Table 1

Summary of studies evaluating the timing of initiation of renal replacement therapy
					BUN at initiation of RRT (mg/dl)		Survival (%)

Study	Year	Mode of RRT	Study design	N	Early	Late	Early	Late

Parsons et al. [25]	1961	IHD	Retrospective	33	120–150	>200	75	12
Fisher et al. [26]	1966	IHD	Retrospective	162	~150	>200	43	26
Kleinknecht et al. [27]	1972	IHD	Retrospective	500	<93	>163	73	58
Conger [28]	1975	IHD	RCT	18	<70	~150	64	20
Gillum et al. [29]	1986	IHD	RCT	34	<60	~100	41	53
Gettings et al. [31]	1999	CRRT	Retrospective	100	<60	>60	39	20
Bouman et al. [12]	2002	CRRT	RCT	106	LV: 48 (40–66)^a	LV: 105 (62–116)^a	LV: 69	LV: 75
					HV: 46 (38–58)^a		HV: 74
Demirkiliç et al. [32]	2004	CRRT	Retrospective^b	61	NS	NS	77	45
Elahi et al. [33]	2004	CRRT	Retrospective^b	64	67 ± 35^c	75 ± 61^c	78	57
Piccinni et al. [34]	2006	CRRT	Retrospective^d	80	NS	NS	55	28
Liu et al. [35]	2006	IHD and CRRT	Observational	243	≤ 76	>76	65	59

^aMedian blood urea nitrogen (BUN; quartiles). ^bRRT started based on urine output <100 ml over 8 hours in early group and based on biochemical parameters in late group. ^cMean BUN ± standard deviation. ^dPatients with sepsis and oliguria; RRT started within 12 hours of ICU admission in early group and based on 'conventional indications'. CRRT, continuous renal replacement therapy; HV, high-volume hemofiltration; IHD, intermittent hemodialysis; LV, low-volume hemofiltration; NS, not specified; RCT, randomized controlled trial; RRT, renal replacement therapy.
Palevsky Critical Care 2007 11:232 doi:10.1186/cc6121