Table 12. Routinely collected data for Hertfordshire Cohort Study.

a) Mortality
Objective:	To investigate the impact on cause-specific mortality of 1) early growth and 2) sociodemographic, lifestyle, medical and biological characteristics in later life. To monitor attrition among HCS members.
Methodology:	37,000 individuals born between 1911 and 1939 were identified from the HV records and flagged on the NHS Central Register for continuous notification of death (Objective 1). Sociodemographic, lifestyle, medical and biological data were collected from subsets of these individuals in later life, including the 3000 participants in HCS (Objective 2).
Source:	Office for National Statistics
Key data availability:
•   Date of death    •   Underlying cause of death (ICD-10)    •   Multiple causes contributing to death (ICD-10)
b) Hospital admissions
Objective:	To investigate risk factors for hospital admission among community dwelling older people.
Methodology:	An extract of Hospital Episode Statistics in-patient data covering the years 1998-2010 was obtained. 8741 admissions experienced by HCS members between the date of their home interview and 31/03/2010 were linked to the study database.
Source:	NHS Digital
Key data availability:
•   Postcode    •   Date of admission    •   Method of admission    •   Source of admission    •   Date of discharge    •   Destination on discharge    •   Main specialty    •   Primary diagnosis (ICD-10)    •   Other diagnoses (ICD-10)    •   Primary procedure (OPCS-4)    •   Other procedures (OPCS-4)