PURPOSE: BACKGROUND: The correlation of commonly used clinical measures of asthma severity with PEFR remains unaddressed.
OBJECTIVE: To determine the association of selected clinical measures of asthma severity with percent predicted PEFR (%PEFR).
METHODS: We studied a prospective cohort of adults (N =102 ) with severe asthma exacerbations (according to GINA guidelines) at ED of a referral centre in India. Clinical data was acquired, including medical and social history, symptoms, vital signs, physical assessment, and spirometry. Predictor variables for this study included baseline manually determined amplitude of paradoxical pulse (PP), oxygen saturation (SpO2 %), respiratory rate (RR) accessory muscle use and Borg Dyspnoea Score (BDS). The outcome measure was %PEFR. Multiple linear regression analyses were performed to determine the associations between predictor variables and %PEFR. A multi-variable analysis was done thereafter to see if the associations remained significant even after adjusting for co-variates.
RESULTS: PEFR was obtainable successfully in 91 out of 102 patients. (90%). In univariate analysis, Sp02% correlated with %PEFR (r = 0.66, P < .001) while, RR (r= 0.56.p=0.006) and BDS correlated negatively with %PEFR (r = - 0.36, P < .04). PP was poorly correlated (r= 0.21, P=0.25). %PEFR was significantly lower in participants with accessory muscle use(25.8 + 7.3) than in those without accessory muscle use (36.4+ 10.2)(P <.0001). In multivariable analysis including the covariates accessory muscle use, PP, age, sex, heart rate, RR and BDS, %SpO2 (P < .0001), RR (p=0.01) and accessory muscle use (P = .002) remained significantly associated with %PEFR, whereas PP (p = .30) and BDS (p= 0.06) did not.
CONCLUSION: Easily measurable (accessory muscle use, RR) and objective (SpO2 %) indices correlate better with pulmonary function than difficult to measure (PP) and patient subjective dyspnoea. (BDS) indices.
CLINICAL IMPLICATIONS: Though PEFR is recommended for assessing severity of asthma.exacerbations, it is not always obtainable. Easily measurable (accessory muscle use, respiratory rate) and objective clinical variables (SpO2%) correlate better with pulmonary function and can be used to form accurate multi-variable clinical indices for predicting severity of asthma exacerbations.
DISCLOSURE: Anupam Singh, No Financial Disclosure Information; No Product/Research Disclosure Information