From: Development of an algorithm for determining smoking status and behaviour over the life course from UK electronic primary care records
WHS
Totals
GP
Missing data
smoker
Ex-smoker
Never smoker
<5
100
124
203
423
Smoker
10
985
194
20
1209
25
133
1323
143
1624
32
83
540
2916
3571
72
1301
2181
3282
6836