Validation of asthma and eczema in population-based Swedish drug and patient registers

Pharmacoepidemiol Drug Saf. 2013 Aug;22(8):850-60. doi: 10.1002/pds.3465. Epub 2013 Jun 11.


Purpose: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Keywords: allergic diseases; asthma outcome research; asthma pharmacology; disease proxy; nationwide; pharmacoepidemiology; prescription prevalence.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Anti-Asthmatic Agents / therapeutic use*
  • Asthma / diagnosis
  • Asthma / drug therapy
  • Asthma / epidemiology*
  • Bronchitis / diagnosis
  • Bronchitis / drug therapy
  • Bronchitis / epidemiology
  • Child
  • Child, Preschool
  • Dermatologic Agents / therapeutic use*
  • Eczema / diagnosis
  • Eczema / drug therapy
  • Eczema / epidemiology*
  • Female
  • Humans
  • Infant
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Registries / statistics & numerical data
  • Sweden / epidemiology
  • Young Adult


  • Anti-Asthmatic Agents
  • Dermatologic Agents