Association of pelvic inflammatory disease (PID) with ovarian cancer: a nationwide population-based retrospective cohort study from Taiwan

Table 2 Incidence and crude and adjusted risks of ovarian cancer according to age, comorbidity and monthly income for women with PID and those without (controls)

	Ovarian cancer			Crude HR (95% CI)	Adjusted HR^† (95% CI)
	Event	PY	IR	Crude HR (95% CI)	Adjusted HR^† (95% CI)
Pelvic inflammatory disease	168	613,316	0.27	1.67 (1.36–2.05)***	1.49 (1.21–1.84)***
Age, years
< 20	11	123,291	0.08	1 (reference)	1 (reference)
20–30	62	559,564	0.11	1.24 (0.65–2.36)	1.16 (0.61–2.22)
30–40	109	545,092	0.19	2.26 (1.21–4.20)**	1.98 (1.04–3.78)*
40–50	121	403,108	0.30	3.38 (1.82–6.27)***	3.01 (1.57–5.75)***
50–60	42	125,894	0.33	3.71 (1.91–7.21)***	3.32 (1.66–6.64)***
≥ 60	20	57,330	0.34	3.82 (1.83–7.97)***	3.31 (1.54–7.10)**
Comorbidity
Lynch syndrome and colon cancer	4	1200	3.33	16.1 (6.01–43.1)***	5.47 (1.48–20.1)*
Breast cancer	4	6104	0.65	3.20 (1.19–8.57)*	1.93 (1.03–5.23)*
Uterus cancer	5	832	6.00	25.5 (11.8–69.0)***	13.9 (5.70–34.2)***
Rectum cancer	3	864	3.47	16.6 (5.33–51.7)***	3.25 (0.72–14.6)
Endometriosis	41	54,969	0.74	3.97 (2.87–5.49)***	2.93 (2.09–4.12)***
Infertility	25	59,497	0.42	2.15 (1.43–3.23)***	1.84 (1.21–2.80)**
Obesity	3	10,516	0.28	1.38 (0.44–4.30)	1.09 (0.35–3.40)
Monthly income (NTD)
< 15,000	130	836,290	0.15	1 (reference)	1 (reference)
15,000–29,999	189	763,730	0.24	1.62 (1.29–2.02)***	1.13 (0.89–1.43)
≥ 30,000	46	214,260	0.21	1.40 (1.00–1.97)*	0.98 (0.69–1.39)

PID pelvic inflammatory disease, HR hazard ratio, PY person-years, IR incidence rate per 1000 person-years, CI confidence interval, NTD New Taiwan dollar
^†HR adjusted for age, Lynch syndrome and colon cancer, breast cancer, uterus cancer, rectum cancer, endometriosis, infertility, obesity, and monthly income
^*P < 0.05, **P < 0.01, ***P < 0.001, versus the reference group

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