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Biomedical subjects

T Dwyer

Publications and source records attributed to T Dwyer.

At least 73 records · Page 4Linked to original sources
PubMed1997

Association between blood pressure and dietary factors in the dietary and nutritional survey of British adults.

OBJECTIVES: To measure the associations among blood pressure, hypertension, and recorded dietary factors. METHODS: Data were analyzed from the computer file of the Dietary and Nutritional Survey of British Adults, in which persons of both sexes aged 16 to 64 years living in private households (excluding pregnant women) had been randomly selected from the United Kingdom Electoral Register. Main outcome measures were systolic blood pressure, diastolic blood pressure, and hypertension (defined as systolic blood pressure of > or = 140 mm Hg, diastolic blood pressure of > or = 90 mm Hg, or both, or receiving antihypertensive medication). RESULTS: After controlling for 24-hour urinary potassium excretion, age, obesity, alcohol intake, and season of interview, a single measure of 24-hour urinary sodium excretion was significantly associated with systolic blood pressure (P < or = .001), diastolic blood pressure (P < .05), and hypertension (P = .009). These associations persisted after controlling for many variables of blood chemistry and dietary intake. CONCLUSIONS: Sodium is positively associated with blood pressure over a range of sodium excretion rates from 70 to 400 mmol/d. This finding supports the international consensus that the risk of hypertension is lower when salt intake is lower and suggests that a proportion of the British population has a sodium excretion rate that is habitually low enough to have some preventive effect.

Adult↗
PubMed1997

Parental history of diabetes in an insulin-treated diabetes registry.

To confirm observations of an excess maternal transmission of Type 2 (non-insulin dependent) diabetes mellitus in a setting which minimizes potential biases and confounders, we explored the patterns of maternal and paternal diabetes in a cohort (n = 1775) of subjects with insulin-treated diabetes mellitus (ITDM) in Tasmania, Australia. In order to identify individuals with Type 1 diabetes or insulin-treated Type 2 diabetes, cases were classified into groups based on their age at diagnosis and subsequent time to commencement of insulin. Individuals initially diagnosed younger than age 30 (predominantly Type 1 diabetes cases) reported a similar percentage of mothers and fathers with diabetes, but individuals diagnosed at age 30 or older (predominantly insulin-treated Type 2 diabetes) reported a maternal excess of diabetes. Having an elevated body mass index was associated with a higher frequency of maternal diabetes, but not of paternal diabetes. Because both childhood-onset Type 1 diabetes and adult-onset insulin-treated Type 2 diabetes cases were subject to the same potential study biases, these results offer support for an excess maternal role in Type 2 diabetes transmission.

Adult↗
PubMed1997

Changes in self-reported skin type associated with experience of sunburning in 14-15 year old children of northern European descent.

Melanoma risk differs by sun-sensitive phenotype, of which self-reported skin type (tendency to burn, inability to tan) is an indicator. If self-reports of skin type are influenced by the amount of sun exposure subjects have had, the two principal determinants of risk are linked, and stratifying by skin type would bias the estimated effect of sun exposure. Our objective was to determine whether teenagers changed their self-reports of skin type after being sunburnt. A random sample (n = 364) of 14-15 year old schoolchildren of northern European ancestry self-assessed and self-reported their skin type before and after their summer holidays. Their responses had high correlation coefficients (girls 0.71, boys 0.54) for repeatability at 4 months, but subjects who sunburnt less (more) frequently than usual that summer revised their skin type assessment to be less (more) sun-sensitive afterwards. We conclude that these 14-15 year olds were influenced by a recent experience of sunburn when reporting their skin type. A more objective measure of phenotype is needed.

Adolescent↗
PubMed1997

Factors related to infant apnoea and cyanosis: a population-based study.

OBJECTIVES: To examine the relationship between infant and parental characteristics and parental report of infant cyanosis and also hospital admission for apnoea/cyanosis. METHODS: A prospective cohort study was conducted. It involved the one-fifth of Tasmanian live births who were assessed, using a perinatal score, as being at higher risk of sudden infant death syndrome (SIDS). From 1 May 1988 to 30 April 1993, 6213 infants (89% of eligible infants) participated in the hospital (4 days postnatal age) and home interview (5 weeks postnatal age). Data on usual sleep position and infant history of cyanosis were collected at home interview. Hospital admission records for apnoea/cyanosis in the first year of life were linked to data on cohort infants in Southern Tasmania. RESULTS: Several factors were related to parental reports of cyanosis, with strong associations observed for very premature infants < 28 weeks (adjusted odds ratio [AOR] 6.06, 95% confidence interval [2.47, 14.85]), history of fits (AOR 5.59 [2.35, 13.13]); and the administration of antihistamine medication during the first month of life (AOR 3.03 [1.12, 8.18]). The median age at hospital admission was 7 weeks postnatal age. A family history of asthma, a history of fits, a history of turning blue while feeding or trouble breathing while feeding were associated with parental reports of cyanosis, breathing difficulties and also with hospital admission for apnoea/cyanosis. Other factors such as prematurity, maternal smoking, bottle feeding and a history of fever were significantly related to the infant history of cyanosis but not to hospital admission. This may partly reflect the low incidence rate (1.37%) for hospitalization for apnoea/cyanosis in the first year of life among these cohort infants. CONCLUSIONS: Several infant and parental characteristics are associated with increased risk of infant apnoea/cyanosis in this study but further population-based work with a larger group of infants hospitalised for apnoea/cyanosis should be conducted. The finding of an association between the administration of antihistamine medication and infant cyanosis highlights the possibility of adverse side-effects if antihistamine medication is administered to young infants.

Age Distribution↗
PubMed1997

Characteristics of infants receiving prompt first diphtheria-tetanus-pertussis immunisation in an infant cohort.

The Centers for Disease Control in the United States have stated that studies to determine factors associated with failure to receive the first recommended dose of diphtheria-tetanus-pertussis are required. We examined an infant cohort to identify family and infant characteristics predictive of prompt first immunisation, to document changes in prompt first immunisation rates over time and to identify reasons for immunisation delay. The study sample consisted of one-fifth of live births in Tasmania at risk of sudden infant death syndrome. From 1 January 1988 to 31 December 1994, families of 8011 infants (83 per cent of eligible infants) participated in a telephone interview when the infants were a median postnatal age of 11 weeks and 3 days. Prompt immunisation was defined as the report by parents of diphtheria-tetanus-pertussis vaccination before a postnatal age of 10 weeks. The proportion of cohort infants promptly immunised increased (P < 0.0001) over time from 1988 to 1994. Prompt immunisation was associated with various characteristics of the infant and family. The proportion of infants promptly immunised decreased as birth order increased and as the interpregnancy interval between the index child and his or her immediately elder sibling decreased. After exclusion of infants not promptly immunised because of illness, birth order and interbirth interval remained significant predictors of prompt immunisation, suggesting that these factors are acting to increase immunisation delay through pathways unrelated to their potential effect on infant illness rates.

Appointments and Schedules↗
PubMed1997

Sleeping position, infant apnea, and cyanosis: a population-based study.

OBJECTIVES: To examine the relationship between usual infant sleeping position and the parental report of infant cyanosis, pallor, breath-holding, and breathing difficulties; and to document hospital admission rates for apnea/cyanosis over time and to describe how admission rates vary by usual sleeping position. METHODS: A prospective cohort study was conducted. It involved the one fifth of Tasmanian live births that were assessed, using a perinatal score, as being at higher risk for sudden infant death syndrome (SIDS). From May 1, 1988 to April 30, 1993, 6213 infants participated in the hospital (4 days postnatal age) and home interview (5 weeks postnatal age) (89% of eligible infants). Data on usual sleep position and infant history of cyanosis were collected at home interview. Hospital admission records for apnea/cyanosis in the first year of life were linked to data on cohort infants in southern Tasmania. RESULTS: Infants who slept supine were not more likely to have been reported to experience cyanosis, pallor, or breathing problems at 1 month of age, when compared with infants sleeping in other positions. In fact, the risk of cyanosis was higher in the prone, face-down sleeping position than in the supine sleeping position (adjusted odds ratio = 4.21, 95% confidence interval [1.33, 13.28]). Among cohort infants in southern Tasmania, hospital admission rates for apnea/cyanosis did not differ by usual sleeping position or year of birth. CONCLUSIONS: Infants usually sleeping supine do not have increased rates of morbidity in relation to parental reports or hospital admissions for apnea/cyanosis. In a location where SIDS and total postneonatal mortality has fallen after intervention to reduce the prevalence of the prone position, rates of hospital admission for apnea/cyanosis have not changed.

Cohort Studies↗
PubMed1996

Assessment of habitual sun exposure in adolescents via questionnaire--a comparison with objective measurement using polysulphone badges.

The reliability and validity of sun exposure questions were examined in a group of 125 schoolchildren aged 14-15 years of northern European ancestry. We compared estimates of erythemally effective dose (EED) obtained from polysulphone badges worn on four consecutive weekend days in late spring to answers to several questions on habitual sun exposure. The polysulphone badge estimates accurately reflected the reported sun exposure of children and were highly correlated with responses to questions on habitual sun exposure obtained 12 months earlier. For the question "During weekends and school holidays, how much time do you usually spend in the sun each day", the Pearson correlation coefficients for the association with EED were 0.36 (girls) and 0.23 (boys). Adjusted for within-person variation in the EED measurements, the correlation coefficients were 0.65 (girls) and 0.43 (boys). For the question "Weekends and school holidays, where do you spend your time", the correlation coefficients were 0.18 (girls) and 0.32 (boys); the adjusted coefficients were 0.30 (girls) and 0.53 (boys). The findings suggest that "habitual' sun exposure in teenage children is a temporally stable behaviour that is reported with an acceptable degree of reliability and validity.

Adolescent↗
PubMed1996

Is this finding relevant? Generalisation and epidemiology.

The decision about whether the findings from analytical epidemiological studies can be extrapolated to another setting is an important one. We discuss some of the issues involved in the process of generalisation. A critical systematic qualitative approach should be used. This involves an assessment of the internal validity of the study and of the nature of the study base. The study subject matter and choice of epidemiologic measure should be considered. A study base similar to the target population is essential if the study is descriptive or if there is concern about effect modifiers whose effects cannot be predicted. In addition, data from quantitative tests of study findings in different populations should be considered.

Data Interpretation, Statistical↗
PubMed1996

Features of infant exposure to tobacco smoke in a cohort study in Tasmania.

STUDY OBJECTIVES: To document changes in smoking style around infants over time and to identify factors associated with the smoking hygiene of mothers and others. DESIGN: A population based cohort study. SETTING: Population based, involving 22% of live births in Tasmania, Australia. PARTICIPANTS: From 1 May 1988 to 30 April, 1993, 6109 infants and their mothers (89% of eligible infants) participated in the hospital and home interview of the cohort study. Infants eligible for cohort entry were those assessed at birth to be at a higher risk of SIDS. MAIN RESULTS: The overall proportion of mothers who smoked during pregnancy and postnatally did not decline. Increasing trends were found for mothers and others not smoking in the same room as baby or while holding or feeding the baby, significant over the five year period. Good smoking hygiene (mother not smoking in the same room as baby) was positively associated with--first birth (OR = 1.74 (1.30, 2.33)), low birth weight (1.69 (1.27, 2.23)), being born after 1 May 1991 (1.67 (1.33, 2.11)), and private health insurance status (1.39 (1.02, 1.90)). Good smoking hygiene was negatively associated with maternal smoking during pregnancy (0.50 (0.31, 0.80)), intention to bottle feed (0.62 (0.49, 0.78)), the level of maternal postnatal smoking, increasing numbers of smokers in the household, and parents cohabiting but unmarried. A similar analysis was conducted for other household residents who smoked. CONCLUSIONS: Changes in maternal smoking prevalence have been small. The exposure of infants to tobacco smoke postnatally has decreased significantly, although a large proportion of infants are still exposed to tobacco smoke. The identification of the above parental and infant factors associated with good smoking hygiene should be useful for health education planning.

Cohort Studies↗
PubMed1996

Exercise-induced bronchial hyperresponsiveness and parental ISAAC questionnaire responses.

The predictive value of parental questionnaire responses for exercise-induced bronchoconstriction in childhood asthma has not been fully clarified. The aim of this study was to compare exercise-induced bronchial hyperresponsiveness in 7 year old children with parental responses to core questions in the International Study of Asthma and Allergies in Childhood (ISAAC) study. A cross-sectional study was conducted on 191 (91% of eligible) children from seven randomly selected schools in Southern Tasmania. Study measurements included a parental questionnaire and exercise challenge testing, using a recently validated 6 min free-running protocol. The response to exercise was assessed using forced expiratory volume in one second (FEV1) measurement. The median percentage fall in FEV1 was significantly higher in children whose parents responded positively to ISAAC questions on a history of wheeze (p = 0.0031) or asthma (p = 0.0005), recent wheeze (p = 0.0005), sleep disturbance due to wheeze (p = 0.0005), or exercise-induced wheeze (p = 0.0015). Receiver operating characteristic (ROC) curve analysis showed exercise-induced bronchial hyperresponsiveness to be a good indicator of current asthma status. Using a 12% or greater fall in FEV1 postexercise as a positive test response, the exercise challenge had sensitivity and specificity estimates for current asthma and exercise-induced wheeze of (0.58 and 0.77) and (0.60 and 0.77), respectively. In conclusion, the respiratory response to exercise was consistent with parental responses to the ISAAC questionnaire in a population-based sample of 7 year old children. These findings will assist interpretation of large ISAAC studies in terms of asthma prevalence.

Adult↗
PubMed1996

Defining obesity in children by biological endpoint rather than population distribution.

OBJECTIVE: To investigate the association of fatness in children with dyslipoproteinemia and high blood pressure, with the purpose of proposing standards for childhood obesity which are directly related to intermediate biological parameters that predict future disease. DESIGN: A cross-sectional study of a large, nationally representative sample of Australian schoolchildren. SUBJECTS: 1834 children aged 9 or 15 years, with skinfolds blood lipid measurements on 1144 and with skinfolds and blood pressure measurements on 1757. MEASUREMENTS: Skinfolds thicknesses measured at four locations (triceps, biceps, subscapular and suprailiac) using holtain calipers, percent body fat calculated from the sum of four skinfolds, Quetelet's index calculated from weight and height, waist and hip circumferences, plasma total cholesterol and triglycerides determined using a Technicon Autoanalyser II, high density lipoprotein cholesterol (HDLC) analysed following precipitation with heparin manganese, and systolic blood pressure (SBP) measured using a standard mercury sphygmomanometer. RESULTS: For 9 years old girls, 15 year old girls and 9 years old boys, dichotomising their HDLC and SBP measurements by percent body fat defined the two groups most homogeneous in terms of a measure of within-group variation. The cut-points in percent body fat were in the ranges 29-35% (girls) and 17-20% (boys). CONCLUSION: It is feasible to use the current biomedical status of individual children to define criteria for obesity. A cut-off point of 30% body mass as fat for girls and 20% for boys appears to be an appropriate standard.

Adolescent↗
PubMed1995

The contribution of changes in the prevalence of prone sleeping position to the decline in sudden infant death syndrome in Tasmania.

OBJECTIVE: To determine the independent contribution of changes in infant sleep position to the recent decline in sudden infant death syndrome (SIDS) rate in Tasmania. DESIGN: (1) A comparison of the whole population incidence of SIDS before and after an intervention to reduce the prevalence of prone sleeping position. (2) A within-cohort analysis of the contribution of sleep position and other exposures to the decline in SIDS after the intervention. SETTING: Tasmania, Australia. PARTICIPANTS: (1) All SIDS cases from 1975 through 1992. (2) A sample of one in five infants born in Tasmania who at perinatal assessment were scored to be at higher risk for SIDS since January 1988. Of 5534 infants included in the study, 39 later died of SIDS. INTERVENTIONS: Multiple public health activities to reduce the prevalence of the prone infant sleeping position in Tasmania and verbal information on the association between prone position and SIDS to cohort participants from May 1, 1991. MAIN OUTCOME MEASURE: Sudden infant death syndrome incidence. RESULTS: The Tasmanian SIDS rate decreased (P < .01) from 3.8 (95% confidence interval [CI], 3.5 to 4.2) deaths per 1000 live births from 1975 through 1990 to a rate of 1.5 (95% CI, 0.9 to 2.2) deaths per 1000 live births in 1991 through 1992. The SIDS mortality rate in the cohort by period of birth was 7.6 (95% CI, 4.9 to 10.3) deaths per 1000 live births for those born from May 1, 1988, through April 30, 1991, and 4.1 (95% CI, 1.3 to 7.0) deaths per 1000 infants for those born from May 1, 1991, through October 31, 1992. The prevalence of usual prone sleeping position at 1 month of age was 29.9% and 4.3% in these two cohorts, respectively (adjusted odds ratio, 0.11; 95% CI, 0.08 to 0.13). Logistic regression demonstrated that 70% of the SIDS rate reduction in the cohort could be accounted for by the decreased prevalence of the prone sleeping position. Other factors examined individually contributed to less than 10% of the SIDS rate reduction. CONCLUSIONS: The major contributing factor to the recent SIDS rate decline in Tasmania has been the reduction in the proportion of infants usually sleeping prone.

Cohort Studies↗
PubMed1995

The 1984 Tasmanian insulin treated diabetes mellitus prevalence cohort: an eight and a half year mortality follow-up investigation.

Total mortality and underlying cause of death were examined in a population-based prevalence cohort (n = 1232) of Tasmanians with insulin-treated diabetes mellitus. Eight and a half years after the establishment of the registry, the cause of death based on death certificate information was determined for the overall cohort and for three classification groups of insulin-treated diabetes: Group A--childhood-onset IDDM cases; Group B--adult-onset IDDM cases; and Group C--adult-onset insulin-treated NIDDM cases. A total of 378 deaths occurred, providing an overall SMR of 2.2 (95% CI 2.0-2.4) compared to the Tasmanian population. Diabetic females experienced a higher SMR (2.6, 95% CI 2.3-3.0) than diabetic males (1.9, 95% CI 1.6-2.2). The all-cause SMRs for the diabetic classification groups were 4.6 (95% CI 3.4-6.1) in Group A, 1.8 (95% CI 1.5-2.1) in Group B, and 2.2 (95% CI 1.9-2.6) in Group C. After adjusting for age, gender and duration of diabetes, the mortality in Group C was significantly higher compared to Group B (odds ratio 1.6, 95% CI 1.2-2.3). This study indicates that people with childhood-onset IDDM experience 4.6 times the death rate compared to the Tasmanian population and that the excess mortality is most pronounced in females.

Adolescent↗