Socioeconomic disparities in survival from childhood leukemia in the United States and globally: a meta-analysis.

BACKGROUND: Despite advancements in the treatment of childhood leukemia, socioeconomic status (SES) may potentially affect disease prognosis. This study aims to evaluate whether SES is associated with survival from childhood leukemia. METHODS: The US National Cancer Institute Surveillance, Epidemiology and End Results Program (SEER) 1973-2010 data were analyzed; thereafter, results were meta-analyzed along with those from survival (cohort) studies examining the association between SES indices and survival from childhood leukemia (end-of-search date: 31 March 2014). Random-effects models were used to calculate pooled effect estimates (relative risks, RRs); meta-regression was also used. RESULTS: We included 29 studies yielding 28 804 acute lymphoblastic leukemia (ALL), 3208 acute myeloblastic leukemia (AML) and 27 650 'any' leukemia (denoting joint reporting of all subtypes) cases. According to individual-level composite SES indices, children from low SES suffered from nearly twofold higher death rates from ALL (pooled RR: 1.83, 95% confidence interval 1.00-3.34, based on four study arms); likewise, death RRs derived from an array of lower area-level SES indices ranged between 1.17 and 1.33 (based on 11 study arms). Importantly, the survival gap between higher and lower SES seemed wider in the United States, with considerably (by 20%-82%) increased RRs for death from ALL in lower SES. Regarding AML, poorer survival was evident only when area-level SES indices were used. Lastly, remoteness indices were not associated with survival from childhood leukemia. CONCLUSION: Children with lower SES suffering childhood leukemia do not seem to equally enjoy the impressive recent survival gains. Special health policy strategies and increased awareness of health providers might minimize the effects of socioeconomic disparities.

Association between gestational diabetes mellitus and subsequent overactive bladder among premenopausal female twins.

OBJECTIVE: To investigate the association between a history of gestational diabetes mellitus (GDM) and overactive bladder (OAB) in women of premenopausal age. DESIGN: Population-based study. SETTING: The Swedish Twin Register. POPULATION: In 2005, a total of 14 094 female twins born between 1959 and 1985 in the Swedish Twin Registry participated in a comprehensive survey on common exposures and complex diseases. Structured questions provided information on GDM and OAB. The present study was designed as a cross-sectional analysis including all women in the cohort having given birth before 2005 (n = 7855). METHODS: A logistic regression model based on generalised estimating equations was used to derive odds ratios (ORs). MAIN OUTCOME MEASURE: The association between a history of GDM and OAB was estimated using ORs with 95% confidence intervals (CIs). RESULTS: The prevalence of OAB in women with a history of GDM was 19.1% compared with 10.7% in women without GDM. This corresponded to a two-fold increased odds of OAB in women with a history of gestational diabetes (OR 2.13, 95% CI 1.48-3.05). After adjusting the analysis for age, body mass index, parity, smoking, and diabetes mellitus, having had GDM was associated with doubled odds of OAB (OR 1.88, 95% CI 1.26-2.80). CONCLUSIONS: A history of GDM was positively associated with OAB among women of premenopausal age. The association does not seem to be mediated by body mass index or type-I or type-II diabetes mellitus.

Birthweight discordant female twins and their offspring: is the intergenerational influence on birthweight due to genes or environment?

STUDY QUESTION: Does the intergenerational influence on birthweight and birth length remain within female dizygotic and monozygotic twin pairs? SUMMARY ANSWER: The intergenerational influence on birthweight and birth length remained within dizygotic but not within monozygotic twin pairs. WHAT IS KNOWN ALREADY: Low birthweight is associated with increased morbidity and mortality in both the short and long term; therefore it is important to understand determinants of fetal growth. There is a known intergenerational association between parents' and offspring's size at birth. STUDY DESIGN, SIZE, DURATION: This is a register-based cohort study with a nested within-twin-pair comparison. The study is retrospective, but based on prospectively collected information. The study population included 8685 monozygotic and like-sexed dizygotic female twins born in Sweden from 1926 to 1985, who had given birth to their first infant between 1973 and 2009. PARTICIPANTS/MATERIALS, SETTING, METHODS: This study is set in Sweden and used data from the Swedish Twin Register and the Swedish Medical Birth Register. We used generalized estimating equations to obtain regression coefficients with 95% confidence intervals (CI) for the outcomes: offspring birthweight and birth length. To control for genetic and shared environmental factors, we performed within-twin-pair analyses in 1479 dizygotic and 1526 monozygotic twin pairs. MAIN RESULTS AND THE ROLE OF CHANCE: In the cohort of both dizygotic and monozygotic twins, there was an association between mother's and offspring's size at birth. Within-dizygotic twin pairs, a 500-g increase from the twin pair's mean birthweight was associated with increased offspring birthweight [70 g (95% CI: 35-106)] and birth length [0.22 cm (95% CI: 0.07-0.38)]. The corresponding increase in birth length of 1 cm was estimated to increase offspring's birthweight by 26 g (95% CI: 12-40) and birth length by 0.11 cm (95% CI: 0.04-0.17). Within-monozygotic twin pairs there were no such associations. LIMITATIONS, REASONS FOR CAUTION: This study is limited to twins who themselves or whose co-twin voluntarily responded to questionnaires. WIDER IMPLICATIONS OF THE FINDINGS: The intergenerational influence on size at birth is suggested to be due to direct or indirect genetic factors.

Epigenetics and assisted reproductive technology.

During gametogenesis, the female and male germ cells undergo a process whereby imprinting marks are erased from the genome. During the later stages of germ-cell development, the methylation marks of the female and male germ lines are re-established. A second phase of demethylation of the genome occurs at the time of fertilization, and during development of the early embryo. Assisted reproductive technology involves several steps that subject the gametes and early developing embryos to environmental stress, and this is the primary reason for an increased interest in the putative link between these techniques and imprinting disorders. Although animal studies support a link between assisted reproductive techniques (ARTs) and imprinting disorders, via altered methylation patterns, data in humans are inconsistent. Here we provide an overview of the field of epigenetics in relation to ARTs.

Effects of coffee and tea consumption on urinary incontinence in female twins.

OBJECTIVES: To assess the effect of coffee and tea consumption on symptoms of urinary incontinence. DESIGN: Population-based study. SETTING: The Swedish Twin Register. POPULATION: In 2005, all twins born between 1959 and 1985 in Sweden (n = 42,852) were invited to participate in a web-based survey to screen for common complex diseases and common exposures. The present study was limited to female twins with information about at least one urinary symptoms and coffee and tea consumption (n = 14,031). MAIN OUTCOME MEASURE: The association between coffee and tea consumption and urinary incontinence, as well as nocturia, was estimated as odds ratios (ORs) with 95% confidence intervals. RESULTS: Women with a high coffee intake were at lower risk of any urinary incontinence (OR 0.78, 95% CI 0.64-0.98) compared with women not drinking coffee. Coffee intake and incontinence subtypes showed no significant associations whereas high tea consumption was specifically associated with a risk for overactive bladder (OR 1.34, 95% CI 11.07-1.67) and nocturia (OR 1.18, 95% CI 1.01-1.38). Results from co-twin control analysis suggested that the associations observed in logistic regression were mainly the result of familial effects. CONCLUSIONS: This study suggests that coffee and tea consumption has a limited effect on urinary incontinence symptoms. Familial and genetic effects may have confounded the associations observed in previous studies.