Female sex hormones have been suggested to increase the risk of gastroesophageal reflux symptoms via a relaxing effect on the lower esophageal sphincter.
Dr Helena Nordenstedt and colleagues from Sweden investigated the relationship of oral contraceptives and postmenopausal hormone therapy to risk of reflux symptoms, controlling for genetic factors and body mass.
|The risk of reflux symptoms was increased by 32%|
The team obtained information on exposures and reflux symptoms by telephone interviews conducted in 1998 to 2002 among women in the Swedish Twin Registry.
Use of oral contraceptives was also assessed in 1973 by questionnaires.
Both cross-sectional and prospective nested case-control designs were used, each with external control analysis.
The cross-sectional design was further submitted to monozygotic co-twin control analysis.
The researchers reported that the cross-sectional study design comprised 4,365 twins with reflux, and 17,321 without.
In ever users of estrogen hormone therpy, the risk of reflux symptoms was increased by 32%.
The team found this association remained in the nested case-control analyses and increased slightly with higher body mass index.
A similar pattern was observed for the use of progestin in the cross-sectional design, but no association remained in the nested case-control analysis.
The researchers noted that use of oral contraceptives was not associated with an increased risk of reflux symptoms.
The team found that the risk estimates remained virtually unchanged after adjustments for potential confounding factors, including genetic factors.
Dr Nordenstedt's team concluded, "This population-based twin study indicates that estrogen hormone therapy is an independent risk factor for reflux symptoms."
"The influence of progestin hormone therapy and oral contraceptives is less consistent."