Cigarette Smoking and Life Expectancy in Schizophrenia

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RESEARCH UPDATE

CASE VIGNETTE

“Ms Patterson” was a 57-year-old Caucasian female with a history of chronic schizophrenia since her 20s. Her psychotic disorder has been stable on ziprasidone, with no psychiatric hospitalizations in the past 10 years. She smoked 2+ packs of cigarettes per day over 30 years.At age 49, Ms Patterson was hospitalized due to a ruptured cerebral aneurysm. Thereafter, she quit smoking for about 3 months, but then returned to smoking 2 packs per day. She also had comorbid hypertension and chronic obstructive pulmonary disease. After seeing the same psychiatrist for 11 years, Ms Patterson moved to another state to live with 1 of her adult children. Approximately 1 year later, she returned to her previous residence. Prior to her outpatient appointment with her long-time psychiatrist, she died at the age of 57 from another cerebrovascular event.

Severe mental illness (SMI)—including schizophrenia, schizoaffective disorder, and bipolar disorder—is associated with decreased life expectancy.¹ An increased prevalence of cigarette smoking is a likely contributor to this burden of premature mortality. More than half of patients with schizophrenia and more than a third of patients with bipolar disorder are cigarette smokers.^2,3 Smokers in the general population have a 7- to 10-year shorter life expectancy than non-smokers.⁴ No previous studies have investigated the effect of smoking on life expectancy in patients with mental disorders, which would inform on the potential impact of smoking cessation interventions.

The Current Study

Accordingly, Chesney and colleagues⁵ investigated the life expectancy at birth according to smoking status in patients with schizophrenia, schizoaffective disorder, and bipolar disorder.The authors obtained data from a large electronic secondary mental health care database: the South London and Maudsley NHS Foundation Trust Biomedical Research Centre Case Register, which contained anonymized data on more than 400,000 patients.⁶

The study population included all patients with an SMI diagnosis (ICD-10 schizophrenia, schizoaffective disorder, and bipolar disorder) between January 2007 and December 2018, reached age 15 before the end of the observation period in 2018, and had information on smoking status. Deaths were identified using the NHS Care Records Service, which records every death in the United Kingdom. Smoking status was classified into current smokers, past smokers, and non-smokers (based on the most frequently recorded smoking status). Past smokers (n=470) and patients with unclear smoking status (n=963) were excluded. Life expectancy at birth based on smoking status was calculated using Chiang’s method of abridged life tables.⁷ Cox regression models were used to estimate mortality hazard ratios (HR), controlling for multiple potential confounding factors.

The authors identified 20,155 patients for inclusion in the cohort (83% current smokers and 17% non-smokers). In females, life expectancy was 67.6 years in current smokers and 74.9 years in non-smokers (a difference of 7.3 years), corresponding to an adjusted HR of 1.42. In males, life expectancy was 63.5 years in current smokers and 68.5 years in non-smokers (a difference of 5.0 years), corresponding to an adjusted HR of 1.49.

Study Conclusions

The authors concluded that in patients with SMI, the gap in life expectancy between current smokers and non-smokers was 7 years in females and 5 years in males. Based on life expectancy in the United Kingdom general population in 2012,⁸ the life expectancy gap for females was 15.1 years for current smokers and 7.8 years for non-smokers. The life expectancy gap for males was 15.2 years for current smokers and 10.2 years for non-smokers. Thus, smoking accounts for about half of the life expectancy gap in women and one-third of the gap in men. The mortality risks associated with smoking were similar to comorbid alcohol and opioid use disorders. Study strengths included the large sample size, use of clinical registry data, and consideration of multiple potential confounding factors.

The Bottom Line

Smoking is associated with decreased life expectancy in patients with SMI. Given the high prevalence in patients with SMI, smoking makes a substantial contribution to premature mortality. Therefore, comprehensive implementation of effective smoking cessation interventions could have a substantial impact on improving life expectancy in this patient population.

Dr Miller is professor in the Department of Psychiatry and Health Behavior, Augusta University, Augusta, Georgia. He is on the Editorial Board and serves as the schizophrenia section chief for Psychiatric Times^TM. The author reports that he receives research support from Augusta University, the National Institute of Mental Health, and the Stanley Medical Research Institute.

References

1. Chesney E, Goodwin GM, Fazel S. Risks of all-cause and suicide mortality in mental disorders: a meta-review. World Psychiatry. 2014;13(2):153-160.

2. Mitchell AJ, Vancampfort D, Sweers K, et al. Prevalence of metabolic syndrome and metabolic abnormalities in schizophrenia and related disorders-a systematic review and meta-analysis. Schizophr Bull. 2013;39(2):306-318.

3. Royal College of Physicians, Royal College of Psychiatrists. Smoking and mental health. RCP. March 28, 2013. Accessed November 5, 2021. https://www.rcplondon.ac.uk/projects/outputs/smoking-and-mental-health

4. Sakata R, McGale P, Grant EJ, et al. Impact of smoking on mortality and life expectancy in Japanese smokers: a prospective cohort study. BMJ. 2012;345:e7093.

5. Chesney E, Robson D, Patel R, et al. The impact of cigarette smoking on life expectancy in schizophrenia, schizoaffective disorder and bipolar affective disorder: an electronic case register cohort study. Schizophr Res. 2021;238:29-35.

6. Perera G, Broadbent M, Callard F, et al. Cohort profile of the South London and Maudsley NHS Foundation Trust biomedical research Centre (SLaM BRC) case register: current status and recent enhancement of an electronic mental health record-derived data resource. BMJ Open. 2016;6(3):e008721.

7. Chiang CL. The Life Table and Its Applications. Krieger Publishing; 1984.

8. Office for National Statistics. Life expectancy at birth and at age 65 by local areas, UK. December 11, 2019. Accessed November 5, 2021. https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/healthandlifeexpectancies/datasets/lifeexpectancyatbirthandatage65bylocalareasuk