Table.

Characteristics of study population and main findings

Characteristic	No of patients
Original study population	138
Moved away three years later	19
Available for study	119
Returned questionnaires	95
Available for spirometry and skin prick testing	85
Able to undergo methacholine challenge with no contraindication	74
Main results from questionnaire
Wheezing or whistling in chest at any time in past 12 months:	38/95
Breathless when wheezing or whistling noise was present	19/38
Wheezing or whistling present in absence of a cold	17/38
Phlegm brought up from chest during day, at night, or in winter:	22/95
Similar phlegm most days for up to 3 months each year	20/22
Diagnosis of asthma by doctor	11/95
Wheezing and positive methacholine test	7/74