Do eosinophil counts correlate differently with asthma severity by symptoms versus peak flow rate?

Discrepancy in asthmatic assessment by symptoms and peak flow rate (PFR) is a frequent dilemma. Currently, total peripheral eosinophil count (TPEC) is under study for asthma evaluation.

To explore the correlation between TPEC and asthma severity assessed by symptoms alone versus symptoms and PFR.

Adults asthmatics were selected from the Asthma Clinic. Severity assessment was based on two methods: symptoms alone or symptoms and PFR. Expiratory PFR was recorded by a Wright peak flow meter. Severity levels included mild intermittent, mild persistent, moderate persistent, and severe persistent. Total peripheral eosinophil count was performed on a Celldyn-3500 counter. Data was analyzed for statistical significance.

Sixty asthmatics aged 15 to 70 years (mean = 34 years), of which 68.3% were female, were studied. Severity levels differed between the two assessment methods in 45% of the cases and showed a predominance of the moderate persistent type. Total peripheral eosinophil count ranged between 22 and 2470 cells/mm3 (mean = 520 +/- SD = 393) and eosinophilia was found in 50% of the cases. Total peripheral eosinophil count showed a high positive correlation with increased asthma severity level assessed by history alone (r = 0.460, P < .001); more than by history and PFR (r = 0.328, P < .05).

The discrepancy between symptoms and PFR is confirmed by these results. A reliable objective parameter in asthma assessment is a continuous challenge. This study advocates the possible supplementation of TPEC as another objective parameter that might help in selecting the appropriate severity level in asthmatics.