The purpose of this study is to provide an updated systematic review to identify studies describing the prevalence of psychosis in order to explore methodological factors that could account for the variation in prevalence estimates. Studies with original data related to the prevalence of psychosis (published between 1990 and 2015) were identified via searching electronic databases and reviewing manual citations. Prevalence estimates were sorted according to prevalence type (point, 12-months and lifetime). The independent association between key methodological variables and the mean effect of prevalence was examined (prevalence type, case-finding setting, method of confirming diagnosis, international classification of diseases, diagnosis category, and study quality) by meta-analytical techniques and random-effects meta-regression. Seventy-three primary studies were included, providing a total of 101 estimates of prevalence rates of psychosis. Across these studies, the pooled median point and 12-month prevalence for persons was 3.89 and 4.03 per 1000 respectively; and the median lifetime prevalence was 7.49 per 1000. The result of the random-effects meta-regression analysis revealed a significant effect for the prevalence type, with higher rates of lifetime prevalence than 12-month prevalence (p<0.001). Studies conducted in the general population presented higher prevalence rates than those carried out in populations attended in health/social services (p = 0.006). Compared to the diagnosis of schizophrenia only, prevalence rates were higher in the probable psychotic disorder (p = 0.022) and non-affective psychosis (p = 0.009). Finally, a higher study quality is associated with a lower estimated prevalence of psychotic disorders (p<0.001). This systematic review provides a comprehensive comparison of methodologies used in studies of the prevalence of psychosis, which can provide insightful information for future epidemiological studies in adopting the most relevant methodological approach.

Background: There is evidence that the prevalence of common mental disorders varies across Europe.Aims: To compare prevalence of common mental disorders in general practice attendees in six European countries.Method: Unselected attendees to general practices in the UK, Spain, Portugal, Slovenia, Estonia and The Netherlands were assessed for major depression, panic syndrome and other anxiety syndrome. Prevalence of DSM–IV major depression, other anxiety syndrome and panic syndrome was compared between the UK and other countries after taking account of differences in demographic factors and practice consultation rates.Results: Prevalence was estimated in 2344 men and 4865 women. The highest prevalence for all disorders occurred in the UK and Spain, and lowest in Slovenia and The Netherlands. Men aged 30–50 and women aged 18–30 had the highest prevalence of major depression; men aged 40–60 had the highest prevalence of anxiety, and men and women aged 40–50 had the highest prevalence of panic syndrome. Demographic factors accounted for the variance between the UK and Spain but otherwise had little impact on the significance of observed country differences.Conclusions: These results add to the evidence for real differences between European countries in prevalence of psychological disorders and show that the burden of care on general practitioners varies markedly between countries.

Reducing the prevalence of depression is a public health challenge for the 21st century. Depression occurs in up to a quarter of general practice attendees,¹ relapse 10 years from first presentation is frequent,² and both residual disability and premature mortality are common.³ Low socioeconomic status^4,5 and female sex⁶ are the 2 most consistently identified risk factors. Socioeconomic risk factors include low income and financial strain,⁴ unemployment,⁴ work stress,⁷ social isolation,⁸ and poor housing.⁵ Other factors, such as family history of depression, play a part.⁹ Additional risk factors identified in adult general practice populations are negative life events, poor physical health, poor marital or other interpersonal relationships, a partner or spouse's poor health, and problems with alcohol.¹⁰ Poor social support, loneliness, and physical disability appear to be particular risks for older adults.^11-13 Estimating overall risk across a range of likely risk factors is essential in efforts to prevent depression. However, effective strategies for prevention are hindered by lack of evidence about the combined effect of known risk factors. Our objectives were to develop a risk algorithm for the onset of major depression in European general practice attendees and test its predictive power in a non-European setting. We modeled our approach on risk indexes for cardiovascular disease,¹⁴ which provide a percentage risk estimate over a given period.

Background: Considering existing knowledge on the relationship between certain environmental factors and incidence rates of psychosis, we carried out a systematic review to provide a broad and updated picture of the incidences of different psychotic disorder subgroups worldwide and how some environmental factors influence these rates.Methods: Studies with original data related to the incidence of psychosis (published between 2000 and 2015) were identified via searching electronic databases (CINAHL, MEDLINE, PSYCINFO, PUBMED, and SCOPUS). Data on the following risk factors were extracted: gender, urbanicity, immigration and socio-economic level. Descriptive appraisals of variation in incidence rates (IR) and incidence rate ratios (IRR), with a 95% confidence interval were calculated. In addition, a meta-analysis was performed to calculate IR pooled by diagnosis group and IRR pooled by diagnosis and gender, urbanity, immigration and socio-economic level, using a random effects model.Results: We identified 33 reports to analyse. Overall IR per 100 000 persons for non-affective psychoses (IR pooled = 22.53 (16.51–28.54)) were higher than affective psychoses (IR pooled = 7.12 (5.03–9.22)). There was an increase in rates of psychosis in menv.women (IRR pooled = 1.54 (1.37–1.72)), in urbanv.rural areas (IRR pooled = 1.64 (1.38–1.95)), in immigrantsv.natives (IRR pooled = 3.09 (2.74–3.49)), and in lower socio-economic level areas (IRR pooled = 1.78 (1.43–2.22)).Conclusions: IR among different psychotic disorders was found to vary depending on gender, urbanicity, and immigration (as most of the previous literature focuses on non-affective psychosis or schizophrenia).