Association between inflammatory joint disease and severe or treatment-resistant depression: population-based cohort and case-control studies in Sweden.

OBJECTIVE: To investigate whether the association between depression and inflammatory joint disease (IJD; rheumatoid arthritis [RA], psoriatic arthritis [PsA], ankylosing spondylitis/spondyloarthropathies [AS], and juvenile idiopathic arthritis [JIA]) is affected by the severity or treatment-resistance of depression. METHOD: Parallel cohort studies and case-control studies among 600,404 patients with a depressive episode identified in Swedish nationwide administrative registers. Prospective and retrospective risk for IJD in patients with depression was compared to matched population comparators, and the same associations were investigated in severe or treatment-resistant depression. Analyses were adjusted for comorbidities and sociodemographic covariates. RESULTS: Patients with depression had an increased risk for later IJD compared to population comparators (adjusted hazard ratio (aHR) for any IJD 1.34 [95% CI 1.30-1.39]; for RA 1.27 [1.15-1.41]; PsA 1.45 [1.29-1.63]; AS 1.32 [1.15-1.52]). In case-control studies, patients with depression more frequently had a history of IJD compared to population controls (adjusted odds ratio (aOR) for any IJD 1.43 [1.37-1.50]; RA 1.39 [1.29-1.49]; PsA 1.59 [1.46-1.73]; AS 1.49 [1.36-1.64]; JIA 1.52 [1.35-1.71]). These associations were not significantly different for severe depression or TRD. CONCLUSION: IJD and depression are bidirectionally associated, but this association does not seem to be influenced by the severity or treatment resistance of depression.

Mental health from 5 years before to 10 years after bariatric surgery in adolescents with severe obesity: a Swedish nationwide cohort study with matched population controls.

BACKGROUND: The long-term effects of bariatric surgery on the mental health of adolescents with severe obesity remain uncertain. We aimed to describe the prevalence of psychiatric health-care visits and filled prescription psychiatric drugs among adolescents with severe obesity undergoing bariatric surgery in the 5 years preceding surgery and throughout the first 10 years after surgery, and to draw comparisons with matched adolescents in the general population. METHODS: Adolescents with severe obesity and who underwent bariatric surgery were identified through the Scandinavian Obesity Surgery Registry. We included adolescents who had bariatric surgery between 2007 and 2017 and were younger than 21 years at time of surgery. Each adolescent patient was matched with ten adolescents from the general population by age, sex, and county of residence. Specialist psychiatric care and filled psychiatric prescriptions were retrieved from nationwide data registers. FINDINGS: 1554 adolescents (<21 years) with severe obesity underwent bariatric surgery between 2007 and 2017, 1169 (75%) of whom were female. At time of surgery, the mean age was 19·0 years [SD 1·0], and the mean BMI was 43·7 kg/m2 (SD 5·5). 15 540 adolescents from the general population were matched with adolescents in the surgery group. 5 years before the matched index date, 95 (6·2%) of 1535 surgery patients and 370 (2·5%) of 14 643 matched adolescents had a psychiatric health-care visit (prevalence difference 3·7%; 95% CI 2·4-4·9), whereas 127 (9·8%) of 1295 surgery patients and 445 (3·6%) of 12 211 matched adolescents filled a psychiatric drug prescription (prevalence difference 6·2%; 95% CI 4·5-7·8). The year before the matched index date, 208 (13·4%) of 1551 surgery patients and 844 (5·5%) of 15 308 matched adolescents had a psychiatric health-care visit (prevalence difference 7·9%; 95% CI 6·2-9·6), whereas 319 (20·6%) of 1551 surgery patients and 1306 (8·5%) of 15 308 matched adolescents filled a psychiatric drug prescription (prevalence difference 12·0%; 10·0-14·1). The prevalence difference in psychiatric health-care visits peaked 9 years after the matched index date (12·0%; 95% CI 9·0-14·9), when 119 (17·6%) of 675 surgery patients and 377 (5·7%) of 6669 matched adolescents had a psychiatric health-care visit. The prevalence difference in filled psychiatric drug prescription was highest 10 years after the matched index date (20·4%; 15·9-24·9), when 171 (36·5%) of 469 surgery patients and 739 (16·0%) of 4607 matched adolescents filled a psychiatric drug prescription. The year before the matched index date, 19 (1·2%) of 1551 surgery patients and 155 (1·0%) of 15304 matched adolescents had a health-care visit associated with a substance use disorder diagnosis (mean difference 0·2%, 95% CI -0·4 to 0·8). 10 years after the matched index date, the prevalence difference had increased to 4·3% (95% CI 2·3-6·4), when 24 (5·1%) of 467 surgery patients and 37 (0·8%) of 4582 matched adolescents had a health-care visit associated with a substance use disorder diagnosis. INTERPRETATION: Psychiatric diagnoses and psychiatric drug prescriptions were more common among adolescents with severe obesity who would later undergo bariatric surgery than among matched adolescents from the general population. Both groups showed an increase in prevalence in psychiatric diagnoses and psychiatric drug prescriptions leading up to the time of surgery, but the rate of increase in the prevalence was higher among adolescents with severe obesity than among matched adolescents. With the exception of health-care visits for substance use disorders, these prevalence trajectories continued in the 10 years of follow-up. Realistic expectations regarding mental health outcomes should be set preoperatively. FUNDING: Swedish Research Council, Swedish Research Council for Health, Working Life and Welfare.

Risk and mortality of testicular cancer in patients with neurodevelopmental or other psychiatric disorders.

BACKGROUND: Both testicular germ cell tumours (TGCT) and neurodevelopmental disorders are associated with urogenital malformations. Few studies have investigated the association between psychiatric disorders and TGCT. We investigated whether history of any psychiatric or neurodevelopmental disorder is associated with increased risk or mortality of TGCT. METHOD: This is a nested case-control study including 6166 TGCT patients diagnosed during 1992-2014, individually matched for age and calendar period to 61,660 controls. We calculated odds ratios (ORs) for the association between type of psychiatric diagnoses and TGCT risk. Among the cases, we used a cohort design and calculated hazard ratios (HRs) of the association between psychiatric diagnose and all-cause and TGCT-specific death. RESULTS: History of a neurodevelopmental disorder (attention deficit hyperactivity disorder, autism spectrum disorder and intellectual disabilities) was associated with an increased risk of seminoma (OR: 1.54; 1.09-2.19). Seminoma patients with neurodevelopmental disorders were younger (34 versus 38 years, p = 0.004) and had more stage IV disease (5.4% versus 1.2%) than those without. Psychiatric history overall was not associated with TGCT. Patient history of any psychiatric disorder was associated with an increased all-cause and TGCT-specific death. CONCLUSIONS: We report an association between neurodevelopmental disorders and testicular seminoma, and an increased TGCT-specific mortality for TGCT patients with psychiatric disorders.

Methodology of the brodalumab assessment of hazards: a multicentre observational safety (BRAHMS) study.

INTRODUCTION: Safe and effective pharmacological treatment is of paramount importance for treating severe psoriasis. Brodalumab, a monoclonal antibody against interleukin (IL) 17 receptor A, was granted marketing authorisation in the EU in 2017. The European Medicines Agency requested a postauthorisation safety study of brodalumab to address potential safety issues raised during drug development regarding major adverse cardiovascular events, suicidal conduct, cancer and serious infections. METHODS AND ANALYSIS: BRodalumab Assessment of Hazards: A Multinational Safety is a multicentre observational safety study of brodalumab running from 2017 to 2029 using population-based healthcare databases from Denmark, Sweden, Norway, Netherlands, Germany and three different centres in Italy. A distributed database network approach is used, such that only aggregate data are exchanged between sites.Two types of designs are used: a case-time-control design to study acute effects of transient treatment and a variation of the new user active comparator design to study the effects of transient or chronic treatment. As comparators, inhibitors of TNF-α, inhibitors of IL-12 and IL-23, and other inhibitors of cytokine IL-17A are included.In the self-controlled case-time-control design, the risk of developing the outcome of interest during periods of brodalumab use is compared within individuals to the risk in periods without use.In the active comparator cohort design, new users of brodalumab are identified and matched to new users of active comparators. Potential baseline confounders are adjusted for by using propensity score modelling. For outcomes that potentially require large cumulative exposure, an adapted active comparator design has been developed. ETHICS AND DISSEMINATION: The study is approved by relevant authorities in Denmark, Norway, Sweden, the Netherlands, Germany and Italy in line with the relevant legislation at each site. Data confidentiality is secured by the distributed network approach. Results will be published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: EUPAS30280.

Prevalence trends and individual patterns of ADHD medication use in pregnancy in Norway and Sweden, 2010-2019.

PURPOSE: This study aimed to describe recent trends in ADHD medication use in pregnancy in Norway and Sweden, including prevalence, individual characteristics, and patterns of use. METHODS: We studied ADHD medication use (amphetamine, dexamphetamine, methylphenidate, atomoxetine, lisdexamfetamine, guanfacine) by year and age in pregnancies from 2010 to 2019 identified from the medical birth registers (gestational age ≥ 22 weeks) linked to prescribed drug registers (Norway, N = 577,116; Sweden, N = 1,118,988). We compared characteristics of those who used any ADHD medication in pregnancy to no use in pregnancy. Discontinuation was defined as no use after first trimester. RESULTS: ADHD medication use increased from 2010 to 2019 by 3.0 users per 1000 pregnancies in Norway (from 2.5 to 5.5/1000) and by 6.3 per 1000 in Sweden (from 1.6 to 7.9/1000), mainly driven by methylphenidate and since 2015 by lisdexamfetamine. Medication use has increased among pregnant individuals of all age groups, with higher use among the youngest. Pregnant individuals who used ADHD medication were less likely to be married/cohabiting, more likely be nulliparous and to smoke. They had particularly high use of co-medication with antidepressants, anxiolytics/hypnotics, and opioids: 42% in Norway and 65% in Sweden used at least one additional class of psychotropic medication. Most individuals discontinued ADHD medication in pregnancy (85% Norway, 78% Sweden). CONCLUSION: ADHD medication use during pregnancy increased in Norway and Sweden in the last decade. However, discontinuation rates during pregnancy were high. Those who used ADHD medication had more risk factors for pregnancy complications including low parity, smoking, and other psychotropic drug use.

Association of In Utero Antipsychotic Medication Exposure With Risk of Congenital Malformations in Nordic Countries and the US.

Importance: Psychiatric disorders are common among female individuals of reproductive age. While antipsychotic medication use is increasing, the safety of such medications in pregnancy is an area with large evidence gaps. Objective: To evaluate the risk of first-trimester antipsychotic exposure with respect to congenital malformations, focusing on individual drugs and specific malformation subtypes. Design, Setting, and Participants: This cohort study used data from nationwide health registers from the 5 Nordic countries and the US and spanned 1996 to 2018. The Nordic cohort included all pregnancies resulting in singleton live-born infants, and the US cohort consisted of publicly insured mothers linked to their live-born infants nested in the nationwide Medicaid Analytic eXtract. Data were analyzed from November 2020 to April 2022. Exposures: One or more first-trimester dispensing of any atypical, any typical, and individual antipsychotic drugs. Main Outcomes and Measures: Any major congenital malformation and specific malformation subtypes previously suggested to be associated with antipsychotic exposure in utero: cardiovascular malformations, oral clefts, neural tube defects, hip dysplasia, limb reduction defects, anorectal atresia/stenosis, gastroschisis, hydrocephalus, other specific brain anomalies, and esophageal disorders. Propensity score stratification was used to control for potential confounders. Pooled adjusted estimates were calculated using indirect standardization. Results: A total of 6 455 324 unexposed mothers (mean maternal age range across countries: 24-31 years), 21 751 mothers exposed to atypical antipsychotic drugs (mean age range, 26-31 years), and 6371 mothers exposed to typical antipsychotic drugs (mean age range, 27-32 years) were included in the study cohort. Prevalence of any major malformation was 2.7% (95% CI, 2.7%-2.8%) in unexposed infants, 4.3% (95% CI, 4.1%-4.6%) in infants with atypical antipsychotic drug exposure, and 3.1% (95% CI, 2.7%-3.5%) in infants with typical antipsychotic drug exposure in utero. Among the most prevalent exposure-outcome combinations, adjusted relative risks (aRR) were generally close to the null. One exception was olanzapine exposure and oral cleft (aRR, 2.1 [95% CI, 1.1-4.3]); however, estimates varied across sensitivity analyses. Among moderately prevalent combinations, increased risks were observed for gastroschisis and other specific brain anomalies after atypical antipsychotic exposure (aRR, 1.5 [95% CI, 0.8-2.6] and 1.9 [95% CI, 1.1-3.0]) and for cardiac malformations after chlorprothixene exposure (aRR, 1.6 [95% CI, 1.0-2.7]). While the association direction was consistent across sensitivity analyses, confidence intervals were wide, prohibiting firm conclusions. Conclusions and Relevance: In this study, considering the evidence from primary and sensitivity analyses and inevitable statistical noise for very rare exposure-outcome combinations, in utero antipsychotic exposure generally was not meaningfully associated with an increased risk of malformations. The observed increased risks of oral clefts associated with olanzapine, gastroschisis, and other specific brain anomalies with atypical antipsychotics and cardiac malformations with chlorprothixene requires confirmation as evidence continues to accumulate.

Long-Term Risk of Skin Cancer and Lymphoma in Users of Topical Tacrolimus and Pimecrolimus: Final Results from the Extension of the Cohort Study Protopic Joint European Longitudinal Lymphoma and Skin Cancer Evaluation (JOELLE).

PURPOSE: Evidence is insufficient to infer whether topical calcineurin inhibitors (TCIs; tacrolimus and pimecrolimus) cause malignancy. The study objective was to estimate the long-term risk of skin cancer and lymphoma associated with topical TCI use in adults and children, separately. PATIENTS AND METHODS: A cohort study in Denmark, Sweden, UK, and the Netherlands was conducted. Adjusted incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were calculated for nonmelanoma skin cancer (NMSC), melanoma, cutaneous T-cell lymphoma (CTCL), non-Hodgkin lymphoma (NHL) excluding CTCL, and Hodgkin lymphoma (HL) in new users of TCIs versus users of moderate/high-potency topical corticosteroids. RESULTS: The study included 126,908/61,841 adults and 32,605/27,961 children initiating treatment with tacrolimus/pimecrolimus, respectively. Follow-up was ≥10 years for 19% of adults and 32% of children. Incidence rate ratios and (95% confidence intervals) for tacrolimus versus corticosteroid users in adults were <1 for melanoma, non-Hodgkin lymphoma, and Hodgkin lymphoma; and 1.80 (1.25-2.58) for cutaneous T-cell lymphoma. For pimecrolimus, IRRs in adults were <1 for non-Hodgkin lymphoma, cutaneous T-cell lymphoma, and Hodgkin's lymphoma; and 1.21 (1.03-1.41) for melanoma; and 1.28 (1.20-1.35) for nonmelanoma skin cancer. In children, results were inconclusive due to few events. In adults, incidence rate ratios ≥5 years after first topical calcineurin inhibitor exposure were not higher than in overall analyses. CONCLUSION: Overall, we found little evidence associating use of topical calcineurin inhibitors with skin cancer and lymphoma; confounding by indication, surveillance bias, and reverse causation may have influenced these results. Even if causal, the public health impact of these excess risks would be low and confined to the first years of exposure.

Risk of breast cancer in risperidone users: A nationwide cohort study.

BACKGROUND: Several antipsychotics, especially risperidone, are known to increase serum prolactin. Hyperprolactinemia has been linked to the development of mammary gland tumors in animal studies. We therefore investigated the risk of breast cancer in a nationwide cohort of women using risperidone or other antipsychotics. METHODS: All women, 18years or older, who initiated treatment with risperidone or any other antipsychotic between 2006 and 2012 were identified in Swedish nationwide registers. Patients with two consecutive dispensations of the same antipsychotic within 3months, no previous cancer diagnosis, and no previous dispensations of paliperidone were included. The final cohort consisted of 55976 women of whom 22908, 24524, and 8544 were exposed to risperidone, other atypical antipsychotics, and typical antipsychotics, respectively. A Cox regression model was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for the association between antipsychotics and breast cancer. RESULTS: Patients were followed prospectively, the mean follow-up time ranging from 2.4 to 2.8years between treatment groups. After adjusting for age, there was no increased risk for breast cancer among risperidone users compared to patients exposed to another atypical antipsychotic (HR 0.94, 95% CI 0.72-1.22) or a typical antipsychotic (HR 1.25, 95% CI 0.94-1.66). Analyses stratified by tumor stage, using active treatment follow-up time, or including only treatment naïve patients did not reveal any noteworthy change in the results. CONCLUSION: Risperidone use does not confer an increased short-term risk of breast cancer compared to other antipsychotic agents.

Suicide risk and antipsychotic side effects in schizophrenia: nested case-control study.

OBJECTIVE: This study explores suicide risk in schizophrenia in relation to side effects from antipsychotic medication. METHODS: Among patients with a first clinical discharge diagnosis of schizophrenia or schizoaffective disorder in Stockholm County between 1984 and 2000 (n = 4000), those who died by suicide within 5 years from diagnosis were defined as cases (n = 84; 54% male). For each case, one individually matched control was identified from the same population. Information on antipsychotic side effects, including extrapyramidal symptoms (EPS) and akathisia, as well as prescriptions of anticholinergic medication, was retrieved from clinical records in a blinded fashion. Adjusted odds ratios (aORs) with 95% confidence intervals (CIs) of the association between suicide and side effects as well as anticholinergic medication were estimated using conditional logistic regression. RESULTS: A lower suicide risk was found in patients with a history of EPS (aOR 0.33, 95% CI 0.12-0.94). There was no statistically significant association between akathisia or anticholinergic medication use and the suicide risk. CONCLUSIONS: A lower suicide risk identified among patients with EPS could potentially reflect higher antipsychotic adherence, exposure to higher dosage, or polypharmacy among these patients. Copyright © 2016 John Wiley & Sons, Ltd.

Diabetes and glucose disturbances in patients with psychosis in Sweden.

OBJECTIVE: The objectives of this study were to (1) analyze the prevalence of diabetes, prediabetes, and antidiabetic medication in patients with psychosis compared with control subjects and (2) determine what factors in patients with psychosis were associated with antidiabetic medication. METHOD: We studied 977 patients with psychosis recruited from outpatient clinics in Stockholm County, Sweden, and they were compared with 3908 non-psychotic control subjects for fasting plasma glucose levels; prevalence of diabetes, prediabetes, antidiabetic treatment, and tobacco use; and blood pressure, weight, height, and waist circumference. Group differences were evaluated with analysis of variance and χ(2) test, and factors associated with antidiabetic treatment were evaluated with logistic regression. RESULTS: Diabetes was observed in 94 (10%) patients with psychosis, 2.7 times the prevalence observed in control subjects. Among patients with psychosis, 87 (10%) had prediabetes (fasting glucose, 6.1-6.9 mmol/L) compared with 149 (3.8%) control subjects. Most patients with psychosis (77%) who had prediabetes fulfilled criteria for metabolic syndrome. In patients with psychosis, both lipid-lowering medication and fasting glucose were significantly associated with antidiabetic treatment. There was no significant relation between antidiabetic treatment and lifestyle factors such as smoking or degree of psychiatric illness. CONCLUSIONS: The high prevalence of impaired fasting glucose and metabolic syndrome in patients with psychosis warrants further clinical research in preventing or delaying the onset of diabetes in these patients by pharmacotherapy and/or lifestyle intervention.

Risk and predictors of attempted and completed suicide in patients with hematological malignancies.

BACKGROUND: Hematological malignancies can cause high levels of distress, but few studies have assessed risk of suicidal behavior among these patients. METHODS: We evaluated risk of attempted and completed suicide in a cohort of 46,309 patients diagnosed with malignant lymphoma, myeloma and leukemia in Sweden 1992 to 2009 and 107,736 cancer-free subjects, using Poisson regression. RESULTS: In all, 146 suicide attempts and 63 completed suicides occurred during a median follow up of 3.1 years (maximum 19 years). The risk of completed suicide was 3.5-fold increased among patients with myeloma [incidence rate ratio (IRR) = 3.52, 95% confidence interval (CI) = 2.05-6.03] and 1.9-fold increased among patients with lymphoma (IRR = 1.87, 95% CI = 1.31-2.67) but not significantly increased among patients with leukemia. Risk of attempted suicide was increased among patients with myeloma (IRR = 2.13, CI = 1.39-3.26) and lymphoma (IRR = 1.34, 95% CI = 1.07-1.69). Both male and female patients were at increased risk of attempted as well as completed suicide. A pre-malignant history of mental disorders conferred 15-fold to 30-fold increased risks, but elevated risks were also observed among patients without such history. CONCLUSIONS: Suicidal actions in patients with hematological malignancies have high suicidal intent, and that subgroups of patients should be monitored for suicidal ideation.

A comparison of cardiovascular risk factors for ten antipsychotic drugs in clinical practice.

It is well known that abdominal obesity, dyslipidemia, and insulin resistance are highly prevalent in patients receiving maintenance treatment with antipsychotics, but there is limited knowledge about the association between cardiovascular risk factors and treatment with antipsychotic drugs. In this naturalistic study we investigated a sample of 809 antipsychotic-treated patients from Swedish psychosis outpatient teams. Cardiovascular risk factors (eg, metabolic syndrome, homeostasis model assessment of insulin resistance, and low-density lipoprotein values) were measured, and their associations to current antipsychotic pharmacotherapy were studied. Ten antipsychotic drugs were compared in a stepwise logistic regression model. For the patients, the presence of the components of metabolic syndrome ranged from 35% for hyperglycemia to 64% for elevated waist circumference. Hypertriglyceridemia was associated with clozapine (odds ratio [OR] = 1.81, 95% confidence interval [CI] 1.08-3.04), reduced high-density lipoprotein with both clozapine and olanzapine (OR = 1.73, 95% CI 1.01-2.97; and OR = 2.03, 95% CI 1.32-3.13), hypertension with perphenazine (OR = 2.00, 95% CI 1.21-3.59), and hyperglycemia inversely with ziprasidone (OR = 0.21, 95% CI 0.05-0.89) and positively with haloperidol (OR = 2.02, 95% CI 1.18-3.48). There were no significant relationships between any of the antipsychotic drugs and increased waist circumference, homeostasis model assessment of insulin resistance, or low-density lipoprotein levels. In conclusion, treatment with antipsychotic drugs is differentially associated with cardiovascular risk factors, even after adjusting for waist circumference, sex, age, and smoking.

Antipsychotics during pregnancy: relation to fetal and maternal metabolic effects.

CONTEXT: Knowledge about the effects of exposure to the newer antipsychotics during pregnancy is limited. OBJECTIVE: To investigate the effects of maternal use of antipsychotics during pregnancy on gestational diabetes and fetal growth. DESIGN: Population-based cohort study comparing women exposed and not exposed to antipsychotics during pregnancy. Exposure was defined as prescriptions filled. SETTING: Swedish national health registers. PARTICIPANTS: All women giving birth in Sweden from July 1, 2005, through December 31, 2009, grouped by filled prescriptions for (1) olanzapine and/or clozapine, the most obesogenic and diabetogenic antipsychotics (n = 169), (2) other antipsychotics (n = 338), or (3) no antipsychotics (n = 357,696). MAIN OUTCOME MEASURES: Odds ratios (ORs) with 95% CIs for gestational diabetes and being small for gestational age (SGA) and large for gestational age for birth weight, birth length, and head circumference. RESULTS: Exposure to other antipsychotics was associated with an increased risk of gestational diabetes (adjusted OR, 1.77 [95% CI, 1.04-3.03]). The risk increase with olanzapine and/or clozapine was of similar magnitude but not statistical significance (adjusted OR, 1.94 [95% CI, 0.97-3.91]). Infants exposed to either group of antipsychotics had increased risks of being SGA on birth weight, whereas only exposure to other antipsychotics yielded increased risks of being SGA for birth length and head circumference. None of the risks for SGA measurements remained significant after adjusting for maternal factors. There were no increased risks of being large for gestational age for birth weight or birth length after exposure to olanzapine and/or clozapine, but the risk increased for head circumference (OR, 3.02 [95% CI, 1.60-5.71]). CONCLUSIONS: Women who used antipsychotics during pregnancy had increased risks of gestational diabetes. The increased risks of giving birth to an SGA infant seemed to be an effect of confounders, such as smoking. Except for macrocephaly, olanzapine and/or clozapine exposure was not associated with anabolic fetal growth.

Childhood leukaemia in Costa Rica, 1981-96.

Childhood leukaemia incidence in Costa Rica during 1981-96, among the highest in the world, was analysed by histology, gender, birth year, time period of diagnosis, age at diagnosis and region. Numbers of cases were extracted from the database of the National Cancer Registry (RNT) of Costa Rica. Person-years at risk were calculated from census data and post-census population estimates. During the follow-up, 918 cases of leukaemia in children under 15 years (510 boys, 408 girls) were reported to the RNT (41% of all childhood malignancies), with an overall age-standardised incidence rate of 56 per million person-years. Acute lymphocytic leukaemia (ALL) represented 79% and acute non-lymphocytic leukaemia (ANLL) 16% of the cases, with rates of 43 and 9 per million person-years respectively. There were downward trends in incidence of total leukaemias, ALL and ANLL and 'not otherwise specified' (NOS) combined. Incidence of ALL was highest at 1-4 years of age in boys and girls, whereas ANLL peaked in girls during the first year of life. During 1991-96, the decrease in ALL was significant (P = 0.042). A multivariable Poisson regression model identified significant excesses of ALL for boys, for age groups 1-4 and 5-9 years and for three out of seven regions. Possible reasons for the high rates in Costa Rica are discussed.

Central nervous system tumours in children in Costa Rica, 1981-96.

Incidence rates of malignant central nervous system (CNS) tumours in children in Costa Rica are presented in an international perspective. For the 16-year period 1981-96, a total of 256 CNS tumours were registered in children below age 15 years by the National Tumour Registry of Costa Rica. The age-standardised incidence rate was 15.2 per million person-years, with a male-to-female ratio of 1.4. The median age-standardised incidence rates of selected registries in other Latin American countries were 19.3, in other developing countries 12.0 and in industrialised countries 29.6 per million person-years. The comparatively low incidence rates in Costa Rica were evident in all diagnostic subgroups, most notably in the youngest age group and for tumours in the brain stem. In the Central Valley, where the capital and the only specialised paediatric hospital are situated, the crude incidence rate was 18.1 [95% CI 15.1, 21.1] compared with 10.5 [95% CI 8.3, 12.8] per million person-years in the rest of the country (RR = 1.7, 95% CI 1.3, 2.3). There was no evidence of any increase over time. The data in this study cannot exclude under-diagnosis and, to a lesser degree, under-registration as a partial explanation of the low incidence rates of malignant CNS tumours in children in Costa Rica.