For this analysis we selected from HSD all subjects aged
>14 years of which information was available about the
diagnosis, BMI and smoking habit.
Cases of COPD were identified on the basis of the ICD-9
codes 491, 492, and 496, and those of asthma on the basis
of the ICD-9 code 493. Since the HSD includes univocal
classification for asthma or COPD, we could not analyze
separately patients suffering from both COPD and asthma
(overlap syndrome).
The BMI was calculated according to the formula of weight
in kilograms divided by the square of the height in meters
squared (weight (kg)/[height (m)2
]). It was categorized as
follows: underweight (