Table 4.

Discriminative ability; number of subjects needed per group

	Specific PROs				Generic PROs
	HOOS			OHS	SF-12		EQ-5D
	Pain	PS	QoL		PCS	MCS	EQ-5D Index	EQ-VAS
Diagnoses a	116 e	57 e	115 e	80 e	51 e	75 d	107 e	56 e
Gender	502 e	456 e	760 e	298 e	1,886,596	2,736	414 e	521 e
Prosthesis groups b	2,295	645 e	10,308	795 e	6,471	1,137	1,124 d	207 e
Age c	15,461	814	685 d	1,566 d	384	361	3,360	270 e

^a Idiopathic OA, other arthritis, childhood diseases, high-impact injuries, and low-impact fractures.

^b Hybrid prostheses, cemented and uncemented prostheses.

^c Less than 50 years old, 50–70 years old, and more than 70 years old.

^d p < 0.05.

^e p < 0.001.