Morbidity was defined by the Royal College of Surgeons Charlson Score, which is based on 14 groups of ICD-10 codes used in specialist and hospital care17
| Condition | ICD-10 codes |
|---|---|
| Myocardial infarction | I22–23, I252 |
| Congestive heart failure | I11, I13, I255, I42–43, I50, I517 |
| Peripheral vascular disease | I70–73, I770–I771, K551, K558–559, R02, Z958–959 |
| Cerebrovascular disease | G45–46, I60–69 |
| Dementia | A810, F00–03, F051, G30–31 |
| Chronic pulmonary disease | I26–27, J40–47, J60–67, J684, J701, J703 |
| Rheumatic disease | M05–06, M09, M120, M315, M32–36 |
| Liver disease | B18, I85, I864, I982, K70-71, K721, K729, K76, R162, Z944 |
| Diabetes mellitus | E10–14 |
| Hemiplegia/paraplegia | G114, G81–83 |
| Renal disease | I12-13, N01, N03, N05, N07–08, N171–172, N18–19, N25, Z49, Z940, Z992 |
| Malignancy | C00–26, C30–34, C37–41, C43, C45–58, C60–76, C80–85, C88, C90–97 |
| Metastatic tumours | C77–79 |
| HIV/AIDS | B20–24 |