Table 1.
Description of denominator populations and condition definitions
| Condition-specific denominator population | Condition definition | ||
|---|---|---|---|
| Diabetic emergency | All individuals (aged ≥11 years) with prevalent diagnoses of diabetes at the start of each week of follow-up; individuals contributed to the study population from whichever was latest of the start of follow-up in the overall population and the date of their first record indicating a diagnosis of diabetes | Any record of diabetes-related hyperglycaemia, hypoglycaemia, ketoacidosis, or diabetic coma. Multiple records occurring within 7 days of each other were considered to represent the same event | |
| Mental health conditions | |||
| Anxiety | All individuals (aged ≥11 years) from the overall study population | Any record of symptoms or diagnoses of social phobia, agoraphobia, panic, generalised anxiety disorder, and mixed anxiety and depression; multiple records occurring within 7 days of each other were considered to represent the same event | |
| Depression | All individuals (aged ≥11 years) from the overall study population | Any record of major depressive disorder, dysthymia, mixed anxiety and depression, and adjustment disorders with depressed mood; we also included codes for depressive symptoms; multiple records occurring within 7 days of each other were considered to represent the same event | |
| Self-harm | All individuals (aged ≥11 years) from the overall study population | Records that indicated explicit or undetermined intention to self-harm, non-suicidal or suicidal self-harm (including overdoses with drugs commonly implicated in suicide, such as paracetamol); multiple records occurring within 7 days of each other were considered to represent the same event | |
| Serious mental illness | All individuals (aged ≥11 years) from the overall study population | Diagnoses of schizophrenia and other psychotic disorders, and bipolar disorders; multiple records occurring within 7 days of each other were considered to represent the same event | |
| Eating disorder | All individuals (aged ≥11 years) from the overall study population | Anorexia nervosa, bulimia nervosa, and other specified feeding and eating disorders; multiple records occurring within 7 days of each other were considered to represent the same event | |
| Obsessive-compulsive disorder | All individuals (aged ≥11 years) from the overall study population | Codes for body dysmorphic disorders, hypochondriasis, hoarding disorder, and body focused repetitive behaviour disorders; multiple records occurring within 7 days of each other were considered to represent the same event | |
| Acute respiratory events | |||
| Asthma exacerbation | All individuals (aged ≥11 years) with a current asthma diagnosis (ie, asthma code in the past 2 years if aged <18 years or the past 3 years if aged ≥18 years); individuals joined the study population from the start of follow-up in the overall population if there was a current asthma diagnosis (within past 2–3 years) at that time, or from the date of their first record indicating an asthma diagnosis within the overall follow-up period; participants remained in the study until there was no current asthma diagnosis or until the end of overall follow-up; they could re-enter the study if there was a later diagnostic code for asthma before the end of overall follow-up; following an existing definition, individuals aged ≥40 years with asthma were considered likely to have COPD (and therefore not included in the asthma denominator population) if they had a subsequent COPD diagnosis recorded within the 2 years following the current asthma record21 | Records for morbidity codes for asthma exacerbations and status asthmaticus, and a primary care prescription for an oral corticoseroid;22 multiple records occurring within 14 days of each other were considered to represent the same event | |
| COPD exacerbation | Adults (aged ≥41 years) with an established diagnosis of COPD and evidence of a smoking history;23 individuals joined the study population from whichever was latest of the start of follow-up in the overall population and the date of their first record indicating diagnosis of COPD | Morbidity codes (in individuals with existing COPD) for COPD exacerbations, lower respiratory tract infections, breathlessness or sputum production, and a new prescription for an oral corticosteroid or antibiotic;24 multiple records occurring within 14 days of each other were considered to represent the same event | |
| Acute cardiovascular events | |||
| Myocardial infarction | All adults (aged ≥31 years) | Any record for myocardial infarction allowing for a 1-year window between successive records; multiple records occurring within 1 year of each other were considered to represent the same event | |
| Unstable angina | All adults (aged ≥31 years) | Any record for unstable angina, allowing for a 6-month window between successive records; multiple records occurring within 6 months of each other were considered to represent the same event | |
| Transient ischaemic attacks | All adults (aged ≥31 years) | Any record for transient ischaemic attack, allowing for a 6-month window between successive records; multiple records occurring within 6 months of each other were considered to represent the same event | |
| Stroke | All adults (aged ≥31 years) | Any record for stroke, allowing for a 1-year window between successive records; multiple records occurring within 1 year of each other were considered to represent the same event | |
| Cardiac failure | All adults (aged ≥31 years) | Given the complexity with capturing acute events for a chronic condition, we only counted an individual's first ever diagnosis with cardiac failure | |
| Venous thromboembolism (pulmonary embolism and deep venous thrombosis) | All adults (aged ≥31 years) | Any record for venous thromboembolism, allowing for a 1-year window between successive records; multiple records occurring within 1 year of each other were considered to represent the same event | |
| Acute alcohol-related event | All adults (aged ≥18 years) | Any record for acute physical or psychological alcohol-related event, including acute alcoholic pancreatitis; multiple records occurring within 14 days of each other were considered to represent the same event | |
COPD=chronic obstructive pulmonary disease.