Gabapentin and Risk of Pancreatic Cancer and Renal Cancer (GPRD)

Risk of Pancreatic Cancer and Renal Cancer in Patients Exposed to Gabapentin in the United Kingdom General Practice Research Database

High doses of gabapentin are associated with pancreatic acinar cell tumors in rats, but there has been no post marketing pancreatic carcinogenicity signal with gabapentin as reported by spontaneous reports in the Adverse Events Reporting System or in the published literature. In a published case-control screening study of the association of gabapentin with 55 cancers, the only cancer that met the screening criteria for possibly increased cancer risk with gabapentin exposure was renal (including renal pelvis) cancer. This association was judged to be likely due to or substantially accentuated by confounding by cigarette smoking, hypertension, and lifestyle (Cancer Causes Control 2009;20:1821-1835).

The primary objective of this study is to determine whether exposure to gabapentin is associated with an increased risk of developing pancreatic cancer or renal cancer in the United Kingdom (UK) General Practice Research Database (GPRD). Almost all members of the UK population are registered with a General Practice, which centralizes the medical information not only from the general practitioners themselves but also from specialist referrals and hospital attendances. Over 487 General Practices contribute data to the GPRD.

The study cohort from which cases and controls are drawn is all subjects in the GPRD 1993-2008. Gabapentin was approved in the UK in May 1993. Entry into the study cohort begins Jan 1, 1993 for all those who are registered in GPRD before that time, and at the time of registration if later than Jan 1, 1993. Patients with a first diagnosis of the respective cancer 1995-2008 are risk set matched with up to 10 controls within the same General Practice for age at cohort entry (within two years), sex, and year of entry into the study cohort (within one year). For cases, the index date is the date of first diagnosis of the respective cancer. The index date for controls is set as the date at which the follow-up time from cohort entry is the same as the case. The index date is chosen so as to give the control equal follow-up time to that of the case for ascertainment of use of gabapentin. Cases and controls will be required to have at least 2 years of follow-up in the study cohort before their index date. Data on gabapentin prescriptions are obtained for cases and controls from study cohort entry to the index date.

Crude and adjusted odds ratios and 95% confidence intervals (CI) will be produced from conditional logistic regression models, with additional analyses evaluating for latency and dose-response. For pancreatic cancer, covariates are smoking, body mass index, diabetes, epilepsy, neuropathic pain, and chronic pancreatitis. For renal cancer, covariates are smoking, body mass index, diabetes, hypertension, diuretic use, epilepsy, and neuropathic pain.

Study Overview

• Status: Completed
• Conditions: Epilepsy; Renal Cell Carcinoma; Hypertension; Diabetes; Restless Legs Syndrome; Pancreatic Cancer; Neuropathic Pain; Chronic Pancreatitis; Renal Cancer; Renal Pelvis Cancer
• Intervention / Treatment: Drug: Gabapentin prescriptions

Detailed Description

Patients were not recruited for nor enrolled in this study. This study is a retrospective observational study. Data from medical records or insurance claims databases are anonymised and used to develop a patient cohort. All diagnoses and treatment are recorded in the course of routine medical practice. Actual number of patients could be less than , as it is possible for a patient to be represented in more than one of the four arms (See "Participant Flow: Overall Study" Table) because of the risk set sampling.

• Study Type: Observational
• Enrollment (Actual): 54202

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

The study cohort from which cases and controls are drawn is all subjects in the UK GPRD 1993-2008. Entry into the study cohort begins Jan 1, 1993 for all those who are registered in GPRD before that time, and at the time of registration if later than Jan 1, 1993. Follow-up ends Dec 31, 2008, or earlier if the respective cancer is diagnosed, or if the subject leaves the GPRD for any reason including death. There are several advantages to the GPRD dataset for this study. It is a large dataset with detailed longitudinal prescription data, and long term follow-up (mean 7 years) to allow for latency in carcinogenicity. It provides good representation of the elderly who are disproportionately affected by pancreatic and renal cancers, and routinely includes data recorded by general practitioners on potential risk factors such as smoking and body mass index.

Description

Inclusion Criteria:

• The study cohort from which cases and controls are drawn is all subjects in the UK GPRD 1993-2008. Entry into the study cohort begins Jan 1, 1993 for all those who are registered in GPRD before that time, and at the time of registration if later than Jan 1, 1993. Follow-up ends Dec 31, 2008, or earlier if the respective cancer is diagnosed, or if the subject leaves the GPRD for any reason including death.

Exclusion Criteria:

• Cases and controls will be required to have at least 2 years of follow-up in the study cohort before their index date (For cases, the index date is the date of first diagnosis of the respective cancer. The index date for controls is set as the date at which the follow-up time from cohort entry is the same as the case.)

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Control
• Time Perspectives: Retrospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

UK GPRD 1993-2008; The study cohort from which cases and controls are drawn is all subjects in the United Kingdom (UK) General Practice Research Database (GPRD) 1993-2008. Each member of the UK population is registered with a General Practice, which centralizes the medical information not only from the general practitioners themselves but also from specialist referrals and hospital attendances. Over 487 General Practices contribute data to the GPRD. Entry into the study cohort begins Jan 1, 1993 for all those who are registered in GPRD before that time, and at the time of registration if later than Jan 1, 1993.

Drug: Gabapentin prescriptions; The exposure of interest is gabapentin use as defined by prescriptions recorded by the GPRD general practitioner (British National Formulary codes). Data on prescriptions for gabapentin will be extracted for each case and control from entry into the study cohort up to the index date (the exposure window). Gabapentin exposure will be parameterized as follows: (1) Ever versus never exposed; (2) Number of prescriptions; (3) Duration of exposure; and (4) Cumulative dose. These parameterizations will also be examined with a 2 year lag time from the index date, limiting the exposure window from entry into the study cohort up to 2 years prior to the index date.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Pancreatic Cancer Cases and Matched Controls With the Indicated Exposure to Gabapentin	Incident pancreatic cancer. Gabapentin Exposure Description: Without 2 year lag = Gabapentin prescription from cohort entry to index date. With 2 year lag = Gabapentin prescription from cohort entry to 2 years prior to index date (to control for prediagnostic prescribing for pain symptoms possibly related to cancer).	The case index date (ID) was the date of incident pancreatic cancer diagnosis ascertained in the GPRD study cohort 1995-2008. The matched control ID was the date at which the follow-up time from his/her cohort entry was the same as that for the case
Number of Pancreatic Cancer Cases and Matched Controls With the Indicated Number of Gabapentin Prescriptions	Incident pancreatic cancer. Gabapentin Exposure Description: Without 2 year lag = Gabapentin exposure from cohort entry to index date. With 2 year lag = Gabapentin exposure from cohort entry to 2 years prior to index date (to control for prediagnostic prescribing for pain symptoms possibly related to cancer). Tertiles without 2 year lag: Tertile 1 (1-2 prescriptions),Tertile 2 (3-8 prescriptions), and Tertile 3 (9-218 prescriptions). Tertile's with 2 year lag: Tertile 1 (1-2 prescriptions), Tertile 2 (3-10 prescriptions),Tertile 3 (11-191 prescriptions).	The case index date (ID) was the date of incident pancreatic cancer diagnosis ascertained in the GPRD study cohort 1995-2008. The matched control ID was the date at which the follow-up time from his/her cohort entry was the same as that for the case
Number of Pancreatic Cancer Cases and Matched Controls With the Indicated Duration of Exposure to Gabapentin	Incident pancreatic cancer. Gabapentin Exposure Description: Without 2 year lag = Gabapentin exposure from cohort entry to index date. With 2 year lag = Gabapentin exposure from cohort entry to 2 years prior to index date (to control for prediagnostic prescribing for pain symptoms possibly related to cancer). Tertile's without 2 year lag: Tertile 1 (0.01 - 1.55 months), Tertile 2 (1.56 - 6.44 months), and Tertile 3 (6.45 - 78.36 months). Tertile's with 2 year lag: Tertile 1 (0.01 - 1.78 months), Tertile 2 (1.79 - 7.20 months), and Tertile 3 (7.21 - 64.13 months).	The case index date (ID) was the date of incident pancreatic cancer diagnosis ascertained in the GPRD study cohort 1995-2008. The matched control ID was the date at which the follow-up time from his/her cohort entry was the same as that for the case
Number of Pancreatic Cancer Cases and Matched Controls With the Indicated Cumulative Dose of Gabapentin	Incident pancreatic cancer. Gabapentin Exposure Description: Without 2 year lag = Gabapentin exposure from cohort entry to index date. With 2 year lag = Gabapentin exposure from cohort entry to 2 years prior to index date (to control for prediagnostic prescribing for pain symptoms possibly related to cancer). Tertile's without 2 year lag: Tertile 1 (0.01 - 33.6 grams), Tertile 2 (33.7 - 185.0 grams), and Tertile 3 (185.1 - 7500.2 grams). Tertile's with 2 year lag: Tertile 1 (0.01 - 39.0 grams), Tertile 2 (39.1 - 210.0 grams), and Tertile 3 (210.1 - 5623.8 grams).	The case index date (ID) was the date of incident pancreatic cancer diagnosis ascertained in the GPRD study cohort 1995-2008. The matched control ID was the date at which the follow-up time from his/her cohort entry was the same as that for the case
Number of Renal Cancer Cases and Matched Controls With the Indicated Exposure to Gabapentin	Incident renal cancer. Gabapentin Exposure Description: Without 2 year lag = Gabapentin prescription from cohort entry to index date. With 2 year lag = Gabapentin prescription from cohort entry to 2 years prior to index date (to control for prediagnostic prescribing for pain symptoms possibly related to cancer).	The case index date (ID) was the date of incident renal cancer diagnosis ascertained in the GPRD study cohort 1995-2008. The matched control ID was the date at which the follow-up time from his/her cohort entry was the same as that for the case.
Number of Renal Cancer Cases and Matched Controls With the Indicated Number of Gabapentin Prescriptions	Incident renal cancer. Gabapentin Exposure Description: Without 2 year lag = Gabapentin exposure from cohort entry to index date. With 2 year lag = Gabapentin exposure from cohort entry to 2 years prior to index date (to control for prediagnostic prescribing for pain symptoms possibly related to cancer). Tertiles without 2 year lag: Tertile 1 (1-2 prescriptions),Tertile 2 (3-8 prescriptions), and Tertile 3 (9-218 prescriptions). Tertile's with 2 year lag: Tertile 1 (1-2 prescriptions), Tertile 2 (3-10 prescriptions),Tertile 3 (11-191 prescriptions).	The case index date (ID) was the date of incident renal cancer diagnosis ascertained in the GPRD study cohort 1995-2008. The matched control ID was the date at which the follow-up time from his/her cohort entry was the same as that for the case.
Number of Renal Cancer Cases and Matched Controls With the Indicated Duration of Exposure to Gabapentin	Incident renal cancer. Gabapentin Exposure Description: Without 2 year lag = Gabapentin exposure from cohort entry to index date. With 2 year lag = Gabapentin exposure from cohort entry to 2 years prior to index date (to control for prediagnostic prescribing for pain symptoms possibly related to cancer). Tertile's without 2 year lag: Tertile 1 (0.01 - 1.55 months), Tertile 2 (1.56 - 6.44 months), and Tertile 3 (6.45 - 78.36 months). Tertile's with 2 year lag: Tertile 1 (0.01 - 1.78 months), Tertile 2 (1.79 - 7.20 months), and Tertile 3 (7.21 - 64.13 months).	The case index date (ID) was the date of incident renal cancer diagnosis ascertained in the GPRD study cohort 1995-2008. The matched control ID was the date at which the follow-up time from his/her cohort entry was the same as that for the case.
Number of Renal Cancer Cases and Matched Controls With the Indicated Cumulative Dose of Gabapentin	Incident renal cancer. Gabapentin Exposure Description: Without 2 year lag = Gabapentin exposure from cohort entry to index date. With 2 year lag = Gabapentin exposure from cohort entry to 2 years prior to index date (to control for prediagnostic prescribing for pain symptoms possibly related to cancer). Tertile's without 2 year lag: Tertile 1 (0.01 - 33.6 grams), Tertile 2 (33.7 - 185.0 grams), and Tertile 3 (185.1 - 7500.2 grams). Tertile's with 2 year lag: Tertile 1 (0.01 - 39.0 grams), Tertile 2 (39.1 - 210.0 grams), and Tertile 3 (210.1 - 5623.8 grams).	The case index date (ID) was the date of incident renal cancer diagnosis ascertained in the GPRD study cohort 1995-2008. The matched control ID was the date at which the follow-up time from his/her cohort entry was the same as that for the case.

Collaborators and Investigators

• Sponsor: GlaxoSmithKline

Study record dates

Study Major Dates

• Study Start: March 1, 2010
• Primary Completion (Actual): August 1, 2010
• Study Completion (Actual): August 1, 2010

Study Registration Dates

• First Submitted: June 3, 2010
• First Submitted That Met QC Criteria: June 3, 2010
• First Posted (Estimate): June 7, 2010

Study Record Updates

• Last Update Posted (Actual): May 30, 2017
• Last Update Submitted That Met QC Criteria: May 24, 2017
• Last Verified: May 1, 2017

More Information

Terms related to this study

• Keywords: epidemiology; pancreatic cancer; renal pelvis cancer; renal cell carcinoma; renal cancer; GPRD; case-control; Gapabentin
• Additional Relevant MeSH Terms: Mental Disorders; Digestive System Diseases; Nervous System Diseases; Neoplasms by Histologic Type; Neoplasms; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Wake Disorders; Urologic Neoplasms; Urogenital Neoplasms; Neoplasms by Site; Kidney Diseases; Urologic Diseases; Adenocarcinoma; Carcinoma; Neoplasms, Glandular and Epithelial; Pain; Neurologic Manifestations; Endocrine System Diseases; Digestive System Neoplasms; Endocrine Gland Neoplasms; Neuromuscular Diseases; Peripheral Nervous System Diseases; Parasomnias; Pancreatic Diseases; Kidney Neoplasms; Carcinoma, Renal Cell; Restless Legs Syndrome; Neuralgia; Pancreatic Neoplasms; Pelvic Neoplasms; Pancreatitis; Pancreatitis, Chronic; Physiological Effects of Drugs; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Central Nervous System Depressants; Peripheral Nervous System Agents; Analgesics; Sensory System Agents; Excitatory Amino Acid Antagonists; Excitatory Amino Acid Agents; Tranquilizing Agents; Psychotropic Drugs; Anti-Anxiety Agents; Anticonvulsants; Antimanic Agents; Gabapentin
• Other Study ID Numbers: 114427; EPI40634 (Other Identifier: GSK); WEUSKOP4774 (Other Identifier: GSK)