Table 1.

Comparisons of oral contraceptive pill (OCP) users and nonusers (n = 571) with ankylosing spondylitis (AS).

VariablesFrequencies (%) or Mean (SD)p
OCP Users, n = 448Non-OCP Users, n = 123
Age, yrs (SD)42.7 (11.5)48.4 (12.1)< 0.0001
Age at menstruation, yrs (SD)12.5 (1.7)12.4 (1.9)0.68
Age at start of back pain, yrs (SD)24.4 (10.4)24.6 (10.3)0.90
Age at diagnosis of AS, yrs (SD)36.5 (11.2)39.1 (11.9)0.02
Age at menopause, yrs (SD)44.8 (9.2)46.3 (7.4)0.28
Race, white vs others400 (91.7)104 (86)0.06
Menstrual cycle regular319 (71.2)91 (74)0.54
Menopause reached141 (31.5)66 (53.7)< 0.0001
Currently pregnant6 (1.3)0 (0)0.35
Past pregnancies300 (67)87 (70.7)0.45
Pregnancy complications142 (47.5)35 (40.7)0.27
Other methods of contraception281 (62.7)62 (51.2)0.02
Tumor necrosis factor inhibitor use293 (65.4)74 (60.2)0.28
Opioid use186 (41.5)56 (45.5)0.47
Past hip surgery19 (4.2)8 (6.5)0.29