The impact of cigarette smoking on life expectancy in schizophrenia, schizoaffective disorder and bipolar affective disorder: An electronic case register cohort study

Severe mental disorders are associated with a life expectancy that is 10–20 years shorter than the general population's. The prevalence of cigarette smoking in these populations is very high. We examined the effect of smoking on life expectancy and survival in patients with a diagnosis of schizophrenia, schizoaffective disorder or bipolar affective disorder from 2007 to 2018 in South East London, UK. Smoking status was determined using unstructured text data extracted from electronic health records. A total of 21,588 patients were identified of which 16,717, (77.4%) were classified as current smokers and 3438 (15.9%) as non-smokers. In female participants, life expectancy at birth was 67.6 years in current smokers (95% CI: 66.4–68.8) and 74.9 years in non-smokers (95% CI: 72.8–77.0), a difference of 7.3 years. In male participants, life expectancy at birth was 63.5 years in current smokers (95% CI: 62.5–64.5) and 68.5 years in non-smokers (95% CI, 64.4–72.6), a difference of 5.0 years. Adjusted survival models found that current smoking status was associated with an increased mortality risk for both females (aHR: 1.42, 95% CI: 1.21–1.66, p < 0.001) and males (aHR: 1.49; 95% CI: 1.25–1.79, p < 0.001). In terms of the effect sizes, these risks were similar to those associated with a diagnosis of co-morbid alcohol or opioid use disorder. Smoking may account for a substantial proportion of the reduced life expectancy in patients with psychotic disorders. Increased emphasis on reducing cigarette smoking in these populations may be the most effective way to reduce the mortality gap with the general population.