Jan Cowan

Publications (4)11 Total impact

• Source

  Available from: thepcrj.org

  Article: Outcomes using exhaled nitric oxide measurements as an adjunct to primary care asthma management.

  Richard S Hewitt, Catherine M Modrich, Jan O Cowan, G Peter Herbison, D Robin Taylor
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  ABSTRACT: Exhaled nitric oxide (FENO) measurements may help to highlight when inhaled corticosteroid (ICS) therapy should or should not be adjusted in asthma. This is often difficult to judge. Our aim was to evaluate a decision-support algorithm incorporating FENO measurements in a nurse-led asthma clinic. Asthma management was guided by an algorithm based on high (>45ppb), intermediate (30-45ppb), or low (<30ppb) FENO levels and asthma control status. This provided for one of eight possible treatment options, including diagnosis review and ICS dose adjustment. Well controlled asthma increased from 41% at visit 1 to 68% at visit 5 (p=0.001). The mean fluticasone dose decreased from 312 mcg/day at visit 2 to 211mcg/day at visit 5 (p=0.022). There was a high level of protocol deviations (25%), often related to concerns about reducing the ICS dose. The % fall in FENO associated with a change in asthma status from poor control to good control was 35%. An FENO-based algorithm provided for a reduction in ICS doses without compromising asthma control. However, the results may have been influenced by the education and support which patients received. Reluctance to reduce ICS dose was an issue which may have influenced the overall results. Australian Clinical Trials Registry # 012605000354684.
  Primary care respiratory journal: journal of the General Practice Airways Group 11/2009; 18(4):320-7.
• Article: Adiposity, asthma, and airway inflammation.

  Christene R McLachlan, Richie Poulton, George Car, Jan Cowan, Susan Filsell, Justina M Greene, D Robin Taylor, David Welch, Avis Williamson, Malcolm R Sears, Robert J Hancox
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  ABSTRACT: Several studies have found obesity to be associated with an increased prevalence of asthma. For reasons that remain unclear, this association has often been reported to be stronger in women than in men. One possible explanation might be that these studies have used body mass index to identify adiposity, which might be a less reliable measure of body fat in men than in women. We sought to explore the association between body fat percentage measured by means of bioelectrical impedance analysis and asthma, airflow obstruction, and airway inflammation in men and women. Respiratory questionnaires, spirometry, bronchodilator response, exhaled nitric oxide level, and percentage of body fat were measured in a population-based cohort of approximately 1000 individuals at age 32 years. There was a significant association between the percentage of body fat and asthma in women (P = .043) but not in men (P = .75). Airflow obstruction was associated with percentage of body fat in women (P = .046), but there was an inverse association in men (P = .010). Bronchodilator responsiveness was also associated with lower body fat in men (P = .004). Airway inflammation, measured by means of exhaled nitric oxide, was not associated with body fat in either women (P = .17) or men (P = .25). Adiposity is associated with asthma and airflow obstruction in women. This does not appear to be mediated by airway inflammation. In men airflow obstruction and bronchodilator responsiveness are associated with a lower percentage of body fat. In women, but not in men, obesity is associated with asthma and airflow obstruction, but there was no association with airway inflammation.
  Journal of Allergy and Clinical Immunology 04/2007; 119(3):634-9. · 11.00 Impact Factor
• Article: Factors affecting exhaled nitric oxide measurements: the effect of sex

  Taylor D Robin, Piush Mandhane, Justina Greene, Robert Hancox, Sue Filsell, Christene McLachlan, Avis Williamson, Jan Cowan, Andrew Smith, Malcolm Sears
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  ABSTRACT: Abstract Background Exhaled nitric oxide (F_ENO) measurements are used as a surrogate marker for eosinophilic airway inflammation. However, many constitutional and environmental factors affect F_ENO, making it difficult to devise reference values. Our aim was to evaluate the relative importance of factors affecting F_ENO in a well characterised adult population. Methods Data were obtained from 895 members of the Dunedin Multidisciplinary Health and Development Study at age 32. The effects of sex, height, weight, lung function indices, smoking, atopy, asthma and rhinitis on F_ENO were explored by unadjusted and adjusted linear regression analyses. Results The effect of sex on F_ENO was both statistically and clinically significant, with F_ENO levels approximately 25% less in females. Overall, current smoking reduced F_ENO up to 50%, but this effect occurred predominantly in those who smoked on the day of the F_ENO measurement. Atopy increased F_ENO by 60%. The sex-related differences in F_ENO remained significant (p < 0.001) after controlling for all other significant factors affecting F_ENO. Conclusion Even after adjustment, F_ENO values are significantly different in males and females. The derivation of reference values and the interpretation of F_ENO in the clinical setting should be stratified by sex. Other common factors such as current smoking and atopy also require to be taken into account.
  Respiratory Research. 01/2007;
• Article: Associations between respiratory symptoms, lung function and gastro-oesophageal reflux symptoms in a population-based birth cohort

  Robert Hancox, Richie Poulton, Taylor D Robin, Justina Greene, Christene McLachlan, Jan Cowan, Erin Flannery, Herbison G Peter, Malcolm Sears, Nicholas Talley
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  ABSTRACT: Abstract Background Several studies have reported an association between asthma and gastro-oesophageal reflux, but it is unclear which condition develops first. The role of obesity in mediating this association is also unclear. We explored the associations between respiratory symptoms, lung function, and gastro-oesophageal reflux symptoms in a birth cohort of approximately 1000 individuals. Methods Information on respiratory symptoms, asthma, atopy, lung function and airway responsiveness was obtained at multiple assessments from childhood to adulthood in an unselected birth cohort of 1037 individuals followed to age 26. Symptoms of gastro-oesophageal reflux and irritable bowel syndrome were recorded at age 26. Results Heartburn and acid regurgitation symptoms that were at least "moderately bothersome" at age 26 were significantly associated with asthma (odds ratio = 3.2; 95% confidence interval = 1.6–6.4), wheeze (OR = 3.5; 95% CI = 1.7–7.2), and nocturnal cough (OR = 4.3; 95% CI = 2.1–8.7) independently of body mass index. In women reflux symptoms were also associated with airflow obstruction and a bronchodilator response to salbutamol. Persistent wheezing since childhood, persistence of asthma since teenage years, and airway hyperresponsiveness since age 11 were associated with a significantly increased risk of heartburn and acid regurgitation at age 26. There was no association between irritable bowel syndrome and respiratory symptoms. Conclusion Reflux symptoms are associated with respiratory symptoms in young adults independently of body mass index. The mechanism of these associations remains unclear.
  Respiratory Research. 01/2006;