To Örebro University

OBJECTIVE: To study the impact of maternal smoking during pregnancy on fractures in offspring during different developmental stages of life.

DESIGN: National register based birth cohort study with a sibling comparison design.

SETTING: Sweden.

PARTICIPANTS: 1 680 307 people born in Sweden between 1983 and 2000 to women who smoked (n=377 367, 22.5%) and did not smoke (n=1 302 940) in early pregnancy. Follow-up was until 31 December 2014.

MAIN OUTCOME MEASURE: Fractures by attained age up to 32 years.

RESULTS: During a median follow-up of 21.1 years, 377 970 fractures were observed (the overall incidence rate for fracture standardised by calendar year of birth was 11.8 per 1000 person years). The association between maternal smoking during pregnancy and risk of fracture in offspring differed by attained age. Maternal smoking was associated with a higher rate of fractures in offspring before 1 year of age in the entire cohort (birth year standardised fracture rates in those exposed and unexposed to maternal smoking were 1.59 and 1.28 per 1000 person years, respectively). After adjustment for potential confounders the hazard ratio for maternal smoking compared with no smoking was 1.27 (95% confidence interval 1.12 to 1.45). This association followed a dose dependent pattern (compared with no smoking, hazard ratios for 1-9 cigarettes/day and >= 10 cigarettes/day were 1.20 (95% confidence interval 1.03 to 1.39) and 1.41 (1.18 to 1.69), respectively) and persisted in within-sibship comparisons although with wider confidence intervals (compared with no smoking, 1.58 (1.01 to 2.46)). Maternal smoking during pregnancy was also associated with an increased fracture incidence in offspring from age 5 to 32 years in whole cohort analyses, but these associations did not follow a dose dependent gradient. In within-sibship analyses, which controls for confounding by measured and unmeasured shared familial factors, corresponding point estimates were all close to null. Maternal smoking was not associated with risk of fracture in offspring between the ages of 1 and 5 years in any of the models.

CONCLUSION: Prenatal exposure to maternal smoking is associated with an increased rate of fracture during the first year of life but does not seem to have a long lasting biological influence on fractures later in childhood and up to early adulthood.

Randomised controlled trials are increasingly conducted as embedded, nested, or using cohorts or routinely collected data, including registries, electronic health records, and administrative databases, to assess if participants are eligible for the trial and to facilitate recruitment, to deliver an embedded intervention, to collect trial outcome data, or a combination of these purposes. This report presents the Consolidated Standards of Reporting Trials (CONSORT) extension for randomised controlled trials conducted using cohorts and routinely collected data (CONSORT-ROUTINE). The extension was developed to look at the unique characteristics of trials conducted with these types of data with the goal of improving reporting quality in the long term by setting standards early in the process of uptake of these trial designs. The extension was developed with a sequential approach, including a Delphi survey, a consensus meeting, and piloting of the checklist. The checklist was informed by the CONSORT 2010 statement and two reporting guidelines for observational studies, the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement and the REporting of studies Conducted using Observational Routinely collected Data (RECORD) statement. The extension includes eight items modified from the CONSORT 2010 statement and five new items. Reporting items with explanations and examples are provided, including key aspects of trials conducted using cohorts or routinely collected data that require specific reporting considerations.

OBJECTIVE: To examine the association between maternal type 1 diabetes and the risk of major birth defects according to levels of glycated haemoglobin (HbA1C) within three months before or after estimated conception.

DESIGN: Population based historical cohort study using nationwide health registers. SETTING Sweden, 2003-15.

PARTICIPANTS: 2458 singleton liveborn infants of mothers with type 1 diabetes and a glycated haemoglobin measurement within three months before or after estimated conception and 1 159 865 infants of mothers without diabetes.

MAIN OUTCOME MEASURES: Major cardiac and non-cardiac birth defects according to glycated haemoglobin levels.

RESULTS: 122 cases of major cardiac defects were observed among 2458 infants of mothers with type 1 diabetes. Compared with 15 cases of major cardiac defects per 1000 infants of mothers without diabetes, the rates among infants of mothers with type 1 diabetes were 33 per 1000 for a glycated haemoglobin level of <6.5% (adjusted risk ratio 2.17, 95% confidence interval 1.37 to 3.42), 49 per 1000 for 6.5% to <7.8% (3.17, 2.45 to 4.11), 44 per 1000 for 7.8% to <9.1% (2.79, 1.90 to 4.12), and 101 per 1000 for >= 9.1% (6.23, 4.32 to 9.00). The corresponding adjusted risk differences were 17 (5 to 36), 32 (21 to 46), 26 (13 to 46), and 77 (49 to 118) cases of major cardiac defects per 1000 infants, respectively. 50 cases of major non-cardiac defects were observed among infants of mothers with type 1 diabetes. Compared with 18 cases of major non-cardiac defects per 1000 infants of mothers without diabetes, the rates among infants of mothers with type 1 diabetes were 22 per 1000 for a glycated haemoglobin level of <6.5% (adjusted risk ratio 1.18, 0.68 to 2.07), 19 per 1000 for 6.5% to <7.8% (1.01, 0.66 to 1.54), 17 per 1000 for 7.8% to <9.1% (0.89, 0.46 to 1.69), and 32 per 1000 for >= 9.1%(1.68, 0.85 to 3.33).

CONCLUSIONS: Among liveborn infants of mothers with type 1 diabetes, increasingly worse glycaemic control in the three months before or after estimated conception was associated with a progressively increased risk of major cardiac defects. Even with glycated haemoglobin within target levels recommended by guidelines (<6.5%), the risk of major cardiac defects was increased more than twofold. The risk of major non-cardiac defects was not statistically significantly increased at any of the four glycated haemoglobin levels examined; the study had limited statistical power for this outcome and was based on live births only.

OBJECTIVES: To study circadian rhythm aspects, national holidays, and major sports events as triggers of myocardial infarction.

DESIGN: Retrospective observational study using the nationwide coronary care unit registry, SWEDEHEART.

SETTING: Sweden.

PARTICIPANTS: 283 014 cases of myocardial infarction reported to SWEDEHEART between 1998 and 2013. Symptom onset date was documented for all cases, and time to the nearest minute for 88%.

INTERVENTIONS: Myocardial infarctions with symptom onset on Christmas/New Year, Easter, and Midsummer holiday were identified. Similarly, myocardial infarctions that occurred during a FIFA World Cup, UEFA European Championship, and winter and summer Olympic Games were identified. The two weeks before and after a holiday were set as a control period, and for sports events the control period was set to the same time one year before and after the tournament. Circadian and circaseptan analyses were performed with Sunday and 24:00 as the reference day and hour with which all other days and hours were compared. Incidence rate ratios were calculated using a count regression model.

MAIN OUTCOME MEASURES: Daily count of myocardial infarction.

RESULTS: Christmas and Midsummer holidays were associated with a higher risk of myocardial infarction (incidence rate ratio 1.15, 95% confidence interval 1.12 to 1.19, P<0.001, and 1.12, 1.07 to 1.18, P<0.001, respectively). The highest associated risk was observed for Christmas Eve (1.37, 1.29 to 1.46, P<0.001). No increased risk was observed during Easter holiday or sports events. A circaseptan and circadian variation in the risk of myocardial infarction was observed, with higher risk during early mornings and on Mondays. Results were more pronounced in patients aged over 75 and those with diabetes and a history of coronary artery disease.

CONCLUSIONS: In this nationwide real world study covering 16 years of hospital admissions for myocardial infarction with symptom onset documented to the nearest minute, Christmas, and Midsummer holidays were associated with higher risk of myocardial infarction, particularly in older and sicker patients, suggesting a role of external triggers in vulnerable individuals.

OBJECTIVE: To examine associations between gabapentinoids and adverse outcomes related to coordination disturbances (head or body injuries, or both and road traffic incidents or offences), mental health (suicidal behaviour, unintentional overdoses), and criminality.

DESIGN: Population based cohort study.

SETTING: High quality prescription, patient, death, and crime registers, Sweden.

PARTICIPANTS: 191 973 people from the Swedish Prescribed Drug Register who collected prescriptions for gabapentinoids (pregabalin or gabapentin) during 2006 to 2013.

MAIN OUTCOME MEASURES: Primary outcomes were suicidal behaviour, unintentional overdoses, head/body injuries, road traffic incidents and offences, and arrests for violent crime. Stratified Cox proportional hazards regression was conducted comparing treatment periods with non-treatment periods within an individual. Participants served as their own control, thus accounting for time invariant factors (eg, genetic and historical factors), and reducing confounding by indication. Additional adjustments were made by age, sex, comorbidities, substance use, and use of other antiepileptics.

RESULTS: During the study period, 10 026 (5.2%) participants were treated for suicidal behaviour or died from suicide, 17 144 (8.9%) experienced an unintentional overdose, 12 070 (6.3%) had a road traffic incident or offence, 70 522 (36.7%) presented with head/body injuries, and 7984 (4.1%) were arrested for a violent crime. In within-individual analyses, gabapentinoid treatment was associated with increased hazards of suicidal behaviour and deaths from suicide (age adjusted hazard ratio 1.26, 95% confidence interval 1.20 to 1.32), unintentional overdoses (1.24, 1.19 to 1.28), head/body injuries (1.22, 1.19 to 1.25), and road traffic incidents and offences (1.13, 1.06 to 1.20). Associations with arrests for violent crime were less clear (1.04, 0.98 to 1.11). When the drugs were examined separately, pregabalin was associated with increased hazards of all outcomes, whereas gabapentin was associated with decreased or no statistically significant hazards. When stratifying on age, increased hazards of all outcomes were associated with participants aged 15 to 24 years.

CONCLUSIONS: This study suggests that gabapentinoids are associated with an increased risk of suicidal behaviour, unintentional overdoses, head/body injuries, and road traffic incidents and offences. Pregabalin was associated with higher hazards of these outcomes than gabapentin.

OBJECTIVE: To assess whether severe psychiatric reactions to trauma and other adversities are associated with subsequent risk of life threatening infections.

DESIGN: Population and sibling matched cohort study.

SETTING: Swedish population.

PARTICIPANTS: 144 919 individuals with stress related disorders (post-traumatic stress disorder (PTSD), acute stress reaction, adjustment disorder, and other stress reactions) identified from 1987 to 2013 compared with 184 612 full siblings of individuals with a diagnosed stress related disorder and 1 449 190 matched individuals without such a diagnosis from the general population.

MAIN OUTCOME MEASURES: A first inpatient or outpatient visit with a primary diagnosis of severe infections with high mortality rates (ie, sepsis, endocarditis, and meningitis or other central nervous system infections) from the Swedish National Patient Register, and deaths from these infections or infections of any origin from the Cause of Death Register. After controlling for multiple confounders, Cox models were used to estimate hazard ratios of these life threatening infections.

RESULTS: The average age at diagnosis of a stress related disorder was 37 years (55 541, 38.3% men). During a mean follow-up of eight years, the incidence of life threatening infections per 1000 person years was 2.9 in individuals with a stress related disorder, 1.7 in siblings without a diagnosis, and 1.3 in matched individuals without a diagnosis. Compared with full siblings without a diagnosis of a stress related disorder, individuals with such a diagnosis were at increased risk of life threatening infections (hazard ratio for any stress related disorder was 1.47 (95% confidence intervals1.37 to 1.58) and for PTSD was 1.92 (1.46 to 2.52)). Corresponding estimates in the population based analysis were similar (1.58 (1.51 to 1.65) for any stress related disorder, P=0.09 for difference between sibling and population based comparison, and 1.95 (1.66 to 2.28) for PTSD, P=0.92 for difference). Stress related disorders were associated with all studied life threatening infections, with the highest relative risk observed for meningitis (sibling based analysis 1.63 (1.23 to 2.16)) and endocarditis (1.57 (1.08 to 2.30)). Younger age at diagnosis of a stress related disorder and the presence of psychiatric comorbidity, especially substance use disorders, were associated with higher hazard ratios, whereas use of selective serotonin reuptake inhibitors in the first year after diagnosis of a stress related disorder was associated with attenuated hazard ratios.

CONCLUSION: In the Swedish population, stress related disorders were associated with a subsequent risk of life threatening infections, after controlling for familial background and physical or psychiatric comorbidities.

OBJECTIVE: To assess the association between stress related disorders and subsequent risk of cardiovascular disease.

DESIGN: Population based, sibling controlled cohort study.

SETTING: Population of Sweden.

PARTICIPANTS: 136 637 patients in the Swedish National Patient Register with stress related disorders, including post-traumatic stress disorder (PTSD), acute stress reaction, adjustment disorder, and other stress reactions, from 1987 to 2013; 171 314 unaffected full siblings of these patients; and 1 366 370 matched unexposed people from the general population.

MAIN OUTCOME MEASURES: Primary diagnosis of incident cardiovascular disease-any or specific subtypes (ischaemic heart disease, cerebrovascular disease, emboli/thrombosis, hypertensive diseases, heart failure, arrhythmia/conduction disorder, and fatal cardiovascular disease)-and 16 individual diagnoses of cardiovascular disease. Hazard ratios for cardiovascular disease were derived from Cox models, after controlling for multiple confounders.

RESULTS: During up to 27 years of follow-up, the crude incidence rate of any cardiovascular disease was 10.5, 8.4, and 6.9 per 1000 person years among exposed patients, their unaffected full siblings, and the matched unexposed individuals, respectively. In sibling based comparisons, the hazard ratio for any cardiovascular disease was 1.64 (95% confidence interval 1.45 to 1.84), with the highest subtype specific hazard ratio observed for heart failure (6.95, 1.88 to 25.68), during the first year after the diagnosis of any stress related disorder. Beyond one year, the hazard ratios became lower (overall 1.29, 1.24 to 1.34), ranging from 1.12 (1.04 to 1.21) for arrhythmia to 2.02 (1.45 to 2.82) for artery thrombosis/embolus. Stress related disorders were more strongly associated with early onset cardiovascular diseases (hazard ratio 1.40 (1.32 to 1.49) for attained age < 50) than later onset ones (1.24 (1.18 to 1.30) for attained age >= 50; P for difference=0.002). Except for fatal cardiovascular diseases, these associations were not modified by the presence of psychiatric comorbidity. Analyses within the population matched cohort yielded similar results (hazard ratio 1.71 (1.59 to 1.83) for any cardiovascular disease during the first year of follow-up and 1.36 (1.33 to 1.39) thereafter).

CONCLUSION: Stress related disorders are robustly associated with multiple types of cardiovascular disease, independently of familial background, history of somatic/psychiatric diseases, and psychiatric comorbidity.

OBJECTIVE: To assess the risk of colorectal cancer (CRC) in first degree relatives (parents and full siblings) of patients with precursor lesions (polyps) for CRC.

DESIGN: Case-control study.

SETTING: Linkage to the multi-generation register and gastrointestinal ESPRESSO (Epidemiology Strengthened by histoPathology Reports in Sweden) histopathology cohort in Sweden.

PARTICIPANTS: 68 060 patients with CRC and 333 753 matched controls.

MAIN OUTCOME MEASURES: Multivariable adjusted odds ratios of CRC according to the number of first degree relatives with a colorectal polyp and the histology of polyps and age at diagnosis in first degree relatives. Subgroup analysis was also performed according to age at CRC diagnosis and evaluated the joint association of family history of colorectal polyps and family history of CRC.

RESULTS: After adjusting for family history of CRC and other covariates, having a first degree relative with a colorectal polyp (8.4% (5742/68 060) in cases and 5.7% (18 860/333 753) in controls) was associated with a higher risk of CRC (odds ratio 1.40, 95% confidence interval 1.35 to 1.45). The odds ratios ranged from 1.23 for those with hyperplastic polyps to 1.44 for those with tubulovillous adenomas. To better put this risk in perspective, the age specific absolute risk of colon and rectal cancers was estimated according to family history of polyps based on the 2018 national CRC incidence in Sweden. For example, the absolute risk of colon cancer in individuals aged 60-64 years with and without a family history of colorectal polyp was, respectively, 94.3 and 67.9 per 100 000 for men and 89.1 and 64.1 per 100 000 for women. The association between family history of polyps and CRC risk was strengthened by the increasing number of first degree relatives with polyps (≥2 first degree relatives: 1.70, 1.52 to 1.90, P<0.001 for trend) and decreasing age at polyp diagnosis (<50 years: 1.77, 1.57 to 1.99, P<0.001 for trend). A particularly strong association was found for early onset CRC diagnosed before age 50 years (≥2 first degree relatives: 3.34, 2.05 to 5.43, P=0.002 for heterogeneity by age of CRC diagnosis). In the joint analysis, the odds ratio of CRC for individuals with two or more first degree relatives with polyps but no CRC was 1.79 (1.52 to 2.10), with one first degree relative with CRC but no polyps was 1.70 (1.65 to 1.76), and with two or more first degree relatives with both polyps and CRC was 5.00 (3.77 to 6.63) (P<0.001 for interaction).

CONCLUSIONS: After adjusting for family history of CRC, the siblings and children of patients with colorectal polyps are still at higher risk of CRC, particularly early onset CRC. Early screening for CRC might be considered for first degree relatives of patients with polyps.

OBJECTIVE: To evaluate if induction of labour at 41 weeks improves perinatal and maternal outcomes in women with a low risk pregnancy compared with expectant management and induction of labour at 42 weeks.

DESIGN: Multicentre, open label, randomised controlled superiority trial.

SETTING: 14 hospitals in Sweden, 2016-18.

PARTICIPANTS: 2760 women with a low risk uncomplicated singleton pregnancy randomised (1:1) by the Swedish Pregnancy Register. 1381 women were assigned to the induction group and 1379 were assigned to the expectant management group.

INTERVENTIONS: Induction of labour at 41 weeks and expectant management and induction of labour at 42 weeks.

MAIN OUTCOME MEASURES: The primary outcome was a composite perinatal outcome including one or more of stillbirth, neonatal mortality, Apgar score less than 7 at five minutes, pH less than 7.00 or metabolic acidosis (pH <7.05 and base deficit >12 mmol/L) in the umbilical artery, hypoxic ischaemic encephalopathy, intracranial haemorrhage, convulsions, meconium aspiration syndrome, mechanical ventilation within 72 hours, or obstetric brachial plexus injury. Primary analysis was by intention to treat.

RESULTS: The study was stopped early owing to a significantly higher rate of perinatal mortality in the expectant management group. The composite primary perinatal outcome did not differ between the groups: 2.4% (33/1381) in the induction group and 2.2% (31/1379) in the expectant management group (relative risk 1.06, 95% confidence interval 0.65 to 1.73; P=0.90). No perinatal deaths occurred in the induction group but six (five stillbirths and one early neonatal death) occurred in the expectant management group (P=0.03). The proportion of caesarean delivery, instrumental vaginal delivery, or any major maternal morbidity did not differ between the groups.

CONCLUSIONS: This study comparing induction of labour at 41 weeks with expectant management and induction at 42 weeks does not show any significant difference in the primary composite adverse perinatal outcome. However, a reduction of the secondary outcome perinatal mortality is observed without increasing adverse maternal outcomes. Although these results should be interpreted cautiously, induction of labour ought to be offered to women no later than at 41 weeks and could be one (of few) interventions that reduces the rate of stillbirths.

TRIAL REGISTRATION: Current Controlled Trials ISRCTN26113652.