Abstract:
This study aimed to identify socio-demographic, anthropometric, lifestyle and medical factors associated with adult lung function. Cross-sectional analysis was carried out in a sample of 5245 individuals aged 50-84 years participating in a randomized clinical trial, the ViDA study, investigating the role of vitamin D to prevent cardio-vascular diseases and respiratory infections. The highest measurements of FEV1 and FVC from three spirometric manoeuvres were included in the analysis. Simple generalized linear model were used to identify significant factors associated with adult lung function. Sub-group analysis was also carried out on participants with acceptable spirometry to assess the validity of the findings from total sample. FEV1 decreased by 30.5 ml and FVC by 32 ml per annual increase in age after sex, height and ethnic adjustment. Females had an approximately 400 ml lower FEV1 and 520 ml lower FVC in comparison to age, ethnic and height matched males. Unit increase in height in centimetre was associated with 34 ml increase in FEV1 and 48 ml increase in FVC. Low BMI (<20 kg/m2) and high BMI (>=30 kg/m2) both were associated with lower lung function in comparison to normal BMI. Maori, Pacific and Asian ethnicities had lower lung volumes compared to European ethnicity. Moderate drinking (15-30 drinks per month) was associated with significantly higher FEV1 compared to never drinkers. Vigorous exercise and stairs climbing were associated with significantly higher lung function. History of diagnosed asthma, COPD, diabetes, heart failure and hypertension were associated with a significantly low lung function. Current hypertension (>140/90 mm of Hg) was not associated with lung function but anti-hypertensive medication was associated with low lung function. Participants who reported symptoms of wheezing, and phlegm production had lower lung function in comparison to those who did not. Participants who reported their health status to be in excellent and good condition had an average of 185 ml and 132 ml higher FEV1, respectively, compared to who rated their health to be in poor condition. Hence, socio-demographic, anthropometric, life style and medical factors associated with adult lung function were identified. Self-reported respiratory symptoms were found to be strongly associated with lung function in this adult sample. Subjective health was also significantly associated with lung function. Further longitudinal studies with representative samples are warranted to establish temporality and explore risk factors such as bio-chemical, psychological, environmental and others.