Persistent use of nicotine replacement therapy: an analysis of actual purchase patterns in a population based sample
- 1Pinney Associates and University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- 2University of Vermont, Burlington, Vermont, USA
- 3Pinney Associates, Seattle, Washington, USA
- 4GlaxoSmithKline Consumer Healthcare, Pittsburgh, Pennsylvania, USA
- Correspondence to: Saul Shiffman, PhD, Pinney Associates, 201 North Craig Street, Suite 320, Pittsburgh, PA 15213, USA;
- Received 10 October 2002
- Accepted 7 May 2003
Background: In 1996, the US Food and Drug Administration (FDA) approved switching nicotine gum and patch from prescription to over-the-counter (OTC) status. Some expressed concerns that broader availability and lack of physician control might increase persistent use of nicotine replacement therapy (NRT)—that is, use beyond the period specified by the FDA approved label.
Objective: To estimate the incidence of persistent use of OTC nicotine gum and patch for periods of > 3 months, ⩾ 6 months, ⩾ 12 months, and ⩾ 24 months.
Design: Analysis of NRT purchase patterns in data from a population based panel of US households that electronically scanned all household purchases between January 1997 and March 2000.
Subjects: In a national panel of 40 000 US households, 2690 recorded NRT purchases.
Results: Among 805 households that purchased nicotine gum, 2.3% of new purchase incidents led to continuous monthly purchase of gum for ⩾ 6 months. For nicotine patches (2050 households) the percentage was 0.9%. For both gum and patch, the incidence of persistent purchase dropped below 0.4% by 24 months. Allowing one month gaps within a “continuous” purchase run resulted in increased estimates (for gum: 6.7% for ⩾ 6 months and 1.0% for ⩾ 24 months; for patch: 1.7% for ⩾ 6 months and 0.05% for ⩾ 24 months).
Conclusion: Persistent use of nicotine gum and patch is very rare and has not increased with the transition to OTC use, despite removal of physician oversight.
- FDA, Food and Drug Administration
- OTC, over-the-counter
- NHIS, National Household Interview Survey
- NRT, nicotine replacement therapy
↵* This change was not based on clinical data, but on a conservative philosophy to limit the duration of use for the OTC medication, since there was not yet experience with wider access to the medication.
↵† To ensure the stability of our estimates, we examined 1000 different random samplings from these data. Results show gum and patch incidences that are similar to those of the single sample estimates in table 2. Thus, we are assured that the sampling did not introduce bias.
↵‡ The estimated prevalence would be 16.5% if one assumes the 2.3% incidence of persistent use based on the analysis of continuous patterns (table 2, top panel), without allowing one month gaps in purchase. Also, an estimate obtained by simply overlaying the distribution displayed in fig 1, to model the experience of successive cohorts of new nicotine gum users, results in a very similar estimated prevalence of 35.8%. Several factors not taken into account in either estimate may cause the prevalence to be underestimated: the censoring of the use patterns in this analysis, the existence of some gum users who may persist for more than 24 months, and the unknown carryover of persistent users from the prescription NRT era (before OTC sales).