Estimates of lifetime risk of suicide in mental disorders were based on selected samples with incomplete follow-up.
To estimate, in a national cohort, the absolute risk of suicide within 36 years after the first psychiatric contact.
Prospective study of incident cases followed up for as long as 36 years. Median follow-up was 18 years.
Individual data drawn from Danish longitudinal registers.
A total of 176,347 persons born from January 1, 1955, through December 31, 1991, were followed up from their first contact with secondary mental health services after 15 years of age until death, emigration, disappearance, or the end of 2006. For each participant, 5 matched control individuals were included.
Absolute risk of suicide in percentage of individuals up to 36 years after the first contact.
Among men, the absolute risk of suicide (95% confidence interval [CI]) was highest for bipolar disorder, (7.77%; 6.01%-10.05%), followed by unipolar affective disorder (6.67%; 5.72%-7.78%) and schizophrenia (6.55%; 5.85%-7.34%). Among women, the highest risk was found among women with schizophrenia (4.91%; 95% CI, 4.03%-5.98%), followed by bipolar disorder (4.78%; 3.48%-6.56%). In the nonpsychiatric population, the risk was 0.72% (95% CI, 0.61%-0.86%) for men and 0.26% (0.20%-0.35%) for women. Comorbid substance abuse and comorbid unipolar affective disorder significantly increased the risk. The co-occurrence of deliberate self-harm increased the risk approximately 2-fold. Men with bipolar disorder and deliberate self-harm had the highest risk (17.08%; 95% CI, 11.19%-26.07%).
This is the first analysis of the absolute risk of suicide in a total national cohort of individuals followed up from the first psychiatric contact, and it represents, to our knowledge, the hitherto largest sample with the longest and most complete follow-up. Our estimates are lower than those most often cited, but they are still substantial and indicate the continuous need for prevention of suicide among people with mental disorders.
Many studies have identified urban-rural differences in schizophrenia risk. Hypothetical underlying cause(s) may include toxic exposures, diet, infections, and selective migration. The authors investigated whether the underlying cause(s) responsible for the urban-rural differences were rooted in families or in individuals. Linking data from the Danish Civil Registration System and the Danish Psychiatric Central Register, a population-based cohort of 711,897 people aged 15 years or more was established. Overall, 2,720 persons developed schizophrenia during the period 1970-2001. The authors evaluated whether the nearest older sibling's place of birth had an independent effect on schizophrenia risk. If the cause(s) responsible for the urban-rural differences are rooted in individuals only, the nearest older sibling's place of birth should have no independent effect. In this analysis, the nearest older sibling's place of birth had an independent effect; among persons who lived in a rural area during their first 15 years of life, the relative risk was 1.59 (95% confidence interval: 1.10, 2.30) if their nearest older sibling had been born in the capital area as compared with a rural area. Some of the cause(s) responsible for the urban-rural differences in schizophrenia risk are rooted in families, but some might also be rooted in individuals.
Comment In: Am J Epidemiol. 2006 Jun 1;163(11):979-8116675534
Infections and activated immune responses can affect the brain through several pathways that might also affect cognition. However, no large-scale study has previously investigated the effect of infections on the general cognitive ability in the general population.
Danish nationwide registers were linked to establish a cohort of all 161,696 male conscripts during the years 2006-2012 who were tested for cognitive ability, which was based on logical, verbal, numerical and spatial reasoning at a mean age of 19.4 years. Test scores were converted to a mean of 100.00 and with a standard deviation (SD) of 15. Data were analyzed as a cohort study with severe infections requiring hospitalization as exposure using linear regression.
Adjusted effect sizes were calculated with non-exposure to severe infections as reference, ranging from 0.12 SD to 0.63 SD on general cognitive ability. A prior infection was associated with significantly lower cognitive ability by a mean of 1.76 (95%CI: -1.92 to -1.61; corresponding to 0.12 SD). The cognitive ability was affected the most by the temporal proximity of the last infection (P
Cites: J Neurosci. 2012 Jan 11;32(2):436-5122238080
OBJECTIVE: Individuals with schizophrenia and their relatives tend to have either higher or lower than expected prevalences of autoimmune disorders, especially rheumatoid arthritis, celiac disease, autoimmune thyroid diseases, and type 1 diabetes. The purpose of the study was to estimate the association of schizophrenia with these disorders as well as a range of other autoimmune diseases in a single large epidemiologic study. METHOD: The Danish Psychiatric Register, the National Patient Register, and a register with socioeconomic information were linked to form a data file that included all 7,704 persons in Denmark diagnosed with schizophrenia from 1981 to 1998 and their parents along with a sample of matched comparison subjects and their parents. The data linkage required that the autoimmune disease occur before the diagnosis of schizophrenia. RESULTS: A history of any autoimmune disease was associated with a 45% increase in risk for schizophrenia. Nine autoimmune disorders had higher prevalence rates among patients with schizophrenia than among comparison subjects (crude incidence rate ratios ranging from 1.9 to 12.5), and 12 autoimmune diseases had higher prevalence rates among parents of schizophrenia patients than among parents of comparison subjects (adjusted incidence rate ratios ranging from 1.3 to 3.8). Thyrotoxicosis, celiac disease, acquired hemolytic anemia, interstitial cystitis, and Sjögren's syndrome had higher prevalence rates among patients with schizophrenia than among comparison subjects and also among family members of schizophrenia patients than among family members of comparison subjects. CONCLUSIONS: Schizophrenia is associated with a larger range of autoimmune diseases than heretofore suspected. Future research on comorbidity has the potential to advance understanding of pathogenesis of both psychiatric and autoimmune disorders.
Studies linking birth weight and mental illness onset are inconclusive. They have primarily focused on the World Health Organization low birth weight threshold (2500 g) and schizophrenia. To our knowledge, low birth weight per se has not been conclusively linked with schizophrenia risk and specificity of the effect to birth weight below the standard threshold or to particular psychiatric diagnoses has not been demonstrated.
To examine whether (1) low birth weight ( or =4500 g) for schizophrenia, any psychiatric diagnoses, and specified psychiatric diagnoses.
Schizophrenia was associated with birth weight less than 2500 g. The association was not restricted to birth weight less than 2500 g and there was a significant linear trend of increasing odds ratios with decreasing birth weight across the birth weight range. This was mirrored for any psychiatric diagnosis and for each of the categories of psychiatric disorder.
Findings suggest there is an association between birth weight and adult mental disorder, but there is no indication this effect is specific to birth weight less than 2500 g or to schizophrenia. Future research should explore common disorder-specific mechanisms that may link birth weight to development of psychiatric disorder in adulthood.
With cesarean section rates increasing worldwide, clarity regarding negative effects is essential. This study aimed to investigate the rate of subsequent stillbirth, miscarriage, and ectopic pregnancy following primary cesarean section, controlling for confounding by indication.
We performed a population-based cohort study using Danish national registry data linking various registers. The cohort included primiparous women with a live birth between January 1, 1982, and December 31, 2010 (n?=?832,996), with follow-up until the next event (stillbirth, miscarriage, or ectopic pregnancy) or censoring by live birth, death, emigration, or study end. Cox regression models for all types of cesarean sections, sub-group analyses by type of cesarean, and competing risks analyses for the causes of stillbirth were performed. An increased rate of stillbirth (hazard ratio [HR] 1.14, 95% CI 1.01, 1.28) was found in women with primary cesarean section compared to spontaneous vaginal delivery, giving a theoretical absolute risk increase (ARI) of 0.03% for stillbirth, and a number needed to harm (NNH) of 3,333 women. Analyses by type of cesarean section showed similarly increased rates for emergency (HR 1.15, 95% CI 1.01, 1.31) and elective cesarean (HR 1.11, 95% CI 0.91, 1.35), although not statistically significant in the latter case. An increased rate of ectopic pregnancy was found among women with primary cesarean overall (HR 1.09, 95% CI 1.04, 1.15) and by type (emergency cesarean, HR 1.09, 95% CI 1.03, 1.15, and elective cesarean, HR 1.12, 95% CI 1.03, 1.21), yielding an ARI of 0.1% and a NNH of 1,000 women for ectopic pregnancy. No increased rate of miscarriage was found among women with primary cesarean, with maternally requested cesarean section associated with a decreased rate of miscarriage (HR 0.72, 95% CI 0.60, 0.85). Limitations include incomplete data on maternal body mass index, maternal smoking, fertility treatment, causes of stillbirth, and maternally requested cesarean section, as well as lack of data on antepartum/intrapartum stillbirth and gestational age for stillbirth and miscarriage.
This study found that cesarean section is associated with a small increased rate of subsequent stillbirth and ectopic pregnancy. Underlying medical conditions, however, and confounding by indication for the primary cesarean delivery account for at least part of this increased rate. These findings will assist women and health-care providers to reach more informed decisions regarding mode of delivery. Please see later in the article for the Editors' Summary.
OBJECTIVE: To study the change in risk of suicide among patients with schizophrenia and related disorders. DESIGN: Nested case-control design with linked data. SETTING: 4 longitudinal Danish registers. PARTICIPANTS: 18,744 people aged up to 75 years who committed suicide in 1981-97 individually matched with 20 controls. RESULTS: Over the time studied the reduction in suicide rate among patients with schizophrenia and schizophrenia spectrum disorder was similar to that seen in the general population (incidence rate ratio 1.00, 95% confidence interval 0.98 to 1.03). The reduction among patients with other psychosis in the schizophrenia spectrum was faster than the reduction seen in the general population. Among people admitted to hospital with schizophrenia the risk of suicide was highest in the first year after first admission, and the excess risk was largest in the younger age groups-that is, the risk decreased per year for every additional year of age. CONCLUSION: The suicide rate among patients with a diagnosis of schizophrenia and related disorders has fallen. This may be due to better psychiatric treatment, reduced access to means of suicide, or improvements in treatment after suicide attempts.