Table 3. Independent risk factors in multivariate analysis.

Variables		Hazard ratio	p	95% confidence interval
Age (yr)		1.06	<0.001	1.06–1.07
Hospital stratification
	Medical centers	Reference
	Regional hospitals	0.64	<0.001	0.57–0.72
	District hospitals	0.50	<0.001	0.41–0.61
	Local hospitals	0.28	0.030	0.09–0.86
Urbanization
	Highly urbanized	Reference
	Moderately urbanized	0.85	0.010	0.75–0.96
	Newly urbanized	0.77	<0.001	0.66–0.91
	Rural areas	0.79	0.010	0.65–0.95
	Others*	0.87	0.240	0.69–1.10
Premium range (NTD/month)
	>15,840 and ≤25,000	Reference
	≤15,840	1.27	<0.001	1.10–1.46
	>25,000	1.23	<0.001	1.10–1.38
Comorbidity
	Depression	1.67	<0.001	1.21–2.30
	Pelvic inflammation	2.73	<0.001	2.32–3.22
Childbearing		0.69	0.010	0.52–0.92

NTD, New Taiwan Dollar.

^*Others includes areas with aged population, agricultural towns and cities, and remote areas.