Table 3.

 Rate ratio estimates of venous thrombosis between users of different types of non-oral hormonal contraception and users of combined oral contraceptives (COC) with levonorgestrel and 30-40 µg oestrogen (reference group)

Outcome, contraception type	Woman years	No with venous thrombosis	Adjusted rate ratio (95% CI)*	P value
All venous thrombosis:
COC with levonorgestrel and 30-40 µg oestrogen	231 675	201	1.00 (reference)	—
COC with norgestimate	298 566	198	1.11 (0.91 to 1.35)	0.305
Patch	6178	7	1.85 (0.87 to 3.94)	0.109
Vaginal ring	50 334	55	1.81 (1.34 to 2.44)	0.0001
Implant	29 497	15	0.88 (0.52 to 1.48)	0.623
Levonorgestrel IUS	239 841	88	0.34 (0.26 to 0.43)	<0.001
Confirmed events:
COC with levonorgestrel and 30-40 µg oestrogen	231 675	144	1.00 (reference)	—
COC with norgestimate	298 566	135	1.11 (0.88 to 1.41)	0.378
Patch	6178	6	2.46 (1.09 to 5.58)	0.031
Vaginal ring	50 334	39	2.02 (1.41 to 2.89)	0.0001
Implant	29 497	5	0.44 (0.18 to 1.07)	0.070
Levonorgestrel IUS	239 841	33	0.18 (0.12 to 0.26)	<0.001
Confirmed events adjusted for length of use:
COC with levonorgestrel and 30-40 µg oestrogen	231 675	144	1.00 (reference)	—
COC with norgestimate	298 566	135	1.09 (0.86 to 1.38)	0.465
Patch	6178	6	2.31 (1.02 to 5.23)	0.045
Vaginal ring	50 334	39	1.90 (1.33 to 2.71)	0.001
Implant	29 497	5	0.43 (0.18 to 1.05)	0.064
Levonorgestrel IUS	239 841	33	0.18 (0.12 to 0.26)	<0.001

Patch=transdermal contraceptive patch (EVRA; Johnson & Johnson, NJ, USA); implant=subcutaneous implant (Implanon; MSD; NJ, USA); vaginal ring=combined hormonal vaginal ring (NuvaRing; MSD, NJ, USA); levonorgestrel IUS=levonorgestrel intrauterine system (Mirena; Bayer Pharma, Berlin, Germany).

*Adjusted for age, calendar year, and education.