Areas of research and clinical approaches to the study of liver abscess

Table 1 Distribution of the number of documents published on liver abscess, by publication type and clinical research approach (2001-2015)

Year	Publication type					Document category (by clinical research approach)
	Article	Review	Letter	Others	Total1	Case reports	Clinical trial	Evaluation studies	Others	Total1
2001	68	13	9	-	90	60	-	-	-	60
2002	60	8	8	1	77	48	1	-	-	49
2003	70	12	12	-	94	63	2	2	1	68
2004	67	16	4	-	87	43	1	1	1	46
2005	62	3	7	-	72	49	1	-	-	50
2006	67	6	13	1	87	55	1	-	-	56
2007	76	6	16	-	98	73	-	1	-	74
2008	53	4	9	-	66	37	1	2	-	40
2009	71	7	12	-	90	59	3	-	-	62
2010	60	9	7	1	77	56	1	1	-	58
2011	79	5	15	-	99	74	-	3	1	78
2012	71	8	7	1	87	63	2	1	-	66
2013	80	9	17	-	106	67	1	-	-	68
2014	77	12	11	2	102	64	2	1	1	68
2015	39	3	4	-	46	31	-	-	1	32
Total	1000	121	151	6	1278	842	16	12	5	875

¹The difference between the two totals is due to the fact that not all documents have been assigned to a category based on their clinical research approach.

Table 2 Distribution of the top 15 countries that have led research on liver abscess, pyogenic liver abscess, and amebic liver abscess (2001-2015)

Liver abscess		Liver abscess, amebic		Liver abscess, pyogenic		Total
Country	n	Country	n	Country	n	Country	n
United States	165	India	69	Taiwan	71	United States	229
Japan	107	Mexico	69	United States	39	Taiwan	185
Taiwan	103	United States	29	China	29	India	145
South Korea	81	France	21	South Korea	21	Japan	144
India	67	Germany	21	Japan	19	South Korea	100
China	53	Japan	18	India	13	China	84
Germany	51	United Kingdom	16	Spain	11	Mexico	81
Spain	48	Taiwan	12	Italy	8	Germany	77
France	42	Malaysia	10	Turkey	7	France	68
United Kingdom	35	Brazil	9	United Kingdom	6	Spain	63
Italy	34	Pakistan	9	Germany	6	United Kingdom	57
Turkey	31	Bangladesh	7	Singapore	6	Italy	49
Singapore	21	Italy	7	Australia	5	Turkey	42
Canada	16	Thailand	6	France	5	Brazil	28
Australia	16	Spain/Turkey	5	Brazil/Canada	5	Singapore	27

Table 3 Distribution of the top 20 descriptors and topic qualifiers assigned to papers on liver abscess and type of liver abscess (2001-2015)

Liver abscess				Liver abscess, amebic				Liver abscess, pyogenic
Descriptor	n	Qualifier	n	Descriptor	n	Qualifier	n	Descriptor	n	Qualifier	n
Liver abscess	1278	Complications	560	Liver abscess, amebic	414	Diagnosis	181	Liver abscess, pyogenic	344	Complications	167
Humans	1227	Diagnosis	555	Humans	352	Parasitology	172	Humans	341	Microbiology	158
Male	845	Microbiology	537	Male	272	Complications	106	Male	266	Diagnosis	152
Female	580	Etiology	495	Entamoeba histolytica	207	Therapeutic use	104	Female	185	Etiology	120
Middle aged	549	Pathology	321	Animals	190	Pathology	102	Middle aged	173	Isolation and purification	95
Adult	411	Surgery	309	Adult	146	Drug therapy	94	Aged	139	Therapeutic use	88
Aged	391	Therapeutic use	307	Middle aged	141	Immunology	93	Adult	128	Therapy	87
Tomography, X-ray computed	363	Isolation and purification	294	Female	127	Isolation & purification	91	Klebsiella pneumoniae	92	Drug therapy	66
Anti-bacterial agents	227	Drug therapy	277	Metronidazole	76	Therapy	75	Klebsiella infections	91	Surgery	64
Drainage	194	Therapy	274	Cricetinae	67	Etiology	72	Anti-bacterial agents	85	Pathology	64
Treatment outcome	181	Radiography	248	Diagnosis, differential	62	Genetics	67	Retrospective studies	74	Radiography	56
Diagnosis, differential	179	Methods	222	Tomography, X-ray computed	59	Epidemiology	62	Tomography, X-ray computed	71	Methods	56
Liver neoplasms	173	Adverse effects	177	Entamoebiasis	52	Metabolism	59	Aged, 80 and over	69	Epidemiology	56
Klebsiella infections	164	Ultrasonography	138	Aged	51	Pathogenicity	59	Treatment outcome	64	Mortality	35
Klebsiella pneumoniae	163	Administration and dosage	97	Liver	48	Methods	58	Drainage	62	Ultrasonography	32
Liver	142	Genetics	95	Treatment outcome	47	Blood	47	Risk Factors	49	Genetics	25
Retrospective studies	133	Epidemiology	91	Antibodies, protozoan	45	Radiography	39	Adolescent	39	Metabolism	24
Animals	131	Pathogenicity	68	Dysentery, amebic	44	Surgery	37	Diagnosis, differential	33	Pathogenicity	19
Aged, 80 and over	118	Classification	67	Antiprotozoal agents	43	Ultrasonography	36	Taiwan	30	Adverse effects	19
Adolescent	94	Secondary	65	Drainage	41	Analysis	35	Prognosis	30	Administration and dosage	16

Table 4 Topic clusters and descriptors integrated within each for papers on liver abscess (2001-2015)

Cluster 1 (13 items)	Cluster 2 (8 items)	Cluster 3 (8 items)	Cluster 4 (7 items)	Cluster 5 (6 items)	Cluster 6 (6 items)	Cluster 5 (5 items)	Cluster 6 (5 items)
Antigens, bacterial	Bile duct neoplasms	Cholecystitis	Contrast media	Catheterization	Biopsy, needle	Anti-bacterial agents	Biopsy
Bacterial capsules	Carcinoma, Hepatocellular	Colonoscopy	Cysts	Cholangio-pancreatography	Risk, assessment	Ceftriaxone	Laparoscopy
Bacterial proteins	Catheter ablation	Echinococcosis, hepatic	Diagnosis, differential	Drainage	Severity of illness index	Gram-positive bacterial infections	Liver
Community-acquired infections	Chemoembolization, Therapeutic	Fatal outcome	Hemangioma	Endosonography	Suction	Metronidazole	Liver cirrhosis
Diabetes complications	Cholangiocarcinoma	Intestinal perforation	Image enhancement	Stents	Time factors	Sepsis	Necrosis
Electrophoresis, gel, pulsed field	Focal nodular Hyperplasia	Splenic diseases	Liver diseases	Ultrasonography, Interventional	Treatment outcome	-	-
Klebsiella infections	Hepatectomy	Tomography, X-ray computed	Sensitivity and specificity	-	-	-	-
Klebsiella pneumoniae	Liver neoplasms	Ultrasonography	-	-	-	-	-
Phenotype	-	-	-	-	-	-	-
Polysaccharides, bacterial	-	-	-	-	-	-	-
Serotyping	-	-	-	-	-	-	-
Virulence	-	-	-	-	-	-	-
Virulence factors	-	-	-	-	-	-	-