The Global Initiative for Asthma (GINA) report has proposed a classification schema for asthma severity. This can help in formulating the management plan for the individual patient.
(1) intermittent vs persistent
(2) if persistent: mild, moderate or severe
Nighttime Asthma Symptoms
PEF or FEV1
< 1 time per week
brief (from a few hours to a few days); asymptomatic between exacerbations
< 2 times per month
>= 80% of predicted; variability < 20%
>= 1 time per week but < 1 time per day
may affect activity and sleep
> 2 times per month
>= 80% of predicted; variability 20-30%
daily; daily use of inhaled short-acting beta-2 agonist
affect activity and sleep
> 1 time per week
> 60% to < 80% of predicted; variability > 30%
continuous; physical activities limited
<= 60% of predicted; variability > 30%
• PEF = peak expiratory flow
• No single test or measurement can accurately classify the level of asthma severity.
• Criteria for defining disease severity are based on symptoms and changes in pulmonary function before initiation of any therapy.
• With exacerbations the severity of disease can change abruptly and dramatically.
Equations for Predicting PEF from Nunn (1989)
Peak expiratory flow for men:
LN(PEF in L/min) =
= (0.544 * LN(age in years)) - (0.0151 * (age in years)) - (74.7 / (height in cm)) + 5.48
Peak expiratory flow for women:
= (0.376 * LN(age in years)) - (0.0120 * (age in years)) - (58.8 / (height in cm)) + 5.63
Equations for FEV(1) from Crapo (1981)
predicted FEV(1) in liters for males =
= ((0.0414 * (height in cm)) + ((-0.0244) * (age in years)) - 2.190
predicted FEV(1) in liters females =
= ((0.0342 * (height in cm)) + ((-0.0255) * (age in years)) - 1.578
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Purpose: To use the level of asthmatic symptoms to separate patients into different severity classes.
Objective: severity, prognosis, stage