To adjust for underestimation of rates using the linked datasets, and to correct for any linkage bias whereby the percentage of eligible cancer records linked varied by socio-demographic characteristics, we calculated weights for strata of age, sex, ethnicity, region, small area deprivation, and time since census.
All direct identifiers, as well as any characteristics that might lead to identification, were omitted from the linked dataset used in the present study.
The linked dataset used for our study remained representative of the GPRD overall, as whole practices rather than individual patients declined or consented to the linkage.
For the linked dataset, we used the same principal diagnosis range and admission source category as those for unlinked data, but disregarded discharge status.
Among patients in the linked dataset, 11.2% were found to have diabetes using Definition 1.c.
We used the recently linked English Hospital Episodes Statistics and General Practice Research Database, 1997 2010, to define events by; a specific upper gastrointestinal bleed code in either dataset, a specific bleed code in both datasets, or a less specific but plausible code from the linked dataset.
Further research is planned to link the TILDA dataset to the national prescribing database (HSE-PCRS) to facilitate the application of 19 additional STOPP criteria and to estimate the cost of PIP using these linked datasets.
We thank staff in the Centre for Epidemiology and Research: Kim Lim for management of the linked datasets and checking programmes used in the analysis, and George Doukas for administering the datasets held on the Health Outcomes and Information Statistical Toolkit HOISTT) data warehouse.
Design Cohort study using a linked dataset.
Using such a linked dataset, we report trends in event rate and case fatality for acute myocardial infarction and examine the relative contributions of changes in these rates to changes in mortality from acute myocardial infarction by sex and age between 2002 and 2010 in England.
