The increasing recalcitrance of smokers in clinical trials II: Pharmacotherapy trials.

Irvin and Brandon (Nicotine & Tobacco Research, 2, 79-84, 2000) reported a significant decline in reported abstinence rates between 1977 and 1996 from clinical trials of cognitive-behavioral smoking cessation treatments based on coping skills training. The present study extends that approach to the analysis of pharmacotherapy trials. A literature search identified 59 studies, published between 1983 and 2000 and conducted in the U.S., that reported post-cessation abstinence rates after treatment with nicotine gum, nicotine patch or any type of placebo medication. Across all three types of treatment conditions and four post-cessation assessment points, negative correlations between publication year and abstinence rates were found. The strongest pattern of negative correlations was found for the placebo conditions. However, the correlations for placebo conditions could be accounted for by the simultaneous shift toward treatments offered in individual rather than group format. No other methodological or subject variable appeared to mediate the declining outcomes. Findings are discussed with respect to the theory that the population of remaining smokers is becoming progressively more dependent and difficult to treat.