Missing laboratory test data in electronic general practice records: analysis of rheumatoid factor recording in the clinical practice research datalink

Cormac J Sammon; Anne Miller; Kamal R Mahtani; Tim A Holt; Neil J McHugh; Raashid A Luqmani; Alison L Nightingale

doi:10.1002/pds.3750

Missing laboratory test data in electronic general practice records: analysis of rheumatoid factor recording in the clinical practice research datalink

Cormac J Sammon, Anne Miller, Kamal R Mahtani, Tim A Holt, Neil J McHugh, Raashid A Luqmani, Alison L Nightingale

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Abstract

PURPOSE: To investigate whether information from the literature could be used to identify periods of practice data in an electronic healthcare database during which rheumatoid factor (RF) test results are likely to be missing-not-at-random (MNAR).

METHODS: RF tests recorded in the Clinical Practice Research Datalink (CPRD) were identified and defined as having a positive, negative or missing result. The proportion of positive test results was then calculated based on (i) complete-case analysis (ii) after restriction to tests from practice years with no missing test results and (iii) following multiple imputation of missing test results. The same three analyses were then carried out after excluding practice years with a proportion of positive tests incompatible with the missing completely at random (MCAR) assumption.

RESULTS: We identified 127 969 RF test records, 30.4% of which did not have an associated test result. Among tests with results available, 19% were positive. Both multiple imputation of the 38 867 missing test results and restriction of the study population to the 491 practice years with complete data had little impact on the percentage of positive tests. Following exclusion of the 544 practice years in which data were likely to be MNAR the percentage of positive tests in all analyses decreased to ~7%.

CONCLUSIONS: Recording of RF tests and RF test results in the CPRD is incomplete, with data likely to be MNAR in many practices. Exclusion of practice years with a high proportion of positive tests brought the distribution of positive tests in the study in line with the literature.

Original language	English
Pages (from-to)	504-509
Journal	Pharmacoepidemiology and Drug Safety
Volume	24
Issue number	5
Early online date	10 Mar 2015
DOIs	https://doi.org/10.1002/pds.3750
Publication status	Published - May 2015

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10.1002/pds.3750

Sammon_RF_methods - REVISION_SEPT2014
This is the peer reviewed version of the following article: Sammon, C. J., Miller, A., Mahtani, K. R., Holt, T. A., McHugh, N. J., Luqmani, R. A., & Nightingale, A. L. (2015). Missing laboratory test data in electronic general practice records: analysis of rheumatoid factor recording in the clinical practice research datalink. Pharmacoepidemiology and Drug Safety, 24(5), 504-509. , which has been published in final form at http://dx.doi.org/10.1002/pds.3750. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."
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title = "Missing laboratory test data in electronic general practice records: analysis of rheumatoid factor recording in the clinical practice research datalink",

abstract = "PURPOSE: To investigate whether information from the literature could be used to identify periods of practice data in an electronic healthcare database during which rheumatoid factor (RF) test results are likely to be missing-not-at-random (MNAR).METHODS: RF tests recorded in the Clinical Practice Research Datalink (CPRD) were identified and defined as having a positive, negative or missing result. The proportion of positive test results was then calculated based on (i) complete-case analysis (ii) after restriction to tests from practice years with no missing test results and (iii) following multiple imputation of missing test results. The same three analyses were then carried out after excluding practice years with a proportion of positive tests incompatible with the missing completely at random (MCAR) assumption.RESULTS: We identified 127 969 RF test records, 30.4% of which did not have an associated test result. Among tests with results available, 19% were positive. Both multiple imputation of the 38 867 missing test results and restriction of the study population to the 491 practice years with complete data had little impact on the percentage of positive tests. Following exclusion of the 544 practice years in which data were likely to be MNAR the percentage of positive tests in all analyses decreased to ~7%.CONCLUSIONS: Recording of RF tests and RF test results in the CPRD is incomplete, with data likely to be MNAR in many practices. Exclusion of practice years with a high proportion of positive tests brought the distribution of positive tests in the study in line with the literature. ",

author = "Sammon, {Cormac J} and Anne Miller and Mahtani, {Kamal R} and Holt, {Tim A} and McHugh, {Neil J} and Luqmani, {Raashid A} and Nightingale, {Alison L}",

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AU - Holt, Tim A

AU - McHugh, Neil J

AU - Luqmani, Raashid A

AU - Nightingale, Alison L

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N2 - PURPOSE: To investigate whether information from the literature could be used to identify periods of practice data in an electronic healthcare database during which rheumatoid factor (RF) test results are likely to be missing-not-at-random (MNAR).METHODS: RF tests recorded in the Clinical Practice Research Datalink (CPRD) were identified and defined as having a positive, negative or missing result. The proportion of positive test results was then calculated based on (i) complete-case analysis (ii) after restriction to tests from practice years with no missing test results and (iii) following multiple imputation of missing test results. The same three analyses were then carried out after excluding practice years with a proportion of positive tests incompatible with the missing completely at random (MCAR) assumption.RESULTS: We identified 127 969 RF test records, 30.4% of which did not have an associated test result. Among tests with results available, 19% were positive. Both multiple imputation of the 38 867 missing test results and restriction of the study population to the 491 practice years with complete data had little impact on the percentage of positive tests. Following exclusion of the 544 practice years in which data were likely to be MNAR the percentage of positive tests in all analyses decreased to ~7%.CONCLUSIONS: Recording of RF tests and RF test results in the CPRD is incomplete, with data likely to be MNAR in many practices. Exclusion of practice years with a high proportion of positive tests brought the distribution of positive tests in the study in line with the literature.

AB - PURPOSE: To investigate whether information from the literature could be used to identify periods of practice data in an electronic healthcare database during which rheumatoid factor (RF) test results are likely to be missing-not-at-random (MNAR).METHODS: RF tests recorded in the Clinical Practice Research Datalink (CPRD) were identified and defined as having a positive, negative or missing result. The proportion of positive test results was then calculated based on (i) complete-case analysis (ii) after restriction to tests from practice years with no missing test results and (iii) following multiple imputation of missing test results. The same three analyses were then carried out after excluding practice years with a proportion of positive tests incompatible with the missing completely at random (MCAR) assumption.RESULTS: We identified 127 969 RF test records, 30.4% of which did not have an associated test result. Among tests with results available, 19% were positive. Both multiple imputation of the 38 867 missing test results and restriction of the study population to the 491 practice years with complete data had little impact on the percentage of positive tests. Following exclusion of the 544 practice years in which data were likely to be MNAR the percentage of positive tests in all analyses decreased to ~7%.CONCLUSIONS: Recording of RF tests and RF test results in the CPRD is incomplete, with data likely to be MNAR in many practices. Exclusion of practice years with a high proportion of positive tests brought the distribution of positive tests in the study in line with the literature.

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Missing laboratory test data in electronic general practice records: analysis of rheumatoid factor recording in the clinical practice research datalink

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