Preparing linked population data for research: cohort study of prisoner perinatal health outcomes

Table 1 Selection of source records and linked records received by researchers for the Mothers and Gestation in Custody (MAGIC) study

	Admitted Patient Data Collection (APDC-M)	Pharmaceutical Drugs of Addiction System (PDAS)	Offender Integrated Management System (OIMS)	Perinatal Data Collection^a (PDC)		Admitted Patient Data Collection (APDC-N)	Register of Congenital Conditions^b (RoCC)
Selection rules	MH^c diagnosis; aged 18–44 years; admitted Jul 00–Dec 06	Authorised for OST^d Jan 98–Dec 06; aged 18–44 years	Incarcerated Jan 98–Dec 06; aged 18–44 years	Birth Jan 98–Dec 06; mother aged 18–44 years		Admitted Jul 00–Jan 07; aged 0–28 days	Birth Jan 00–Dec 06
	<-------------Linked by mother -------------->				<------- Linked by baby ------->
Event	MH^c admission	Authority for OST^d	Incarceration	Maternity^a	Birth^a	Neonatal episode
Selected^e	230,139	…	…	…	563,547	202,500
Received^e	60,464^f	14,481^f	9,042^f	93,284	94,996^f	37,081^f
Person	Woman admitted with MHM	Woman authorised for OST	Prisoner	Mother	Baby	Ill neonate	Baby with anomaly
Selected^e	81,896	12,526	10,372	404,144	563,547	…	9,945
Received^e
Linked	27,511	3,008	3,087	28,973	42,724	32,888	1,384^f
Unlinked	–	–	–	37,504	52,272	–	–
Total	27,511	3,008	3,087	66,477	94,996	32,888	1,384

Notes:
^a PDC birth records are unique to a mother-baby pair
^b RoCC were provided as person-based records. Person identifiers are removed from the register after 5 years
^c Mental health (MH) admission episodes include one or more ICD10-AM [11] diagnoses of a psychiatric disorder (F00-F09, F20-F99), self-harm (X60-X84, Y10-Y19, Y87.0, Z91.5), drug use (F11-F19, T40, T42, T43), alcohol use (E24.4, F10, G31.2, G62.1, G72.1, I426, K29.2, K70, K86.0, O35.4, R78.0, T51, X45, X65, Y15, Y57.3, Y90, Y91, Z50.2, Z71.4, Z72.1), or flagged as a psychiatric admission
^d OST is opiate substation therapy
^e The number of records supplied by source data custodians for record linkage were reported to researchers by the CHeReL. Received records were those made available to researchers after linkage or generated from the data received
^f The six data sets that were received by researchers
… not available – not applicable

ISSN: 1471-2288