Our companion article discusses concerns from various quarters about the way insurers handle mental health risks and some of the underwriting practicalities. What sort of magnitude of risk does mental illness present? We offer a handful of observations drawn from dozens of journal articles in our research library.

There is plenty of evidence that, generally, mortality is elevated in mental illness. That it should be so in the more severe forms such as schizophrenia and bipolar disorder should be no surprise, but it is interesting to note that even milder conditions may present an extra risk.

For example, in a meta-analysis1 of ten large UK prospective cohort studies comprising over 68,000 people (over 8,000 of whom died) followed for a mean of 8.2 years, the authors found a positive relationship between ‘psychological distress’ and all-cause mortality. Degree of distress was derived from scoring of answers to the General Health Questionnaire, a 12-question psychometric screening tool for identifying minor psychiatric disorders in the general population.

For low scores of 1-3 there was an age-and sex-adjusted hazard ratio (HR) of 1.20; for scores 4-6 the HR was 1.43; and for high scores of 7-12 it was 1.94. A similar relationship was found for cardiovascular disease deaths and deaths from external causes. Only in the high-score group was there an excess of cancer deaths.

While studies consistently demonstrate excess mortality there is no great consistency in the degree of elevation, superficially at least. Joukamaa and colleagues2 found risk ratios in Finnish schizophrenic men and women of 3.3 and 2.3 respectively. Harris and Barraclough3, on the other hand, in a meta-analysis noted an all-cause standardised mortality ratio (SMR) of only 157% in schizophrenic patients (compared with 136% for major depression and 202% for bipolar disorder).

Numerous studies have found that excess mortality in mental disorders is caused by natural as well as unnatural causes, as suggested above. For example, in the investigation by Joukamaa et al the relative risk of respiratory death was increased both in men and women – although the cardiovascular mortality risk was increased only in men with neurotic depression.

Mental illness appears to influence the prognosis of somatic conditions. Milano and Singer4 reported on a study of over 10,000 individuals with or without depression and diabetes. They found that, compared with individuals with neither depression nor diabetes, the excess death rate (EDR) in those with depression and diabetes exceeded the sum of the EDRs of the groups with depression alone and diabetes alone.

Ethnicity may influence general health in individuals with mental illness. In an investigation by Das-Munshi et al5 in the UK, among subjects with unipolar depression adjusted HRs for all-cause mortality in ethnic minority groups relative to the White British group were 0.62 for Black Caribbean individuals, 0.53 for Black Africans and 0.69 for South Asians.

In a similar investigation, also conducted by Das-Munshi and colleagues6, although SMRs were broadly similar in different ethnic groups with severe mental illness, the south Asian group had a reduced SMR for cancer mortality (49%). Within the cohort with severe mental illness, hazard ratios for all-cause mortality and sub-hazard ratios for natural-cause and unnatural-cause mortality were lower in most ethnic minority groups relative to the White British group

It may be debatable whether chronic fatigue syndrome is a mental illness but a 2016 Lancet article7 was co-authored by several senior psychiatric physicians who reported a follow-up of 2,147 patients (of whom 17 died) over a seven-year period. There was no significant difference in age-standardised and sex-standardised mortality ratios for all-cause mortality (SMR 114%) or cancer-specific mortality (139%) when compared with the general population in England and Wales. This remained the case when deaths from suicide were removed from the analysis. However, there was a significant increase in suicide-specific mortality.

While journal articles such as those referred to are helpful, underwriting cannot consist of applying a rating merely determined by the diagnosis, and what most studies lack is the granularity of data that would reveal the effect of severity, number of episodes, response to treatment, environmental factors, etc. While they can indicate the overall level of risk – albeit with a fair amount of variation between them, perhaps driven by cultural factors, diagnostic criteria and study entry criteria – stratification of risk within a group ascribed a particular diagnosis remains educated guesswork (and requiring underwriters to use much more judgment than is necessary for many other impairments).

And level of risk is determined by factors not immediately associated with psychiatric illness, such as somatic conditions; might lifestyle factors such as smoking and alcohol contribute to the excess of natural deaths? Ethnicity appears to be a factor too, although anti-discrimination laws may prevent the use of such information. But there are lessons here for underwriting disability policies (mental illness is likely to be just one cause of excess claims) and critical illness (in particular the increased incidence of cardiovascular disease and cancer).

  1. Russ TC et al. Association between psychological distress and mortality: individual participant pooled analysis of ten prospective cohort studies. Brit Med J 2012;345:e4933
  2. Joukamaa M et al. Mental disorders and cause-specific mortality. Brit J Psychiat 2001;179:498-502
  3. Harris et al. Excess mortality of mental disorder. Brit J Psychiat 1998;173:11-53
  4. Milano AF, Singer RB. Mortality in co-morbidity (II) – excess death rates derived from a follow-up study on 10,025 subjects divided into four groups with or without depression and diabetes mellitus. J Ins Med 2007;39:160-66
  5. Das-Munshi et al. Depression and cause-specific mortality in an ethnically diverse cohort from the UK: 8-year prospective study. Psychol Med. 2018 Sep 5:1-13
  6. Das-Munshi et al. Ethnicity and excess mortality in severe mental illness: a cohort study. Lancet Psych 2017;4(5):389-99
  7. Roberts E et al. Mortality of people with chronic fatigue syndrome: a retrospective cohort study in England and Wales from the South London and Maudsley NHS Foundation Trust Biomedical Research Centre (SLaM BRC) Clinical Record Interactive Search (CRIS) Register. Lancet 2016;387(10028):1638-43