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Health outcome data

VERIFICATION AND ADJUDICATION

All the health outcomes collected from different sources are processed, checked, and standardised before being integrated into the central database. Since most disease outcomes are chiefly reported by the attending hospitals, the outcomes are typically accurate (e.g. more than 90% of reported stroke diagnoses are confirmed by brain imaging) with no further verification required.

As certain major diseases such as stroke and cancer have a heterogeneous aetiology, the routinely collected information about disease types and main subtypes (e.g. cancer histology) tended to be incomplete so CKB developed and implemented procedures and IT systems to undertake detailed outcome verification and adjudication based on the retrieved medical notes. Currently this work covers (stroke, heart diseases, cancer, and chronic kidney diseases but will be gradually extended to several other diseases (e.g. heart failure). This allows more reliable characterisation of disease types and relevant subtypes (e.g. lacunar ischaemic stroke) beyond that routinely recorded through disease registers.

 

FOLLOW-UP AND DATA LINKAGE

Health related outcome data collected includes cause-specific mortality, morbidity for four major diseases (stroke, IHD, cancers, and diabetes) and any episode of hospitalisation. The vital status of study participants is monitored regularly through official residential records and death certificates reported to the regional CDC, where each regional study coordinating office is based. All participant deaths are coded, using the ICD-10, by trained staff ‘blinded’ to baseline information. Causes of death from official death certificates are supplemented, if necessary, by review of medical records which are usually available.

Information on disease incidence for stroke, IHD, cancers, and diabetes is also collected through linkage with established disease registries in CKB study areas. Electronic linkage with the national health insurance system now covers about 98% of participants, and records details of all events for which participants were hospitalised including disease description, diagnostic procedures and ICD-10 code. By the end of 2021, about 14% (more than 70,000) of the participants were known to have died. More than 60% had been hospitalised for some reason. There were a total of about 1.5 million episodes of hospitalisation of any type. Only approximately 1% were lost to follow-up.