Estimating the effect of current, previous and never use of drugs in studies based on prescription registries

Lars Hougaard Nielsen; Ellen Løkkegaard; Anne Helms Andreasen; Yrsa Andersen Hundrup; Niels Keiding; Lars Hougaard Nielsen; Ellen Løkkegaard; Anne Helms Andreasen; Yrsa Andersen Hundrup; Niels Keiding

doi:10.1002/pds.1693

Estimating the effect of current, previous and never use of drugs in studies based on prescription registries

Lars Hougaard Nielsen, Ellen Løkkegaard, Anne Helms Andreasen, Yrsa Andersen Hundrup, Niels Keiding, Lars Hougaard Nielsen, Ellen Løkkegaard, Anne Helms Andreasen, Yrsa Andersen Hundrup, Niels Keiding

9 Citations (Scopus)

Abstract

PURPOSE: Many studies which investigate the effect of drugs categorize the exposure variable into never, current, and previous use of the study drug. When prescription registries are used to make this categorization, the exposure variable possibly gets misclassified since the registries do not carry any information on the time of discontinuation of treatment.In this study, we investigated the amount of misclassification of exposure (never, current, previous use) to hormone therapy (HT) when the exposure variable was based on prescription data. Furthermore, we evaluated the significance of this misclassification for analysing the risk of breast cancer. MATERIALS AND METHODS: Prescription data were obtained from Danish Registry of Medicinal Products Statistics and we applied various methods to approximate treatment episodes. We analysed the duration of HT episodes to study the ability to identify discontinuation of therapy from prescription data. Furthermore, we compared to results based on self-reported duration of HT from the Danish Nurse Cohort.Finally, we analysed the effect of HT exposure on time to breast cancer for the different prescription based exposure variables as well as for self-reported HT use. RESULTS: The results of time to discontinuation varied strongly across the different HT assessments. However, misclassification of HT exposure at baseline was limited and hence analysis of the effect of HT on time to breast cancer showed stability across the different exposure assessments with Hazard Ratios ranging from 1.68 to 1.78 for current use compared to never use. CONCLUSIONS: The findings suggest that it is possible to estimate the effect of never, current and previous use of HT on breast cancer using prescription data.

Original language	English
Journal	Pharmacoepidemiology and Drug Safety
Volume	18
Issue number	2
Pages (from-to)	147-53
Number of pages	6
ISSN	1053-8569
DOIs	https://doi.org/10.1002/pds.1693 https://doi.org/10.1002/pds.1693
Publication status	Published - 2009

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Nielsen, L. H., Løkkegaard, E., Andreasen, A. H., Hundrup, Y. A., Keiding, N., Nielsen, L. H., Løkkegaard, E., Andreasen, A. H., Hundrup, Y. A., & Keiding, N. (2009). Estimating the effect of current, previous and never use of drugs in studies based on prescription registries. Pharmacoepidemiology and Drug Safety, 18(2), 147-53. https://doi.org/10.1002/pds.1693, https://doi.org/10.1002/pds.1693

Nielsen, LH, Løkkegaard, E, Andreasen, AH, Hundrup, YA, Keiding, N, Nielsen, LH, Løkkegaard, E, Andreasen, AH, Hundrup, YA & Keiding, N 2009, 'Estimating the effect of current, previous and never use of drugs in studies based on prescription registries', Pharmacoepidemiology and Drug Safety, vol. 18, no. 2, pp. 147-53. https://doi.org/10.1002/pds.1693, https://doi.org/10.1002/pds.1693

@article{04540f30179411de8478000ea68e967b,

title = "Estimating the effect of current, previous and never use of drugs in studies based on prescription registries",

abstract = "PURPOSE: Many studies which investigate the effect of drugs categorize the exposure variable into never, current, and previous use of the study drug. When prescription registries are used to make this categorization, the exposure variable possibly gets misclassified since the registries do not carry any information on the time of discontinuation of treatment.In this study, we investigated the amount of misclassification of exposure (never, current, previous use) to hormone therapy (HT) when the exposure variable was based on prescription data. Furthermore, we evaluated the significance of this misclassification for analysing the risk of breast cancer. MATERIALS AND METHODS: Prescription data were obtained from Danish Registry of Medicinal Products Statistics and we applied various methods to approximate treatment episodes. We analysed the duration of HT episodes to study the ability to identify discontinuation of therapy from prescription data. Furthermore, we compared to results based on self-reported duration of HT from the Danish Nurse Cohort.Finally, we analysed the effect of HT exposure on time to breast cancer for the different prescription based exposure variables as well as for self-reported HT use. RESULTS: The results of time to discontinuation varied strongly across the different HT assessments. However, misclassification of HT exposure at baseline was limited and hence analysis of the effect of HT on time to breast cancer showed stability across the different exposure assessments with Hazard Ratios ranging from 1.68 to 1.78 for current use compared to never use. CONCLUSIONS: The findings suggest that it is possible to estimate the effect of never, current and previous use of HT on breast cancer using prescription data.",

author = "Nielsen, {Lars Hougaard} and Ellen L{\o}kkegaard and Andreasen, {Anne Helms} and Hundrup, {Yrsa Andersen} and Niels Keiding and Nielsen, {Lars Hougaard} and Ellen L{\o}kkegaard and Andreasen, {Anne Helms} and Hundrup, {Yrsa Andersen} and Niels Keiding",

note = "Keywords: Breast Neoplasms; Cohort Studies; Denmark; Drug Prescriptions; Drug Utilization Review; Female; Hormone Replacement Therapy; Humans; Pharmacoepidemiology; Questionnaires; Registries",

year = "2009",

doi = "10.1002/pds.1693",

language = "English",

volume = "18",

pages = "147--53",

journal = "Pharmacoepidemiology and Drug Safety",

issn = "1053-8569",

publisher = "JohnWiley & Sons Ltd",

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}

TY - JOUR

T1 - Estimating the effect of current, previous and never use of drugs in studies based on prescription registries

AU - Nielsen, Lars Hougaard

AU - Løkkegaard, Ellen

AU - Andreasen, Anne Helms

AU - Hundrup, Yrsa Andersen

AU - Keiding, Niels

AU - Nielsen, Lars Hougaard

AU - Løkkegaard, Ellen

AU - Andreasen, Anne Helms

AU - Hundrup, Yrsa Andersen

AU - Keiding, Niels

N1 - Keywords: Breast Neoplasms; Cohort Studies; Denmark; Drug Prescriptions; Drug Utilization Review; Female; Hormone Replacement Therapy; Humans; Pharmacoepidemiology; Questionnaires; Registries

PY - 2009

Y1 - 2009

N2 - PURPOSE: Many studies which investigate the effect of drugs categorize the exposure variable into never, current, and previous use of the study drug. When prescription registries are used to make this categorization, the exposure variable possibly gets misclassified since the registries do not carry any information on the time of discontinuation of treatment.In this study, we investigated the amount of misclassification of exposure (never, current, previous use) to hormone therapy (HT) when the exposure variable was based on prescription data. Furthermore, we evaluated the significance of this misclassification for analysing the risk of breast cancer. MATERIALS AND METHODS: Prescription data were obtained from Danish Registry of Medicinal Products Statistics and we applied various methods to approximate treatment episodes. We analysed the duration of HT episodes to study the ability to identify discontinuation of therapy from prescription data. Furthermore, we compared to results based on self-reported duration of HT from the Danish Nurse Cohort.Finally, we analysed the effect of HT exposure on time to breast cancer for the different prescription based exposure variables as well as for self-reported HT use. RESULTS: The results of time to discontinuation varied strongly across the different HT assessments. However, misclassification of HT exposure at baseline was limited and hence analysis of the effect of HT on time to breast cancer showed stability across the different exposure assessments with Hazard Ratios ranging from 1.68 to 1.78 for current use compared to never use. CONCLUSIONS: The findings suggest that it is possible to estimate the effect of never, current and previous use of HT on breast cancer using prescription data.

AB - PURPOSE: Many studies which investigate the effect of drugs categorize the exposure variable into never, current, and previous use of the study drug. When prescription registries are used to make this categorization, the exposure variable possibly gets misclassified since the registries do not carry any information on the time of discontinuation of treatment.In this study, we investigated the amount of misclassification of exposure (never, current, previous use) to hormone therapy (HT) when the exposure variable was based on prescription data. Furthermore, we evaluated the significance of this misclassification for analysing the risk of breast cancer. MATERIALS AND METHODS: Prescription data were obtained from Danish Registry of Medicinal Products Statistics and we applied various methods to approximate treatment episodes. We analysed the duration of HT episodes to study the ability to identify discontinuation of therapy from prescription data. Furthermore, we compared to results based on self-reported duration of HT from the Danish Nurse Cohort.Finally, we analysed the effect of HT exposure on time to breast cancer for the different prescription based exposure variables as well as for self-reported HT use. RESULTS: The results of time to discontinuation varied strongly across the different HT assessments. However, misclassification of HT exposure at baseline was limited and hence analysis of the effect of HT on time to breast cancer showed stability across the different exposure assessments with Hazard Ratios ranging from 1.68 to 1.78 for current use compared to never use. CONCLUSIONS: The findings suggest that it is possible to estimate the effect of never, current and previous use of HT on breast cancer using prescription data.

U2 - 10.1002/pds.1693

DO - 10.1002/pds.1693

M3 - Journal article

C2 - 19072775

SN - 1053-8569

VL - 18

SP - 147

EP - 153

JO - Pharmacoepidemiology and Drug Safety

JF - Pharmacoepidemiology and Drug Safety

IS - 2

ER -

Estimating the effect of current, previous and never use of drugs in studies based on prescription registries

Abstract

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