Table 2.

HRs and 95% CIs of CRC risk associated with melatonin use

	Individuals, n	Person-years	CRC diagnoses, n	IR, per 10,000 person-years	Crude			Adjusteda
					HR	95% CI	P value	HR	95% CI	P value
Ever use of melatonin
No	175,971	744,141	954	12.82	1			1
Yes	58,657	245,304	255	10.40	0.80	0.71–0.91	<0.001	0.82	0.72–0.92	0.001
Cancer site
Proximal colon
Nonusers	175,971	744,141	380	5.11	1			1
Melatonin users	58,657	245,304	112	4.57	0.88	0.74–1.06	0.184	0.89	0.74–1.08	0.237
Distal colon
Nonusers	175,971	744,141	272	3.66	1			1
Melatonin users	58,657	245,304	71	2.89	0.78	0.62–0.99	0.037	0.80	0.63–1.01	0.058
Rectum
Nonusers	175,971	744,141	283	3.80	1			1
Melatonin users	58,657	245,304	66	2.69	0.70	0.55–0.89	0.004	0.73	0.58–0.93	0.011
Stage at cancer diagnosis
Stage I or II
Nonusers	175,971	744,141	418	5.62	1			1
Melatonin users	58,657	245,304	110	4.48	0.79	0.66–0.95	0.013	0.78	0.65–0.94	0.010
Stage III or IV
Nonusers	175,971	744,141	420	5.64	1			1
Melatonin users	58,657	245,304	110	4.48	0.78	0.65–0.94	0.010	0.82	0.68–0.99	0.041

CCI, Charlson Comorbidity Index; CI, confidence interval; COPD, chronic obstructive pulmonary disease, CRC, colorectal cancer; HR, hazard ratio; IR, incidence rate.

^aAdjusted for age at index, sex, education, family history of CRC, personal history of inflammatory bowel disease, use of colonoscopy, obesity, COPD, CCI, use of aspirin, use of statin, and use of metformin.