. 2022 Nov 16;6(4):BJGPO.2022.0049. doi: 10.3399/BJGPO.2022.0049

Table 2. Definition of risk factors for adverse course of COVID-19.

Risk factor	Definition and ICPC-1 codes where relevant
Age	Patients aged ≥70 years as of 1 January 2020
Sex	Male
Obesity	Body mass index >29 as of 1 January 2020
Smoking	Patents with an active or previous smoking status as of 1 January 2020
Heart disease^a	K74 Angina pectoris, K75 and K76 Myocardial infarction, K77 Heart failure, K78 Atrial fibrillation
Diabetes mellitus^a	T90 Diabetes mellitus
Severe chronic respiratory disease^a	R91 Chronic bronchitis, R89 Congenital anomaly respiratory, R91 Bronchiectasis, R95 COPD
HIV infection^a	B90 use of antiviral medication for HIV infection
Severe renal disease^a	U99 (.01) Renal impairment and eGFR <25 ml/min/1.73 m²
Severe liver disease^a	D97 Cirrhosis, Liver failure of liver decompensation, Contraindication label liver impairment
Down's syndrome^a	A90 (.01) Down's syndrome

^aThese risk factors were merged into one comorbidity variable. The presence of each single risk factor or disease was counted as one and added together as count variable. COPD = chronic obstructive pulmonary disease. eGFR = estimated glomerular filtration rate. ICPC-1 = International Classification of Primary Care codes first edition.