Where used:
| Attribute | CIGARETTES PER DAY | references in description NUMBER OF YEARS SMOKED |
| Class | TOBACCO USAGE | has attribute NUMBER OF YEARS SMOKED |
| Data Element | ESTIMATED PACK YEARS | references in description NUMBER OF YEARS SMOKED |
| Attribute | CIGARETTES PER DAY | references in description NUMBER OF YEARS SMOKED |
| Class | TOBACCO USAGE | has attribute NUMBER OF YEARS SMOKED |
| Data Element | ESTIMATED PACK YEARS | references in description NUMBER OF YEARS SMOKED |