Effects of Smoking Status on Remission and Metabolic and Cognitive Outcomes in Schizophrenia Patients Treated with Clozapine.

Background: Even though clozapine is the recommended last-resort antipsychotic, many patients fail to respond and show treatment-refractory psychotic symptoms. Smoking has been suggested as a possible risk factor for poor clozapine response, hampering remission and negatively impacting somatic outcomes.
Methods: Our aim was to test whether smoking status is associated with remission rates and other symptomatic and somatic outcomes. We therefore assessed remission rates according to The Remission in Schizophrenia Working Group (RSWG) criteria, and metabolic and cognitive outcomes among patients with schizophrenia-spectrum disorders treated with clozapine for at least 6 months. For analyses, we grouped our cohort into 3 groups according to clozapine treatment duration (6 months, 2 years, 5 years).
Results: One hundred five patients were included in our analyses and grouped according to their clozapine treatment duration. In the 6-months analyses, patients who smoked were significantly more likely to be younger of age (p=0.002) despite on average shorter duration of clozapine treatment (p=0.041) and significantly more likely to be treated with mood-stabilizing co-medication (p=0.030) compared to nonsmokers. Remission rates (p=0.490), as well as a set of metabolic and cognitive variables did not differ between the 2 groups. A related pattern could be observed for the 2- and 5-years analyses.
Conclusions: Smoking behavior among clozapine-treated schizophrenia patients might delineate a cohort with an earlier onset of the disease. Nevertheless, most findings comparing disease-specific and clinical outcomes among smokers and nonsmokers were negative. Further research is needed to identify strategies to overcome insufficient remission rates in this patient group.
Competing Interests: E. Wagner reports no conflicts of interest. T. Oviedo-Salcedo reports no conflict of interest. I. Maurus reports no conflict of interest. N. Pelzer reports no conflict of interest. W. Strube received speakership reimbursement by Mag and More. S. Gutwinski reports no conflict of interest. S. Schreiter reports no conflict of interest. P. Kleymann reports no conflict of interest. C.L. Morgenroth reports no conflict of interest. C. Okhuijsen-Pfeifer reports no conflicts of interest. J. Luykx reports no conflict of interest. P. Falkai was honorary speaker for Janssen-Cilag, Astra-Zeneca, Eli Lilly, Bristol Myers-Squibb, Lundbeck, Pfizer, Bayer Vital, SmithKline Beecham, Wyeth, and Essex. During the last 5 years he was a member of the advisory boards of Janssen-Cilag, AstraZeneca, Eli Lilly, and Lundbeck. Presently, he is a member of the advisory boards of Richter Pharma, Abbot, and Otsuka, T. Schneider-Axmann reports no conflict of interest. A. Hasan has been invited to scientific meetings by Lundbeck, Janssen-Cilag, and Pfizer, and he received paid speakerships from Desitin, Janssen-Cilag, Otsuka, and Lundbeck. He was a member of Roche, Otsuka, Lundbeck, and Janssen-Cilag advisory boards.
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