Cardiovascular disease is the leading cause of death worldwide. By 2030, the estimated global cost of cardiovascular disease is expected to top $1 trillion and account for over 23.6 million deaths (Benjamin et al., 2017). Cardiovascular disease is the second leading cause of death in Japan and while the United States (U.S.) has seen a decline in the number of people with cardiovascular disease, Japan has seen an increased incidence especially in metropolitan men (Kitakaze, 2015). Symptom recognition in acute coronary syndrome (ACS) remains a global issue and some symptoms may not be recognized by patients. In a sample of European, Chinese, and South Asian patients, women were more likely to delay seeking treatment and patients of Chinese and South Asian descent were more likely to identify symptoms as non-urgent (King-Shier et al., 2015). Ethnic differences in symptoms were found in a diverse sample of patients from the U.S. with Caucasian patients reporting more atypical symptoms than Korean, Indian, and Chinese patients. While differences in presentation existed, the symptoms were not correlated with a final diagnosis of ACS so the predictive value of symptoms is unclear (Greenslade et al., 2012). There are ethnic differences in ACS symptom presentation (Greenslade et al., 2012; Kurich, Lasiuk, & Norris, 2017), but no studies published in English were identified that specifically examined the Japanese population.
While fatigue is a common symptom prior to and at the time of an ACS event in the U.S., little research has been conducted with a Japanese population. As the world becomes increasingly global, it is imperative that practitioners understand the potential ethnic variations in symptom expression. It is also important that researchers from around the globe work together to complete cross cultural comparative research to further expand the knowledge base. After a lack of research published in English specifically assessing symptoms in Japanese patients, a cardiovascular researcher from the U.S. sought out and developed a collaborative relationship with a colleague from Japan. The ensuing collaboration led to the formation of a research team, grant applications, and the pursuit of research endeavors in the U.S. and Japan.
The purpose of this study was to identify common symptoms of ACS and identify whether fatigue was a common symptom in a sample of patients from Japan. The institutional review board at each site reviewed and approved the research.
Methods:
Japanese patients (N = 48) were recruited during hospitalization for ACS from two university hospitals in Japan for this descriptive, cross sectional study. All patients completed the ACS Symptom Checklist (ACS symptoms), Fatigue Symptom Inventory (intensity of fatigue and interference from fatigue), Patient Health Questionnaire 9 (depressive symptoms), and Generalized Anxiety Disorder 7 (anxiety) during hospitalization for ACS. The ACS Symptom Checklist and Fatigue Symptom Inventory were translated into Japanese for this study. Each instrument was translated into Japanese, the translation was checked by a second individual, and then the tools were back translated into English by a separate individual to assure the translation was accurate. Data were collected from 2016-2017 by researchers in Japan.
Results:
The sample was primarily male (83%) and entirely of Japanese descent. The mean age was 64 years (SD 11.3 years). The most frequently reported symptom was palpitations (62.5%), followed by lightheaded (60%), arm pain (50%), shoulder pain (47.9%), and upper back pain (41.7%). The least reported symptom was shortness of breath (12.5%), followed by chest pressure (16.7%), chest pain (18.7%), indigestion (20.8%), and chest discomfort (22.9%). Unusual fatigue was reported by 27.1% of participants. In this sample, 54% of participants reported no depressive symptoms, 21% reported mild depressive symptoms, and 25% reported moderate or moderately severe depressive symptoms on the Patient Health Questionnaire 9 (PHQ9). On the Generalized Anxiety Disorder 7 (GAD7), only 12.5% of participants reported having anxiety.
Fatigue intensity and interference with activities of daily living were measured using the Fatigue Symptom Inventory (FSI). Seventy-nine percent of participants reported clinically meaningful fatigue as evidenced by an average fatigue intensity score ≥ 3. When asked to rate fatigue on the day they were least fatigued, the mean score was 2.55 ± 1.89, indicating that even on the day of least fatigue, the majority of participants experienced fatigue. On the day participants were most fatigued, a mean score of 5.63 ± 2.60 was reported and, on an average day, the mean was 4.40 ± 2.22 indicating clinically significant fatigue on the average day. The average FSI interference score was 3.60 ± 2.07 indicating that fatigue interfered with normal daily activities.
Conclusion:
While chest pain, discomfort, and pressure were reported by less than 23% of the sample, the same symptoms demonstrated the highest sensitivity for ACS diagnosis in a sample of adults in the U.S. (DeVon, Rosenfeld, Steffen, & Daya, 2014). While chest pain, discomfort, and pressure are predictive of ACS diagnosis, these symptoms are not as frequently experienced by the elderly or women in the U.S. (Rosenfeld et al., 2015). Consistently using typical symptoms to identify ACS patients may lead clinicians to misdiagnose or delay treatment in some patients who are more likely to report atypical symptoms.
Fatigue intensity reported by patients in Japan is similar to patients with stable coronary heart disease in the U.S., but interference with daily activities from fatigue was worse (Eckhardt, DeVon, Piano, Ryan, & Zerwic, 2014). Overall, participants in the current sample reported clinically significant fatigue. While only 27.1% of participants reported unusual fatigue as a symptom, nearly 80% reported clinically significant fatigue indicating that while fatigue was present, it was not consistently recognized as a symptom. Overall, participants in Japan did not report the same symptom profile as published data from the U.S.; however, clinically significant fatigue was experienced by the majority of Japanese participants similar to reports of fatigue in ACS patients in the U.S.
While identifying common symptoms is important, the researchers also learned a great deal about cross cultural collaborative research. Planning research that spans countries is challenging for a multitude of reasons. Researchers must work together to overcome obstacles like ineffective communication, misunderstandings, and differing institutional review board requirements. While leveraging technology is an important way to communicate and collaborate, nothing can replace the power of personal meetings. The ability to meet with collaborators, tour research facilities, and establish a relationship is extremely essential. Cross cultural collaborative research is not easy, but it is crucial in the global society. Lessons learned from this cross cultural collaboration include clarity in communication and development of ongoing relationships.