed for the remainder of analysed exposures, although there was a weak association with birth weight below 3000 g (OR 1.19; 95 % CI 1.04–1.37), though not for “low birth weight” <2500 g (OR 0.90; 95 % CI 0.70–1.16). The increase in risk associated with having older siblings was consistent in a multivariate analysis adjusting for possible confounders (OR 1.23; 95 % Cl 1.09–1.39). The direction and magnitude of the point estimates were also consistent in several sensitivity analyses and when stratifying by sex.

Conclusions

Having older siblings was associated with an increased risk for developing AS. These results need to be repeated and confirmed in other cohorts.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-0917-1) contains supplementary material, which is available to authorized users.

Fetal programming and systemic sclerosis

OBJECTIVE

This study investigated whether birthweight is linked to an increased risk of the development of systemic sclerosis.

STUDY DESIGN

This was a multicenter case-control study with perinatal data that were obtained from 332 cases with systemic sclerosis and 243 control subjects. Birthweight was treated as a dichotomous variable (<2500 g vs ≥2500 g); low birthweight was defined as a weight <2500 g; small for gestational age was defined as birthweight <10th percentile for gestational age adjusted for sex. The relationship between systemic sclerosis and both low birthweight and small for gestational age was expressed with the crude (univariate analysis) and adjusted (multivariate analysis) odds ratio (OR).

RESULTS

Significantly increased ORs were observed in the univariate analysis for low birthweight (OR, 2.59; 95% confidence interval [CI], 1.39-5.05) and small for gestational age (OR, 2.60; 95% CI, 1.34-5.32) subjects. Similarly increased risks were confirmed for both conditions in the multivariate analysis (OR, 3.93; 95% CI, 1.92-8.07; and OR, 2.58; 95% CI, 1.28-5.19), respectively.

CONCLUSION

Low birthweight and small for gestational age at birth are risk factors for the adult onset of systemic sclerosis.

Maternal pre-pregnancy BMI, gestational weight gain, and infant birth weight: A within-family analysis in the United States

In the United States, the high prevalence of unhealthy preconception body weight and inappropriate gestational weight gain among pregnant women is an important public health concern. However, the relationship among pre-pregnancy BMI, gestational weight gain, and newborn birth weight has not been well established. This study uses a very large dataset of sibling births and a within-family design to thoroughly address this issue. The baseline analysis controlling for mother fixed effects indicates maternal preconception overweight, preconception obesity, and excessive gestational weight gain significantly increase the risk of having a high birth weight baby, respectively, by 1.3, 3 and 3.9 percentage points, while underweight before pregnancy and inadequate gestational weight gain increase the low birth weight incidence by 1.4 and 2 percentage points. The benchmark results are robust in a variety of sensitivity checks. Since poor birth outcomes especially high birth weight and low birth weight have lasting adverse impacts on one's health, education, and socio-economic outcomes later in life, the findings of this research suggest promoting healthy weight among women before pregnancy and preventing inappropriate weight gain during pregnancy can generate significant intergenerational benefits.

Prediction of future rheumatoid arthritis

Rheumatoid arthritis (RA) results from an interaction between genetic susceptibility and environmental factors. Several of these factors are known, such as family history of RA, high birth weight, smoking, silica exposure, alcohol nonuse, obesity, diabetes mellitus, rheumatoid factor, anti-citrullinated protein antibody, and genetic variants such as the shared epitope and protein tyrosine phosphatase nonreceptor type 22. The impact of these factors can be modeled in the 2 main groups at risk of RA: family members of patients with RA and seropositive persons with or without arthralgia. Current models have the potential to select individuals for preventive strategies.

Newborn infant characteristics and risk of future rheumatoid arthritis: a twin-control study

Low birth weight has been proposed as a risk factor for rheumatoid arthritis (RA). The twin-control study design provides an opportunity to investigate the significance of potential prenatal determinants for adult morbidity by accounting for maternal characteristics and early environmental and genetic factors. We investigated the association between birth weight and RA in a sample of 42 twin pairs discordant for rheumatoid arthritis in which valid information on birth weight, birth length, and order was available from midwife records. Difference plot and conditional logistic regression were used to investigate the relationship between RA and birth weight or birth order adjusting for birth length and sex. The intra-pairwise birth weight differences, i.e., RA twin minus co-twin, ranged from -750 to 1,100 g, mean 78 g (95 % CI -13 to 70), 146 g (95 % CI (-36 to 329) in monozygotic, 32 g (95 % CI -90 to 154) in dizygotic, same sex and 69 g (95 % CI -122 to 260) in dizygotic, opposite sex twin pairs. The odds ratio for birth weight as risk factor for RA was 1.00 (95 % CI 0.997-1.003) when adjusting for birth length, birth order, and sex, irrespective of ACPA status. The odds ratio for developing RA as first born twin was 2.33 (95 % CI 0.97-5.60) when adjusting for birth length, birth weight, and sex, irrespective of ACPA status. In this twin-control study, birth weight was not associated with the development of RA in adult life. Being born first may predispose to RA.

Very low, low and heavy weight births in Hong Kong SAR: how important is socioeconomic and migrant status?

Identification of modifiable factors and mediators linked to low and heavy birth weight is crucial in reducing infant mortality and health care expenditure. The present paper explores the associations of socio-demographic factors and immigrant status of parents with adverse pregnancy outcomes in Hong Kong. The analysis compares very low birth weight (VLBW: <1500 g), low birth weight (LBW: ≥ 1500 g and <2500 g) and heavy birth weight births (HBW: ≥ 4500 g) with births of normal weight (≥ 2500 g and <4500 g) using multinomial regression modelling of a large dataset of 828,975 births of singletons occurring between 1995 and 2009. The findings indicate the expected significant adverse associations between teenage and advanced age of the mother with compromised birth outcomes; teenage motherhood, however, has a protective effect against HBW births. A strong socioeconomic gradient is apparent, more marked among LBW births; low educational attainment of the father, low occupational class, public housing and single motherhood are strongly related to adverse pregnancy outcomes. Regarding immigrant status, women born in South and South-East Asia exhibit consistently higher odds of a compromised outcome. Women born in Hong Kong have significantly higher chances of LBW births while Mainland Chinese and parents from developed countries face higher odds of HBW births. The study identifies high-risk groups such as teenage, older and single mothers, South-East Asians and couples of low socioeconomic profile. Implementation of policies supporting these groups would be beneficial.

Early life factors and risk of inflammatory bowel disease in adulthood

BACKGROUND

Early life factors have been postulated to play a role in development of immune tolerance and intestinal microbiome, which in turn may influence the risk of inflammatory bowel disease.

METHODS

We conducted a prospective cohort study of 60,186 U.S. women enrolled since 1976 in the Nurses Health Study (NHS) I and 86,495 women enrolled since 1989 in the NHS II with no history of ulcerative colitis (UC) or Crohn's disease (CD). Information about breastfeeding, birth weight, and preterm birth were collected in 1992 in NHS I and 1991 in NHS II. Diagnoses of CD and UC were confirmed through review of medical records. We used Cox proportional hazards models to calculate hazard ratios and 95% confidence intervals.

RESULTS

Among 146,681 women over 3,373,726 person-years of follow-up, we documented 248 cases of CD and 304 cases of UC through 2007 in NHS II and 2008 in NHS I. The median age of diagnosis was 51 for CD and 49 for UC. Compared with women who were not breastfed, women who were breastfed had multivariate-adjusted hazard ratios of 0.99 (95% confidence interval, 0.76-1.30) for CD and 1.03 (95% confidence interval, 0.81-1.32) for UC. Similarly, low or high birth weight and preterm birth were not significantly associated with risk of UC or CD.

CONCLUSIONS

In 2 large prospective cohorts of U.S. women, we did not observe a significant association between early life factors including having been breastfed, birth weight, preterm birth, and risk of adult-onset UC and CD.

Early menopause and severity of rheumatoid arthritis in women older than 45 years

Introduction

We aimed to investigate whether recognized hormonal predictors of rheumatoid arthritis (RA) also influence the severity of RA.

Methods

One hundred thirty-four incident RA cases identified by four different local and national registers, who had participated in a community-based health survey between 1991 and 1996, were included. By a retrospective structured review of the medical records, information on the use of disease-modifying antirheumatic drugs (DMARDs), erosions on radiographs, rheumatoid factor (RF) status, and disability measured by using the health assessment questionnaire (HAQ) were collected. The variables were added to the SPSS TwoStep Cluster Analysis to reveal natural groupings of RA severity. Known hormonal predictors analyzed were breastfeeding history, history of oral contraceptive (OC) use, and menopausal age.

Results

The mean age at RA diagnosis was 63.4 years; 72% were RF positive, and 28% had received biological treatment. Three clusters were identified, one with severe RA, one with mild/moderate RF-positive RA, and one with mild/moderate RF-negative RA. A significant difference (P = 0.005) was found in the distribution of clusters between patients with a history of early menopause compared with those with menopause after 45 years, with a higher proportion with mild/moderate RF-negative RA in the early-menopause subset. No major difference in severity of the disease was noted depending on OC use or history of breastfeeding.

Conclusions

Early menopause was associated with a milder form of RA. Hormonal changes may influence pathways that are distinct from those leading to severe, progressive disease.

Environmental and gene-environment interactions and risk of rheumatoid arthritis

Multiple environmental factors including hormones, dietary factors, infections, and exposure to tobacco smoke, as well as gene-environment interactions, have been associated with increased risk for rheumatoid arthritis (RA). The growing understanding of the prolonged period before the first onset of symptoms of RA suggests that these environmental and genetic factors are likely acting to drive the development of RA-related autoimmunity long before the appearance of the first joint symptoms and clinical findings that are characteristic of RA. This article reviews these factors and interactions, especially those that have been investigated in a prospective fashion before the symptomatic onset of RA.

Childhood socioeconomic factors and perinatal characteristics influence development of rheumatoid arthritis in adulthood

BACKGROUND

Rheumatoid arthritis (RA) has been associated with lower socioeconomic status (SES), but the reasons for this are not known.

OBJECTIVE

To examine childhood SES measures, SES trajectory and other perinatal factors in relation to RA.

METHODS

The sample included 50 884 women, aged 35-74 (84% non-Hispanic white) enrolled 2004-9 in a US national cohort study. In baseline questionnaires, cases (N=424, 0.8%) reported RA diagnosis after age 16, ever use of disease-modifying antirheumatic drugs or steroids for RA and ≥6 weeks bilateral joint swelling. Childhood SES measures are presented as OR and 95% CI adjusted for age and race/ethnicity. Analyses of perinatal factors also adjusted for childhood SES, and joint effects of childhood and adult SES and smoking exposures were evaluated.

RESULTS

Patients with RA reported lower childhood household education (<12 years vs college degree; OR=1.7; 95% CI 1.1 to 2.5), food insecurity (OR=1.5, 95% CI 1.1 to 2.0) and young maternal age (<20 vs 20-34 years; OR=1.7, 95% CI 1.2 to 2.5), with a trend (p<0.0001) for increasing number of adverse factors (OR=3.0; 95% CI 1.3 to 7.0; 4 vs 0 factors) compared with non-cases. Low birth weight (<2500 g) [corrected] and preconception paternal smoking were independently associated with RA. Together, lower childhood SES and adult education (<college degree) were associated with RA (interaction p=0.03), with a joint effect magnitude similar to a history of paternal and adult smoking.

CONCLUSIONS

RA was associated with low childhood SES sustained into adulthood, with cumulative effects across multiple measures, suggesting the importance of other unmeasured factors linking SES and RA.

Precipitating and perpetuating factors of rheumatoid arthritis immunopathology: linking the triad of genetic predisposition, environmental risk factors and autoimmunity to disease pathogenesis

Rheumatoid arthritis (RA) is considered to occur when genetic and environmental factors interact to trigger immunopathological changes and consequently an inflammatory arthritis. Over the last few decades, epidemiological and genetic studies have identified a large number of risk factors for RA development, the most prominent of which comprise cigarette smoking and the shared epitope alleles. These risks appear to differ substantially between anti-cyclic citrullinated peptide (ACPA)-positive and ACPA-negative disease. In this article, we will summarise the risk factors for RA development that have currently been identified, outlining the specific gene-environment and gene-gene interactions that may occur to precipitate and perpetuate autoimmunity and RA. We will also focus on how this knowledge of risk factors for RA may be implemented in the future to identify individuals at a high risk of disease development in whom preventative strategies may be undertaken.

Alteration of antioxidant defense status precedes humoral immune response abnormalities in macrosomia

Background

This study aimed to investigate whether the anomalies affecting the antioxidant and humoral immune defenses could start at birth and to check whether the decrease in antioxidant defenses may precede the immune abnormalities in macrosomic newborns.

Material/Methods

Thirty macrosomic and 30 sex-matched control newborns were recruited for a retrospective case-control study at the Maghnia Maternity Hospital of Tlemcen Department (Algeria).

Results

The serum IgG levels were similar in both groups. However, plasma ORAC, albumin, vitamin E, SOD, CAT and GSH-Px levels were significantly decreased in macrosomic as compared to control newborns, yet no difference was observed after adjustment for weight. Additionally, serum concentrations of complement C3, MDA and XO were significantly higher in macrosomic as compared to controls before adjustment for weight. Moreover, macrosomia was significantly associated with high levels of complement C3 (OR=8, p=0.002); whereas no association with those of IgG was observed (OR<1, p>0.05). Furthermore, macrosomia was significantly associated with low levels of ORAC (OR=4.96, p=0.027), vitamin E (OR=4.5, p=0.018), SOD (OR=6.88, p=0.020) and CAT (OR=5.67, p=0.017), and with high levels of MDA (OR=10.29, p=0.005).

Conclusions

Abnormalities of the humoral defense system in excessive weight could be preceded by alterations of the anti-oxidative defense and by inflammatory response and activation of innate immunity at birth. Additionally, excessive weight could be a potential factor contributing to decreased anti-oxidative capacity and increased oxidative stress.

An association between high birth weight and schizophrenia in a Finnish schizophrenia family study sample

Longitudinal cohort studies have implicated an association between both low and high birth weight and schizophrenia. It has been suggested that schizophrenia associated genes could augment an individual's susceptibility to adverse prenatal and perinatal environmental events. We investigated the association between birth weight and schizophrenia in a large Finnish schizophrenia family study sample. We utilized the birth weight data of 1051 offspring from 315 Finnish families with at least one offspring with a diagnosis of schizophrenia. We used a multivariate COX frailty model to analyze the effect of birth weight on the risk of developing schizophrenia within the families. Using information from the Medication Reimbursement Register and patient interviews, we further investigated the association of maternal type 2 diabetes and schizophrenia risk among offspring. High birth weight (>4000g) was associated with a 1.68-fold increase in schizophrenia susceptibility. Maternal diabetes at the time of data collection, a proxy for gestational diabetes, was associated with a 1.66-fold increase in the risk of developing schizophrenia among offspring. Our results corroborate recent findings showing an association between high birth weight and schizophrenia. Our results also point to a potential birth-weight independent association between maternal type 2 diabetes and schizophrenia among offspring.

The influence of early life factors on the risk of developing rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease that develops as a result of the interaction between genetic and environmental risk factors. Although increasing evidence shows the importance of genes in determining the risk of RA, it is clear that environmental factors also have a vital role. Studies to date have tended to concentrate on environmental influences around the time of disease onset. However, a number of pieces of evidence, including the fact that autoantibodies, such as rheumatoid factor (RF), can develop several years before the onset of clinical disease, suggest that environmental factors may influence disease susceptibility during early life. Several recent studies lend weight to this possibility, with an increased risk of RA in the offspring of mothers who smoked during pregnancy and in those with higher birth weight. There has also been a suggestion that the risk of RA is reduced in breast-fed infants. We describe the evidence surrounding the effect of early life factors on the risk of developing RA and possible mechanisms by which they may act.

The environment, geo-epidemiology, and autoimmune disease: Rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease characterized by a distinctive pattern of bone and joint destruction. RA patients have an increased risk of death. The incidence and prevalence of RA vary across populations, statistical methods, and disease definitions. In North America and Northern Europe, the incidence of RA is estimated at 20-50 cases per 100,000 population and the prevalence at 0.5-1.1%. Lower incidences and prevalences have been reported in Southern Europe, and few data are available for developing countries. Some studies showed declining incidences and prevalences after the 1960s. RA is a multifactorial disease that results from interactions between genetic and environmental factors. The main genetic factors are HLA-DRB1 and the tyrosine-phosphatase gene PTPN22. Among environmental factors implicated in the development of RA, smoking shows the strongest association with RA susceptibility and is also linked to worse outcomes. The aim of this review is to discuss the available data on the incidence and prevalence of RA, as well as the genetic and environmental risk factors associated with RA.

Early life factors and adult-onset rheumatoid arthritis

OBJECTIVE

Early life factors have been associated with risk of developing autoimmune disease in adulthood. We investigated the association of preterm birth and being breastfed with the incidence of rheumatoid arthritis (RA) in 2 large prospective cohorts.

METHODS

We studied participants from the Nurses' Health Study (NHS) and the Nurses' Health Study II (NHSII) who provided information on perinatal factors. The NHS (n = 121,701) and NHSII (n = 116,608) are large prospective cohorts of women followed since 1976 and 1989, respectively. Incident RA was confirmed using the American College of Rheumatology criteria and a medical record review. Cox models were used to estimate the hazard ratio of RA associated with being born preterm and being breastfed and its duration, adjusting for potential confounders. Random effects metaanalytic methods were used to compute combined estimates from the 2 cohorts.

RESULTS

We found no statistically significant association between preterm birth and incident RA [relative risk (RR) = 1.1, 95% CI 0.8, 1.5]. Being breastfed was not associated with increased incidence of RA (RR = 1.0, 95% CI 0.7, 1.4), regardless of the duration of breastfeeding.

CONCLUSION

In these cohorts of women, neither being preterm birth nor being breastfed was associated with the onset of RA.

Environmental influences on risk for rheumatoid arthritis

PURPOSE OF REVIEW

To examine new environmental factors and provide updates on known risk factors for rheumatoid arthritis (RA) in the past 2 years (2006-2008). This review is timely given the expanding information on treatment, pathogenesis and genetic risk factors for RA.

RECENT FINDINGS

High consumption of red meat does not increase risk of RA, whereas alcohol intake may be protective. The role of vitamin D and oral contraceptives as modifiers of disease risk remains equivocal. Other factors associated with increased risk of RA include higher birthweight, living in the northeastern United States compared with other regions of the country, and lower socioeconomic status. Duration of breastfeeding is inversely associated with RA risk. Several studies have now demonstrated that anti-citrullinated protein antibody positive RA has a specific association with environmental risk factors such as smoking.

SUMMARY

Recent studies have increased our understanding of environmental exposures that modify risk for RA such as smoking and alcohol intake. Other factors such as birthweight, breastfeeding, socioeconomic status and region of birth have also been demonstrated to contribute to risk. ACPA status is associated with specific environmental factors and is therefore important to incorporate into present and future studies.

Early rheumatoid arthritis and body composition

OBJECTIVES

RA is associated with joint destruction and cardiovascular diseases (CVDs). Possible predictors for CVD are early changes in body composition. We therefore evaluated whether lean mass of arms and legs (LMAL), total body fat mass (BFM) or truncal fat distribution (TFD) are altered early in RA, and if so, which factors are associated.

METHODS

We included 132 RA patients (95 women) with disease duration of < or =12 months. Disease activity score (DAS28), HAQ, BMI, comorbidity, smoking and medications were recorded. Total and regional lean mass and fat mass were measured with DXA. Data were compared with 132 age- and gender-matched controls, and possibly associated factors were analysed in linear regression models.

RESULTS

LMAL was low in patients for both women and men (P = 0.007 and <0.001, respectively). BMI (P = 0.012), BFM (P = 0.014) and TFD (P < 0.001) were higher than expected in RA women. In bivariate analyses, all adjusted for age and current smoking, disease duration was independently associated with low LMAL in women (P = 0.021). High BFM was associated with HAQ x disease duration in men (P = 0.033) and DAS28 in women (P = 0.011). High TFD was associated with a history of diabetes or CVD in men with RA (P = 0.005).

CONCLUSIONS

Low LMAL, high BFM and high TFD are present in early RA patients. The long-term significant consequences of these abnormalities need to be determined.

What epidemiology has told us about risk factors and aetiopathogenesis in rheumatic diseases

This article will review how epidemiological studies have advanced our knowledge of both genetic and environmental risk factors for rheumatic diseases over the past decade. The major rheumatic diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, psoriatic arthritis, ankylosing spondylitis, systemic lupus erythematosus, scleroderma, osteoarthritis, gout, and fibromyalgia, and chronic widespread pain, will be covered. Advances discussed will include how a number of large prospective studies have improved our knowledge of risk factors, including diet, obesity, hormones, and smoking. The change from small-scale association studies to genome-wide association studies using gene chips to reveal new genetic risk factors will also be reviewed.