Validation of an Index for Functionally Important Respiratory Symptoms among Adults in the Nationally Representative Population Assessment of Tobacco and Health Study, 2014–2016

Abstract

The purpose of this study is to validate the seven-item wheezing module from the International Study of Asthma and Allergies in Children (ISAAC) in the nationally representative Population Assessment of Tobacco and Health Study. Adult participants with complete Wave 2–3 data were selected, including those with asthma but excluding those with COPD and other respiratory diseases (n = 16,295). We created a nine-point respiratory symptom index from the ISAAC questions, assessed the reliability of the index, and examined associations with self-reported asthma diagnosis. Threshold values were assessed for association with functional outcomes. The weighted prevalence for one or more respiratory symptom was 18.0% (SE = 0.5) for adults without asthma, 70.1% (SE = 1.3) for those with lifetime asthma, 75.7% (SE = 3.7) for adults with past-year asthma not on medications, and 92.6% (SE = 1.6) for those on medications. Cronbach’s alpha for the respiratory symptom index was 0.86. Index scores of ≥2 or ≥3 yielded functionally important respiratory symptom prevalence of 7–10%, adequate sensitivity and specificity for identifying asthma, and consistent independent associations with all functional outcomes and tobacco use variables. Respiratory symptom index scores of ≥2 or ≥3 are indicative of functionally important respiratory symptoms and could be used to assess the relationship between tobacco use and respiratory health.

Tobacco Use and Respiratory Symptoms Among Adults: Findings From the Longitudinal Population Assessment of Tobacco and Health (PATH) Study 2014–2016

“…25 The full validation of this measure is published elsewhere. 26 Because the validation supported cutoff values of of ≥2 and ≥3, we examined both as a test of the sensitivity of the findings to respiratory symptom severity.…”

Youth E-Cigarette Use and Functionally Important Respiratory Symptoms: The Population Assessment of Tobacco and Health (PATH) Study Waves 3 and 4

“…The module includes 7 questions which have been widely used in adolescent populations globally. An index of functionally important respiratory symptoms (hereafter referred to as the “respiratory symptom index”) has been generated through the validation of the 7 items in a PATH adult cohort (with no respiratory disease such as chronic obstructive pulmonary disease (COPD)) [ 12 ].…”

“…Following prior research that created and validated the respiratory symptom index [ 12 ], we calculated the index based on 7 questions (“Have you ever had wheezing or whistling in the chest at any time in the past? [Yes/No]”; “Have you had wheezing or whistling in the chest in the past 12 months?…”

“…An index score of <2 was defined as having no functionally important respiratory symptoms, and an index of ≥2 as having functionally important respiratory symptoms. The cut-off value was recommended in the prior study of a PATH adult cohort that concluded the threshold values of ≥2 and ≥3 were associated with functional pulmonary impairment [ 12 ]. We chose the more sensitive cut point (≥2) in an effort to capture more subtle functional changes present in youth who are likely to have less cumulative exposure than adult users [ 15 ].…”

“…An index of functionally important respiratory symptoms (hereafter referred to as the “respiratory symptom index”) has been generated through the validation of the seven-question International Study of Asthma and Allergies in Children (ISAAC) wheezing module from items in a PATH adult cohort [ 10 , 11 , 12 ]. The index has been recommended as a respiratory outcome for studies (both cross-sectional and longitudinal) assessing the effects of tobacco use on respiratory health.…”