Table 2.

Examples of the top rule for subsets.

Comorbidities	Keywordsa	Top rule	Lift	Count
Cardiovascular disease	‘x.michd’	{diffwalk,x.casthm1,x.rfhype5,x.rfsmok3} => {x.michd}	1.43	2783
Chronic pulmonary disease	chccopd1,’ ‘x.casthm1’	{diffalon,x.casthm1,x.drdxar1,x.rfsmok3} => {diffwalk}	1.93	2643
Rheumatoid arthritis	‘x.drdxar1’	{diffalon,x.casthm1,x.drdxar1,x.rfsmok3} => {diffwalk}	1.93	2676
Diabetes	‘diabete3’	{diffwalk,x.casthm1,x.rfchol1,x.rfhype5,x.rfsmok3} => {diabete3}	1.53	2726
Cancer	‘chcocncr’	{chcocncr,x.casthm1} => {x.age65yr}	1.2	2697

^aWe used the variable code to represent each variable. The meaning of the code is shown in Multimedia Appendix 1.