National data bases and classification of death in Sweden Sven Cnattingius, MD, PhD

The Swedish Birth Register Population-based Population-based ~100,000 births per year ~100,000 births per year Prospectively collected information on maternal, pregnancy and infant characteristics Prospectively collected information on maternal, pregnancy and infant characteristics

Variables in the Birth Register Maternal characteristics: Maternal characteristics: Age, parity, smoking, height, weight, country of birth – No SES; Pregnancy and delivery complications; Pregnancy and delivery complications; Birth weight, sex, gestational age; Birth weight, sex, gestational age; Infant diagnoses Infant diagnoses Stillbirths and live births Stillbirths and live births

Stillbirths in the Birth Register ≥28 completed weeks ≥28 completed weeks Antepartal and intrapartal Antepartal and intrapartal No registration of causes of death No registration of causes of death No information from autopsy, about chromosomal anomalies or infections No information from autopsy, about chromosomal anomalies or infections

TWO CLASSIFICATIONS OF CAUSES OF DEATH IN STILLBIRTHS AND NEONATAL (0-27) DEATHS Ingrid Winbo Fredrik Serenius Gisela Dahlquist Bengt Källén

I.IMPLICATIONS FOR CLINICAL MANAGEMENT ”THE MODIFIED WIGGLESWORTH CLASSIFICATION” (INT J EPIDEMIOL 1997;26: )

”THE MODIFIED WIGGLESWORTH CLASSIFICATION” LETHAL MALFORMATIONS LETHAL MALFORMATIONS SPECIFIC CONDITIONS* SPECIFIC CONDITIONS* ANTEPARTAL STILLBIRTHS* ANTEPARTAL STILLBIRTHS* INTRAPARTAL ASPHYXIA* INTRAPARTAL ASPHYXIA* IMMATURITY IMMATURITY UNCLASSIFIABLE CAUSES UNCLASSIFIABLE CAUSES

ALL DEATHS IN SWEDEN % Lethal malformations23 Specific conditions 5 Antepartal death43 Intrapartal asphyxia11 Immaturity16 Unclassifiable 2

Validation using medical records Total concordance: 88% Computer programme overestimates antepartal stillbirths (237 vs. 209) at the expense of: at the expense of: lethal malformations lethal malformations specific conditions specific conditions intrapartal asphyxia intrapartal asphyxia

II. Neonatal and Intrauterine death Classification according to Etiology (NICE) Etiology-oriented, similar to the Aberdeen model Winbo et al. Int J Epidemiol 1998;27:

CLASSIFICATION OF DEATHS BY ” NICE” % 1. CONGENITAL ANOMALIES MULTIPLE BIRTHS* 7 3. MATERNAL DISEASES* 4 4. SPECIFIC FETAL CONDITIONS* 1 5. UNEXPLAINED SGA* 9 6. PLACENTAL ABRUPTION* 8 7. OBSTETRIC COMPLICATION* 4 8. UNEXPLAINED PRETERM AP DEATH* UNEXPLAINED TERM AP DEATH* SPECIFIC INFANT CONDITIONS UNEXPLAINED ASPHYXIA* UNEXPLAINED IMMATURITY 8

WIGGLESWORTH VS. NICE WIGGLESWORTH VS. NICE WIGGLESWORTH NICE AP STILLBIRTHS (%) MULTIPLE BIRTH 6 MATERNAL DISEASE 5 SPECIFIC FETAL CONDITION 0 UNEXPLAINED SGA 16 PLACENTAL ABRUPTION 10 OBSTETRIC COMPLICATION 4 UNEXPLAINED PRETERM AP STILLBIRTH 23 UNEXPLAINED TERM AP STILLBIRTH TOTAL100

VALIDATION OF NICE UNEXPLAINED SGA (yes/no) RECORDS COMPUTERYESNO YES NO SENSITIVITY:30/32: 94% POSITIVE PREDICTIVE VALUE:30/42: 71%

VALIDATION OF NICE MATERNAL DISEASE (yes/no) RECORDS COMPUTERYESNO YES NO SENSITIVITY:29/45: 64% POSITIVE PREDICTIVE VALUE:29/34: 85%

VALIDATION OF NICE VALIDATION OF NICE SENSITIVITY % MULTIPLE BIRTH 88 MATERNAL DISEASE 64 SPECIFIC FETAL CONDITION 64 UNEXPLAINED SGA 94 PLACENTAL ABRUPTION 91 OBSTETRIC COMPLICATION 38 UNEXPLAINED PRETERM AP STILLBIRTH 76 UNEXPLAINED TERM AP STILLBIRTH 88

SMOKING AND RISK OF DEATH NICE Classification CAUSE OF DEATH OR MATERNAL DISEASE 1.0 UNEXPLAINED SGA 2.0 PLACENTAL ABRUPTION 2.8 OBSTETRIC COMPLICATION 1.1 UNEXPLAINED PRETERM AP DEATH 1.1 UNEXPLAINED TERM AP DEATH 1.1 Winbo et al. Acta Obstet Gynecol Scand 2001;80:235-44

HIGH MATERNAL AGE (>35 YEARS) AND RISK OF DEATH NICE Classification CAUSE OF DEATH OR MATERNAL DISEASE 1.8 UNEXPLAINED SGA 2.0 PLACENTAL ABRUPTION 1.2 OBSTETRIC COMPLICATION 1.4 UNEXPLAINED PRETERM AP DEATH 1.6 UNEXPLAINED TERM AP DEATH 1.9 Winbo et al. Acta Obstet Gynecol Scand 2001;80:235-44

CLASSIFICATION OF STILLBIRTHS –”REVISED NICE” estimated % 1. MULTIPLE BIRTHS 5 2. MATERNAL DISEASES 5 3. UNEXPLAINED SGA PLACENTAL ABRUPTION OBSTETRIC COMPLICATION 4 6. UNEXPLAINED PRETERM AP DEATH UNEXPLAINED TERM AP DEATH34 8. INTRAPARTAL STILLBIRTHS 4

OUTCOME IN SECOND BIRTH Source: Surkan et al, N Eng J Med. 2004; 350:777-85