TABLE 4.

Effects of patient factors, type of tooth, treatment visits on extraction adjusted using Cox regression analysis

Parameters	Hazard ratioa	Standard error	P	95% confidence interval
Gender
Male	ref.
Female	0.704	0.004	0.000	0.693-0.714
Age (years)
20-29	ref.
30-49	1.719	0.016	0.000	1.671-1.767
50-64	2.563	0.024	0.000	2.490-2.638
≧65	2.959	0.027	0.000	2.864-3.058
Household income quantile
Low	ref.
Highest	0.934	0.009	0.001	0.910-0.958
High-middle	0.950	0.010	0.006	0.924-0.977
High	0.947	0.009	0.000	0.922-0.972
Low-middle	0.976	0.010	0.108	0.949-1.005
Lowest (Medical beneficiary)	0.995	0.033	0.937	0.907-1.090
Health insurance subscription type
Local subscribers	ref.
Employee	0.952	0.003	0.000	0.945-0.960
Institution type
Local clinic	ref.
Hospital	1.054	0.020	0.353	0.993-1.120
Tertiary Hospital	0.949	0.037	0.300	0.849-1.061
Number of visits
Single-visit for treatment	ref.
Multiple visits for treatment	0.802	0.006	0.000	0.788-0.816
Tooth type
Mandibular molar	ref.
Mandibular premolar	0.954	0.006	0.000	0.937-0.972
Mandibular anteriors	0.674	0.006	0.000	0.658-0.691
Maxillary molar	0.514	0.006	0.000	0.499-0.530
Maxillary premolar	0.506	0.005	0.000	0.491-0.521
Maxillary anteriors	0.440	0.007	0.000	0.420-0.460

^aHazard ratio is the relative risk of having adverse reaction when compared with the reference group=1. A hazard ratio >1 indicates a higher risk of developing an adverse outcome (i.e., loss of tooth) relative to the reference group=1