Colorectal cancer incidence on the General Practice Research Database

Abstract

PURPOSE: The General Practice Research Database (GPRD) contains longitudinal patient medical records collected within UK primary care. This study aimed to identify incident cases of colorectal cancer on the GPRD and to compare incidence rates for 2007 with those reported by the UK cancer registries. METHODS: Algorithms were created to identify incident cases of colorectal cancer on the GPRD and cases were required to have additional medical codes to support the diagnosis. Age-specific and sex-specific incidence rates for 2007 were calculated using the GPRD data and compared with those reported by the cancer registries. RESULTS: Trends in colorectal cancer by age and sex were similar for the two data sources; however, the incidence of colorectal cancer on the GPRD was lower than that of the registries, particularly when supporting evidence was required: 57.0 compared with 70.2 per 100 000 per year for men and 42.0 compared with 56.6 per 100 000 per year for women. Inclusion of cases without supporting evidence still resulted in lower rates but increased the GPRD rates to 63.7 and 48.4 for men and women, respectively. The largest discrepancy was observed in the older age groups. CONCLUSION: Colorectal cancer rates on the GPRD were lower than those reported by UK cancer registries, especially when requiring supporting evidence in addition to a diagnosis code. It appears that the requirement of supporting evidence on the GPRD for colorectal cancer identification may result in some true cases being excluded, particularly in the very elderly. Copyright © 2012 John Wiley & Sons, Ltd.

Cancer diagnosed by emergency admission in England: an observational study using the general practice research database

“…The discrepancy between earlier estimates and ours here may be due to differences in case assignment (diagnosis during two or three years compared with first-ever diagnosis, respectively) [31]. Compared to other sources such as cancer registries, GPRD data have produced a lower incidence of cancer but the GPRD also appears to contain valid and reliable records of cancer diagnoses [19,20]. …”

“…This finding may again be due to the sample size or the cancer types included in the study. With known sex-differences in risk and outcomes by different types of cancers, further research and especially studies by cancer type should continue to consider sex as a potential predictor [8,11,16,20]. …”

“…It includes clinical and non-clinical data, which can be linked with other data sources such as disease registries. It is renowned for its representational coverage of the English population and is well validated for epidemiological and biomedical research, including studies on cancer [15-20]. GPRD performs preliminary data cleaning to ensure that the data are of a consistent acceptable standard for research purposes (up-to-standard, UTS).…”

Colorectal Cancer Risk Reduction following Macrogol Exposure: A Cohort and Nested Case Control Study in the UK

“…A number of verification studies have shown the recording of CRC on the GPRD to be reliable [23], [29]–[32]. Comparison of CRC incidence on the GPRD to that reported by the national cancer registries has found age at diagnosis to be very similar, but CRC incidence rates on the GPRD were slightly lower than those reported by the national cancer registries [23]. It is possible therefore that we may have missed a small number of CRC cases and as a result unidentified cases could have been selected in principle as a matched control.…”

“…The algorithms used to identify incident cases of CRC have been described elsewhere [23]. To summarise, individuals were identified as newly diagnosed with CRC if they had one of the following:…”