Biomedical subjects

Louis S Pilotto

Publications and source records attributed to Louis S Pilotto.

8 recordsLinked to original sources

PubMed2006

Vegetation fires, particulate air pollution and asthma: a panel study in the Australian monsoon tropics.

We examined the relationship between particulate matter (PM) <10 and <2.5 microns in diameter (PM10 and PM2.5) generated by vegetation fires and daily health outcomes in 251 adults and children with asthma over a 7-month period. Data were analysed using generalized estimating equations adjusted for potential environmental confounders, autocorrelation, weekends and holidays. PM10 ranged from 2.6 - 43.3 microg m-3and was significantly associated with onset of asthma symptoms, commencing oral steroid medication, the mean daily symptom count and the mean daily dose of reliever medication. Similar results were found for PM2.5. No associations were found with the more severe outcomes of asthma attacks, increased health care attendances or missed school/work days. These results help fill a gap in the evidence about the population health impacts of lower levels of pollution characteristic of deliberate landscape burning to control fuel loads versus the better documented risks of more intense and severely polluting wildfires.

Adolescent↗

PubMed2006

Cluster randomized controlled trials in primary care: an introduction.

BACKGROUND: Cluster randomized trials occur when groups or clusters of individuals, rather than the individuals themselves, are randomized to intervention and control groups and outcomes are measured on individuals within those clusters. Within primary care, between 1997 and 2000, there has been a virtual doubling in the number of published cluster randomized trials. A recent systematic review, specifically within primary care, found study quality to be both generally lower than that reported elsewhere and not to have shown any recent quality improvement. OBJECTIVE: To discuss the design, conduct and analysis of cluster randomized trials within primary care in terms of the appropriate expertise required, potential bias, ethical considerations and expense. DISCUSSION: Compared with trials that involve the randomization of individual participants, cluster randomized trials are more complex to design and analyse and, for a given sample size, have decreased power and a broadening of confidence intervals. Cluster randomized trials are specifically prone to potential bias at two levels-the cluster and individual. Regarding the former, it is recommended that cluster allocation be undertaken by a party independent to the research team and careful consideration be given to ensure minimal cluster attrition. Bias at the individual level can be overcome by identifying trial participants before randomization and at this time obtaining consent for intervention, data collection or both. A unique ethical aspect to cluster randomized trials is that cluster leaders may consent to the trial on behalf of potential cluster members. Additional costs of cluster randomized trials include the increased number of patients required, the complexity in their design and conduct and, usually, the need to recruit clusters de novo. CONCLUSION: Cluster randomized trials are a powerful and increasingly popular research tool. They are uniquely placed for the conduct of research within primary-care clusters where intracluster contamination can occur. Associated methodological issues are straightforward and surmountable and just need careful consideration and management.

Bias↗

PubMed2006

A cohort study of indoor nitrogen dioxide and house dust mite exposure in asthmatic children.

OBJECTIVE: The purpose of this study was to investigate dose-response relationships between asthma symptoms and indoor nitrogen dioxide (NO2) and house dust mite allergen (HDM) in children. METHODS: Asthmatic children from 18 primary schools in Adelaide, Australia, kept a daily symptoms diary over 12 weeks. Home and classroom NO2 levels were measured repeatedly in winter 2000. HDM levels were obtained from beds. Lung function tests were performed at the beginning and at the end of the study period. RESULTS: Data on exposure and respiratory outcomes were gathered for 174 children. For school exposure, the estimated relative symptom rate (RR) for a 10-ppb increase in NO2 for difficulty breathing during the day was 1.09 (95% confidence interval [CI] = 1.03-1.15), at night 1.11 (95% CI = 1.05-1.18), and for chest tightness at night 1.12 (95% CI = 1.07-1.17). Significant symptom rate increases were also found for kitchen NO2 exposure. This was supported by a negative dose-response relationship between percentage predicted forced expiratory volume in 1 second and NO2 (-0.39%; 95% CI = -0.76 to -0.02) for kitchen exposure. Significant threshold effects using a 10-microg/g cutoff point for HDM exposure were established in the sensitized children for nighttime wheeze (RR = 3.62, 95% CI = 1.49-8.77), daytime cough (RR = 1.64, 95% CI = 1.14-2.36), and daytime asthma attack (RR = 1.95, 95% CI = 1.06-3.60). CONCLUSION: This study has established reliable risk estimates for exacerbations of asthma symptoms in children based on dose-response investigations of indoor NO2 and HDM.

Adolescent↗

PubMed2004

Randomized controlled trial of unflued gas heater replacement on respiratory health of asthmatic schoolchildren.

BACKGROUND: Previous studies do not provide a clear picture of the relationship between nitrogen dioxide (NO(2)) exposure and asthma. METHODS: Eighteen schools using unflued gas heating in winter were randomly allocated to either retain their heaters (10 control schools) or to have replacement flued gas or electric heaters installed at the beginning of winter (8 intervention schools). Fortnightly telephone interviews were used to record daily individual asthma symptoms that occurred over 12 weeks (including winter). Lung function and histamine challenge tests were performed at baseline and the end of the study. NO(2) was measured in each school classroom on 9 days and in each household on 3 days spread over the study period. RESULTS: From 199 primary school children that met the eligibility criteria, 45 intervention and 73 control children agreed to participate. Baseline characteristics were similar between groups. Difficulty breathing during the day (Relative Risk [RR] = 0.41; 95% CI: 0.07, 0.98) and night (RR = 0.32; 95% CI: 0.14, 0.69), chest tightness during the day (RR = 0.45; 95% CI: 0.25, 0.81), and daytime asthma attacks (RR = 0.39; 95% CI: 0.17, 0.93) were significantly reduced in the intervention group. Percentage predicted forced expiratory volume in one second (FEV(1)), the concentration of histamine inducing a 20% fall in FEV(1) (PD(20)), and the dose-response slope (DRS) were similar between groups at follow-up. Mean (standard deviation) NO(2) levels were 15.5 (6.6) parts per billion (ppb) and 47.0 (26.8) ppb in the intervention and control schools respectively (P < 0.001). CONCLUSIONS: Asthma symptoms were reduced following a replacement intervention that removed high exposure to NO(2). Such replacement should be considered a public health priority for schools using unflued gas heating during winter.

Air Pollutants↗

PubMed2004

Trial of nurse-run asthma clinics based in general practice versus usual medical care.

OBJECTIVE: The aim of this study was to assess the ability of nurse-run asthma clinics based in general practice compared with usual medical care to produce at least a moderate improvement in the quality of life of adults with asthma. METHODOLOGY: A randomized controlled trial involving 80 asthma clinic and 90 usual medical care asthma participants, aged 18 years and older was conducted in 11 general practices in Adelaide. The main outcome measure was the St George's respiratory questionnaire (SGRQ), from which quality-of-life scores were used to assess therapeutic benefit. Lung function measurements and health services utilization data were also collected. RESULTS: One hundred and fifty-three participants (90%) were reviewed at follow up after 6-9 months. There was little difference between groups in baseline measures or for the 6-month follow-up outcomes, including the mean difference in total SGRQ scores (-0.5, 95% confidence interval (CI) -4.0, 2.9) and the mean difference in percentage predicted FEV(1) (2.3%, 95% CI -0.7, 5.3 pre-bronchodilator; 0.4%, 95% CI -5.1, 5.9 post-bronchodilator). Trends in health services utilization were noted. CONCLUSIONS: Nurse-run asthma clinics based in general practice and usual medical care were similar in their effects on quality of life and lung function in adults. These findings cannot be generalized to hospital outpatients and other clinics that manage more severe asthmatic patients.

Adult↗

PubMed2003

Environmental exposure to carcinogens causing lung cancer: epidemiological evidence from the medical literature.

OBJECTIVE: In 2000 there were 1.1 million lung or bronchial cancer deaths worldwide, with relatively limited evidence of causation other than for smoking. We aimed to search and appraise the literature regarding evidence for a causal relationship between air pollution and lung cancer according to the 10 Bradford Hill criteria for causality. METHODOLOGY: A MEDLINE search was performed using the following key words: 'lung neoplasm', 'epidemiology', 'human', 'air pollution'and 'not molec*'. The criteria for inclusion was: cited original research that described the study population, measured environmental factors, was of case control or cohort design, and was undertaken after 1982. RESULTS: Fourteen papers (10 case control, four cohort studies) fulfilled the search criteria, with a sample size ranging from 101 cases and 89 controls, to a cohort of 552 cases and 138 controls. Of the 14 papers that fulfilled the search criteria the number of papers addressing each of the Bradford Hill criteria were as follows: Strength of association: eight studies demonstrated significant positive associations between environmental exposure and lung cancer with a relative risk range of 1.14-5.2. One study found a negative association with relative risk 0.28. Consistency: eight of 14 studies found significant positive associations and one of 14 a significant negative association. Specificity: tobacco smoking and occupational exposure were addressed in all studies (often crudely with misclassification). Temporality: exposure prior to diagnosis was demonstrated in nine studies. Dose-response relationship: evident in three studies. Coherence, analogy: not addressed in any study. CONCLUSION: Evidence for causality is modest, with intermediate consistency of findings, limited dose-response evidence and crude adjustment for important potential confounders. Large studies with comprehensive risk factor quantification are required to clarify the potentially small effect of air pollution given the relatively large effects of tobacco smoking and occupational carcinogen exposure.

Air Pollutants↗

PubMed2003

Hospital attendance prediction tool also identifies impaired quality of life in adults with asthma in general practice.

STUDY OBJECTIVE: To assess the ability of an adult risk screening questionnaire (RSQ), previously shown to predict attendance at hospital emergency departments, to identify impaired quality of life in adult patients with asthma in general practice. DESIGN: Baseline data from an RCT of asthma clinics in general practice, using the St. George Respiratory Questionnaire (SGRQ) to measure quality of life. SETTING: Twelve general practices in Adelaide, Australia. RESULTS: A total of 184 adult asthmatics were recruited, with a mean (standard deviation) age of 50.3 years (16.6 years). Age, gender, weight, number of comorbidities, smoking status, FEV1 and percent predicted FEV1 (pre-and post-bronchodilator), peak flow (pre and post), and RSQ were independently related to SGRQ scores. After adjusting for potential confounders, an RSQ score predictive of hospital attendance was also associated with an average increase (worsening) in SGRQ total score of 11.9 (95% CI: 7.6, 16.3), an average increase in activity score of 9.0 (2.5, 15.5), symptom score of 14.8 (8.6, 21.0), and impact score of 13.1 (8.6, 17.6). These represent clinically significant differences. CONCLUSION: An RSQ score predictive of hospital attendance should alert the general practitioner to explore and address symptom, activity, and impact domains associated with impaired quality of life in adult asthma.

Asthma↗

PubMed2002

Effect of beta lactam antibiotic use in children on pneumococcal resistance to penicillin: prospective cohort study.

OBJECTIVE: To examine the relation between use of antibiotics in a cohort of preschool children and nasal carriage of resistant strains of pneumococcus. DESIGN AND PARTICIPANTS: Prospective cohort study over two years of 461 children aged under 4 years living in Canberra, Australia. MAIN OUTCOME MEASURES: Use of drugs, respiratory symptoms, and visits to doctors were documented in a daily diary by parents of the children during 25 months of observation. Isolates of pneumococci, which were cultured from nasal swabs collected approximately six monthly, were tested for antibiotic resistance. RESULTS: From the four swab collections 631 positive pneumococcal isolates from 461 children were found, of which 13.6% were resistant to penicillin. Presence of penicillin resistant pneumococci was significantly associated with children's use of a beta lactam antibiotic in the two months before each swab collection (odds ratio 2.03 (95% confidence interval 1.15 to 3.56, P=0.01)). The odds ratio of the association remained >1 (though did not reach significance at the 0.05 level) for use in the six months before swab collection. The association was seen in children who received only penicillin or only cephalosporin antibiotics in that period. The odds ratio was 4.67 (1.29 to 17.09, P=0.02) in children who had received both types of beta lactam in the two months before their nasal swab. The modelled odds of carrying penicillin resistant pneumococcus was 4% higher for each additional day of use of beta lactam antibiotics in the six months before swab collection. CONCLUSIONS: Reduction in beta lactam use could quickly reduce the carriage rates of penicillin resistant pneumococci in early childhood. In view of the propensity of these organisms to be spread among children in the community, the prevalence of penicillin resistant organisms may fall as a consequence.

Anti-Bacterial Agents↗