High mortality in people with severe mental illness (SMI) such as schizophrenia has been clearly shown in many studies.^1,2 Patients with SMI have a life expectancy that is 15–20 years shorter than that of the general population.³ This reduced life expectancy in people with SMI contrasts with the recent trend of increased longevity in the general population. As a result, there is a substantial mortality gap between people with mental illness and the general population.⁴

A recent systematic review and meta-analysis further confirmed that patients with schizophrenia have much higher mortality than the general population. In this study, patients with schizophrenia had a mortality risk ratio of 2.94 when compared to the general population.² Additionally, the mortality risk of patients with schizophrenia was still significant when compared with controls who had other medical conditions. Most studies in this systematic review and meta-analysis were mainly from high-income countries. However, similar findings have been reported in low- and middle-income countries (LMICs). In a 5-year outpatient follow-up study of a cohort of patients with schizophrenia in a rural setting in Ethiopia by Teferra et al., the overall standard mortality ratio (SMR) was 5.98.⁵ Contrary to this finding, Khamker et al. did not find a significant SMR in patients who were hospitalised in a psychiatric hospital in South Africa from 2001 to 2005.⁶ Khamker et al. hypothesised that this unusual finding – mortality in people with SMI not being significantly higher than the general population – was because of the acquired immunodeficiency syndrome (AIDS) pandemic that caused excess mortality in the general population of South Africa.

In South Africa’s Gauteng province, palliative psychiatric care is provided in hospital settings known as long-term care facilities (LTCFs). This care is in addition to community-based mental health services that include community residential care provided by non-governmental organisations (NGOs). Robertson and Makgoba conducted a mortality analysis on a group of patients in Johannesburg who were rapidly discharged from LTCFs to community-based NGOs that were ill-equipped to care for patients with SMI.⁷ In their analysis, they found that 9% of patients had died between March 2016 and April 2017, with an overall age-adjusted death rate of 63/1000 population. The overall SMR in this study population was 4.9.

The SMR is an important epidemiological metric used to assess the relative increase or decrease in mortality within a study cohort compared to the general population. It is typically represented as a ratio or percentage, where an SMR of 1.0 indicates equality between observed and expected deaths. Standard mortality ratios exceeding 1.0 indicate a higher mortality rate than expected in the study group, while values below 1.0 suggest fewer deaths than anticipated.^8,9 The SMR is a useful measure of mortality because it considers how demographic factors, environmental factors, socioeconomic status, healthcare access and specific diseases can impact mortality within a population.¹⁰ Standard mortality ratios in people with SMI have increased significantly during the 1970s, 1980s and 1990s, from 1.84 to 2.98 to 3.20, respectively, compared to the general population and further confirms the increased mortality in people with SMI.^11,12

The causes of mortality in SMI include non-natural causes such as suicide and injuries as well as natural causes such as cardiovascular and related causes, diabetes mellitus, infectious diseases and lifestyle-related causes. In a 12-year cross-sectional study conducted in Ontario, Canada, cardiovascular-related diseases (CVDs) were the main cause of death in patients with psychotic disorders followed by neoplastic, metabolic and respiratory causes.¹³ A 24-year retrospective registry study conducted in Sweden revealed that individuals with schizophrenia had a threefold higher mortality rate from CVDs compared to the general population.¹⁴

Lifestyle factors are directly linked to cardiovascular complications that are found in patients with SMI. People with schizophrenia have reduced physical activity, increased smoking and make poor dietary choices which all increase the risk of cardiovascular diseases as well as the risk of neoplasms.^11,15,16

While there is rich literature on mortality in people with SMI from high income countries, there is a notable paucity in research with regards to the mortality rate in patients with SMI in LMICs such as South Africa. The existing South African literature has focussed on mortality among people living with SMI in hospital setting as well as the findings by Robertson and Makgoba in NGOs.⁷ To our knowledge, there has not been a mortality analysis in patients with SMI admitted in a LTCF. The objective of this study was to determine the annual mortality rate and overall mortality rate in psychiatric patients admitted at Solomon Stix Morewa Memorial Hospital (SSMMH), a LTCF in Johannesburg, South Africa, during the period from 01 March 2017 to 28 February 2022. Additionally, the study described the socio-demographic profile, the psychiatric data and other medical data of all the patients who were admitted at SSMMH during this study period.

The overall mortality rate in this study was 8%, with a SMR of 1.28 (95% CI = 0.85–1.71). This indicates significantly high mortality among individuals with SMI at SSMMH compared to the general population, consistent with the broader literature.^7,12,20 Of significance is that this SMR was lower than that found by Robertson and Makgoba in a similar cohort of patients but in a different setting (community-based NGOs vs. LTCF).⁷ The mortality analysis by Robertson and Makgoba was done in a setting that was characterised by poor quality of care.²¹ It can therefore be inferred that patients with SMI need to be cared for in an appropriate setting as they present with complicated psychiatric disorders and medical comorbidities. Interestingly, the SMR of 1.28 observed in this study was also lower than those reported in other local and global studies, which have ranged from 2.58 to 5.98.^6,22 Possible explanations for the relatively lower SMR include the comprehensive care model at SSMMH, with full-time physicians collaborating closely with psychiatrists and dedicated nursing staff to ensure prompt medical treatment and medication adherence. Additionally, the high utilisation of anti-psychotic medications, including clozapine, which has been associated with a 30% – 50% reduced mortality risk compared to non-use, may have contributed to the lower mortality observed in this cohort.²³

High mortality rates were seen in the older age group of 60–69 years (SMR 2.7) and among the female participants. Other studies have reported similar findings in terms of the SMR in this age group.^2,24,25,26 While mortality is expected to increase with ageing, it is noteworthy that the mortality in older people with SMI is higher than in the general population. Severe mental illness is associated with accelerated ageing because of multiple factors such as inflammation, lifestyle factors, genetic factors and there is also evidence of accelerated brain ageing.²⁷

The high mortality rate among females is in keeping with the findings from the study conducted by Robertson and Makgoba with a SMR of 3.9 for men and 6.3 for women. Contrary to this finding, other studies have however reported a higher mortality rate among males.^5,28 In a study conducted by Nhiwatiwa et al. on the occurrence of hyponatraemia in patients with SMI at SSMMH, a similar cohort to the current study, it was found that 52.1% of the females had hyponatraemia at least once during the admission, while only 26.3% of the males had hyponatraemia at least once in their admission.²⁹ It is likely that there are specific factors that increased vulnerability of females to mortality in this cohort of patients, and hyponatraemia could be one of those factors.

While annual SMR could not be calculated in this study, there was high crude mortality rate in the years 2020 (3%) and 2021 (5%) compared to the years 2018, 2019 and 2022, with 2019 having no recorded death at SSMMH. Most deaths occurred in the years 2020 and 2021 (82%) at SSMMH. This increased mortality in these 2 years is likely because of COVID-19 pandemic which had its highest impact in terms of mortality in the years 2020 to 2021 in South Africa.^30,31 It worth noting that this increase in mortality at SSMMH in 2020 and 2021 did bring SMR at SSMMH to the high levels that have been reported in literature which is further evidence that the increased mortality at SSMMH in these years was accompanied by excess deaths in the general population.

Similar to other studies, key contributors to mortality in this cohort included advanced age, a diagnosis of schizophrenia and the presence of medical comorbidities such as hypertension or type 2 diabetes.^2,3,14,32 People with schizophrenia have increased mortality and have a life expectancy 15–20 years shorter than the general population.^12,33,34,35 Proposed factors that are associated with the increased mortality in schizophrenia include the high rates of suicide, homicide and other unnatural causes, as well as the impact of cognitive decline and substance use on vulnerability and healthcare access.^33,36 There is an approximately 10% lifetime risk of suicide in people with schizophrenia.³⁷

However, suicide as a cause of death was not reported in this study.

The study findings revealed a strong association between medical comorbidities and mortality rates. Approximately 66% of participants presented with comorbid medical conditions, predominantly hypertension (38%) and type 2 diabetes (18%). Notably, every deceased participant had at least one medical comorbidity, most commonly hypertension (35%) and diabetes (18%). This pattern of increased prevalence of cardiometabolic conditions among individuals with mental illness has been consistently observed across various studies.³⁴ The elevated rates of hypertension and diabetes in schizophrenia can be attributed to a multitude of factors, including sedentary lifestyles, poor dietary habits, substance use and the metabolic side effects of anti-psychotic medications.³⁴ A local South African study conducted in KwaZulu-Natal further corroborated these findings, showing that one-fifth of patients with SMI on anti-psychotics met the criteria for metabolic syndrome, with a higher prevalence among women and the elderly.³⁸

Compounding this burden, individuals with mental illness often receive sub-optimal medical care because of stigma, a lack of healthcare education and limited access to services, leading to inadequate management of cardiometabolic conditions and associated complications.^39,40,41 These complex factors contribute to the high prevalence of medical comorbidities and their adverse impact on mortality in this vulnerable population.

Cardiovascular-related conditions were the leading cause of death, accounting for over half (53%) of the mortalities (see Table 5).This finding is in keeping with the existing literature, which identifies cardiovascular diseases as the primary driver of mortality in individuals with schizophrenia.⁴² Other studies have reported that among individuals with SMI, preventable physical illnesses, particularly cardiovascular diseases, respiratory conditions and infections, account for most fatalities.^43,44 In a study by de Barros et al., respiratory-related conditions were the second leading cause of death, responsible for 35% of the mortalities, potentially exacerbated by factors such as overcrowded psychiatric wards, poor hygiene and high smoking rates among this population.⁴⁵

This study confirms that people with SMI have increased mortality rates. Various factors, such as older age, female gender, specific psychiatric diagnoses and the existence of medical comorbidities, exhibit positive correlations with an elevated risk of mortality within this population. From this study, it can be hypothesised that placement in a LTCF offers some protective factors than being in a poorly resourced NGO.