Comparison of reported prevalences of recent asthma in longitudinal and cross-sectional studies

A potential source of bias in prevalence rates reported for symptoms and diagnoses of asthma in longitudinal studies could arise if repeated questioning of subjects or previous experience of lung function and airway responsiveness tests increased awareness of respiratory symptoms. We wished to determine the extent of any such bias by comparing reported prevalence rates from a longitudinal and cross-sectional study within similar populations. The prevalences of wheezing in the last year, waking with chest tightness, waking with shortness of breath, waking with coughing, having an attack of asthma in the last year, and current use of medications for asthma were determined using identical questions in two populations. Self-completed questionnaire responses of 946 subjects, 21 yrs of age, participating in the seventh respiratory assessment in the longitudinal Dunedin Multidisciplinary Health and Development Research Study were compared with responses provided by 991 subjects, aged 20-22 yrs, completing a postal questionnaire on one occasion only for the New Zealand section of the European Community Respiratory Health Study. The prevalence rates were not significantly different between the two populations, for all of the reported symptoms and for medication use. Differences in responses between genders were similar in each study, with all responses being more common in females. We conclude that repeated questioning regarding respiratory symptoms and repeated lung function and bronchial challenge testing in a longitudinal study of asthma did not bias prevalence rates compared with those obtained in a similar population of the same age studied on only one occasion.

This article has been cited by other articles:

				M. R Partridge Has ISAAC told us as much as it can? Where now? Thorax, June 1, 2009; 64(6): 462 - 463. [Full Text] [PDF]

				S R Dalziel, H H Rea, N K Walker, V Parag, C Mantell, A Rodgers, and J E Harding Long term effects of antenatal betamethasone on lung function: 30 year follow up of a randomised controlled trial Thorax, August 1, 2006; 61(8): 678 - 683. [Abstract] [Full Text] [PDF]

				C. Janson, R. de Marco, S. Accordini, E. Almar, M. Bugiani, A. Carolei, L. Cazzoletti, I. Cerveri, A. Corsico, E. Duran-Tauleria, et al. Changes in the use of anti-asthmatic medication in an international cohort Eur. Respir. J., December 1, 2005; 26(6): 1047 - 1055. [Abstract] [Full Text] [PDF]

				M. R. Sears, J. M. Greene, A. R. Willan, E. M. Wiecek, D. R. Taylor, E. M. Flannery, J. O. Cowan, G. P. Herbison, P. A. Silva, and R. Poulton A Longitudinal, Population-Based, Cohort Study of Childhood Asthma Followed to Adulthood N. Engl. J. Med., October 9, 2003; 349(15): 1414 - 1422. [Abstract] [Full Text] [PDF]

				D. Gautrin, A.J. Newman-Taylor, H. Nordman, and J-L. Malo Controversies in epidemiology of occupational asthma Eur. Respir. J., September 1, 2003; 22(3): 551 - 559. [Abstract] [Full Text] [PDF]

				C. Cole Johnson, D. R. Ownby, E. M. Zoratti, S. Hensley Alford, L. K. Williams, and C. L. M. Joseph Environmental Epidemiology of Pediatric Asthma and Allergy Epidemiol. Rev., December 1, 2002; 24(2): 154 - 175. [Full Text] [PDF]

				E. Rönmark, E. Jönsson, T. Platts-Mills, and B. Lundbäck Incidence and Remission of Asthma in Schoolchildren: Report From the Obstructive Lung Disease in Northern Sweden Studies Pediatrics, March 1, 2001; 107(3): 37e - 37. [Abstract] [Full Text]