Summary of COPD risk factors operationalised with respect to life period

COPD risk factorCritical life period and age of cohort members when data were collectedCumulative exposure
CategoryIndividual factorIn utero/at birthChildhoodAdulthood
0 years of age7 years of age11 years of age16 years of age23 years of age33 years of age42 years of age
Smoking exposurePassive smoke exposureSmoking status during pregnancy (4 months)Living with a smokerLiving with smoker at any stageCombined passive smoking exposure (in utero, childhood and adulthood) personal smoking in adulthood
Personal smoking statusPersistent smoker ever smoker, and never smoker
SCSC (occupation and classified as: professional/managerial, unskilled nonmanual, skilled manual, unskilled manual)SC of male headSC of male headOwn SCCombined social class at birth, 11 and 42 years (range 0–9), with higher scores indicating lower social class
AsthmaAsthmaReport of ever having asthma or bronchitisEver asthma in adulthoodChildhood and adulthood reporting of asthma
OthersLow birth weightBirth weight <2.5 kg
Preterm birthGestation age <37 weeks
PneumoniaEver had pneumonia
Occupation exposureMinimal or potential occupational exposure to dust, gases and fume
Biomass exposureParaffin or solid fuel as heating source

SC: social class.