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Selection of medical diagnostic codes for analysis of electronic patient records. Application to stroke in a primary care database

Selection of medical diagnostic codes for analysis of electronic patient records. Application to stroke in a primary care database
Selection of medical diagnostic codes for analysis of electronic patient records. Application to stroke in a primary care database
BACKGROUND: Electronic patient records from primary care databases are increasingly used in public health and health services research but methods used to identify cases with disease are not well described. This study aimed to evaluate the relevance of different codes for the identification of acute stroke in a primary care database, and to evaluate trends in the use of different codes over time.

METHODS: Data were obtained from the General Practice Research Database from 1997 to 2006. All subjects had a minimum of 24 months of up-to-standard record before the first recorded stroke diagnosis. Initially, we identified stroke cases using a supplemented version of the set of codes for prevalent stroke used by the Office for National Statistics in Key health statistics from general practice 1998 (ONS codes). The ONS codes were then independently reviewed by four raters and a restricted set of 121 codes for 'acute stroke' was identified but the kappa statistic was low at 0.23.

RESULTS: Initial extraction of data using the ONS codes gave 48,239 cases of stroke from 1997 to 2006. Application of the restricted set of codes reduced this to 39,424 cases. There were 2,288 cases whose index medical codes were for 'stroke annual review' and 3,112 for 'stroke monitoring'. The frequency of stroke review and monitoring codes as index codes increased from 9 per year in 1997 to 1,612 in 2004, 1,530 in 2005 and 1,424 in 2006. The one year mortality of cases with the restricted set of codes was 29.1% but for 'stroke annual review,' 4.6% and for 'stroke monitoring codes', 5.7%.

CONCLUSION: In the analysis of electronic patient records, different medical codes for a single condition may have varying clinical and prognostic significance; utilisation of different medical codes may change over time; researchers with differing clinical or epidemiological experience may have differing interpretations of the relevance of particular codes. There is a need for greater transparency in the selection of sets of codes for different conditions, for the reporting of sensitivity analyses using different sets of codes, as well as sharing of code sets among researchers.
1932-6203
e7168
Gulliford, M.C.
443b6214-b206-405a-b13b-b93541e2defc
Charlton, J.
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Ashworth, M.
a70c436c-8405-4518-806d-1003fd9d5386
Rudd, A.G.
5d7b9b1b-61c2-48ad-a52d-507de9d4f40f
Toschke, A.M.
d60030c2-b280-4b05-a5e6-e628dedb862d
Delaney, B.
8f83ca0d-1d8e-4305-b67d-17017c925290
Grieve, A.
957dc084-75d0-425b-9c97-ac8ffbf7630e
Heuschmann, P.U.
0f602642-da39-47a0-acae-af7b6d30e6d0
Little, P.
1bf2d1f7-200c-47a5-ab16-fe5a8756a777
Redfern, J.
cf140b79-59d3-4d0a-a199-6793db62caba
van Staa, T.
7e263d59-ecc2-41f2-8b20-3f934d09c2c9
Wolfe, C.
a3a8f950-5654-4800-8366-fba53032c900
Yardley, L.
64be42c4-511d-484d-abaa-f8813452a22e
McDermott, L.
6b7131fb-da9b-4062-a297-81c923a73369
eCRT Research Team
Gulliford, M.C.
443b6214-b206-405a-b13b-b93541e2defc
Charlton, J.
0177b4df-4db7-4de8-b4bd-143b8e3ba169
Ashworth, M.
a70c436c-8405-4518-806d-1003fd9d5386
Rudd, A.G.
5d7b9b1b-61c2-48ad-a52d-507de9d4f40f
Toschke, A.M.
d60030c2-b280-4b05-a5e6-e628dedb862d
Delaney, B.
8f83ca0d-1d8e-4305-b67d-17017c925290
Grieve, A.
957dc084-75d0-425b-9c97-ac8ffbf7630e
Heuschmann, P.U.
0f602642-da39-47a0-acae-af7b6d30e6d0
Little, P.
1bf2d1f7-200c-47a5-ab16-fe5a8756a777
Redfern, J.
cf140b79-59d3-4d0a-a199-6793db62caba
van Staa, T.
7e263d59-ecc2-41f2-8b20-3f934d09c2c9
Wolfe, C.
a3a8f950-5654-4800-8366-fba53032c900
Yardley, L.
64be42c4-511d-484d-abaa-f8813452a22e
McDermott, L.
6b7131fb-da9b-4062-a297-81c923a73369

Gulliford, M.C., Charlton, J., Ashworth, M., Rudd, A.G., Toschke, A.M., Delaney, B., Grieve, A., Heuschmann, P.U., Little, P., Redfern, J., van Staa, T., Wolfe, C., Yardley, L. and McDermott, L. , eCRT Research Team (2009) Selection of medical diagnostic codes for analysis of electronic patient records. Application to stroke in a primary care database. PLoS ONE, 4 (9), e7168. (doi:10.1371/journal.pone.0007168). (PMID:19777060)

Record type: Article

Abstract

BACKGROUND: Electronic patient records from primary care databases are increasingly used in public health and health services research but methods used to identify cases with disease are not well described. This study aimed to evaluate the relevance of different codes for the identification of acute stroke in a primary care database, and to evaluate trends in the use of different codes over time.

METHODS: Data were obtained from the General Practice Research Database from 1997 to 2006. All subjects had a minimum of 24 months of up-to-standard record before the first recorded stroke diagnosis. Initially, we identified stroke cases using a supplemented version of the set of codes for prevalent stroke used by the Office for National Statistics in Key health statistics from general practice 1998 (ONS codes). The ONS codes were then independently reviewed by four raters and a restricted set of 121 codes for 'acute stroke' was identified but the kappa statistic was low at 0.23.

RESULTS: Initial extraction of data using the ONS codes gave 48,239 cases of stroke from 1997 to 2006. Application of the restricted set of codes reduced this to 39,424 cases. There were 2,288 cases whose index medical codes were for 'stroke annual review' and 3,112 for 'stroke monitoring'. The frequency of stroke review and monitoring codes as index codes increased from 9 per year in 1997 to 1,612 in 2004, 1,530 in 2005 and 1,424 in 2006. The one year mortality of cases with the restricted set of codes was 29.1% but for 'stroke annual review,' 4.6% and for 'stroke monitoring codes', 5.7%.

CONCLUSION: In the analysis of electronic patient records, different medical codes for a single condition may have varying clinical and prognostic significance; utilisation of different medical codes may change over time; researchers with differing clinical or epidemiological experience may have differing interpretations of the relevance of particular codes. There is a need for greater transparency in the selection of sets of codes for different conditions, for the reporting of sensitivity analyses using different sets of codes, as well as sharing of code sets among researchers.

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Published date: September 2009
Organisations: Primary Care & Population Sciences, Psychology

Identifiers

Local EPrints ID: 350027
URI: https://eprints.soton.ac.uk/id/eprint/350027
ISSN: 1932-6203
PURE UUID: 8acb4589-aa4a-4d39-82bb-fd650e7fba55
ORCID for L. Yardley: ORCID iD orcid.org/0000-0002-3853-883X

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Date deposited: 15 Mar 2013 16:49
Last modified: 01 Oct 2019 00:56

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