Cardiovascular disease (CVD) presents a persistent and significant global health challenge, contributing to substantial morbidity, mortality, and imposing a considerable economic burden on healthcare systems worldwide [1, 2]. In China, the prevalence of CVD continues to surge, with an estimated 330 million current cases, solidifying its position as a primary cause of death in the nation [3, 4]. Effective management of CVD is crucial for improving patient outcomes and reducing the risk of recurrent events. A critical aspect of CVD management is the assessment of cardiopulmonary function and exercise capacity, which are closely related to factors such as treatment outcomes, quality of life, disease progression, and prognosis [5, 6, 7].

Cardiopulmonary exercise testing (CPET) serves as a valuable tool for the comprehensive evaluation of patients’ cardiopulmonary function and exercise capacity [8, 9]. However, its high cost and technical demands limit its applicability, particularly in primary medical institutions. As a result, the development of low-cost, accessible, and easy-to-operate methods for diagnosing and assessing CVD has become increasingly important. In CPET, a commonly used threshold for peak oxygen uptake (Peak VO${}_2$) to assess prognosis in patients with heart failure is 16 mL/kg/min [10, 11]. Patients with a Peak VO${}_2$ below this threshold are considered to have a worse prognosis.

The Duke Activity Status Index (DASI) questionnaire, originally developed in English, consists of 12 self-reported items and provides a practical and effective approach for estimating a patient’s functional capacity [12]. These items encompass various daily activities with differing physical exertion levels, including personal care, ambulation, household tasks, and recreational activities. Each item is assigned a specific point based on the energy expenditure required for the activity. Patients indicate whether they can perform each activity without difficulty (“Yes” or “No”), and the total DASI score is calculated by summing the points of all “Yes” items, ranging from 0 to 58.2. Higher score signify better functional capacity. DASI score have been found to correlate with quality of life in heart failure patients [13, 14] and to predict postoperative risk in patients undergoing inpatient noncardiac surgery [15, 16]. Moreover, the DASI questionnaire has demonstrated its prognostic value, as higher score have been associated with improved outcomes and reduced mortality rates in CVD patients [17, 18].

Although the questionnaire has been used in Chinese patient populations [19, 20, 21], its reliability and validity in this specific group have not been thoroughly investigated. Furthermore, in our previous study [20] involving Chinese patients with pulmonary hypertension, we discovered a weak correlation (r = 0.467) between the DASI score obtained from the original questionnaire and Peak VO${}_2$, a correlation that was even weaker compared to earlier foreign research findings [12, 22]. Notably, during the questionnaire completion process, patients expressed unfamiliarity with certain physical activities listed in the original DASI, such as baseball and bowling, which may contribute to the weak correlation. Moreover, studies examining the relationship between the DASI and Peak VO${}_2$ in Chinese populations are limited, with previous research utilizing estimated Peak VO${}_2$ from treadmill tests. Consequently, it is crucial to culturally adapt the DASI questionnaire to ensure its precision in assessing the exercise capacity of the Chinese population.

The primary objective of this investigation is to culturally adapt and validate the DASI questionnaire for Chinese CVD patients. This includes an exploration of the questionnaire’s reliability and validity. Additionally, we will explore whether the adapted questionnaire can effectively identify patients with a better or worse prognosis based on a Peak VO${}_2$ threshold of 16 mL/kg/min. We hypothesize that the culturally adapted DASI can reflect the participants’ exercise capacity more accurately, as represented by a stronger correlation between the DASI score and Peak VO${}_2$, and serve as a simple tool to identify CVD patients with better prognosis.

Our findings demonstrate that the culturally adapted DASI questionnaire possesses acceptable reliability, validity, and the ability to predict long-term prognosis in Chinese CVD patients. These results support that the culturally adapted DASI for the Chinese population can provide a reasonably accurate reflection of the exercise capacity of Chinese CVD patients, endorsing the use of DASI as a valuable assessment tool for this patient population.

The reliability of the culturally adapted Chinese version of the DASI questionnaire was found to be consistent with those reported in other populations [12, 37, 38], suggesting that the cultural adaptation process successfully maintained the questionnaire’s psychometric properties. Concerning construct validity, our exploratory factor analysis identified three factors that collectively accounted for more than half of the total variance, differing from the two factors typically found in most validation studies [14, 38]. These factors represent different dimensions of functional capacity, reflecting the original design intention of the DASI questionnaire. In our study, the factor loadings of item 9 showed a relatively equal contribution to both factor 2 (0.522) and factor 3 (0.534). This indicates that item 9 is incapable of distinguishing between various levels of metabolic cost in physical activities, a situation also noted in the Brazilian version of the DASI [38]. In that study, item 9 was assigned a value of 4 METs during development, but the analysis results showed its correlation with higher METs activities. This could stem from the notable prevalence of urban residents among our study participants. The gardening or farm work activities described in item 9 are activities that are not commonly practiced by urban residents in China. Nevertheless, we have chosen to retain this item due to China’s identity as an agrarian nation, where a substantial proportion of the population resides in rural areas.

In the present study, we observed a moderate positive correlation between DASI score and Peak VO${}_2$, consistent with previous studies [12, 38]. This correlation is stronger than the weak correlation (r = 0.467, p 0.001) we found in our previous study using the original DASI questionnaire [20]. Several key factors may contribute to this enhanced correlation. First, we culturally adapted the DASI questionnaire to better align with the physical activity habits of the Chinese population, making it easier for patients to understand and respond to DASI questions. Second, compared to our previous research, this study included an additional 18 patients. A larger sample size typically enhances the reliability of statistical analyses and facilitates the more accurate detection of correlations.

Notably, this study’s most prominent advantage is the utilization of CPET for assessing Peak VO${}_2$, which offers a more accurate and reliable evaluation of exercise capacity compared to other studies that rely solely on the six-minute walk test or estimating Peak VO${}_2$ [22, 37, 38, 39]. The observed positive correlation between DASI score and Peak VO${}_2$ supports the criterion validity of the culturally adapted DASI questionnaire and suggests its potential usefulness for healthcare professionals in assessing a patient’s cardiovascular health. To further investigate whether the DASI score could be used to evaluate pulmonary function during exercise, we analyzed the correlation between the DASI score and VE/VCO${}_2$ slope, an important indicator reflecting pulmonary gas exchange efficiency, disease severity and prognosis [40, 41]. However, the correlation in this study is somewhat weak, suggesting that the DASI score may not be a comprehensive index for evaluating cardiorespiratory function.

When categorizing patients into groups with better or worse long-term prognosis based on the Peak VO${}_2$ $>$16 mL/kg/min criterion, our study evaluated the discriminative ability of the DASI in differentiating between these two groups. The findings indicated that the DASI had an ‘acceptable’ discriminative ability for identifying CVD patients with a better long-term prognosis, consistent with results from other CVD studies. An optimal cut-off value of 36.85 was identified for a better long-term prognosis, demonstrating satisfactory sensitivity and specificity. Moreover, the difference of LVEF between groups further validates the clinical utility of the cut-off value, considering LVEF is a strong predictor of poor prognosis in patients with CVD [42, 43]. A study conducted by Mustafaoglu et al. [44] demonstrated that a DASI score exceeding 26 was associated with a better long-term prognosis in patients with pulmonary hypertension, exhibiting a sensitivity of 0.74 and a specificity of 0.88. Furthermore, in a study investigating the relationship between preoperative DASI score and postoperative prognosis [15], patients with DASI score lower than 34 were found to have an increased risk of postoperative complications, including mortality and myocardial injury. Although these studies demonstrated that lower DASI score are predictors of poor prognosis, the calculated cut-off values for the DASI differ substantially. Our study’s cut-off value of 36.85 is higher than the values obtained in the other two studies. The variation in cut-off values may be attributed to differences in the physical condition of the patient populations. In the study conducted by Mustafaoglu et al. [44], the mean distance traversed in the 6-minute walk test and the DASI score were 427.1 m and 27.9 respectively, suggesting a diminished exercise capacity in these patients relative to those in our study. In contrast, Wijeysundera et al.’s [15] research revealed that 57% of their participants had a subjective functional capacity assessment falling within the range of 4 to 10 metabolic equivalents, suggesting a moderate level of functional capacity. Their study also reported an average DASI score of 40.5, similar to the DASI score observed in our study’s population. Another factor influencing the variation is the specific criteria used for categorizing prognosis in these studies. It is plausible that the extent of functional impairment would differ across diseases, which could explain the varying cut-off values. The key takeaway, however, is that the DASI can provide a prognostic cut-off value for different diseases, highlighting its clinical utility.

It is important to acknowledge the inherent limitations of the DASI questionnaire, such as the reliance on patients’ self-reporting, which may introduce biases or inaccuracies in the assessment due to factors like memory lapses or social desirability. However, the results of the educational level (Table 1) in this study indicated that patients of varying educational backgrounds can effectively understand and complete the questionnaire, showcasing its suitability across education levels. Furthermore, it offers advantages such as ease of administration, low cost, minimal burden on patients, and a demonstrated correlation with exercise capacity. Therefore, the findings may hold implications for healthcare teams, particularly in primary healthcare settings within the context of China. The adapted DASI questionnaire, to be specific, could play a role in cardiac rehabilitation, assisting healthcare professionals in tailoring individualized exercise programs, monitoring patients’ progress, and evaluating the effectiveness of interventions to improve functional capacity and overall cardiovascular health.

This study has several limitations that warrant consideration. Firstly, the single-center design may limit the generalizability of our findings - conducting multicenter studies could provide more robust evidence. Secondly, as shown in the data scatter plot in Fig. 2, the DASI score is not a perfect measure of exercise capacity. Therefore, when a precise assessment of exercise capacity is necessary, DASI cannot replace exercise testing [12]. Thirdly, being a cross-sectional study, it does not assess the relationship between DASI score and clinical endpoints. Prospective cohort studies could help investigate this relationship. Fourthly, the participant selection may have introduced bias, as some patients were unable to complete the CPET or were excluded for other reasons, and future studies should consider refining screening criteria. Moreover, this study did not assess test-retest reliability or the sensitivity of DASI to functional capacity changes over time, which should be explored in future research.

This study validates the culturally adapted DASI questionnaire as a straightforward and efficient tool for reasonably evaluating exercise capacity in Chinese CVD patients. This adapted questionnaire demonstrated satisfactory reliability and validity in this patient group, as well as the ability to discern patients with a better long-term prognosis, thus assisting in the identification of high-risk CVD patients.

CVD, cardiovascular disease; CPET, cardiopulmonary exercise testing; Peak VO${}_2$, peak oxygen uptake; DASI, Duke Activity Status Index; BMI, body mass index; ECG, electrocardiogram; ROC, receiver operating characteristics; AUC, area under ROC curve; RER, respiratory exchange ratio; RPE, rating of perceived exertion; LVEF, left ventricular ejection fraction; METs , metablic equivalents.

The data presented in this study are available on request from the corresponding author.

YXL and HFZ designed the research study, wrote the manuscript, and designed the table and figure. HFZ analyzed the data. MFL, GLZ and TW collected data. MYX and JWD provided help with data collection. LG, HM and QSG revised the manuscript, and were involved in the acquisition, analysis, and interpretation of data for the work, and obtained final approval. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

Informed consent was obtained from all subjects involved in the study. The study was conducted in accordance with the Declaration of Helsinki, and approved by the ethical review committee of Guangdong Provincial People’s Hospital (KY2023-053-02).

We would like to thank all the participants in the study.

This research was supported by the grants from Start-up Funding of National Natural Science Foundation of China (No.8207050582, 8217142362) and High-level Hospital Construction Project of Guangdong Provincial People’s Hospital (DFJH201922).

The authors declare no conflict of interest.