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. 2019 Sep 30;59(6):1262–1271. doi: 10.1093/rheumatology/kez405

Table 4.

Association between exposures after day 139 and preterm birth for RA

Time-dependent medication exposure after gestational day 139a n Preterm birth Person- weeks Rate (per 1000/ week) Crude HR (95% CI) Adjusted HRb (95% CI) Mutually adjusted HRc (95% CI)
Oral corticosteroid 253 51 4530 11.3 2.81 (1.80, 4.39) 1.64 (0.92, 2.92) 1.83 (1.01, 3.32)
No oral corticosteroid 368 31 7415 4.2 Reference Reference Reference
B-DMARD 215 25 4146 6.0 0.90 (0.56, 1.44) 0.91 (0.56, 1.47) 0.85 (0.52, 1.37)
No B-DMARD 389 57 7798 7.3 Reference Reference Reference
NB-DMARD 102 12 2092 5.7 0.83 (0.45, 1.53) 0.90 (0.48, 1.68) 0.94 (0.49, 1.78)
No NB-DMARD 447 70 9852 7.1 Reference Reference Reference
No medication of interest 234 18 4044 4.5 NA NA NA
Oral corticosteroid ≥10 mg/dayd 141 32 1836 17.4 4.57 (2.79, 7.49) 2.45 (1.32, 4.56) 2.47 (1.32, 4.63)
Oral corticosteroid <10 mg/dayd 177 19 2610 7.3 1.80 (1.02, 3.19) 1.18 (0.60, 2.30) 1.23 (0.63, 2.41)
No oral corticosteroid 371 31 7469 4.2 Reference Reference Reference
DMARD 266 33 5263 6.3 0.90 (0.58, 1.39) 0.89 (0.57, 1.41) 0.88 (0.56, 1.40)
No DMARD 335 49 6606 7.4 Reference Reference Reference
No medication of interest 232 18 4074 4.4 NA NA NA
a

An additional 30 days of exposure was added to reported end dates of use for oral corticosteroids and DMARDs.

b

One model for each medication of interest. HR adjusted for quintiles of the propensity score: last menstrual period year (<2009, ≤2009), maternal age, race and ethnicity (Non-Hispanic White, Other), multiple gestation, ≥5 servings of alcohol in the first trimester, autoimmune disease comorbidity (IBD, lupus or ankylosing spondylitis), oral corticosteroid cumulative dose trajectory before gestational day 110 (high, low, none), non-steroidal anti-inflammatory drug before gestational day 110 (any, none) and HAQ Disability Index, pain score and global score at enrolment.

c

One model, adjusting for each medication exposure group of interest and each associated propensity score.

d

Prednisone equivalent dose.

B-DMARD, biologic disease modifying antirheumatic drug; HR, hazard ratio; NA, not applicable; NB-DMARD, non-biologic disease-modifying antirheumatic drug.