Comorbidity within mental disorders: a comprehensive analysis based on 145 990 survey respondents from 27 countries.

AIMS: Epidemiological studies indicate that individuals with one type of mental disorder have an increased risk of subsequently developing other types of mental disorders. This study aimed to undertake a comprehensive analysis of pair-wise lifetime comorbidity across a range of common mental disorders based on a diverse range of population-based surveys. METHODS: The WHO World Mental Health (WMH) surveys assessed 145 990 adult respondents from 27 countries. Based on retrospectively-reported age-of-onset for 24 DSM-IV mental disorders, associations were examined between all 548 logically possible temporally-ordered disorder pairs. Overall and time-dependent hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards models. Absolute risks were estimated using the product-limit method. Estimates were generated separately for men and women. RESULTS: Each prior lifetime mental disorder was associated with an increased risk of subsequent first onset of each other disorder. The median HR was 12.1 (mean = 14.4; range 5.2-110.8, interquartile range = 6.0-19.4). The HRs were most prominent between closely-related mental disorder types and in the first 1-2 years after the onset of the prior disorder. Although HRs declined with time since prior disorder, significantly elevated risk of subsequent comorbidity persisted for at least 15 years. Appreciable absolute risks of secondary disorders were found over time for many pairs. CONCLUSIONS: Survey data from a range of sites confirms that comorbidity between mental disorders is common. Understanding the risks of temporally secondary disorders may help design practical programs for primary prevention of secondary disorders.

The cost of mental disorders: a systematic review.

AIMS: To identify and synthesise the literature on the cost of mental disorders. METHODS: Systematic literature searches were conducted in the databases PubMed, EMBASE, Web of Science, EconLit, NHS York Database and PsychInfo using key terms for cost and mental disorders. Searches were restricted to January 1980-May 2019. The inclusion criteria were: (1) cost-of-illness studies or cost-analyses; (2) diagnosis of at least one mental disorder; (3) study population based on the general population; (4) outcome in monetary units. The systematic review was preregistered on PROSPERO (ID: CRD42019127783). RESULTS: In total, 13 579 potential titles and abstracts were screened and 439 full-text articles were evaluated by two independent reviewers. Of these, 112 articles were included from the systematic searches and 31 additional articles from snowball searching, resulting in 143 included articles. Data were available from 48 countries and categorised according to nine mental disorder groups. The quality of the studies varied widely and there was a lack of studies from low- and middle-income countries and for certain types of mental disorders (e.g. intellectual disabilities and eating disorders). Our study showed that certain groups of mental disorders are more costly than others and that these rankings are relatively stable between countries. An interactive data visualisation site can be found here: https://nbepi.com/econ. CONCLUSIONS: This is the first study to provide a comprehensive overview of the cost of mental disorders worldwide.

Delivery by caesarean section and childhood cancer: a nationwide follow-up study in three countries.

OBJECTIVE: To investigate the association between delivery by caesarean section and risk of childhood cancer. DESIGN: A population-based, follow-up study using register data from three countries. SETTING: Denmark, Sweden and Finland. POPULATION: Children born in Denmark (1973-2007), Sweden (1973-2006) and Finland (randomly selected sample of 90%, 1987-2007; n = 7,029,843). METHODS: Exposure was delivery by caesarean section and the outcome was childhood cancer diagnosis. Follow-up started from birth and ended at the first of the following dates: cancer diagnosis, death, emigration, day before 15th birthday or end of follow-up. Cox regression was used to obtain hazard ratios. MAIN OUTCOME MEASURES: Childhood cancer diagnosis. RESULTS: A total of 882,907 (12.6%) children were delivered by caesarean section. Of these, 30.3% were elective (n = 267,603), 35.9% unplanned (n = 316,536) and 33.8% had no information on planning (n = 298,768). Altogether, 11,181 children received a cancer diagnosis. No evidence of an increased risk of childhood cancer was found for children born by caesarean section (hazard ratio, 1.05; 95% confidence interval, 0.99, 1.11). No association was found for any major type of childhood cancer, or when split by the type of caesarean section (elective/unplanned). CONCLUSION: The evidence does not suggest that caesarean section is a risk factor for the overall risk of childhood cancer and possibly not for subtypes of childhood cancer either.