Application of Big Data analysis in gastrointestinal research

Table 3 Examples of studies on gastric cancer research by utilization of large healthcare datasets

Gastric cancer
Country/Region	Database	Area of research	Sample size	Design, statistical methods and 3V	Application
Taiwan, China	Taiwan National Health Insurance Database (NHID)	GC	80255	Nationwide retrospective cohort study	Early vs late H. pylori eradication on GC risk
		Wu et al[46], 2009
				Comparison with general population to derive SIR
				Volume, Velocity and Variety
		GC	52161	Nationwide retrospective cohort study	Association between NSAIDs and GC
		Wu et al[48], 2010
				Comparison with general population to derive SIR
				Volume, Velocity and Variety
Hong Kong, China	Clinical Data Analysis and Reporting System (CDARS)	GC	63397	Territory-wide retrospective cohort study	Association between PPIs and GC
		Cheung et al[51], 2018
				PS regression adjustment
				Volume, Velocity and Variety
		GC	63605	Territory-wide retrospective cohort study	Association between aspirin and GC
		Cheung et al[49], 2018
				PS regression adjustment
				Volume, Velocity and Variety
		GC	63397	Territory-wide retrospective cohort study	Effect of H. pylori eradication among different age groups
		Leung et al[47], 2018
				Comparison with general population to derive SIR
				Volume, Velocity and Variety
		GC	7266	Territory-wide retrospective cohort study	Association between metformin and GC
		Cheung et al[50], 2018
				PS regression adjustment
				Sensitivity analysis: PS weighting by IPTW and PS matching
				Volume, Velocity and Variety
Sweden	Swedish Cancer Registry	GC	797067	Nationwide retrospective cohort study	Association between PPIs and GC
		Brusselaers et al[53], 2017
	Swedish Prescribed Drug Registry			Comparison with general population to derive SIR
				Volume, Velocity and Variety
		GC	95176	Nationwide retrospective cohort study	Effect of H. pylori eradication on GC risk
		Doorakkers et al[45], 2018
				Comparison with general population to derive SIR
				Volume, Velocity and Variety
United States	Kaiser Permanente (KP)	GC	61684	Retrospective cohort study	Association between different PPIs and GC
		Schneider et al[55], 2016
				Volume, Velocity and Variety

This list is not exhaustive, but serves to provide a few distinct examples of how Big Data analysis can generate high-quality research outputs in the field of gastroenterology and hepatology. 3V: Volume/velocity/variety; GC: Gastric cancer; SIR: Standardized incidence ratio; H. pylori: Helicobacter pylori; NSAIDs: Non-steroidal anti-inflammatory drugs; PS: Propensity score; PPIs: Proton pump inhibitors; IPTW: Inverse probability of treatment weighting.