prerecorded message then inquired whether any house-
hold member was $ 18 years of age and had experi-
enced respiratory symptoms (eg, shortness of breath,
wheezing, increased mucus or sputum, prolonged
cough) within the past 6 months. Households with afﬁr-
mative responses were subsequently contacted by the
local study coordinator for a follow-up call. The house-
hold member reporting respiratory symptoms was
verbally consented and screened for eligibility to partic-
ipate in the study over the telephone.8,9
Exclusion criteria included the following: (1) a history of
diagnosis of lung or airway disease, (2) use of respiratory
inhalers aside from as-needed salbutamol, (3) contrain-
dications for spirometry (eg, occurrences of myocardial
infarction, stroke, aortic or cerebral aneurysm, eye sur-
gery, detached retina within the last 3 months), (4)
inability or refusal to provide informed consent, (5) be-
ing in the third trimester of pregnancy, and (6) being<
18 years of age.
Each participant completed the Asthma Screening Ques-
tionnaire (ASQ)10 via telephone. Individuals aged$ 60
years, and those aged< 60 years who scored< 6 points
on the ASQ, also completed the COPD-Diagnostic
Questionnaire.11,12 Participants scoring $ 6 points on
the ASQ or$ 20 points on the COPD-Diagnostic Ques-
tionnaire were invited to the study site for pre- and post-
bronchodilator (BD) spirometry.
A control group without respiratory symptoms was
selected randomly using identical random digit dialing
methods. Control patients reported no respiratory
symptoms in the preceding 6 months and obtained a
score of 0 on the ASQ. Participants were recruited as
control patients if they could be matched with an indi-
vidual from the undiagnosed group based on age (/C6 5
years) and sex. This matching process aimed to have
similar demographic proﬁles between the control group
and the newly found cases. This matching was imple-
mented solely to ensure demographic comparability
across the study groups and not for pairing patients
for statistical analysis purposes.
All participants ﬁlled out the COPD Assessment Test
(CAT) questionnaire. Elevated CAT scores indicate a
greater burden of respiratory symptoms impacting
daily activities and health status. 13 The St. George ’s
Respiratory Questionnaire (SGRQ) 14-16 was used to
assess respiratory disease-related quality of life. Higher
SGRQ scores indicate poorer health status. Both the
CAT and SGRQ questionnaires were completed prior
to spirometry to avoid inﬂuencing patients’ perceptions
of their dyspnea.
Classiﬁcation of Undiagnosed Cases
Certiﬁed study personnel administered spirometry tests
before and after BD use. Participants showing an in-
crease of at least 12% and 200 mL in their FEV1 after
receiving 400mg of salbutamol were classiﬁed as having
spirometry indicative of asthma.17 Those whose post-BD
ratio of FEV1/FVC fell below the lower 95% conﬁdence
limit (ie, FEV1/FVC < lower limit of normal) were clas-
siﬁed as having spirometry indicative of COPD.18 Partic-
ipants meeting the criteria for both conditions were
labeled as having COPD. Those with a post-BD
FEV1 < 80% of the predicted normal and a post-BD
FEV1/FVC ratio > 0.70 were classi ﬁed as having
spirometry indicative of preserved ratio impaired
spirometry (PRISm). PRISm was de ﬁned based on
post-BD spirometry values for a more speciﬁc classiﬁca-
tion.19 Participants not meeting criteria for asthma,
COPD, or PRISm were labeled as having normal
spirometry.
Assessment of the Impact of Participants’ Dyspnea
Although neither the CAT nor the SGRQ are dyspnea-
speciﬁc tools, both are recommended by the Global Initia-
tive for Chronic Obstructive Lung Disease to evaluate
symptoms, including dyspnea,20 and both yield a richer
assessment of dyspnea than the modi ﬁed Medical
Research Council breathlessness scale.20 Fifteen questions
were taken from the CAT and SGRQ questionnaires that
referred to individuals’ experiences with dyspnea, and a