Gastroesophageal reflux disease and its related factors among women of reproductive age: Korea Nurses’ Health Study

Gastroesophageal reflux disease (GERD) occurs when the lower esophageal sphincter relaxes inappropriately, thereby permitting gastric acid to enter the distal esophagus. The most common symptoms associated with GERD are heartburn and acid regurgitation [1]. GERD is a chronic disease that tends to relapse and cause extra-esophageal complications, including aspiration pneumonia, reflux-induced asthma, reflux cough syndrome, and laryngitis [2]. GERD can also lead to esophageal complications such as erosive esophagitis, bleeding and peptic strictures, and chronic GERD increases the risk of Barrett’s esophagus, which can progress to esophageal cancer [2, 3]. Persistent GERD symptoms may also lead to sleep deprivation, lower quality of life, and decreased work productivity [4‐6]. In fact, more than 50% of GERD patients experience heartburn when awake [7], and nighttime reflux causes sleep disorders [4]. Therefore, it is important to diagnose and treat GERD before it progresses.

In South Korea, the prevalence of GERD was 7.1% in 2012 among adults aged 20–69 years [8]. Furthermore, the number of patients diagnosed with GERD increased, from 1.99 million in 2008 to 3.36 million in 2012 (an increase of about 69%). Over that same period, the total medical costs related to GERD increased by 50.2% [9]. Women are inordinately represented in this population: female patients with GERD account for as much as 60.3% of adult patients aged less than 65 years [10], and during pregnancy, GERD is reported by 40–85% of women [11]. Women also tend to have a higher frequency of GERD symptoms and lower quality of life when compared to male patients with GERD [1].

Besides sex, the known risk factors of GERD include age, medication use [12‐15], lack of physical exercise, increased psychological stress, low or high body mass index (BMI), unhealthy eating habits, increased alcohol consumption, and cigarette smoking [14, 15]. Furthermore, frequent night-shift workers were 1.38 times more likely to develop GERD [16].

Women constitute 97% of the nursing workforce in South Korea, of which the majority are of reproductive age (20–45 years) according to statistical data of license information system in 2016 [17]. Fixed-shift nurses are rare in Korea, with most nurses experiencing rotating shifts on a regular basis, including night shifts. Nurses on rotating shifts with frequent night duties tend to have poor sleep quality, which leads to a lack of physical activity, and higher BMI and poor eating habits [18]. Frequent night work can have a number of other adverse physical and mental health consequences for nurses [19], such as the high prevalence of binge eating found among Korean nurses [20]. Given their night-shift duties, and its association with other health problems, Korean nurses may have a higher risk of developing GERD. However, the prevalence of GERD, and the impact of rotating night-shifts, health behaviors in response to stressful work factors (e.g., irregular diet, smoking, alcohol intake, etc.), BMI, and depressive mood on GERD, have not been fully explored in previous studies.

In this study, the estimated prevalence of GERD diagnosed within 1 year prior to the survey among nurses aged 24–45 years was 5.7%. This is slightly higher than the reported rate of 4.8% among Korean women in 2007 [27], In the general Korean population aged 20–69 years, the prevalence of GERD was reported as 7.1% in 2012, although it did not differentiate rates by gender [8]. Our finding is also similar to the rate (5.2–8.5%) across East Asia in general over the past decade (2005–2015), as found in a systematic review [28].

The factors found to be independently associated with GERD were cigarette smoking history, being underweight or overweight, and having depression. Interestingly, for smoking history, we found a statistically significant association for former smoking, but no association for current smoking or never smoking. These results might be partly due to the small number of current smokers (1.4%) in our study sample. Several epidemiologic studies have similarly reported that cigarette smoking (i.e., at least one pack per day or habitual smoking) is a risk factor for GERD in East Asian populations [12‐15, 28]. Furthermore, this study found that former smokers (n = 40, 3.4%) had a significantly higher risk of GERD compared to those who never smoked (n = 1128, 95.2%). While former smoking in women should be an important consideration, future studies need to further explore the role of current smoking in GERD among reproductive women.

The results concerning alcohol drinking in our study conflict with those of previous studies. In our study, roughly half of respondents reported drinking less than once per month, and alcohol consumption was not associated with GERD prevalence. In contrast, previous studies identified that a drinking frequency of at least once a week within the past year was a risk factor for GERD [13, 14]. This should be clarified in further prospective studies.

Obesity has previously been found to be a strong risk factor for GERD [29]; however, limited evidence exists for Asian populations, possibly because of the relatively smaller variance in BMI among members of the Asian population compared to among Western populations. The distribution of BMI categories in our sample of Korean nurses was as follows: normal (61.7%), overweight (19.8%), and underweight (18.4%). We found that both underweight and overweight were associated with higher odds of GERD, with underweight having a more substantial influence than overweight. Previous studies also identified BMI as an important factor for GERD prevalence among Japanese participants. However, because these studies targeted both sexes, the differences in prevalence were not as high as those in our study, given that women have a lower BMI increase rate than men [30]. The prevalence of underweight was generally high in our sample, possibly because it included only female nurses, People may become underweight after developing GERD because it limits food consumption or cause loss of appetite. In contrast, the observed association with overweight might be due to weight gain: even moderate weight gain among persons of normal weight can cause or exacerbate reflux symptoms [31]. Unfortunately, the cross-sectional nature of our study prevents us from clarifying these potential causal associations.

We found that the odds of GERD increased with increasing levels of self-reported depression. Past studies have indicated that GERD causes depression [32] and that depression is associated with an increased risk of GERD [33]. One Chinese study found that patients with GERD often exhibit depression, and that those with severe depression tend to require intensive GERD treatment [34]. These findings are consistent with those of our study. Again, although our study could not infer a causal relationship because of its cross-sectional nature, our findings suggest a potential link between depression and GERD risk among Korean women.

As for study limitations, we failed to control for all relevant variables, such as the type and quantity of intake of food (e.g., coffee, instant foods), and did not have access to participants’ medical records. These failures are a result of the limitations of collecting data through national surveys. Also, a self-reported questionnaire was used to obtain disease diagnosis.

Based on these limitations, we recommend that the following be considered in future research:

Our investigation of factors associated with GERD prevalence among nurses of reproductive age revealed that a history of past smoking, being underweight and overweight, and depression status are risk factors for GERD. These findings highlight that, to lower GERD prevalence among women of reproductive age, it is necessary to develop measures to monitor former smokers, and to assist overweight and underweight women in achieving and maintaining a normal weight. Furthermore, the identified factors should be considered during the assessment of GERD symptoms.

The findings also have implications for maternal health. Around 5.7% of women of reproductive age reported being diagnosed with GERD in the past year, and their symptoms are likely to worsen during pregnancy. Accordingly, more comprehensive studies on the health of working young women and proactive management of GERD before pregnancy are needed. Accessible programs within the workplace that can aid weight management and alleviate depressive mood are needed, as are further prospective studies on not only nurses, but also a more diverse population of young working women.