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

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.

RCT Entities:   Population Interventions Outcomes