Abstract
Background/Aims Persistent oncogenic human papillomavirus (HPV) infection may lead to precancerous lesions, which health providers may remove using surgical procedures before the lesions progress to cervical cancer. This paper describes the methods used to establish a retrospective cohort of Kaiser Permanente Northwest (KPNW) members to test hypotheses that surgical procedures involving the cervix affect subsequent reproductive health and pregnancy outcomes.
Methods The HMORN Virtual Data Warehouse (VDW) was used to obtain health plan enrollment, diagnosis, procedure, pharmacy, and demographic data for 14- to 53-year-old female KPNW members during the study years, 1998–2009. A list of CPT and ICD-9 codes was used to identify women who were exposed to destructive or excisional procedures of interest. A group of unexposed women was selected by frequency-matching on age. Contraceptive data for all women in the cohort was pulled to account for time on and off various contraceptive methods, including: oral contraceptives, intrauterine devices (IUDs), implantable and injectable hormonal methods.
Results An age-matched cohort of 86,898 women was retrospectively established to compare the reproductive health outcomes of 4,138 women who were exposed to surgical cervical procedures to a 1:20 age-matched group of unexposed women. The demographic and contraceptive method use characteristics were similar for the exposed and unexposed members of the cohort. However, a greater proportion of exposed women than unexposed women used contraceptives at some point during the study period.
Conclusions We used the VDW tables to establish a retrospective cohort of women in which the effect of cervical procedures related to precancerous cervical lesions on reproductive health outcomes may be studied. An analytic dataset has been set up to perform Cox proportional hazards regression analyses adjusting for contraceptive use
