SUPPLEMENTAL MATERIAL

European Journal of Epidemiology

Cerebrovascular and ischemic heart disease in young adults born preterm – a population-based Swedish cohort study

Authors and affiliations: Peter Uedaa MD PhD; Sven Cnattingiusa MD, PhD; Olof Stephanssona,b MD, PhD; Erik Ingelssonc MD, PhD; Jonas F. Ludvigssond MD, PhD; Anna-Karin Edstedt Bonamya MD, PhD a Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden b Department of Women’s and Children’s Health, Karolinska Institutet, Stockholm, Sweden c Department of Medical Sciences, Molecular Epidemiology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden. d Department of Pediatrics, Örebro University Hospital, Örebro, Sweden and Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Sweden.

Corresponding author: Anna-Karin Edstedt Bonamy. Email: [email protected]

1 Supplemental Table 1 Malformation diagnoses potentially related to either the exposures (preterm birth or low birth weight) or to the outcomes (cerebrovascular disease and ischemic heart disease).

ICD 10 ICD 8&9 Malformations of the nervous system Q00-Q07 740-7429

Malformations of the circulatory system Q20-28 (excluding Q25.0*) 7450-7479 (excluding 7470.09* and 747A*)

Congenital malformation syndromes due to known Q86 7598 exogenous causes, not elsewhere classified

Other specified congenital malformation syndromes Q87 7430, 7555, 7560, 7567, affecting multiple systems 7568, 7571, 7586, 7598

Other congenital malformations, not elsewhere classified Q89 7590 - 7599

Chromosomal abnormalities Q90-99 7580-7589

*Patent ductus arteriosus

2 Supplemental Table 2 Number of outcomes by ICD-10 codes for cerebrovascular disease

ICD-10 code group n Percent G45 Transient cerebral ischaemic attacks and related syndromes 170 17.8 I60 Subarachnoid haemorrhage 163 17.1 I61 Intracerebral haemorrhage 177 18.5 I62 Other nontraumatic intracranial haemorrhage 68 7.1 I63 Cerebral infarction 171 17.9 I64 Stroke, not specified as haemorrhage or infarction 26 2.7 I65 Occlusion and stenosis of precerebral arteries, not resulting in cerebral infarction 13 1.4 I66 Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction 8 0.8 I67 Other cerebrovascular diseases 155 16.2 I68 Cerebrovascular disorders in diseases classified elsewhere 4 0.4 Total 955 100

Supplemental Table 3 Number of outcomes by ICD-10 codes for ischemic heart disease.

ICD-10 code group n Percent I20 Angina pectoris 59 32.8 I21 Acute myocardial infarction 43 23.9 I22 Subsequent myocardial infarction 1 0.6 I23 Certain current complications following acute myocardial infarction 18 10.0 I24 Other acute ischaemic heart diseases 9 5.0 I25 Chronic ischaemic heart disease 50 27.8 Total 180 100

3 Supplemental Table 4 Gestational age and birth weight for gestational age and hazard ratios (HR) and 95% confidence intervals

(95% CI) for cerebrovascular disease and ischemic heart disease, respectively. Subjects born in Sweden

1983 to 1995 with follow-up from 15 years of age to December 31, 2010. Subjects with missing information on maternal smoking are excluded from both the crude and adjusted model.

Cerebrovascular disease a Gestational age N Cases, n Crude HR Adjusted (weeks) (95% CI) b HR (95% CI)

<32 6757 8 1.80 (0.90-3.61) 1.73 (0.86- 3.48) 32-36 60285 45 1.04 (0.77-1.41) 1.02 (0.75- 1.38) 37-41 994104 710 1.00 (ref) 1.00 (ref)

≥42 166808 128 1.09 (0.91-1.32) 1.07 (0.88- 1.29) Birth weight for gestational age (SD) <-2 38665 34 1.18 (0.83-1.66) 1.04 (0.72- 1.49) -2 to -1 179641 146 1.11 (0.92-1.33) 1.06 (0.88- 1.27) >-1 to +1 819263 577 1.00 (ref) 1.00 (ref) >+1 to +2 150427 101 0.98 (0.79-1.21) 0.99 (0.80- 1.22) >+2 39958 33 1.21 (0.85-1.72) 1.21 (0.85- 1.72)

Ischemic heart disease

4 a Gestational age N Cases, n Crude HR Adjusted (weeks) (95% CI) b HR (95% CI)

<32 6757 0 - - 32-36 1.56 (0.88-2.76) 1.58 (0.89- 60285 13 2.82) 37-41 994104 136 1.00 (ref) 1.00 (ref)

≥42 0.94 (0.59-1.49) 0.86 (0.54- 166808 21 1.38) Birth weight for gestational age (SD) <-2 1.02 (0.45-2.31) 0.94 (0.41- 38665 6 2.17) -2 to -1 1.08 (0.72-1.61) 1.00 (0.66- 179641 29 1.51) >-1 to +1 819263 118 1.00 (ref) 1.00 (ref) >+1 to +2 0.66 (0.38-1.15) 0.68 (0.39- 150427 14 1.19) >+2 0.54 (0.17-1.69) 0.55 (0.17- 39958 3 1.72) a Stratified by sex. Subjects with missing data on maternal smoking during pregnancy are excluded. b Stratified by sex and adjusted for maternal characteristics (country of birth, birth period, education, age, cardiovascular disease, preeclampsia, parity, smoking) and birth weight for gestational age or gestational age.

Subjects with missing data on maternal smoking during pregnancy are excluded.

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