Chronic kidney disease severely deteriorates the outcome of gastrointestinal bleeding: A meta-analysis

Table 1 Modified Newcastle-Ottawa Scale criteria

Adapted Newcastle-Ottawa Scale Items	High-quality items carrying a low risk of bias (green)	Low-quality items carrying a high (red) or an unknown (yellow) risk of bias
Item 1: Representativeness of the initial study population - patients with GI bleeding and CKD/ESRD	All patients with upper or lower GI bleeding and CKD/ESRD were included.	Low: any selection criteria were applied to the study population (e.g., only transplanted patients).
		Unknown: no data on selection process.
Item 2: Representativeness of the initial study population - patients with GI bleeding without CKD/ESRD	All patients with upper or lower GI bleeding without CKD/ESRD included.	Low: any selection criteria were applied to the study population.
		Unknown: no data on selection process.
Item 3: Ascertainment of exposure	We defined chronic renal failure as present when eGFR was < 60 mL/min at least 3 mo. We defined end-stage renal disease as a condition where hemodialysis or chronic peritoneal dialysis is performed at least for 3 mo.	Low: CKD or ESRD is not present in all of the patients.
		Unknown: no definitions of the conditions mentioned are provided.
Item 4: Comparability of cohorts A	Study controls for age: no significant difference was detected.	Low: significant difference was detected.
		Unknown: no statement.
Item 5: Comparability of cohorts B	Study controls for taking ulcerogenic drugs: no significant difference was detected	Low: significant difference was detected between taking ulcerogenic drugs.
		Unknown: no comparison made by taking ulcerogenic drugs.
Item 6: Follow-up time for rebleeding	The follow-up time is clearly defined.	Low: incomplete follow-up
		Unknown: no follow-up time is mentioned.

CKD: Chronic kidney disease; ESRD: End-stage renal disease.

Table 2 Basic characteristics of the studies included in the meta-analysis

Ref.	Country	Study type	Years of study	Group	Sample size	Age	Mortality	Transfusion	Rebleeding	Length of hospitalization
Boyle et al[17], 1983	United States	Retrospective	1977-1981	Control	40	54 ± 21	√	√	-	√
				CKD (mix)	20	59 ± 41
Cheung et al[10], 2010	Canada	Retrospective	2000-2006	Control	50	67 ± 13	√	√	√	√
				CKD	50	71 ± 13
				ESRD	50	68 ± 12
Hung et al[25], 2014	Taiwan	Retrospective	2007	Control	6322	54.6 ± 13.3	√	-	-	-
				ESRD	110	NR
Sood et al[9], 2012	United States	Retrospective	2007	Control	347245	NR	√	-	-	-
				CKD	35985	NR
				ESRD	14983	NR
Tsai et al[16], 1996	Taiwan	Prospective	1991-1994	Control	640	55.7 ± 16.22	√	√	√	-
				ESRD	58	64.1 ± 11.42
Zuckerman et al[26], 1985	United States	Retrospective	1980-1983	Control	423	63 (16-96)3	-	-	√	-
				CKD (mix)	59	57 (24-84)3

¹Data expressed as mean ± SEM (standard error of mean);

²Data expressed as mean ± SD (standard deviation);

³Data expressed as median (interquartile range). NR: Not reported; CKD: Chronic kidney disease; ESRD: End-stage renal disease.

Table 3 Stars based on the Modified Newcastle-Ottawa Scale

Ref.	Item 1	Item 2	Item 3	Item 4	Item 5	Item 6	Total (*)
Boyle et al[17], 1983	*	*	-	*	*		4
Cheung et al[10], 2010	*	*	*	*	*	*	6
Hung et al[25], 2014	*	*	-	-	-		2
Sood et al[9], 2012	*	*	-	-	-		2
Tsai et al[16], 1996	*	*	*	-	*	-	4
Zuckerman et al[26], 1985	*	*	-	-	-	*	3