Before revision: Regional differences A survey conducted by the ISSAC Steering Committee conducted a study from 1992 to 1993 in adults aged 22 to 44 comparing the prevalence of asthma in 10 developed countries.
After revision: Regional differences A survey conducted by the ISSAC Steering Committee was, from 1992 to 1993 in adults aged 22 to 44 comparing the prevalence of asthma in 10 developed countries.