Stats >> Training >> Stats #36: Practice Exercises

1. Review the following abstract. What corroborating evidence can you find in the abstract itself? Is there a plausible scientific mechanism that would explain how various aspects of the domestic environment might cause snoring problems?

Snoring In Primary School Children and Domestic Environment: A Perth School Based Study. Zhang G, Spickett J, Rumchev K, Lee AH, Stick S. Respir Res 2004: 5(1); 19. [Medline] [Abstract] [Full text] [PDF]

Background: The home is the predominant environment for exposure to many environmental irritants such as air pollutants and allergens. Exposure to common indoor irritants including volatile organic compounds, formaldehyde and nitrogen dioxide, may increase the risk of snoring for children. The aim of this study was to investigate domestic environmental factors associated with snoring in children. Methods: A school-based respiratory survey was administered during March and April of 2002. Nine hundred and ninety six children from four primary schools within the Perth metropolitan area were recruited for the study. A sub-group of 88 children aged 4–6 years were further selected from this sample for domestic air pollutant assessment. Results: The prevalences of infrequent snoring and habitual snoring in primary school children were 24.9% and 15.2% respectively. Passive smoking was found to be a significant risk factor for habitual snoring (odds ratio (OR) = 1.77; 95% confidence interval (CI): 1.20–2.61), while having pets at home appeared to be protective against habitual snoring (OR = 0.58; 95% CI: 0.37–0.92). Domestic pollutant assessments showed that the prevalence of snoring was significantly associated with exposure to nitrogen dioxide during winter. Relative to the low exposure category (<30 μg/m3), the adjusted ORs of snoring by children with medium (30 – 60 μg/m3) and high exposures (> 60 μg/m3) to NO2 were 2.5 (95% CI: 0.7–8.7) and 4.5 (95% CI: 1.4–14.3) respectively. The corresponding linear dose-response trend was also significant (P = 0.011). Conclusion: Snoring is common in primary school children. Domestic environments may play a significant role in the increased prevalence of snoring. Exposure to nitrogen dioxide in domestic environment is associated with snoring in children.

2. The following is the list of competing interests that David Sackett lists at the British Medical Journal.

Competing interests: David Sackett has been wined, dined, supported, transported, and paid to speak by countless pharmaceutical firms for over 40 years, beginning with two research fellowships and interest-free loans that allowed him to stay to finish medical school. Dozens of his randomised trials have been supported in part (but never in whole) by pharmaceutical firms, who have never received or analysed primary data and never had power of veto over any reports, presentations, or publications of the results. He has twice worked as a paid consultant to advise pharmaceutical firms whether their products caused lethal side effects; on both occasions he told them "yes." He has testified as an unpaid expert witness for a patient who sued a manufacturer of oral contraceptives after having a stroke and as a paid expert in preparing a class action suit against a manufacturer of prosthetic heart valves. He was paid by a pharmaceutical firm to develop "levels of evidence" for determining the causation of adverse drug reactions. His wife inherited and sold stock in a pharmaceutical company. While head of a division of medicine he enforced the banning of drug detail personnel from clinical teaching units (despite the threat of withdrawal of drug industry funding for residents' research projects). He received the Pharmaceutical Manufacturers' Association of Canada Medal of Honour (and cash) for "contributions to medical science in Canada" for the decade 1984-94. His most recent award (the 2001 Senior Investigator Award of the Canadian Society of Internal Medicine) was sponsored by Merck Frosst Canada. Posted at bmj.bmjjournals.com/cgi/content/full/324/7336/539/DC1 

Which of these interests might be relevant in the editorial he coauthored?