Does clinical trial subject selection restrict the ability to generalize use and cost of health services to "real life" subjects?

Int J Technol Assess Health Care. 2003 Winter;19(1):8-16. doi: 10.1017/s0266462303000023.


Objectives: To explore one aspect of the external validity of the randomized controlled trial (RCT), specifically how being selected for inclusion in a trial and having participated has influenced the use and cost of asthma-related health services.

Methods: Services used by asthmatic users of inhaled corticosteroids (iCSTs) having previously participated in an RCT (TS, n = 46) were compared with individuals who had never participated (NS, n = 51).

Results: TS were more likely to use higher (> or = 400 microg) daily doses of iCSTs than NS (OR, 3.3; 95% Cl, 1.1-8.3) but less likely to visit emergency departments (OR, 0.3; 95% Cl, 0.1-0.7). Total asthma-related costs did not differ significantly.

Conclusions: Subject differences may impede generalizing from RCTs to real life.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenal Cortex Hormones / administration & dosage
  • Adrenal Cortex Hormones / economics
  • Adult
  • Aged
  • Asthma / drug therapy*
  • Asthma / economics
  • Bronchodilator Agents / administration & dosage
  • Bronchodilator Agents / economics
  • Canada
  • Cost-Benefit Analysis
  • Drug Evaluation / economics
  • Female
  • Health Care Costs
  • Health Services / economics
  • Health Services / statistics & numerical data*
  • Health Services Research
  • Humans
  • Male
  • Middle Aged
  • Nebulizers and Vaporizers
  • Patient Selection*
  • Randomized Controlled Trials as Topic*


  • Adrenal Cortex Hormones
  • Bronchodilator Agents