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Quan Z, Purser C, Baker RC, Dwyer T, Bhagat R, Sheng Y, Leszczynski JR. Determination of Derivatized Urea in Exhaled Breath Condensate by LC-MS. J Chromatogr Sci 2010; 48:140-4. [DOI: 10.1093/chromsci/48.2.140] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Van Itallie A, Dwyer T, Steele R, Mummery K. The electronic outpatient cardiac rehabilitation (eOCR) trial: Study protocol. J Sci Med Sport 2010. [DOI: 10.1016/j.jsams.2009.10.310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Cleland VJ, Ball K, Magnussen C, Dwyer T, Venn A. Cleland et al. Respond to "Physical Activity Over the Life Course". Am J Epidemiol 2009. [DOI: 10.1093/aje/kwp274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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104
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Kemp A, Ponsonby AL, Dwyer T, Cochrane J, Pezic A, Carmichael A, Carlin J, Jones G. The interaction between early life upper respiratory tract infection and birth during the pollen season on rye-sensitized hay fever and ryegrass sensitization--a birth cohort study. Pediatr Allergy Immunol 2009; 20:536-44. [PMID: 19175891 DOI: 10.1111/j.1399-3038.2008.00817.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Studies on early life viral respiratory infection and subsequent atopic disease in childhood have conflicting findings. Animal models show that viral respiratory infection in conjunction with allergen presentation can enhance sensitization. This prospective study assesses the influence of an upper respiratory tract infection (URI) in the first month of life and the season of birth on the development of hay fever and ryegrass allergen sensitization in childhood. From a Tasmanian cohort born during 1988 and 1989, a group of 498 children were followed up at 8 yr and another different group of 415 children were followed up at 16 yr. The ryegrass pollen season in Tasmania occurs in November and December. Forty-four (9.6%) children in Follow-up sample 1 and 47 (12.5%) children in Follow-up sample 2 were born in the pollen season. The parental report of an early upper respiratory tract infection (EURI) was documented prospectively by a home interview at 1 month of age (median age 5.1 wk). Sensitization to ryegrass and house dust mite (HDM) was determined at 8 yr of age by skin prick testing and at 16 yr by ImmunoCap. Ryegrass sensitized hay fever was defined as a positive response to a question on hay fever plus the presence of ryegrass allergy. For children tested at age 8 and born in the pollen season, a EURI by postnatal interview was associated with an increased risk of ryegrass sensitization (OR 5.80 95% CI 1.07, 31.31) but not for children with a EURI born outside the pollen season (OR 0.62 95% CI 0.35, 1.08). Similarly, EURI was significantly associated with early onset (< or = 8 yr) ryegrass sensitized hay fever for children born in the pollen season (AOR 4.78 95% CI 1.17, 19.47) but was not associated with early onset ryegrass sensitized hay fever for children born outside the pollen season (AOR 0.76 95% CI 0.43, 1.33). These findings suggest that early life viral URI interacts with ryegrass allergen exposure in the development of ryegrass allergen sensitization and ryegrass sensitized hay fever symptoms.
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Dwyer T, Ponsonby AL. Sudden infant death syndrome and prone sleeping position. Ann Epidemiol 2009; 19:245-9. [PMID: 19344862 DOI: 10.1016/j.annepidem.2009.01.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Accepted: 01/30/2009] [Indexed: 10/21/2022]
Abstract
In this review, we describe the epidemiological work conducted by ourselves and others on prone sleep position and sudden infant death. What we have learned since 1990 is that the prone sleep position was a major component of a casual pathway that was operating in over half of the SIDS deaths that were occurring in developed countries at the end of the 1980. It has been estimated that advice to place infants supine to sleep may have saved in the order of 850 infants annually in Australia and other countries. The story of the SIDS epidemic is an example of the contribution that epidemiology can make to the understanding and prevention of an important public health problem.
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Ponsonby AL, Catto-Smith AG, Pezic A, Dupuis S, Halliday J, Cameron D, Morley R, Carlin J, Dwyer T. Association between early-life factors and risk of child-onset Crohn's disease among Victorian children born 1983-1998: a birth cohort study. Inflamm Bowel Dis 2009; 15:858-66. [PMID: 19107784 DOI: 10.1002/ibd.20842] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND The incidence of Crohn's disease (CD) with onset before age 16 has increased. Several perinatal characteristics have been associated with CD. Our objective was to examine the temporal change in CD incidence by period of birth and the extent that this could be attributed to perinatal characteristics associated with higher CD risk. METHODS A record linkage study was conducted utilizing the perinatal records of Victorian births 1983-1998 inclusive and a state-based CD registry. Proportional hazards models were used to investigate the perinatal factors in relation to the onset of CD by age 16. Further, a nested case control study was conducted to examine the association between sibling exposure and CD risk. RESULTS The CD incidence rate for births 1983-1998 was 2.01 (95% confidence interval [CI] 1.79, 2.27) per 100,000 child-years. A birth cohort effect was demonstrated, with higher CD risk for 1992-1998 versus 1983-1991 births (hazard ratio [HR] 1.56; 95% CI 1.18, 2.06). Perinatal characteristics associated with higher CD risk included urban location, higher socioeconomic status, married mother, a congenital abnormality and delivery by elective cesarean section. Sibling exposure during the first 6 years of life was not associated with CD risk. The increased CD incidence among more recent births was not accounted for by changes in these measured perinatal factors. CONCLUSIONS The temporal increase in CD incidence documented for births up to 1990 has continued for children born after 1991 and was not accounted for by temporal changes in the measured perinatal factors.
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Dickinson JL, Perera DI, van der Mei AF, Ponsonby AL, Polanowski AM, Thomson RJ, Taylor BV, McKay JD, Stankovich J, Dwyer T. Past environmental sun exposure and risk of multiple sclerosis: a role for the Cdx-2 Vitamin D receptor variant in this interaction. Mult Scler 2009; 15:563-70. [DOI: 10.1177/1352458509102459] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Multiple studies have provided evidence for an association between reduced sun exposure and increased risk of multiple sclerosis (MS), an association likely to be mediated, at least in part, by the vitamin D hormonal pathway. Herein, we examine whether the vitamin D receptor ( VDR), an integral component of this pathway, influences MS risk in a population-based sample where winter sun exposure in early childhood has been found to be an important determinant of MS risk. Three polymorphisms within the VDR gene were genotyped in 136 MS cases and 235 controls, and associations with MS and past sun exposure were examined by logistic regression. No significant univariate associations between the polymorphisms, rs11574010 ( Cdx-2A > G), rs10735810 ( Fok1T > C), or rs731236 ( Taq1C > T) and MS risk were observed. However, a significant interaction was observed between winter sun exposure during childhood, genotype at rs11574010, and MS risk ( P = 0.012), with the ‘G’ allele conferring an increased risk of MS in the low sun exposure group (≤2 h/day). No significant interactions were observed for either rs10735810 or rs731236, after stratification by sun exposure. These data provide support for the involvement of the VDR gene in determining MS risk, an interaction likely to be dependent on past sun exposure.
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Trivedi S, Magnussen C, Otahal P, Dwyer T, Raitakari O, Venn A. Fitness in Childhood and Change in Fitness from Childhood to Adulthood are Associated with Left Ventricular Mass in a Population-based Sample of Young Adults. Heart Lung Circ 2009. [DOI: 10.1016/j.hlc.2009.05.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Hetzel BS, Dwyer T. Response to: Tobias et al. on the decline of CHD mortality in New Zealand. Aust N Z J Public Health 2008; 32:579-80. [PMID: 19076755 DOI: 10.1111/j.1753-6405.2008.00316.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Dwyer T, van der Mei I, Ponsonby AL, Taylor BV, Stankovich J, McKay JD, Thomson RJ, Polanowski AM, Dickinson JL. Melanocortin 1 receptor genotype, past environmental sun exposure, and risk of multiple sclerosis. Neurology 2008; 71:583-9. [PMID: 18711112 DOI: 10.1212/01.wnl.0000323928.57408.93] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Low past sun exposure, fair skin type, and polymorphisms of the MC1R gene have been associated with multiple sclerosis (MS) risk. We aimed to investigate the interplay between melanocortin 1 receptor gene variants, red hair/fair skin phenotype, and past environmental sun exposure in MS. METHODS Population-based case-control study in Tasmania, Australia, involving 136 cases with MS and 272 controls randomly drawn from the community and matched on sex and year of birth. Measures included past sun exposure by calendar and questionnaire, spectrophotometric skin type, and MC1R genotype, with any MC1R Arg151Cys, Arg160Trp, or Asp294His alleles present denoted as red hair color (RHC) variant. RESULTS The association between RHC variant genotype and MS was more evident for women (odds ratio 2.02 [1.15-3.54]) than for men (odds ratio 0.65 [0.27-1.57]) (difference in effect, p = 0.03). The RHC variant genotype was associated with behavioral sun avoidance. In addition, increasing summer sun exposure at ages 6 through 10 years was associated with reduced MS risk among those with no RHC variant (p = 0.03), but not among those with RHC variant genotype (p = 0.15; difference in effect, p = 0.02). Similar findings were evident for other past sun exposure measures and when the sample was restricted to women only. CONCLUSION The interplay between red hair color variant genotype, red hair/fair skin phenotype, and multiple sclerosis (MS) is complex. The modification of past sun exposure by MC1R genotype provides further support that ultraviolet radiation or derivatives such as vitamin D may be causally related to a reduced MS risk.
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Dwyer T, Blizzard L, Patterson B, Ponsonby AL, Martin K, Quinn S, Sale MM, Richards SM, Morley R, Rich S, Dickinson JL. Association between birth weight and adolescent systolic blood pressure in a caucasian birth cohort differs according to skin type, CRH promoter or 11beta-HSD2 genotype. Arch Dis Child 2008; 93:760-7. [PMID: 18456686 DOI: 10.1136/adc.2007.129122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To examine whether the inverse association between birth weight and blood pressure varies by skin pigmentation and/or related genotypes. STUDY DESIGN 671 children from a predominantly caucasian birth cohort were followed-up to adolescence (mean (SD) age 14.4 (0.64)). METHODS Data on birth weight, socioeconomic status, maternal antenatal smoking, adolescent blood pressure and polymorphisms of candidate genes were obtained and analysed by multiple linear regression. RESULTS An increase in birth weight of 1 kg was associated with an non-significant difference in adolescent systolic blood pressure of -0.53 mm Hg (95% CI -1.72 to 0.66) per kg after adjustment for child age and cohort entry criteria. The inverse association between birth weight and systolic blood pressure was stronger for those with darker skin (> or =2% melanin) (difference in effect, p = 0.02), those with more copies of the C allele of corticotropin-releasing hormone (CRH) +T1273C (p = 0.06), and those with more copies of the short (< or =236 bp) form of the 11beta-HSD2{CA}n(repeat) microsatellite (p = 0.03). CONCLUSIONS These findings add to the evidence that cortisol-related pathways may account for at least part of the observed birth weight-blood pressure associations.
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Paul SL, Blizzard L, Patton GC, Dwyer T, Venn A. Parental smoking and smoking experimentation in childhood increase the risk of being a smoker 20 years later: the Childhood Determinants of Adult Health Study. Addiction 2008; 103:846-53. [PMID: 18412765 DOI: 10.1111/j.1360-0443.2008.02196.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS To examine the long-term effects of childhood smoking experimentation and exposure to parental smoking on adult smoking risk. METHODS Data were from a 20-year follow-up of 9-15-year-olds who completed questionnaires in the 1985 Australian Schools Health and Fitness Survey (n=6559). The relative risks (RR) of adult current smoking in 2004-05 for childhood exposure to smoking experimentation (never, a few puffs, <10 cigarettes, >10 cigarettes) and parental smoking (none, father, mother, both parents) in 1985, with adjustment for confounders, were estimated by log binomial modelling. Analyses were stratified by age (9-13 and 14-15 years) and sex. FINDINGS Participation at follow-up was 54% (n=3559). Childhood smoking experimentation increased the risk of being a current smoker particularly for 14-15-year-old experimenters of more than 10 cigarettes [males, RR 2.72, 95% confidence interval (CI) 1.74-4.25; females, RR 6.39, 95% CI 2.85-14.33]. Parental smoking was associated with adult current smoking risk, particularly for 9-13-year-olds with two smoking parents (males, RR 1.53, 95% CI 1.19-1.96; females, RR 1.99, 95% CI 1.52-2.61) and older males with smoking mothers (RR 1.82, 95% CI 1.22-2.73). Parental smoking was not associated with childhood smoking experimentation. CONCLUSIONS These findings suggest that any childhood smoking experimentation increases the risk of being a smoker 20 years later. As exposure to parental smoking predicted current smoking, parents should be aware of the association between their own smoking behaviour and that of their children.
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Jones G, Dwyer T, Hynes KL, Parameswaran V, Udayan R, Greenaway TM. A prospective study of urinary electrolytes and bone turnover in adolescent males. Clin Nutr 2007; 26:619-23. [PMID: 17904253 DOI: 10.1016/j.clnu.2007.06.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 03/19/2007] [Accepted: 06/27/2007] [Indexed: 11/22/2022]
Abstract
BACKGROUND & AIMS The role of excessive salt on bone metabolism in children is uncertain. The aim of this 6-week prospective study was to describe the association between urinary electrolytes and bone turnover markers in a convenience sample of adolescent boys (N = 136, mean age 16 yr). METHODS Urinary electrolytes (sodium, potassium, calcium and magnesium) were assessed on spot overnight urines on three occasions to minimise regression dilution bias. Bone turnover was assessed by bone specific alkaline phosphatase (BAP) and urinary pyridinoline (PYR) at baseline and follow up. RESULTS In multivariate analysis, urinary sodium (but not other electrolytes) was positively associated with both PYR and BAP both before and after taking short-term growth into account (both p < 0.05) and explained 3-6% of the variation in bone turnover markers. Urinary sodium was associated with urinary magnesium (r = +0.26, p < 0.05) but only weakly with calcium (r = +0.18, p = 0.08). Urinary potassium was significantly associated with urinary magnesium (r = -0.24, p < 0.05). CONCLUSION High urinary sodium (which largely reflects dietary sodium intake in our location) results in a high bone turnover state in adolescent boys which is most likely detrimental for bone. Other urinary electrolytes are not related to bone turnover but may influence bone via other pathways.
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Lucas RM, Ponsonby AL, McMichael AJ, van der Mei I, Chapman C, Coulthard A, Dear K, Dwyer T, Kilpatrick TJ, Pender MP, Taylor B, Valery P, Williams D. Observational analytic studies in multiple sclerosis: controlling bias through study design and conduct. The Australian Multicentre Study of Environment and Immune Function. Mult Scler 2007; 13:827-39. [PMID: 17881396 DOI: 10.1177/1352458507077174] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rising multiple sclerosis incidence over the last 50 years and geographic patterns of occurrence suggest an environmental role in the causation of this multifactorial disease. Design options for epidemiological studies of environmental causes of multiple sclerosis are limited by the low incidence of the disease, possible diagnostic delay and budgetary constraints. We describe scientific and methodological issues considered in the development of the Australian Multicentre Study of Environment and Immune Function (the Ausimmune Study), which seeks, in particular, to better understand the causes of the well-known MS positive latitudinal gradient. A multicentre, case-control design down the eastern seaboard of Australia allows the recruitment of sufficient cases for adequate study power and provides data on environmental exposures that vary by latitude. Cases are persons with an incident first demyelinating event (rather than prevalent multiple sclerosis), sourced from a population base using a two tier notification system. Controls, matched on sex, age (within two years) and region of residence, are recruited from the general population. Biases common in case-control studies, eg, prevalence-incidence bias, admission-rate bias, non-respondent bias, observer bias and recall bias, as well as confounding have been carefully considered in the study design and conduct of the Ausimmune Study. Multiple Sclerosis 2007; 13 : 827—839. http://msj.sagepub.com
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Barr ELM, Zimmet PZ, Welborn TA, Jolley D, Magliano DJ, Dunstan DW, Cameron AJ, Dwyer T, Taylor HR, Tonkin AM, Wong TY, McNeil J, Shaw JE. Risk of cardiovascular and all-cause mortality in individuals with diabetes mellitus, impaired fasting glucose, and impaired glucose tolerance: the Australian Diabetes, Obesity, and Lifestyle Study (AusDiab). Circulation 2007; 116:151-7. [PMID: 17576864 DOI: 10.1161/circulationaha.106.685628] [Citation(s) in RCA: 503] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Diabetes mellitus increases the risk of cardiovascular disease (CVD) and all-cause mortality. The relationship between milder elevations of blood glucose and mortality is less clear. This study investigated whether impaired fasting glucose and impaired glucose tolerance, as well as diabetes mellitus, increase the risk of all-cause and CVD mortality. METHODS AND RESULTS In 1999 to 2000, glucose tolerance status was determined in 10,428 participants of the Australian Diabetes, Obesity, and Lifestyle Study (AusDiab). After a median follow-up of 5.2 years, 298 deaths occurred (88 CVD deaths). Compared with those with normal glucose tolerance, the adjusted all-cause mortality hazard ratios (HRs) and 95% confidence intervals (CIs) for known diabetes mellitus and newly diagnosed diabetes mellitus were 2.3 (1.6 to 3.2) and 1.3 (0.9 to 2.0), respectively. The risk of death was also increased in those with impaired fasting glucose (HR 1.6, 95% CI 1.0 to 2.4) and impaired glucose tolerance (HR 1.5, 95% CI 1.1 to 2.0). Sixty-five percent of all those who died of CVD had known diabetes mellitus, newly diagnosed diabetes mellitus, impaired fasting glucose, or impaired glucose tolerance at baseline. Known diabetes mellitus (HR 2.6, 95% CI 1.4 to 4.7) and impaired fasting glucose (HR 2.5, 95% CI 1.2 to 5.1) were independent predictors for CVD mortality after adjustment for age, sex, and other traditional CVD risk factors, but impaired glucose tolerance was not (HR 1.2, 95% CI 0.7 to 2.2). CONCLUSIONS This study emphasizes the strong association between abnormal glucose metabolism and mortality, and it suggests that this condition contributes to a large number of CVD deaths in the general population. CVD prevention may be warranted in people with all categories of abnormal glucose metabolism.
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van der Mei IAF, Ponsonby AL, Dwyer T, Blizzard L, Taylor BV, Kilpatrick T, Butzkueven H, McMichael AJ. Vitamin D levels in people with multiple sclerosis and community controls in Tasmania, Australia. J Neurol 2007; 254:581-90. [PMID: 17426912 DOI: 10.1007/s00415-006-0315-8] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 02/02/2006] [Accepted: 05/11/2006] [Indexed: 10/23/2022]
Abstract
BACKGROUND Adequate 25(OH)D levels are required to prevent adverse effects on bone health. Population-based data on factors associated with 25(OH)D levels of people with MS have been lacking. OBJECTIVES To examine the prevalence and determinants of vitamin D insufficiency in a population-based sample of MS cases and controls, and to compare 25(OH)D status between MS cases and controls, taking into account case disability. METHODS We conducted a population based case-control study in Tasmania, Australia (latitude 41-43 degrees S) on 136 prevalent cases with MS confirmed by magnetic resonance imaging and 272 community controls, matched on sex and year of birth. Measurements included serum 25(OH)D, sun exposure, skin type, dietary vitamin D intake and disability including EDSS. RESULTS A high prevalence of vitamin D insufficiency was found in MS cases and controls. Among MS cases, increasing disability was strongly associated with lower levels of 25(OH)D and with reduced sun exposure. Cases with higher disability (EDSS > 3) were more likely to have vitamin D insufficiency than controls (OR = 3.07 (1.37, 6.90) for 25(OH)D </= 40 nmol/l), but cases with low disability were not (OR = 0.87 (0.41, 1.86)). CONCLUSION The strong associations between disability, sun exposure and vitamin D status indicate that reduced exposure to the sun, related to higher disability, may contribute to the high prevalence of vitamin D insufficiency found in this population-based MS case sample. Active detection of vitamin D insufficiency among people with MS and intervention to restore vitamin D status to adequate levels should be considered as part of the clinical management of MS.
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Ponsonby AL, Dwyer T, van der Mei I, Kemp A, Blizzard L, Taylor B, Kilpatrick T, Simmons R. Asthma onset prior to multiple sclerosis and the contribution of sibling exposure in early life. Clin Exp Immunol 2007; 146:463-70. [PMID: 17100766 PMCID: PMC1810417 DOI: 10.1111/j.1365-2249.2006.03235.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Higher sibling exposure is associated with a reduced risk of asthma and other T helper 2 (Th2)-type disorders, possibly through a beneficial effect of higher infection load. The effect on Th1 disorders such as multiple sclerosis (MS) is less clear. Here we examine the association between asthma and MS, taking into account early life sibling exposure. A population-based case-control study in Tasmania, Australia based on 136 cases of magnetic resonance imaging (MRI)-confirmed MS and 272 community controls, matched on sex and year of birth. Study measures include cumulative exposure to total, older or younger siblings by age 6 years, history of doctor-diagnosed asthma and serological IgG responses to herpes viruses. MS cases were more likely (P = 0.02) than controls to have asthma which began before age of onset of MS symptoms compared to the corresponding age for controls. The absence of younger sibling exposure by age 6 years potentiated (P = 0.04) the association between asthma and MS. Compared to those with younger sibling exposure and no asthma, the adjusted odds ratio for MS for those with asthma and no younger sibling exposure was 7.22 (95% CI: 2.52, 20.65). Early life sibling exposure was associated with altered IgG serological responses to Epstein-Barr virus (EBV) and herpes simplex virus 1 (HSV1) in adulthood. Reduced early life sibling exposure appeared to contribute to the excess of asthma among MS cases by the time of MS onset. MS development may reflect factors that relate to a general immuno-inflammatory up-regulation of immune activity as well as disease specific factors. The link between early life sibling exposure and the immune response to herpes group viral antigens is consistent with a protective role for early life infections.
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van der Mei IAF, Blizzard L, Ponsonby AL, Dwyer T. Validity and reliability of adult recall of past sun exposure in a case-control study of multiple sclerosis. Cancer Epidemiol Biomarkers Prev 2006; 15:1538-44. [PMID: 16896046 DOI: 10.1158/1055-9965.epi-05-0969] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Measurement of past sun exposure through recall by adults has the potential for measurement error. We aimed to investigate aspects of validity and reliability of self-reported past sun exposure. METHODS A population-based case-control study was conducted in Tasmania on 136 cases with multiple sclerosis and 272 age- and sex-matched community controls. Repeat interviews on 52 cases and 52 controls were done on average 11 weeks after the initial interview. Sun exposure was assessed by questionnaire and lifetime calendar. Other measurements included serum 25-hydroxyvitamin D, actinic damage, and skin phenotype. RESULTS There was an association between recent sun exposure and serum vitamin D (time in the sun: r = 0.22, P < 0.01; activities outside: r = 0.31, P < 0.01 for controls) and between lifetime sun exposure and actinic damage [correlation between 0.34 (P < 0.01) and 0.17 (P = 0.01) for controls]. The test-retest weighted kappa statistic of self-reported sun exposure ranged from 0.43 to 0.74. Recall of childhood/adolescent sun exposure by standardized questioning was no less reproducible than recall of recent adult sun exposure and no less reliable when made with the calendar method. Comparing the questionnaire and calendar method, the measures of childhood/adolescent sun exposure had a similar predictive validity for multiple sclerosis. CONCLUSIONS The results of this study provide further evidence that adults are able to recall past sun exposure with shown validity and reliability and present information about the possible reasons for the good reliability of recalled sun exposure measures.
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van der Mei IAF, Blizzard L, Ponsonby AL, Dwyer T. Validity and reliability of adult recall of past sun exposure in a case-control study of multiple sclerosis. Cancer Epidemiol Biomarkers Prev 2006. [PMID: 16896046 DOI: 10.1158/1055-] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Measurement of past sun exposure through recall by adults has the potential for measurement error. We aimed to investigate aspects of validity and reliability of self-reported past sun exposure. METHODS A population-based case-control study was conducted in Tasmania on 136 cases with multiple sclerosis and 272 age- and sex-matched community controls. Repeat interviews on 52 cases and 52 controls were done on average 11 weeks after the initial interview. Sun exposure was assessed by questionnaire and lifetime calendar. Other measurements included serum 25-hydroxyvitamin D, actinic damage, and skin phenotype. RESULTS There was an association between recent sun exposure and serum vitamin D (time in the sun: r = 0.22, P < 0.01; activities outside: r = 0.31, P < 0.01 for controls) and between lifetime sun exposure and actinic damage [correlation between 0.34 (P < 0.01) and 0.17 (P = 0.01) for controls]. The test-retest weighted kappa statistic of self-reported sun exposure ranged from 0.43 to 0.74. Recall of childhood/adolescent sun exposure by standardized questioning was no less reproducible than recall of recent adult sun exposure and no less reliable when made with the calendar method. Comparing the questionnaire and calendar method, the measures of childhood/adolescent sun exposure had a similar predictive validity for multiple sclerosis. CONCLUSIONS The results of this study provide further evidence that adults are able to recall past sun exposure with shown validity and reliability and present information about the possible reasons for the good reliability of recalled sun exposure measures.
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Andreasyan K, Ponsonby AL, Dwyer T, Morley R, Riley M, Dear K, Cochrane J. Higher maternal dietary protein intake in late pregnancy is associated with a lower infant ponderal index at birth. Eur J Clin Nutr 2006; 61:498-508. [PMID: 17136041 DOI: 10.1038/sj.ejcn.1602552] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
AIM A high ponderal index at birth has been associated with later obesity and it has been suggested that intervention to prevent obesity and its sequela should consider the antenatal period. In this context, we investigated the association between maternal nutrition and birth anthropometry. DESIGN We analyzed data on 1040 mother-infant pairs collected during the Tasmanian Infant Health Survey (TIHS), Tasmania, 1988-1989. Maternal dietary intake during pregnancy was measured by food frequency questionnaire (FFQ) applied soon after birth. Outcomes of interest were birth weight, birth length, head circumference, ponderal index, head circumference -to-ponderal index ratio, placenta-to-birth weight ratio and head circumference-to-birth length index. RESULTS In multiple regression model, an increase of 10 g of absolute protein intake/day was associated with a reduction in birth weight of 17.8 g (95% CI: -32.7, -3.0; P=0.02). Protein intake was also associated negatively with ponderal index (beta=-0.01; 95% CI: -0.02, -0.00; P=0.01). A 1 % increase in carbohydrate intake resulted in a 1% decline in placental weight relative to birth weight. Higher protein intake in the third trimester was associated with a reduced ponderal index among large birth weight infants but not low birth weight infants. CONCLUSIONS This raises the possibility that any effect of high protein in altering infant anthropometry at birth may involve changes in body composition and future work to examine how a high-protein diet influences body composition at birth is warranted.
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Dwyer T, Hosmer D, Hosmer T, Venn AJ, Blizzard CL, Granger RH, Cochrane JA, Blair SN, Shaw JE, Zimmet PZ, Dunstan D. The inverse relationship between number of steps per day and obesity in a population-based sample – the AusDiab study. Int J Obes (Lond) 2006; 31:797-804. [PMID: 17047641 DOI: 10.1038/sj.ijo.0803472] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Physical activity (PA) is inversely associated with obesity but the effect has been difficult to quantify using questionnaires. In particular, the shape of the association has not yet been well described. Pedometers provide an opportunity to better characterize the association. METHODS Residents of households over the age of 25 years in randomly selected census districts in Tasmania were eligible to participate in the AusDiab cross-sectional survey conducted in 1999-2000. 1848 completed the AusDiab survey and 1126 of these (609 women and 517 men) wore a pedometer for 2-weekdays. Questionnaire data on recent PA, TV time and other factors were obtained. The outcomes were waist circumference (in cm) and body mass index (BMI) (kg/m(2)). RESULTS Increasing daily steps were associated with a decline in the obesity measures. The logarithmic nature of the associations was indicated by a sharper decline for those with lower daily steps. For example, an additional 2000 steps for those taking only 2000 steps per day was associated with a reduction of 2.8 (95% confidence interval (CI): 2.1,4.4) cm in waist circumference among men (for women; 2.2 (95% CI: 0.6, 3.9 cm)) with a baseline of only 2000, steps compared to a 0.7 (95% CI 0.3, 1.1) cm reduction (for women; 0.6 (95% CI: 0.2, 1.0)) for those already walking 10,000 steps daily. In the multivariable analysis, clearer associations were detected for PA and these obesity measures using daily step number rather than PA time by questionnaire. INTERPRETATION Pedometer measures of activity indicate that the inverse association between recent PA and obesity is logarithmic in form with the greatest impact for a given arithmetic step number increase seen at lower levels of baseline activity. The findings from this study need to be examined in prospective settings.
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Shaw KA, Srikanth VK, Fryer JL, Blizzard L, Dwyer T, Venn AJ. Dual energy X-ray absorptiometry body composition and aging in a population-based older cohort. Int J Obes (Lond) 2006; 31:279-84. [PMID: 16788568 DOI: 10.1038/sj.ijo.0803417] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The aims of this cross-sectional study were (1) to examine the effect of age on body composition in older adults using dual-energy X-ray absorptiometry (DXA) and (2) to evaluate the agreement of DXA with standard indirect anthropometric measures (body mass index (BMI), waist circumference and waist-to-hip ratio (WHR)). RESEARCH METHODS AND PROCEDURES A population-based sample of 731 adults aged between 50 and 79 years underwent measurement of BMI, waist circumference, WHR, DXA total body fat mass, DXA % total body fat, DXA % trunk fat and DXA lean body mass. Linear regression was used to test for trend in measures of body composition between age categories in men and women. Partial correlations and Bland-Altman analysis were used to examine the agreement of DXA measures with indirect measures. RESULTS DXA lean body mass decreased significantly with increasing age in both sexes (P<0.05). In males, BMI (P=0.01) and body weight (P<0.01) decreased with age, and in females, WHR (P=0.05), DXA % total fat (P=0.02) and DXA % trunk fat (P=0.05) increased with age. There was good agreement between DXA measures of fatness and indirect anthropometric measures, except for WHR, which showed greater variability in its comparisons with DXA. CONCLUSION Using the highly sensitive and direct DXA method of measuring body composition, a decline in lean body mass and an increase in adiposity was observed with aging. Except for WHR, indirect anthropometric measures generally showed high levels of agreement with DXA fat measures in this older cohort.
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Haythe J, Dwyer T, Burke E, Green P, Almuti K, Itescu S, Marboe C, Mancini D. 189. J Heart Lung Transplant 2006. [DOI: 10.1016/j.healun.2005.11.197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Dunstan DW, Salmon J, Owen N, Armstrong T, Zimmet PZ, Welborn TA, Cameron AJ, Dwyer T, Jolley D, Shaw JE. Associations of TV viewing and physical activity with the metabolic syndrome in Australian adults. Diabetologia 2005; 48:2254-61. [PMID: 16211373 DOI: 10.1007/s00125-005-1963-4] [Citation(s) in RCA: 281] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Accepted: 07/11/2005] [Indexed: 10/25/2022]
Abstract
AIMS/HYPOTHESIS We analysed a sample of Australian adults to determine the strength of associations of TV viewing and participation in physical activity with the metabolic syndrome. METHODS This population-based cross-sectional study included 6,241 adults aged > or =35 years who were free from diagnosed diabetes mellitus and self-reported ischaemic disease and were not taking lipid-lowering or antihypertensive drugs. The metabolic syndrome was defined according to the 1999 World Health Organization criteria. Participants self-reported TV viewing time and physical activity time for the previous week. RESULTS The adjusted odds ratio of having the metabolic syndrome was 2.07 (95% CI 1.49-2.88) in women and 1.48 (95% CI 0.95-2.31) in men who watched TV for >14 h per week compared with those who watched < or =7.0 h per week. Compared with those who were less active (<2.5 h per week), the odds ratio for the metabolic syndrome was 0.72 (95% CI 0.58-0.90) in men and 0.53 (95% CI 0.38-0.74) in women who were active (> or =2.5 h per week). Longer TV viewing (>14 h per week) was associated with an increased risk of insulin resistance, obesity and dyslipidaemia in both men and women. A total physical activity time of > or =2.5 h per week was associated with a reduced prevalence of both insulin resistance and dyslipidaemia in both sexes and reduced prevalence of both obesity and hypertension in women. CONCLUSIONS/INTERPRETATION Increased TV viewing time was associated with an increased prevalence of the metabolic syndrome, while physical activity was associated with a reduced prevalence. Population strategies addressing the metabolic syndrome should focus on reducing sedentary behaviours such as TV viewing, as well as increasing physical activity.
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Horváth I, Hunt J, Barnes PJ, Alving K, Antczak A, Baraldi E, Becher G, van Beurden WJC, Corradi M, Dekhuijzen R, Dweik RA, Dwyer T, Effros R, Erzurum S, Gaston B, Gessner C, Greening A, Ho LP, Hohlfeld J, Jöbsis Q, Laskowski D, Loukides S, Marlin D, Montuschi P, Olin AC, Redington AE, Reinhold P, van Rensen ELJ, Rubinstein I, Silkoff P, Toren K, Vass G, Vogelberg C, Wirtz H. Exhaled breath condensate: methodological recommendations and unresolved questions. Eur Respir J 2005; 26:523-48. [PMID: 16135737 DOI: 10.1183/09031936.05.00029705] [Citation(s) in RCA: 851] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Collection of exhaled breath condensate (EBC) is a noninvasive method for obtaining samples from the lungs. EBC contains large number of mediators including adenosine, ammonia, hydrogen peroxide, isoprostanes, leukotrienes, nitrogen oxides, peptides and cytokines. Concentrations of these mediators are influenced by lung diseases and modulated by therapeutic interventions. Similarly EBC pH also changes in respiratory diseases. The aim of the American Thoracic Society/European Respiratory Society Task Force on EBC was to identify the important methodological issues surrounding EBC collection and assay, to provide recommendations for the measurements and to highlight areas where further research is required. Based on the currently available evidence and the consensus of the expert panel for EBC collection, the following general recommendations were put together for oral sample collection: collect during tidal breathing using a noseclip and a saliva trap; define cooling temperature and collection time (10 min is generally sufficient to obtain 1-2 mL of sample and well tolerated by patients); use inert material for condenser; do not use resistor and do not use filter between the subject and the condenser. These are only general recommendations and certain circumstances may dictate variation from them. Important areas for future research involve: ascertaining mechanisms and site of exhaled breath condensate particle formation; determination of dilution markers; improving reproducibility; employment of EBC in longitudinal studies; and determining the utility of exhaled breath condensate measures for the management of individual patients. These studies are required before recommending this technique for use in clinical practice.
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