Prevalence represents the overall proportion of individuals in a population who have the disorder of interest. It is different from incidence, which represents only the new cases that have developed over a particular time period. Point prevalence is the proportion of individuals in a population who have the disorder at a given point in time (e.g., at one-month post-trauma), while period prevalence is the proportion of individuals in a population who have the disorder over specific time periods (e.g., one to two months post-trauma). Lifetime prevalence is the proportion of individuals in a population who have ever had the disorder and lifetime morbid risk also includes those who had the disorder but who were deceased at the time of the survey.

What is the evidence for worldwide prevalence of PTSD?

Moderate quality evidence finds the lifetime worldwide prevalence of PTSD in the general population is around 3.9%. In people known to have been exposed to trauma, the rate is 5.6%.

The prevalence of delayed-onset PTSD is around 5.6% (diagnosis >6 months post-trauma). People showing a delayed onset were mostly veterans and other professionals with earlier subclinical symptoms.

The point prevalence of PTSD reduces over time from 28.8% at one-month post-trauma to 17% at one-year post-trauma. This trend reverses in people exposed to intentional traumas such as war and assault, rather than people exposed to non-intentional traumas such as accidents and natural disasters, with rates increasing from 11.8% at one-month post-trauma to 23.3% at one-year post-trauma after exposure to intentional traumas.

October 2021

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Prevalence quantifies the proportion of individuals in a population who have a disease during a specific time period, while incidence refers to the number of new cases of disease that develop in a population during a specific time period. In disorders of short duration, incidence and prevalence rates may be similar, however with disorders of long duration such as with bipolar disorder there can be variation between the two. Point prevalence is the proportion of individuals who manifest a disorder at a given point in time, period measures the proportion of individuals who manifest a disorder during a specified period (e.g. one year), lifetime is the proportion of individuals in the population who have ever manifested a disorder who are alive on a given day and lifetime morbid risk also includes those deceased at the time of the assessment.

What is the evidence on worldwide prevalence of bipolar disorder?

Moderate to high quality evidence suggests the lifetime worldwide prevalence of bipolar disorder is around 1%, and the one-year prevalence is around 0.5%. Rates were higher for bipolar I disorder than for bipolar II disorder.

October 2021

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Prevalence quantifies the proportion of individuals in a population who have a disease during a specific time period, while incidence refers to the number of new cases of disease that develop in a population during a specific time period. In disorders of short duration, incidence and prevalence rates may be similar, however with disorders of long duration such as with schizophrenia there can be variation between the two. Point prevalence is the proportion of individuals who manifest a disorder at a given point in time, period measures the proportion of individuals who manifest a disorder during a specified period (e.g. one year), lifetime is the proportion of individuals in the population who have ever manifested a disorder who are alive on a given day and lifetime morbid risk also includes those deceased at the time of the assessment.

What is the worldwide prevalence of schizophrenia?

Moderate to high quality evidence suggests worldwide prevalence for any non-affective psychotic disorder, including schizophrenia, is around 0.40% for one year prevalence and around 0.75% for lifetime prevalence. For schizophrenia specifically, point prevalence is around 0.42%, one year prevalence is around 0.30%, lifetime prevalence is around 0.50%, and lifetime morbid risk prevalence is around 0.72%.

Lifetime prevalence rates were higher in cohort studies than in cross-sectional studies, higher in studies from Europe than in studies from North America, higher in more recent studies than in older studies, and higher in lower quality studies than in higher quality studies. These variances in lifetime prevalence rates were similar for one year prevalence rates, apart from North American studies finding higher one year prevalence rates than European studies.

High quality evidence suggests the worldwide, age-standardised point prevalence in 2016 was 0.28%. This rate was similar in males and females, across regions, and over time (1990 to 2016), although the number of cases increased over time (13 million to 21 million) due to population growth.

April 2022

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