Table 3.

Subgroup analysis based on study location, type of participants and population size

Subgroups	No. of studies	No. of patients	OR and P value for mortality of different symptoms
			GI symptom	I 2 for GI symptom	Diarrhea	Nausea/vomiting	Abdominal pain
1. Study location
1.1 Asia	28	39,501 (72%)	1.43, P=0.01	54.7%	1.32, P=0.21	1.3, P=0.36	1.07, P=0.85
Sub-subgroups for studies in Asia:
1.1.1 GI group older than non-GI group	7	32,894	2.43, P<0.01	66.9%
1.1.2 GI group younger than non-GI group	6	3048	1.2, P=0.29	15.8%
1.2 America	12	8324 (15%)	0.64, P<0.01	42.7%	0.81, P=0.37	0.84, P=0.8	NA
Sub-subgroups for studies in America:
1.2.1 GI group older than non-GI group	NA	NA	NA	NA
1.2.2 GI group younger than non-GI group	5	3990	0.55, P<0.01	30.6%
1.3 Europe	10	2653 (5%)	0.4, P<0.01	77%	0.51, P=0.07	0.7, P=0.51	0.61, P=0.76
Sub-subgroups for studies in Europe:
1.3.1 GI group older than non-GI group	NA	NA	NA	NA
1.3.2 GI group younger than non-GI group	3	805	0.23, P<0.01	84%
1.4 Other	3	4767(8%)	0.92, P=0.83	87.8%	0.93, P=0.92	NA	NA
2. Only include critically ill patients?
3.1 Yes	6	1124(2%)	1.42, P=0.36	74.6%	1.3, P=0.45	0.92, P=0.71	0.75, P=0.45
3.2 No	47	54,121 (98%)	0.83, P=0.1	78.3%	0.92, P=0.69	1.37, P=0.28	2.67, P=0.05
3. Population size
4.1 <500	36	7436 (13%)	0.93, P=0.66	72.1%	1.05, P=0.82	1.19, P=0.51	1.04, P=0.92
4.2 >=500	17	47,809 (87%)	0.84, P=0.25	85.7%	0.94, P=0.83	1.16, P=0.68	NA
4. Average age of GI group and non-GI group
4.1 GI group older than non-GI group	8	33,294 (60%)	1.89, P=0.02	69%
4.2 GI group younger than non-GI group	14	7843 (14%)	0.61, P=0.01	80%
4.3 Unknown	31	14,058 (26%)	0.89, P=0.36	64%

OR, odds ratio; GI, gastrointestinal; NA, not available