Dementia Phenotypes in Primary Care, Hospital, and National Mortality Registries

Dementia Phenotypes in Primary Care, Hospital, and National Mortality Registries: a Cohort Study in Linked Electronic Health Records

Most patients with dementia in the UK use their local hospitals and general (family) practices throughout their illness. Linked electronic health records from primary care, hospital and death certificates records therefore provide useful information about the diagnosis and prognosis of patients who develop dementia.

In this study we will assess the validity of dementia diagnoses in linked primary care, hospital and death records, by examining the timing of important health transitions in patients with recorded dementia, and we will estimate the lifetime risk of recorded dementia in different age and sex groups

Study Overview

• Status: Unknown
• Conditions: Dementia
• Intervention / Treatment: Other: This is not an intervention study

Detailed Description

Dementia is a clinical syndrome with insidious onset that is difficult to diagnose in its earliest stages. Presentation to healthcare depends not only upon the rates of disease progression, but also on social support, recognition by clinicians, and patients' and carers' fear of diagnosis. Maintaining complete follow up in cohorts of patient with dementia is difficult, because patients with dementia are frequently lost to follow up.

Most patients with dementia in the UK use their local hospitals and general (family) practices throughout their illness. Linked electronic health records from primary care, hospital and death certificates records should therefore provide useful information about the diagnosis and prognosis of patients who develop dementia with minimal loss to follow-up rates and improved completeness of diagnosis.

Demonstrating that patients with recorded dementia have an earlier onset of typical symptoms, functional impairment and death than patients in the general population would support the veracity of diagnosed dementia recorded in electronic health records and its use as an outcome or exposure in cohort studies and for evaluating policy. Previous studies have found that dementia is poorly recorded in routine clinical practice in comparison to face-to-face studies, although this varies by setting and region. However, ascertainment may be improved by examining linked, longitudinal resources. Comparing the lifetime risk of dementia calculated from linked electronic health records with lifetime risks from other sources will also be a useful information to support the use of linked electronic health records in dementia research.

Electronic health records contain information on important health transitions in patients with dementia: from the earliest stage of the illness (depression, anxiety, memory complaints); the development of cognitive impairment that manifest as loss of capacity or missed appointments; and significant functional impairment, with admission to nursing homes or hospital admission. In this study, we will assess the validity of dementia diagnoses in linked primary care, hospital and death records, by examining the timing of important health transitions in patients with recorded dementia, and estimate the lifetime risk of recorded dementia in different age and sex groups.

• Study Type: Observational
• Enrollment (Anticipated): 51000

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom
    • London Farr Institute of Health Informatics

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Patients registered in English general practices contributing with data to the CALIBER research platform from 1997 onward.

Description

Inclusion Criteria:

• Patients aged 18 years and over
• Registered with a participating general practice during the study period
• Minimum one year of records prior to study entry meeting CPRD data quality criteria
• Followed on or after 1 January 1997

Exclusion Criteria:

• Patients without recorded gender
• Less than 1 year of follow-up between study entry and date of administrative censoring

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Dementia; Patients with a recorded diagnosis of dementia in primary or secondary care	Other: This is not an intervention study; This study is based on the retrospective analysis of linked electronic health records.
Non-dementia; Patients without a recorded diagnosis of dementia in primary or secondary care	Other: This is not an intervention study; This study is based on the retrospective analysis of linked electronic health records.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of patients with dementia diagnosis (any type) in primary care that also are recorded in secondary care		10 years
Factors associated with dementia diagnosis (any type) recording in mortality data only	These will be estimated from multivariable logistic regression models	10 years
Symptoms associated with subsequent diagnosis of dementia	These will be estimated from multivariable logistic regression models	10 years
Lifetime risk of dementia (any type)		10 years
Lifetime risk of mortality associated with dementia (any time)		10 years
Factors associated with dementia diagnosis (any type) recording in secondary care only	These will be estimated from multivariable logistic regression models	10 years
Factors associated with dementia diagnosis (any type) recording in primary care only	These will be estimated from multivariable logistic regression models	10 years
Proportion of patients with dementia diagnosis (any type) in primary care that also are recorded in mortality data		10 years
Proportion of patients with dementia diagnosis (any type) in secondary care that also are recorded in mortality data		10 years

Secondary Outcome Measures

Outcome Measure	Time Frame
Proportion of patients with Alzheimer's disease in primary care that are also diagnosed in secondary care	10 years
Proportion of patients with vascular dementia in primary care that are also diagnosed in secondary care	10 years
Lifetime risk of Alzheimer's disease	10 years
Lifetime risk of vascular dementia	10 years
Lifetime risk of mortality associated with Alzheimer's disease	10 years
Proportion of patients with Alzheimer's disease in primary care that are also diagnosed in mortality data	10 years
Proportion of patients with Alzheimer's disease in secondary care that are also recorded in mortality data	10 years
Proportion of patients with vascular dementia in primary care that are also recorded in secondary care	10 years
Proportion of patients with vascular dementia in secondary care that are also recorded in mortality data	10 years

Collaborators and Investigators

• Sponsor: University College, London
• Collaborators: University of Leeds; Medical Research Council; University of Edinburgh

Study record dates

Study Major Dates

• Study Start: September 1, 2015
• Primary Completion (Anticipated): October 1, 2015
• Study Completion (Anticipated): December 1, 2015

Study Registration Dates

• First Submitted: September 3, 2015
• First Submitted That Met QC Criteria: September 11, 2015
• First Posted (Estimate): September 15, 2015

Study Record Updates

• Last Update Posted (Estimate): September 15, 2015
• Last Update Submitted That Met QC Criteria: September 11, 2015
• Last Verified: September 1, 2015

More Information

Terms related to this study

• Keywords: Dementia; Validity; Mortality; Electronic health records
• Additional Relevant MeSH Terms: Mental Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurocognitive Disorders; Dementia
• Other Study ID Numbers: 15_138