Direct comparison of first-contact <i>versus</i> longitudinal register-based case finding in the same population: early evidence that the incidence of schizophrenia may be three times higher than commonly reported

Hogerzeil, Simon J.; Hemert, Albert M. van; Rosendaal, Frits R.; Süsser, Ezra; Hoek, Hans W.

doi:10.1017/s003329171400083x

Cited by 25 publications

(37 citation statements)

References 38 publications

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“…If the low rates for these migrant groups decreased the overall rate of the reference population, then our IRRs would overestimate the difference between groups. However, the incidence rate that we report for the general population is higher than estimates from other jurisdictions, 38 although consistent with other Canadian estimates 39,40 and with estimates obtained from studies using a longitudinal sampling frame, 41 as was done in the current analysis. This likely does not explain the differences in rates that we observed between groups.…”

Section: Strengths and Limitationssupporting

confidence: 91%

Incidence of psychotic disorders among first-generation immigrants and refugees in Ontario

Anderson

Cheng

Süsser

et al. 2015

CMAJ

117

125

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Background: Evidence suggests that migrant groups have an increased risk of psychotic disorders and that the level of risk varies by country of origin and host country. Canadian evidence is lacking on the incidence of psychotic disorders among migrants. We sought to examine the incidence of schizophrenia and schizoaffective disorders in first-generation immigrants and refugees in the province of Ontario, relative to the general population. Methods:We constructed a retrospective cohort that included people aged 14-40 years residing in Ontario as of Apr. 1, 1999. Population-based administrative data from physician billings and hospital admissions were linked to data from Citizenship and Immigration Canada. We used Poisson regression models to calculate age-and sex-adjusted incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for immigrant and refugee groups over a 10-year period.Results: In our cohort (n = 4 284 694), we found higher rates of psychotic disorders among immigrants from the Caribbean and Bermuda (IRR 1.60, 95% CI 1.29-1.98). Lower rates were found among immigrants from northern Europe (IRR 0.50, 95% CI 0.28-0.91), southern Europe (IRR 0.60, 95% CI 0.41-0.90) and East Asia (IRR 0.56, 95% CI 0.41-0.78). Refugee status was an independent predictor of risk among all migrants (IRR 1.27, 95% CI 1.04-1.56), and higher rates were found specifically for refugees from East Africa (IRR 1.95, 95% CI 1.44-2.65) and South Asia (IRR 1.51, 95% CI 1.08-2.12). Interpretation:The differential pattern of risk across ethnic subgroups in Ontario suggests that psychosocial and cultural factors associated with migration may contribute to the risk of psychotic disorders. Some groups may be more at risk, whereas others are protected. AbstractCMAJ Podcasts: author interview at soundcloud.com/cmajpodcasts/psychotic-disorders See also www.cmaj.ca/lookup

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Section: Strengths and Limitationssupporting

confidence: 91%

Incidence of psychotic disorders among first-generation immigrants and refugees in Ontario

Anderson

Cheng

Süsser

et al. 2015

CMAJ

117

125

View full text Add to dashboard Cite

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“…In our study, case participants were based on contact with mental health services, which may have led to some underestimation of the true incidence of psychiatric disorders within the population, although register-based approaches appear to lead to more complete case ascertainment than first contact designs (Hogerzeil et al, 2014). Nevertheless, if migrants and their children had differential treatment-seeking behaviours compared with Swedish-born individuals, differential ascertainment bias could have affected our results.…”

Section: Strengths and Limitationsmentioning

confidence: 97%

Risk of schizophrenia, schizoaffective, and bipolar disorders by migrant status, region of origin, and age-at-migration: A national cohort study of 1.8 million people

Dykxhoorn¹,

Hollander²,

Magnusson³

et al. 2018

Preprint

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Background: We assessed whether risk of various psychotic disorders and non-psychotic bipolar disorder (including mania) varied by migrant status, region of origin, or age-at-migration, hypothesizing that risk would only be elevated for psychotic disorders. Methods: We established a prospective cohort of 1,796,257 Swedish residents born between 1982-97, followed from their 15th birthday, or immigration to Sweden after age 15, until diagnosis, emigration, death, or end of 2011. Cox proportional hazards models were used to model hazard ratios by migration-related factors, adjusted for covariates. Results: All psychotic disorders were elevated among migrants and their children compared with Swedish-born individuals, including schizophrenia and schizoaffective disorder (adjusted hazard ratio [aHR] - migrants: 2.20, 95%CI: 1.96-2.47; aHR-children: 2.00, 95%CI: 1.79-2.25), affective psychotic disorders (aHR-migrant: 1.42, 95%CI: 1.25-1.63; aHR-children: 1.22 95%CI: 1.07-1.40), and other non-affective psychotic disorders (aHR-migrant: 1.97, 95%CI: 1.81-2.14; aHR-children: 1.68, 95%CI: 1.54-1.83). For all psychotic disorders, risks were generally highest in migrants from Africa (i.e. aHR-schizophrenia: 5.24, 95%CI: 4.26-6.45) and elevated at most ages-of-migration. By contrast, risk of non-psychotic bipolar disorders was lower for migrants (aHR: 0.58, 95%CI: 0.52-0.64) overall, and across all ages-of-migration except infancy (aHR: 1.20; 95%CI: 1.01-1.42), while risk for their children was similar to the Swedish-born population (aHR: 1.00, 95%CI: 0.93-1.08). Conclusions: Increased risk of psychiatric disorders associated with migration and minority status may be specific to psychotic disorders, with exact risk dependent on region of origin.

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“…Different study designs dominated different outcomes: for instance, a large proportion of schizophrenia studies were population registers, potentially contributing to this pooled estimate being higher than the pooled estimate of non-affective disorders (a broader category). Whilst individual studies 30,31 have conducted direct comparisons between different study designs, this is the first systematic review to have investigated such differences. More research is required to fully understand heterogeneity in incidence rates between these types of study.…”

Section: Interpretation Of Findingsmentioning

confidence: 99%

Pre-print full manuscript

Jongsma¹,

Turner²,

Kirkbride³

et al. 2018

Preprint

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BackgroundThe last comprehensive international systematic review of the incidence of psychotic disorders was published in 2004. New epidemiological data, from different settings, now permit a broader understanding of global variation. We synthesized this literature to examine variation by demographic characteristics and study methodology.MethodsWe followed PRISMA guidelines and registered our systematic review on PROSPERO (ID: CRD42018086800). We searched PubMed, Embase, Web of Science, PsychInfo and bibliographies, and directly contacted authors, to obtain citations of original research published between 2002 and 2017 on incidence of non-organic adult-onset psychotic disorder. Quality of yield was assessed. Data were evaluated using univariable random-effects meta-analysis, and meta-regression. ResultsFrom 56,721 records, 177 met inclusion criteria. The pooled incidence of all psychotic disorders was 26.6 (95% confidence interval [CI]:22.0-31.7) per 100,000 person-years. Pooled incidence of non-affective disorders was 18.7 (95%CI:14.8-23.7) per 100,000 person-years, and 4.6 (95%CI:3.1-6.8) for affective psychotic disorders. Heterogeneity was high (I2≥99.0%). Men were at higher risk of all psychotic disorders (incidence rate ratio [IRR]: 1.44, 95%CI:1.27-1.62) and non-affective disorders (IRR:1.60, 95%CI:1.44-1.87), but not of affective psychotic disorders (IRR:0.87, 95%CI:0.75-1.00). Ethnic minorities were also at excess risk of all psychotic disorders (IRR:1.75, 95%CI:1.53-2.00), including non-affective disorders (IRR:1.71, 95%CI:1.40-2.09). Meta-regression revealed that population registers reported higher rates of non-affective disorders (IRR:9.64, 95%CI:2.72-31.82), schizophrenia (IRR:2.51, 95%CI:1.24-5.21) and bipolar disorder (IRR:4.53, 95%CI:2.41-8.51) than first contact study designs. DiscussionThere is marked variation in incidence of psychotic disorders by personal characteristics and place. Some geographical variation could be partially explained by differences in case ascertainment methods.

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Direct comparison of first-contact versus longitudinal register-based case finding in the same population: early evidence that the incidence of schizophrenia may be three times higher than commonly reported

Abstract: The incidence of schizophrenia was three times higher in a longitudinal register study than in a high-quality first-contact study conducted in the same population. Risk estimates based only on first-contact studies may have been affected by selection bias.

Cited by 25 publications

References 38 publications

Incidence of psychotic disorders among first-generation immigrants and refugees in Ontario

Incidence of psychotic disorders among first-generation immigrants and refugees in Ontario

Risk of schizophrenia, schizoaffective, and bipolar disorders by migrant status, region of origin, and age-at-migration: A national cohort study of 1.8 million people

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