Aims: To compare the measurements of asthma control using Canadian Thoracic Society (CTS) Asthma Management Consensus Summary and Global Initiative for Asthma (GINA) guidelines composite indices with and without spirometry.
Methods: Asthma control parameters were extracted from electronic medical records (EMRs) of patients ≥6 years old at two primary care sites. Asthma control ratings calculated according to CTS and GINA criteria were compared.
Results: Data were available from 113 visits by 93 patients, aged 6-85 years (38.7 ± 24.8; mean ± SD). The proportion of visits at which individuals' asthma was completely controlled was 22.1% for CTS symptoms only and 9.7% for CTS with spirometry (p < .01); and 17.7% versus 14.1% for GINA symptoms only versus symptoms with spirometry (p = .125).
Conclusions: Asthma control ratings using GINA and CTS criteria are discordant in more than half of the patients deemed "in control" by at least one scale. Differences in the spirometry criterion threshold are primarily responsible for this discordance. Failure to include spirometry as part of the control index consistently overestimates asthma control and may underestimate future risk of exacerbations.