Table 1.

Comparison of two adverse event classification systems and the ‘reconciled’ version taken forward in this study

Forster et al13 (patients experiencing adverse events after discharge)		Brennan et al24 (patients experiencing adverse events in hospital)		Reconciled
Health Outcome	Proportion with the outcome	Health states	Proportion in each state	Health states	Proportion in each state
Death	0	Death	0.136	Death	0.05
Permanent disability*	0.03	Permanent disability >50%	0.026	Permanent disability >50%	0.02
		Permanent disability ≤50%	0.039	Permanent disability ≤50%	0.03
Readmission	0.21	Moderate impairment, recovery >6 months	0.028	Moderate impairment, recovery >6 months	0.10
A & E visit	0.11	Moderate impairment, recovery 1–6 months	0.137	Moderate impairment, recovery 1–6 months	0.30
Physician visit	0.14
No extra use of health service	0.51	Minimal impairment, recovery <1 month†	0.634	Minimal impairment, recovery <1 month	0.50

*These patients were also assumed to be readmitted to hospital (the observed readmission in the study was 24%).

†Brennan et al included an ‘unclassified’ category for 6.5% of adverse events—we have subsumed this into the ‘minimal impairment’ category.