Studies of OTC NRT versus OTC placebo
| Study | Product | n | Cigs/day | Visits | Follow up (months) | Outcome | Biochemical variation |
|---|---|---|---|---|---|---|---|
| Davidson et al28 | Patch | 802 | ⩾20 | 10 | 6 | Repeated point prevalence | Yes |
| Hays et al31 | Patch | 643 | ⩾15 | 8 | 6 | Continuous abstinence | No |
| Shiffman et al27 | Patch | 567 | >0 | 3 | 2.5 | Prolonged abstinence | Yes |
| Sonderskov et al30 | Patch | 278 | ⩾20 | 3 | 6 | Repeated point prevalence | No |