5 results for Pearce, N.

  • Using directed acyclic graphs to consider adjustment for socioeconomic status in occupational cancer studies

    Richiardi, L.; Barone-Adesi, F.; Merletti, F.; Pearce, N.

    Journal article
    Massey University

    There is an ongoing debate on whether analyses of occupational studies should be adjusted for socioeconomic status (SES). In this paper directed acyclic graphs (DAGs) were used to evaluate common scenarios in occupational cancer studies with the aim of clarifying this issue. It was assumed that the occupational exposure of interest is associated with SES and different scenarios were evaluated in which ( a) SES is not a cause of the cancer under study, (b) SES is not a cause of the cancer under study, but is associated with other occupational factors that are causes of the cancer, (c) SES causes the cancer under study and is associated with other causal occupational factors. These examples illustrate that a unique answer to the issue of adjustment for SES in occupational cancer studies is not possible, as in some circumstances the adjustment introduces bias, in some it is appropriate and in others both the adjusted and the crude estimates are biased. These examples also illustrate the benefits of using DAGs in discussions of whether or not to adjust for SES and other potential confounders.

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  • Characteristics of ovarian cancer in women residing in Aotearoa, New Zealand: 1993-2004

    Firestone, R. T.; Wong, K. C.; Ellison-Loschmann, L.; Pearce, N.; Jeffreys, M.

    Journal article
    Massey University

    Background: Few studies have compared ovarian cancer rates between different ethnic groups in the same country. The aim of this study was to describe ethnic patterns in the incidence and mortality of ovarian cancer in New Zealand, and to investigate ethnic and socioeconomic differences in the grade and stage of ovarian cancer. Methods: Data on all women registered with ovarian cancer on the New Zealand Cancer Registry (1993-2004) were analysed. Population data were taken from the 1996 and 2001 census. Logistic regression was used to estimate associations between ethnicity, deprivation and tumour characteristics. Results: Age-standardised incidence rates were highest in Pacific women, intermediate in Maori women, and lowest in non-Maori, non-Pacific women. Age-standardised mortality rates showed the same pattern. Ovarian cancer subtypes differed by ethnic group. There was no significant association between socioeconomic deprivation and tumour grade or stage. Age-adjusted models showed that Maori women were more likely to have well differentiated tumours and less likely to present at a later stage compared to non-Maori, non-Pacific women. These patterns were partly explained by socioeconomic deprivation, and were not apparent for Pacific women. Conclusions: Pacific and Maori women experience higher incidence of ovarian cancer and mortality, compared to non-Maori, non-Pacific women. Maori women seemed to have better prognostic factors (local stage and well differentiated tumours) than non-Maori, non-Pacific women. More work is needed to improve current cancer prevention strategies, particularly in Pacific women.

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  • Regional variations in asthma hospitalisations among Maori and non-Maori

    Ellison-Loschmann, L.; King, R.; Pearce, N. (2004)

    Journal article
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Aim: To examine regional patterns of asthma hospitalisations in Maori and non-Maori. Methods: We studied asthma hospitalisations in Maori and non-Maori during 1994-2000. Hospitalisation rates for Maori and non-Maori were calculated for ages 5-34 years in each of the 74 territorial authorities (TAs), of which 15 are urban and 59 predominantly rural. The data were also analysed separately for Maori and non-Maori in the age groups 0-4, 5-14, 15-34 and 35-74 years. Results: For Maori, the highest hospitalisation rates were in Tauranga, Invercargill, Wanganui, South Wairarapa and Gisborne; the lowest rates were in Rodney, Tasman, Franklin, Waitaki and North Shore City. The rate of asthma hospitalisation was higher in Maori than non-Maori in each age-group: 0-4 years relative risk (RR) = 1.43; 5-14 years RR = 1.08; 15-34 years RR = 1.31; 35-74 years RR = 2.97. The differences were higher in rural areas (RR 1.65, 1.17, 1.34 and 3.13 respectively) than in urban areas (RR 1.25, 1.00, 1.22, 2.79 respectively). Conclusions: These analyses confirm previous evidence that asthma hospitalisation rates are higher in Maori than in non-Maori, despite the fact that asthma prevalence is similar in Maori and non-Maori children. They also indicate that this excess of hospitalisations is higher in rural than in urban areas, although the difference is not large.

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  • Stratigraphy, age and correlation of middle Pleistocene silicic tephras in the Auckland region, New Zealand: A prolific distal record of Taupo Volcanic Zone volcanism

    Alloway, B.; Westgate, J.; Pillans, B.; Pearce, N.; Newnham, R.; Byrami, M.; Aarburg, S. (2004)

    Journal article
    The University of Auckland Library

    An open access copy of this article is available from the publishers website. Coastal sections in the Auckland region reveal highly carbonaceous and/or highly weathered clay-dominated cover-bed successions with numerous discrete distal volcanic ash (tephra) layers, fluvially reworked siliciclastic (tephric) deposits, and two widely distributed pyroclastic density current (PDC deposits generated from explosive silicic volcanism within the Taupo Volcanic Zone (TVZ). The younger of the two PDC deposits (informally named Waiuku tephra) is glass-isothermal plateau fission-track (ITPFT) dated at 1.00 ᄆ 0.03 Ma and occurs in a normal polarity interval interpreted as the Jaramillo Subchron. Waiuku tephra is correlated with Unit E sourced from the Mangakino Volcanic Centre of the TVZ. Waiuku tephra can be subdivided into two distinctive units enabling unequivocal field correlation: a lower stratified unit (dominantly pyroclastic surge with fall component) and an upper massive to weakly stratified unit (pyroclastic flow). At many sites in south Auckland, Waiuku tephra retains basal "surge-like" beds (<1.4 m thickness). This provides clear evidence for primary emplacement and is an exceptional feature considering the c. 200 km this PDC has travelled from its TVZ source area. However, at many other Auckland sites, Waiuku tephra displays transitional sedimentary characteristics indicating lateral transformation from hot, gas-supported flow/surge into water-supported mass flow and hyperconcentrated flow (HCF) deposits. The older PDC deposit is dated at 1.21 ᄆ 0.09 Ma, is enveloped by tephras that are ITPFT-dated at 1.14 ᄆ 0.06 Ma (above) and 1.21 ᄆ 0.06 Ma (below), respectively, and occurs below a short normal polarity interval (Cobb Mountain Subchron) at c. 1.19 Ma. This PDC deposit, correlated with Ongatiti Ignimbrite sourced from the Mangakino Volcanic Centre of TVZ, has laterally transformed from a gas-supported, fine-grained pyroclastic flow deposit at Oruarangi, Port Waikato, into a water-supported volcaniclastic mass flow deposit farther north at Glenbrook Beach. The occurrence of Ongatiti Ignimbrite in Auckland significantly extends its northward distribution. Large numbers of post- and pre-Ongatiti rhyolitic tephra layers, ranging in age from c. 1.31 to 0.53 Ma, are also recognised in the region, with some up to 0.5 m in compacted fallout thickness. Although some tephras can be attributed to known TVZ eruptions (e.g., Ahuroa/Unit D), many have yet to be identified in proximal source areas and remain uncorrelated. However, some can be reliably correlated to tephra layers occurring in marine to nearshore sequences of Wanganui Basin and deep-sea cores retrieved east of North Island. The identification of previously unrecognised mid-Pleistocene TVZ-sourced tephra deposits in the Auckland region, and their correlation to the offshore marine record, represent an advance in the construction of a higher resolution history for the TVZ where, close to eruptive source, the record is fragmentary and obscured by deep burial, or erosion, or both.

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  • The burden of symptoms of asthma, allergic rhinoconjunctivitis and atopic eczema in children and adolescents in six New Zealand centres: ISAAC Phase One

    Asher, M.I.; Barry, D.; Clayton, T.; Crane, J.; D'Souza, W.; Ellwood, P.; Ford, R.P.K.; Mackay, R.; Mitchell, E.A.; Moyes, C.; Pattemore, P.; Pearce, N.; Stewart, A.W. (2001)

    Journal article
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Aim. To describe the burden of symptoms of asthma, allergic rhinoconjunctivitis and atopic eczema in children in six New Zealand centres. Methods. The International Study of Asthma and Allergies in Childhood (ISAAC) Phase One was undertaken in Aukland, Bay of Plenty, Hawke's Bay, Wellington, Nelson and Christchurch during 1992-1993. In each centre, approximately 3000 six to seven year old children and 3000 thirteen to fourteen year old adolescents were studied, a total of 37 592 participants. Both age groups answered written questionnaires and the adolescents a video questionnaire about asthma sypmtoms. Results. The prevalences of symptoms were high, for asthma 25% and 30%, allergic rhinoconjunctivitis 10% and 19%, and atopic eczema 15% and 13% in each age group respectively. More than 40% of participants had symptoms in the last year of at least one condition, most commonly asthma. There were no significant differences among regions, except for six to seven year olds in Nelson who had significantly lower prevalences of some symptoms of asthma and allergic rhinoconjunctivitis. Conclusions. Asthma and allergies are common in New Zealand, with resultant morbidity and cost. However, there is little regional variation with the exception of lower rates in Nelson children. Explanations for these findings will be the subject of further studies.

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