Short communication The association between synthetic bedding and adverse respiratory outcomes among skin-prick test positive and skin-prick test negative children Background: Synthetic bedding has been associated with increased child wheeze and also higher allergen levels in several studies. We aimed to examine whether the association between synthetic bedding and adverse respiratory outcomes was more evident among skin-prick test (SPT) positive children. Methods: A cross-sectional survey involving a population sample of 758 (81% of eligible) school children aged 8–10 years from randomly selected schools in the Australian Capital Territory in 1999. Parental questionnaires for ISAAC respiratory symptoms and child bedding were obtained. SPT results of 10 common allergens were available on 722 of the subjects (77% of those eligible). Synthetic pillow or quilt use was termed synthetic upper bedding. Results: Synthetic quilt use was associated with asthma (Adjusted Odds Ratio 1.67 (1.05, 2.65)), recent wheeze (AOR 1.63 (1.03, 2.59)) and allergic rhinoconjunctivitis (AOR 2.11 (1.33, 3.34)) among SPT-positive children. However, these associations were not apparent for SPT-negative children. Similarly, increasing synthetic upper bedding use was associated with more than 12 episodes of wheeze among SPT-positive children (AOR 1.69 (1.08, 2.64), P=0.02, per category) but not SPT-negative children (AOR 0.77 (0.26, 2.21), P=0.6, per category). Conclusion: The apparent association between synthetic upper bedding and adverse respiratory outcomes was evident among SPT-positive but not SPT- negative children. Prospective intervention studies that aim to examine the effect of upper bedding composition on child asthma among SPT-positive children are required. A.-L. Ponsonby, 1,2 . P. Gatenby, 3 . N. Glasgow, 3 . R. Mullins, 4 . M. Hurwitz, 3 . T. McDonald 5 . 1 National Center for Epidemiology and Population Health, Australian National University, 2 Menzies Center for Population Health Research, University of Tasmania, 3 Canberra Clinical School, University of Sydney, 4 Department of Science and Design, University of Canberra, 5 Department of Paediatrics, Monash Medical Center, Monash University, Australia Key words: aeroallergen, sensitization, childhood, asthma, house dust mite, bedding. Dr A.-L. Ponsonby National Center for Epidemiology and Population Health Innovations Building Eggleston Road Australian National University ACT 0200 Australia Accepted for publication 18 October 2001 An adverse role for synthetic bedding on asthma in childhood has been suggested by recent studies. Several cross-sectional studies have now reported nonfeather pillows or synthetic bedding to be associated with an increased wheeze in childhood (1–6. ). A London study found that the increasing use of nonfeather pillows from 1978 to 1991 was estimated to explain more than half the prevalence increase in current childhood wheeze (7. ). In addition, two cross-sectional studies have reported a positive association between nonfeather pillows or synthetic bedding and rhinitis (8,9. ). The association between synthetic bedding and adverse respiratory symptoms may, to some extent, reflect that in recent decades patients with asthma and perennial rhinitis have previously been advised to replace feather bedding with ‘hypo-allergenic’ syn- thetic-filled bedding. However, reviews on this issue reveal that the evidence base for such advice is not strong (10–12. ). To reduce the likelihood of this selection bias, several of the studies have also restricted the analysis only to those subjects who did not report changing their bedding owing to respiratory symptoms or adjusted for reported allergen avoidance (1–3,8,9. ). Despite this, the positive association between non- feather or synthetic bedding and wheeze or rhinitis remained evident. Higher allergen levels within syn- thetic bedding may explain the association between synthetic upper bedding and adverse respiratory out- comes. Synthetic pillows have higher levels of house dust mite (HDM) (13–15. ), cat and dog allergens (16. ) than feather pillows. Higher HDM mattress levels have also been associated with synthetic pillows (17. ). We postulated that if the adverse respiratory effect of synthetic bedding was owing to a higher allergen load, then the adverse effect of synthetic bedding would be more evident among children who were sensitized to aeroallergens rather than nonsensitized children. We investigated this issue by examining how the association Allergy 2002: 57: 247–253 Printed in UK. All rights reserved Copyright # Blackwell Munksgaard 2002 ALLERGY ISSN 0105-4538 247