Number of studies reporting (n, %) | Number of studies providing adjustment or stratification (n, %) | |
Patient age | 936 (95.0) | 145 (14.7) |
Comorbidities | 402 (40.8) | 146 (14.8) |
ASA status | 74 (7.5) | 33 (3.4) |
Case urgency | 730 (74.1) | 693 (70.4) |
HIV status | 45 (4.6) | 25 (2.5) |
Clinical Risk Score | 331 (33.6) | 141 (14.3) |
Reporting of case urgency required presentation of the proportion of planned versus emergent cases, or a population consisting exclusively of either planned or emergent cases. The latter group was considered to have reported mortality ‘stratified’ on urgency. ‘Adjustment or stratification’ implies a statistical analysis of the risk factor in relation to mortality, or mortality provided for separate strata.