A total of 10,545 participants returned the GERD questionnaire (86% response rate). Among these, 2,497 (24%) reported GERD symptoms less than once a month, 1,302 (12%) once a month, 986 (9%) once a week, 1,027 (10%) several times a week, and 297 (3%) daily. Therefore, 2,310 (22%) women reported symptoms at least once a week (frequent GERD cases). There were 3,394 women who reported experiencing both heartburn and acid regurgitation (55% of those with symptoms). Although 4,330 (41%) women reported having no heartburn or acid regurgitation in the previous year, 414 of these asymptomatic women also reported taking medications often used for GERD symptoms, such as proton pump inhibitors. To avoid potential misclassification, these women were excluded from the analysis, leaving 3,916 women who were considered as non-cases.
Among those with GERD symptoms, the majority (3,419; 55%) described their symptoms as moderate in severity, while 2,396 (39%) described their symptoms as mild, 273 (4%) described their symptoms as severe, and 30 (0.5%) described their symptoms as very severe. Data about severity was missing for 97 (1.5%) women. Information about the year of onset of symptoms was available for only 45% of the cases. Among those who provided duration information, 1,180 (43%) had GERD symptoms for less than five years, 400 (14%) had symptoms for five to 9.99 years, and 1,185 (43%) had symptoms for 10 or more years.
Characteristics of participants with frequent GERD symptoms and those without symptoms are presented in . Women with frequent GERD were more likely to have a higher BMI; to have used hormone therapy, asthma or anti-hypertensive medications; to have greater daily caloric intakes; and to perform less physical activity. At the time of the survey, women with GERD were less likely to be active smokers, but more likely to be former smokers. Other dietary factors, including alcohol consumption, were similar between the two groups.
Characteristics of Participants With and Without Gastroesophageal Reflux Disease (GERD) Symptoms
A dose-dependent relationship was observed between increasing BMI and frequent reflux symptoms in both univariate and multivariate analyses (). This relationship continued across all categories of BMI including those <25 kg/m2. Women with a BMI of 22.5–24.9 were approximately 40% more likely to report frequent GERD symptoms than women with BMI 20–22.49, while overweight (BMI 25–30) and obese (BMI≥30) women were two to three times as likely to report frequent symptoms. Women in the lowest BMI category (<20) had less risk for frequent GERD symptoms than those with BMI 20–22.49 (multivariate OR 0.67; 95% CI 0.48–0.93).
Figure 1 GERD symptoms were defined as heartburn (“a burning pain or discomfort behind the breast bone in your chest”) and/or acid regurgitation (“a bitter or sour-tasting fluid coming into your throat or mouth”). Frequent GERD (more ...)
This same trend was observed among the entire population of women experiencing GERD symptoms at least once in the last year, among women reporting moderate to very severe symptoms several times a week or daily, those experiencing only heartburn or only acid regurgitation, and those experiencing nocturnal symptoms (all P for trend <0.001; data not shown). We found that, of the overall prevalence of frequent reflux symptoms among the entire cohort with BMI 20 or greater, 51% was accounted for by excessive body weight, defined as a BMI of 22.5 or higher. For women with a BMI of 22.5–24.9, 25% of their increased risk could be accounted for by their excess weight. For women with a BMI ≥25, 60% of their increased risk could be accounted for by their excess weight.
We also examined the influence of waist-to-hip ratio (W:H), assessed in 1986, as an alternative measure of adiposity. We observed a similar dose-response trend in risk of reflux symptoms (all P for trend <0.001; data not shown). For example, compared to those in the lowest W:H quintile, women in the highest quintile had a multivariate OR of 1.88 (95% CI 1.45–2.45) for reporting frequent GERD symptoms. When BMI and W:H were introduced simultaneously in our model, the contribution of W:H was blunted (OR for the highest quintile 1.34; 95% CI 1.02–1.76) while that for BMI did not change. In general, our findings from all analyses were similar between age-adjusted univariate and multivariate models, suggesting minimal confounding by the other covariates tested. Furthermore, our findings did not vary significantly when other dietary factors such as citrus, onions, tomatoes, total fat, fruits, and vegetables were included in our model (data not shown).
The relationship between BMI and GERD symptoms persisted when various degrees of severity of symptoms were evaluated (all P for trend <0.001; ). Compared to women with BMI 20–22.49, women with BMI 22.5–24.9 had a 36% to 50% increase in risk for experiencing mild and moderate symptoms. In contrast, the risk of severe or very severe symptoms was elevated only among overweight women (BMI ≥25), although smaller numbers of women reporting this degree of symptoms (n=256) may have prevented us from detecting an elevated risk among women with normal BMI. Women with BMI <20 appeared to have some protection against symptoms of all degrees of severity with multivariate OR’s ranging from 0.55 to 0.70 ().
Association Between BMI and Frequent Gastroesophageal Reflux Disease (GERD) Symptoms Symptoms
We found the same dose-response trends for symptoms across all categories of BMI regardless of symptom duration (data not shown). When we performed analyses using BMI from 1994 for those with less than five years of symptoms and BMI from 1984 for those with 10+ years of symptoms, we found a similar dose-response trend in risk of GERD symptoms. Compared to women with BMI 20.0–22.49, women with BMI <20 had a multivariate OR of 0.29 (95% CI 0.11–0.73) for reporting a recent onset (<5 years) of frequent GERD symptoms, while those with BMI 22.5–24.9 had a multivariate OR of 1.46 (95% CI 1.07–1.99) for reporting chronic (10+ years) frequent GERD symptoms.
To further assess the relationship between BMI and reflux we analyzed the effect of weight change on the risk of experiencing GERD symptoms. Among women who experienced a gain in weight over the previous 14 years, a dose-dependent increase in risk of symptoms was observed (). Those women with a rise in BMI of over 3.5 kg/m2 more than doubled their risk of having frequent GERD symptoms. However risks were significantly decreased among women who lost weight during the same time period, with a nearly 40% reduction in risk of frequent GERD symptoms among those with a decrease in BMI of more than 3.5 kg/m2 (O.R. 0.64; 95% CI 0.42–0.97 compared to women without a change in BMI). A similar trend was also observed when considering change in BMI over a longer duration, namely between participants’ reported weight at age 18 and 1998 and when the analysis was restricted to women whose BMI in 1984 was <25 (). The O.R. for frequent reflux in women whose BMI was <25 kg/m2 in 1984 but subsequently increased by >3.5 kg/m2 was 2.8 (1.63–4.82).
Association of Weight Change (Between 1984 and 1998) and Risk of Frequent Gastroesophageal Reflux Disease (GERD) Symptoms.