Australian and New Zealand journal of public health, 2011
Background: This study, in a region with relatively low industrial activity, used a highly specif... more Background: This study, in a region with relatively low industrial activity, used a highly specific marker for traffic emissions, accounted for the inherent fetal growth potential, and used complete record linkage of births, midwife notifications, deaths, hospital morbidity and birth defect records.Methods: Clinical records were obtained for pregnancies between 2000 and 2006 in three areas of Perth, Western Australia (n=3,501). We used carbon monoxide as a marker for locally derived traffic emissions, and assessed exposure using the AusRoads dispersion model. Fetal growth was characterised by proportion of optimal birth weight and investigated using multivariate mixed-effects regression.Results: Exposure in the third trimester was associated with a -0.49% (sd=0.23%) change in proportion of optimal birth weight per 10 ÎĽg/m3 increase in locally derived traffic emissions. However, this result was confined to one of the three study areas due to elevated exposure misclassification among women in the other two areas. Among this group, a neonate who would have otherwise attained an optimal birth weight of 3.5 kg would be expected to be born 58 g lighter for an interquartile increase in third trimester exposure, which was approximately half of the effect observed for maternal smoking during pregnancy.Conclusion: We observed an association between maternal exposure to traffic emissions and reduced fetal growth. This effect was supported by sensitivity analyses but only observed in one of the three study areas. Further studies are required to corroborate our results.
Background The risks of adverse obstetric outcomes among young women survivors of colorectal canc... more Background The risks of adverse obstetric outcomes among young women survivors of colorectal cancer (CRC) are uncertain. Methods This Western Australian, whole-jurisdictional linked-data, retrospective cohort study compared maternal and neonatal outcomes of first postcancer pregnancies among women CRC survivors against randomly selected pregnancies of women with no cancer history. Logistic regression models were used to investigate a range of adverse outcomes independently associated with CRC and its surgical and adjunctive treatments. Results Among 627,762 deliveries during the study period (1983–2007), 232 were first pregnancies following CRC. Whether following laparoscopic or open cancer surgery, these pregnancies were independently associated with a significantly increased risk of antepartum hemorrhage [odds ratios (ORs): 1.25; 2.13 for the respective procedures], postpartum hemorrhage (ORs: 1.61; 3.31), Cesarean delivery (ORs: 2.42; 4.24), infant low Apgar score (ORs: 1.32; 2.64), need for neonatal resuscitation (ORs: 1.49; 3.20), and special care admission (ORs: 1.42; 2.87). A history of open (but not laparoscopic) cancer surgery was associated with increased risk of gastrointestinal obstruction during pregnancy (OR 1.17) and prolonged postpartum hospitalization (OR 3.11). Neither was significantly associated with perinatal death. Among women with previous CRC, rectal (versus colonic) malignancy was independently associated with a significantly higher risk of overall maternal and neonatal adverse outcomes (ORs: 3.73 and 2.73, respectively), as was radiotherapy (ORs: 4.24 and 2.81, respectively). Chemotherapy was independently associated with a marginally but significantly higher risk of overall maternal but not neonatal outcomes (ORs: 1.11; 0.98). Open versus laparoscopic cancer surgery was associated with a significantly higher risk of antepartum and postpartum hemorrhage, low Apgar score, need for neonatal resuscitation, and neonatal special care admission. Conclusions Previous CRCs, particularly rectal and radiation-treated tumors, appear to confer an increased likelihood of adverse outcomes in subsequent pregnancies. Laparoscopic technique for CRC surgery may reduce adverse gestational outcomes.
Background This study had two principal objectives: (i) to investigate the relationship between a... more Background This study had two principal objectives: (i) to investigate the relationship between asthma severity and proximity to major roadways in Perth, Western Australia; (ii) to demonstrate a more accurate method of exposure assessment for traffic pollutants using an innovative GIS-based measure that fully integrates all traffic densities around subject residences. Methods We conducted a spatial case-control study, in which 'cases' were defined as individuals aged under 19 years of age with more severe asthma (defined here as two or more emergency department contacts with asthma in a defined 5-year period) versus age- and gender-matched 'controls' with less severe asthma (defined here as one emergency department contact for asthma). Traffic exposures were measured using a GIS-based approach to determine the lengths of the roads falling within a buffer area, and then multiplying them by their respective traffic counts. Results We examined the spatial relationship between emergency department contacts for asthma at three different buffer sizes: 50 metres, 100 metres and 150 metres. No effect was noted for the 50 metre buffer (OR = 1.07; 95% CI: 0.91-1.26), but elevated odds ratios were observed with for crude (unadjusted) estimates OR = 1.21 (95% CI: 1.00-1.46) for 100 metre buffers and OR = 1.25 (95% CI: 1.02-1.54) for 150 metre buffers. For adjusted risk estimates, only the 150 metre buffer yielded a statistically significant finding (OR = 1.24; 95% CI:1.00-1.52). Conclusions Our study revealed a significant 24% increase in the risk of experiencing multiple emergency department contacts for asthma for every log-unit of traffic exposure. This study provides support for the hypothesis that traffic related air pollution increases the frequency of health service contacts for asthma. This study used advanced GIS techniques to establish traffic-weighted buffer zones around the geocoded residential location of subjects to provide an accurate assessment of exposure to traffic emissions, thereby providing a quantification of the ranges over which pollutants may exert a health effect.
Australian and New Zealand journal of public health, 2011
Background: This study, in a region with relatively low industrial activity, used a highly specif... more Background: This study, in a region with relatively low industrial activity, used a highly specific marker for traffic emissions, accounted for the inherent fetal growth potential, and used complete record linkage of births, midwife notifications, deaths, hospital morbidity and birth defect records.Methods: Clinical records were obtained for pregnancies between 2000 and 2006 in three areas of Perth, Western Australia (n=3,501). We used carbon monoxide as a marker for locally derived traffic emissions, and assessed exposure using the AusRoads dispersion model. Fetal growth was characterised by proportion of optimal birth weight and investigated using multivariate mixed-effects regression.Results: Exposure in the third trimester was associated with a -0.49% (sd=0.23%) change in proportion of optimal birth weight per 10 ÎĽg/m3 increase in locally derived traffic emissions. However, this result was confined to one of the three study areas due to elevated exposure misclassification among women in the other two areas. Among this group, a neonate who would have otherwise attained an optimal birth weight of 3.5 kg would be expected to be born 58 g lighter for an interquartile increase in third trimester exposure, which was approximately half of the effect observed for maternal smoking during pregnancy.Conclusion: We observed an association between maternal exposure to traffic emissions and reduced fetal growth. This effect was supported by sensitivity analyses but only observed in one of the three study areas. Further studies are required to corroborate our results.
Background The risks of adverse obstetric outcomes among young women survivors of colorectal canc... more Background The risks of adverse obstetric outcomes among young women survivors of colorectal cancer (CRC) are uncertain. Methods This Western Australian, whole-jurisdictional linked-data, retrospective cohort study compared maternal and neonatal outcomes of first postcancer pregnancies among women CRC survivors against randomly selected pregnancies of women with no cancer history. Logistic regression models were used to investigate a range of adverse outcomes independently associated with CRC and its surgical and adjunctive treatments. Results Among 627,762 deliveries during the study period (1983–2007), 232 were first pregnancies following CRC. Whether following laparoscopic or open cancer surgery, these pregnancies were independently associated with a significantly increased risk of antepartum hemorrhage [odds ratios (ORs): 1.25; 2.13 for the respective procedures], postpartum hemorrhage (ORs: 1.61; 3.31), Cesarean delivery (ORs: 2.42; 4.24), infant low Apgar score (ORs: 1.32; 2.64), need for neonatal resuscitation (ORs: 1.49; 3.20), and special care admission (ORs: 1.42; 2.87). A history of open (but not laparoscopic) cancer surgery was associated with increased risk of gastrointestinal obstruction during pregnancy (OR 1.17) and prolonged postpartum hospitalization (OR 3.11). Neither was significantly associated with perinatal death. Among women with previous CRC, rectal (versus colonic) malignancy was independently associated with a significantly higher risk of overall maternal and neonatal adverse outcomes (ORs: 3.73 and 2.73, respectively), as was radiotherapy (ORs: 4.24 and 2.81, respectively). Chemotherapy was independently associated with a marginally but significantly higher risk of overall maternal but not neonatal outcomes (ORs: 1.11; 0.98). Open versus laparoscopic cancer surgery was associated with a significantly higher risk of antepartum and postpartum hemorrhage, low Apgar score, need for neonatal resuscitation, and neonatal special care admission. Conclusions Previous CRCs, particularly rectal and radiation-treated tumors, appear to confer an increased likelihood of adverse outcomes in subsequent pregnancies. Laparoscopic technique for CRC surgery may reduce adverse gestational outcomes.
Background This study had two principal objectives: (i) to investigate the relationship between a... more Background This study had two principal objectives: (i) to investigate the relationship between asthma severity and proximity to major roadways in Perth, Western Australia; (ii) to demonstrate a more accurate method of exposure assessment for traffic pollutants using an innovative GIS-based measure that fully integrates all traffic densities around subject residences. Methods We conducted a spatial case-control study, in which 'cases' were defined as individuals aged under 19 years of age with more severe asthma (defined here as two or more emergency department contacts with asthma in a defined 5-year period) versus age- and gender-matched 'controls' with less severe asthma (defined here as one emergency department contact for asthma). Traffic exposures were measured using a GIS-based approach to determine the lengths of the roads falling within a buffer area, and then multiplying them by their respective traffic counts. Results We examined the spatial relationship between emergency department contacts for asthma at three different buffer sizes: 50 metres, 100 metres and 150 metres. No effect was noted for the 50 metre buffer (OR = 1.07; 95% CI: 0.91-1.26), but elevated odds ratios were observed with for crude (unadjusted) estimates OR = 1.21 (95% CI: 1.00-1.46) for 100 metre buffers and OR = 1.25 (95% CI: 1.02-1.54) for 150 metre buffers. For adjusted risk estimates, only the 150 metre buffer yielded a statistically significant finding (OR = 1.24; 95% CI:1.00-1.52). Conclusions Our study revealed a significant 24% increase in the risk of experiencing multiple emergency department contacts for asthma for every log-unit of traffic exposure. This study provides support for the hypothesis that traffic related air pollution increases the frequency of health service contacts for asthma. This study used advanced GIS techniques to establish traffic-weighted buffer zones around the geocoded residential location of subjects to provide an accurate assessment of exposure to traffic emissions, thereby providing a quantification of the ranges over which pollutants may exert a health effect.
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Papers by Gavin Pereira