Validation of asthma and eczema in population-based Swedish drug and patient registers
Article first published online: 11 JUN 2013
Copyright © 2013 John Wiley & Sons, Ltd.
Pharmacoepidemiology and Drug Safety
Volume 22, Issue 8, pages 850–860, August 2013
How to Cite
Örtqvist, A. K., Lundholm, C., Wettermark, B., Ludvigsson, J. F., Ye, W. and Almqvist, C. (2013), Validation of asthma and eczema in population-based Swedish drug and patient registers. Pharmacoepidem. Drug Safe., 22: 850–860. doi: 10.1002/pds.3465
- Issue published online: 21 JUL 2013
- Article first published online: 11 JUN 2013
- Manuscript Accepted: 29 APR 2013
- Manuscript Revised: 2 APR 2013
- Manuscript Received: 7 DEC 2012
- allergic diseases;
- asthma outcome research;
- asthma pharmacology;
- disease proxy;
- prescription prevalence;
Validated measures of asthma and eczema at the population level remain a challenge. Our aim was to ascertain if register-based information on asthma/eczema medication can function as a proxy for an asthma/eczema diagnosis and to validate register-based asthma diagnoses.
Information was requested on all 0–45-year-old individuals with reported asthma/eczema medication and/or diagnoses in the Swedish Prescribed Drug Register and National Patient Register, between July 2005 and December 2009 (N = 250 691). Medical records for 1952 randomly selected individuals were reviewed to estimate the proportion of individuals with the following: (1) asthma/eczema medication that fulfilled predefined criteria of asthma/eczema (positive predictive value (PPV)) and (2) a register-based asthma diagnosis verified as asthma by predefined criteria.
Positive predictive value for asthma by predefined criteria ranged between 0.75 (95%CI: 0.70–0.78) to 0.94 (95%CI: 0.91–0.96), depending on age group. In pre-school children, PPV for asthma in combination with obstructive bronchitis was 0.87 (95%CI: 0.83–0.90), and PPV for eczema was estimated to 0.45 (95%CI: 0.38–0.51). Eighty percent of children 0–4.5 years and 99% of children >4.5–17 years with a register-based diagnosis of asthma were verified as asthmatics.
Asthma medication is a suitable proxy for asthma in older children and adults; the same approach is insufficient for eczema. This validation study of two Swedish registers opens for future large nation-wide register-based studies on asthma. Copyright © 2013 John Wiley & Sons, Ltd.