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Table of Contents
Year : 2019  |  Volume : 33  |  Issue : 3  |  Page : 160-163

Avoidable mortality among long-stay patients with schizophrenia under different smoking-restriction settings

1 Department of Psychiatry, Taipei Veterans General Hospital, Yuli Branch, Yuli, Taiwan
2 Department of Public Health, Tzu Chi University, Hualien, Taiwan

Date of Submission16-May-2019
Date of Decision04-Jul-2019
Date of Acceptance04-Jul-2019
Date of Web Publication30-Sep-2019

Correspondence Address:
Kan- Yuan Cheng
No. 91, Xing-Xing Street, Yuli Township, Hualien County 981
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/TPSY.TPSY_31_19

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Objective: Patients with schizophrenia are at a greater risk of avoidable death. Although smoking is a modifiable factor to reduce the mortality gap, the rate of quitting smoking in these inpatients is still lower than that in the general population. We examined avoidable mortality among long-stay patients with schizophrenia under different smoking-restriction environments. Methods: A total of 1998 male and 459 female patients with schizophrenia who was admitted to Taipei Veterans General Hospital, Yuli Branch, in Taiwan, received follow-ups for 11 years to be estimated for the standardized mortality ratios (SMRs) of avoidable causes of death. During that period, all the male patients had stayed in smoking-allowed wards, but all the female patients had not. Results: The mean ± standard deviation age of the patients was 57.8 ± 17.0 years. Of the 993 decedents in total, 411 died of avoidable causes (41.4%). Compared with the general population, male patients had significantly higher mortality due to avoidable causes (SMR = 1.96, 95% confidence interval [CI] = 1.77–2.16, p < 0.05) and in terms of indicators of medical care (SMR = 2.41, 95% CI = 2.17–2.67, p < 0.05); however, the female patients did not (SMR = 1.22, 95% CI = 0.67–2.05; SMR = 1.57, 95% CI = 0.86–2.64, respectively). Conclusion: Male patients had higher mortality gaps due to avoidable causes and in terms of indicators of medical care. But female patients who all had stayed in tobacco-free settings did not. Environmental smoking restriction might be related to the diminished avoidable mortality gaps in patients with schizophrenia.

Keywords: cause of death, death rate, premature death, tobacco

How to cite this article:
Cheng KY, Chen SY. Avoidable mortality among long-stay patients with schizophrenia under different smoking-restriction settings. Taiwan J Psychiatry 2019;33:160-3

How to cite this URL:
Cheng KY, Chen SY. Avoidable mortality among long-stay patients with schizophrenia under different smoking-restriction settings. Taiwan J Psychiatry [serial online] 2019 [cited 2023 Mar 22];33:160-3. Available from: http://www.e-tjp.org/text.asp?2019/33/3/160/268319

  Introduction Top

Patients with schizophrenia are at higher risk of both natural and unnatural death than people in the general population [1],[2]. Possible explanations for the increased natural mortality among patients with schizophrenia include a greater prevalence of unhealthy lifestyles [3], vulnerability of physical comorbidities [4], and potential adverse effects of antipsychotic drugs [5]. In addition, patients with schizophrenia are also at greater risk of both suicide and accidents, leading to unnatural death [1],[6].

By analyzing the mechanisms in single cause of deaths, several infections, systemic diseases, and accidents can be prevented by suitable medical care, or warning signals can be detected earlier during the implementation of national policy [7]. Dying of such causes is considered an avoidable death in a modern health-care system. Measurement of mortality due to avoidable causes can offer information to improve the quality of medical care or the practice of national policies to reduce premature death in a specific subpopulation [7]. Unfortunately, several studies have reported that schizophrenic patients living in institutions have had a higher avoidable death rate than those in the general population in recent decades [8],[9]. Therefore, various interventions, such as injection of vaccines to prevent several infections [10], prescribing newly developed medications to improve medical care [11], checking metabolic profiles regularly for earlier detection of problems [12], and establishing a healthier lifestyle [13], are recommended to reduce the excessive mortality in patients with schizophrenia. As a large proportion of premature deaths are related to tobacco use, and smoking cessation is often suggested as a lifestyle modification for those patients [1],[13].

Since 2009, schizophrenic patients in Taiwan have been given the opportunity to stop smoking in hospitals because smoking is forbidden in public areas under Taiwan's Tobacco Hazards Prevention Act. All psychiatric wards for female patients in Taipei Veterans General Hospital, Yuli Branch (VGH-YL), have been smoke free since their initial establishment before 2009, while in contrast, male schizophrenic patients in VGH-YL could smoke during hospitalization until 2009 because all long-stay facilities have allowed smoking for male patients since their initial setup. Although tobacco use is associated with increased mortality, the quitting rates for smokers with mental illnesses are lower than those in the general population [14]. Therefore, the long-term effects of banning smoking among schizophrenic patients are worthy of evaluation. In this study, we intended to investigate the avoidable mortality gaps between long-stay patients with schizophrenia and those in the general population under two different smoking-restriction settings.

  Methods Top

Study sample

A total of 2,457 patients with admission diagnoses of schizophrenia who had been hospitalized for at least one year prior to December 31, 1997, was recruited through identification from the digital inpatient registration database at VGH-YL in Taiwan [15]. All eligible patients were retrospectively followed up from January 1, 1998 to December 31, 2008. Patients who left the hospital during the study period were withdrawn from the study. The above study protocol was approved by the institutional review board of Taipei VGH-YL with approval number of 99-08-02A on August 4, 2010. No need of obtaining signed informed consents from the study participants was also permitted in the IRB approval.

Categorization of causes of death

We linked the data to the National Death Certification System in Taiwan with identification numbers of all the recruited patients to identify decedents and their causes of death. As a proportion of cases in which patients with schizophrenia commit suicide or suffer accidents can be considered preventable [1], we classified the causes of death into avoidable, unavoidable, and unnatural categories initially. Furthermore, “avoidable causes of death” were categorized into those related to medical care and those related to national policy indicators based on the European Community Working Group list [8],[9]. Medical care indicators included causes of death amenable to treatment by qualified medical practitioners, for example, antibiotic treatment, screening and early detection of cases, medications for metabolic syndrome, or surgery. Causes of death related to national health policy indicators can be prevented by implementing national health policies or public health interventions. In the International Classification of Diseases, Nine revision (ICD-9), categorization system, the category of “unnatural causes of death” includes suicide, injuries, and accidents (ICD-9: E950-E959, E980-E989). The third category, “unavoidable causes of death,” consists of all causes of death except for avoidable or unnatural causes of death.

Statistical analysis

The Chi-square test was used for categorical variables. Standardized mortality ratios (SMRs) were calculated as the ratio of the number of observed deaths in this study cohort to the number of deaths expected in the general population of Taiwan. We estimated 95% confidence intervals (95% CIs) of SMRs following a Poisson distribution.

All the study data were calculated using the Statistical Package for Social Science software version 15.0 for Windows (SPSS Inc., Chicago, Illinois, USA). The differences between groups were considered significant if p < 0.05.

  Results Top

[Table 1] summarizes the number of deaths due to avoidable causes by the two indicators in this study population. The mean ± standard deviation age of the study participants was 57.8 ± 17.0 years. A total of 1998 patients was male (81.3%). Most of the study participants had at least a two-year hospitalization period in the initial follow-up (the 25th percentile = 1.98 years) [15]. The most common avoidable cause of death was respiratory disease, except for asthma (n = 229, 60.6%), followed by tuberculosis (n = 50, 13.3%) and stroke (n = 33, 8.7%), in indicators of medical care quality [Table 1]. Liver cirrhosis (n = 18, 54.5%) was the most prevalent disease with regard to indicators of national health policy.
Table 1: Distribution of avoidable causes of death in the 2,457 long-stay patients with schizophrenia in Yuli Veterans Hospital in Taiwan

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The mortality gaps with regard to avoidable, unavoidable, and unnatural causes of death are shown in [Table 2]. Deaths due to avoidable causes covered 42.5% of the male patients and 23.7% of the female patients. As compared with the general population in Taiwan, the whole study population had higher death rates due to avoidable (SMR = 1.92, 95% CI = 1.74–2.12), unavoidable (SMR = 2.44, 95% CI = 2.24–2.65), and unnatural causes (SMR = 1.99, 95% CI = 1.48–2.62). Male patients had a significantly elevated risk of avoidable death (SMR = 1.96, 95% CI = 1.77–2.16, p < 0.05), but female patients did not (SMR = 1.22, 95% CI = 0.67–2.05, nonsignificant difference). Both male and female patients had significantly higher unavoidable death rates than the general population (SMR = 2.42, 95% CI = 2.21–2.65, p < 0.05; SMR = 2.69, 95% CI = 1.91–3.64, p < 0.05, respectively). But female patients had a much larger mortality gap due to unnatural causes than male patients (SMR = 4.81, 95% CI = 2.20–9.14, p < 0.05; SMR = 1.77, 95% CI = 1.27–2.65, p < 0.05, respectively).
Table 2: Gaps in mortality from avoidable and unavoidable causes of death between the 2,457 long-stay patients with schizophrenia in Yuli Veterans Hospital and the general population in Taiwan

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  Discussion Top

According to our results, we found that long-stay patients with schizophrenia in Taiwan had a risk of death due to avoidable causes almost twofold higher than that of the general population [Table 1]. An excess mortality due to avoidable causes has also been reported in a Finnish study and a Swedish study, both conducted on long-stay psychiatric patients using the same list of avoidable causes of death without age limits [8],[9]. The Finnish study by Räsänen et al. has revealed higher avoidable mortality for both male patients (SMR = 1.88) and female patients (SMR = 3.24) [8]. Those investigators proposed that the female Finnish psychiatric patients have been more vulnerable to the long-term effects of smoking [8]. Meanwhile, respiratory malignancy or diseases comprised two-thirds of the deaths which have been reported due to avoidable causes among female patients in the Finnish study [8]. But respiratory diseases only affected 50% of our female patients, and none of them died of stroke, hypertensive disease, asthma, or malignant neoplasm of the trachea, bronchus, or lung [Table 1]. Those results supported that the smaller mortality gap existed due to avoidable causes in the female patients in our study [Table 2] might be related to the improvements in prevention from diseases of the circulatory and respiratory systems and lung cancer.

For medical care indicators, we found that our male patients had an SMR of 2.41 [Table 2], which is similar to the results of the Finnish study (SMR = 2.56) [8]. A death rate gap in medical care indicators for long-stay male patients with schizophrenia has also been reported in the Swedish study (SRR = 4.58) [9]. On the contrary, the female patients in this study did not have any significantly higher avoidable mortality rate in medical care indicators in comparison with the general population (SMR = 1.57, 95% CI = 0.86–2.64, nonsignificant difference). An earlier Taiwanese study reported that 66.7% and 20.5% of male and female inpatients with schizophrenia, respectively, are current smokers [16]. According to an annual report of smoking rates from the Ministry of Health and Welfare, Taiwan, in 2008, in the male and female adult population of Taiwan, the rates have been found to be 38.6% and 4.8%, respectively (www.dep.mohw.gov.tw/DOS/cp-1720-7369-113). The large gap in smoking prevalence between the general population and male inpatients with schizophrenia can explain the higher avoidable mortality gap in medical care indicators demonstrated in our results. Compared with female smokers with schizophrenia, male patients with schizophrenia who smoke have an earlier age of onset, more psychotic symptoms, a poorer response to antipsychotic treatment, and higher antipsychotic dosage requirements [17]. Smoking in male patients can attenuate the health-care burden due to greater physical comorbidity and more severe psychiatric illness [18]. In contrast, tobacco-free settings can reverse the gap in smoking prevalence in female patients, which might diminish the avoidable death risk due to medical care indicators.

Male patients did not have a significantly higher avoidable mortality due to national policy indicators than the general population in this study [Table 2]. There was also no female patient in our study died of these indicators [Table 1]. An Australian study reported that staff who have worked in smoking-restricted units are more likely to assess psychiatric inpatients' smoking status than staffs who have had never worked in a restricted unit with three times [19]. Therefore, a tobacco-free policy can result in better smoking care for persons with mental illnesses in institutions. The other explanation is that the hospital had also followed the national policy in which the physicians arranged annularly chest X-ray examination for all inpatients and serum liver enzymes, serum alpha fetal protein levels, and abdominal ultrasound examination for carriers of hepatitis C or B virus during the investigation period [15].

Our study participants [Table 2] had a higher risk of unnatural death than the general population (P < 0.05). In fact, these unnatural deaths mostly arose from accidents (n = 43, SMR = 2.28, 95% CI = 1.48 - 2.62), not due to suicide (n = 4, SMR = 0.7, 95% CI = 0.19 -1.80), or undetermined external causes (n = 4, SMR = 3.64, 95% CI = 0.99 - 9.32) in our study [Table 2]. More than half of the unnatural deaths were due to suffocation (n = 25, 58.1%). The use of several psychiatric medications, such as thioridazine and lithium, can increase the risk of choking in psychiatric patients [20]. The pattern of fast eating, anxiolytic use, and poor self-care are also associated with the risk of choking in psychiatric patients [21]. Therefore, monitoring eating patterns, improving oral hygiene, and shifting to psychiatric medications with a lower risk of choking may prevent suffocation in these patients.

The increased rates of unavoidable death were found among both the male and female patients in our study [Table 2]. Those findings are similar to results reported in previous studies [8],[9]. Compared with the general population, schizophrenic patients have a poorer self-care ability and worse personal hygiene. A higher pain tolerance [22], poor cognitive function, or active psychotic symptoms in schizophrenic patients can also mask symptoms or signs in physical examination [1]. Those are the obstacles within the health-care system due to the patients' conditions relating to their mental illness.

Study limitations

The readers are warned against overinterpreting the study results because this study has the following two major limitations:

  • To measure the actual smoking exposure is difficult when taking part in outdoor activities in the female patients.
  • We also could not confirm the proportion of male patients who were exposed to smoking or second-hand smoking.


During the 11-year follow-up period, the smaller mortality gap due to avoidable causes in female patients with schizophrenia compared with that in male patients might be related to smoking restriction in the living environment. A restrictive smoking strategy should be considered to decrease complications owing to tobacco use and diminish the avoidable mortality gap in long-stay patients with schizophrenia based on our findings.

  Financial Support and Sponsorship Top

The study funding was from Taipei Veterans General Hospital, Yuli Branch, in Taiwan.

  Conflicts of Interest Top

Both authors declare no conflicts of interests in this article.

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  [Table 1], [Table 2]

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