Objective: To compare the indications for hospital admission between current, former, and never smokers and to compare their costs per hospital admission, testing the hypothesis that the cost per hospital admission would be higher for smokers than for former and never smokers. Patients and Methods: This study used a retrospective nested cohort design, with cohort membership determined by cigarette smoking status (current, former, or never). Propensity score–matching techniques were used to control for differences between groups other than smoking status. Participants were admitted to Mayo Clinic Hospital, Rochester, Minnesota, between May 5, 2012, and August 10, 2014, and lived in the areas covered by postal codes included in Olmsted County, Minnesota. Results: Compared with never smokers, a significantly higher proportion of admissions in current smokers were for diseases of the respiratory system, diseases of the circulatory system, infectious and parasitic diseases, mental illness, and injury or poisoning (P<.001 for all). The average cost per admission (without regard to admission indication) did not depend on smoking status. Accounting for dependence of admission indication on smoking status, there were no significant differences in costs between current and never smokers ($199 less per admission for current smokers; 95% CI −$820 to $423; P=.53) but costs in current smokers were actually significantly less than costs in former smokers (by −$870 per admission; 95% CI, −$1665 to −$76; P=.03). Conclusion: There is no evidence that the cost of hospital admission is higher in current smokers than in never or former smokers, even when controlling for admission indication, in a general population of medical and surgical patients. Trial Registration: clinicaltrials.gov Identifier: NCT01575145.
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