Table 3 Candidate predictors

Candidate predictor

Units/categories

Definition

Variable type (number of categories)

Source data

 Age

Years

Year of birth subtracted from the year of study entry

Continuous

Primary care

 Sex

Male/female

As recorded

Categorical (2)

Primary care

 Ethnicity

White/mixed/Asian/Black/others

As recorded (codes collapsed into the five Census categories [18])

Categorical (5)

Primary care, secondary care

 Social deprivation

Index quintile

Patient Level Index of Multiple Deprivation, based on patient postcode

Categorical (5; data not accessible as continuous)

Secondary care

Candidate predictor

Units

Definition

Variable type

Source data

 BMI

Index (kg/m²)

As recorded

Continuous

Primary care

 Alcohol consumption

Non-drinker/ex-drinker/occasional drinker/moderate drinker/heavy drinker

Based on the records of daily and weekly units and drinker status codes [31] with equal classification for both sexes

Categorical (5)

Primary care

 Smoking

Non-smoker/ex-smoker/current smoker

As recorded

Categorical (3)

Primary care

 Use of injected drugs

Present/absent

As recorded

Categorical (2)

Primary care

Candidate predictor

Units

Definition

Variable type

Source data

 Hypertension

Present/absent

Diagnosis of hypertension or record of at least three high blood pressure readings within 1 year or at least two systolic or diastolic high blood pressure readings or prescriptions for blood pressure lowering medication within 6 months

Categorical (2)

Primary care, secondary care

 Diabetes

Type 1/type 2/

uncertain type/no diabetes

Diagnosis of diabetes and type

Categorical (4)

Primary care, secondary care

 Inflammatory bowel disease

Present/absent

Diagnosis of Crohn’s disease or ulcerative colitis

Categorical (2)

Primary care, secondary care

 Mental illness and behavioural disorders

Present/absent

Diagnosis of schizophrenia, psychosis, bipolar disorder, another mood affective disorder, depression, anxiety or phobia, reaction to stress or adjustment disorder

Categorical (2)

Primary care, secondary care

 Psoriasis

Present/absent

Primary and secondary care diagnoses, or diagnosis in one data source only and supportive information through referral, dermatologist visit, medication or positive laboratory test

Categorical (2)

Primary care, secondary care

 Cardiovascular disease

Present/absent

Diagnosis of stable or unstable angina, myocardial infarction, cerebrovascular disease, peripheral arterial disease, another atherosclerotic disease, heart failure, bradycardia, tachycardia, cardiac valve disorder, endocarditis, venous thromboembolism, atrial fibrillation or cardiomyopathy

Categorical (2)

Primary care, secondary care

 Cancer

Present/absent

As recorded

Categorical (2)

Primary care, secondary care

 HIV

Positive/negative

As recorded

Categorical (2)

Primary care, secondary care

 Co-morbidity score

Score

Charlson co-morbidity index excluding liver disease

Continuous

Primary care, secondary care

Candidate predictor

Units

Definition

Variable type

Source data

 Albumin

g/L

As recorded

Continuous

Primary care

 ALP

units/L

As recorded

Continuous

Primary care

 ALT

units/L

As recorded

Continuous

Primary care

 AST

units/L

As recorded

Continuous

Primary care

 Bilirubin

μmol/L

As recorded

Continuous

Primary care

 GGT

units/L

As recorded

Continuous

Primary care

 High-density lipoprotein

mmol/L

As recorded

Continuous

Primary care

 Low-density lipoprotein

mmol/L

As recorded

Continuous

Primary care

 Triglycerides

mmol/L

As recorded

Continuous

Primary care

 Total cholesterol

mmol/L

As recorded

Continuous

Primary care

 Platelet count

count/L

As recorded

Continuous

Primary care

Candidate predictor

Units

Definition

Variable type

Source data

 Bariatric surgery

Yes/no

As recorded

Categorical (2)

Primary care, secondary care

 Paracetamol overdose

Yes/no

As recorded

Categorical (2)

Primary care, secondary care

 Statins

Yes/no

Prescription of statins or statins with ezetimibe

Categorical (2)

Primary care

 Prescription non-steroid anti-inflammatory drugs

Yes/no

Prescription

Categorical (2)

Primary care

 Opioid substitution treatment

Yes/no

Prescription for methadone or buprenorphine

Categorical (2)

Primary care

 Cardiovascular drugs

Yes/no

Prescription for antiplatelet, antiarrhythmic, fibrinolytic, positive inotropic, hypertension and heart failure-related or lipid-regulating (excluding statins) drugs or beta blockers, diuretics, nitrates or warfarin

Categorical (2)

Primary care

 Antibiotics

Yes/no

As recorded

Categorical (2)

Primary care

 HAV vaccination

Received/not received

As recorded

Categorical (2)

Primary care

 HBV vaccination

Received/not received

As recorded

Categorical (2)

Primary care

 Pneumococcal vaccination

Received/not received

As recorded

Categorical (2)

Primary care

 Influenza vaccination

Received/not received

As recorded

Categorical (2)

Primary care