A survey of knowledge of prevention of venous thromboembolism in patients undergoing major orthopedic surgery

Background: Patients undergoing major orthopedic surgery are at an extremely high risk of developing venous thromboembolism, which deserves adequate attention. However, few studies have focused on knowledge of prevention of venous thromboembolism. The study had three objectives: (1) to investigate knowledge of prevention of venous thromboembolism in patients undergoing major orthopedic surgery, (2) to analyze its influential factors, and (3) to provide evidence for interventions. Methods: The convenience sampling method was adopted to select 464 patients who underwent major orthopedic surgery in a third-level first-class hospital in Beijing. A self-designed questionnaire was administered to these patients to investigate their knowledge of prevention of venous thromboembolism. Results: Of the 464 respondents, 32.1% had good knowledge of prevention of venous thromboembolism, and 30.8% had poor knowledge of it. In total, 40.1% of the participants had a clear understanding of the risk factors for venous thromboembolism, and 31% had a poor understanding. The clinical manifestations of venous thromboembolism were well understood by 29.3% participants and poorly understood by 40.9% participants. In total, 13.8% participants had knowledge of preventive measures for venous thromboembolism, and 31.2% had poor knowledge of such preventive measures. Living condition, knowledge of venous thromboembolism before hospitalization, and receiving knowledge of prevention of venous thromboembolism during hospitalization were important factors affecting the knowledge of prevention of venous thromboembolism in patients undergoing major orthopedic surgery. Conclusions: The knowledge level of prevention of venous thromboembolism in patients undergoing major orthopedic surgery is poor, and medical personnel should pay full attention to this issue and disseminate knowledge of prevention of venous thromboembolism during hospitalization to improve patients’ knowledge of this condition.


Introduction
Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is the third leading cause of cardiovascular-associated deaths worldwide [1]. 3 According to Virchow's triad [2], the pathogenesis of VTE includes three main factors: hypercoagulability, reduced blood flow or stasis, and vessel damage due to injury or disease. Patients undergoing major orthopedic surgery (total hip arthroplasty-THA, total knee arthroplasty-TKA, hip fracture surgery-HFS) have all three risk factors and are at an extremely high risk of developing VTE [3][4][5][6]. VTE is an important complication of major orthopedic surgery; thus, this condition deserves adequate attention and standard preventive efforts.
Patients undergoing major orthopedic surgery should receive thromboprophylactic interventions, including health education, properly implemented basic prevention strategies, physical prevention strategies, and appropriate antithrombotic drugs. Many studies have focused on preventive measures for VTE [7][8][9][10]; however, few have focused on knowledge of prevention of VTE in patients undergoing major orthopedic surgery. In a previous qualitative study [11], the understanding of VTE prevention in patients undergoing major orthopedic surgery was shown to be poor. Subsequently, health education on VTE prevention was strengthened. However, there is still a lack of data clearly showing the knowledge levels of VTE prevention in patients undergoing major orthopedic surgery. To fill this research gap, the present study aimed to investigate knowledge of prevention of VTE in patients undergoing major orthopedic surgery, to analyze its influential factors and provide evidence for continuous quality improvement.

Design
A survey design was used in this study. It was conducted from December 2018 to October 2019. The study was approved by the institutional review board of the China-Japan Friendship Hospital (2019-107-K75) and adhered to the Helsinki Declaration.

Survey sample
Convenience sampling was adopted to select 464 patients who underwent major orthopedic surgery in a third-level first-class hospital in Beijing. Inclusion criteria were as follows: patients who (1) underwent major orthopedic surgery (THA, TKA, HFS), (2) were older than 18 years, and (3) provided written informed consent and voluntarily participated. Exclusion criteria were as follows: patients who 4 (1) underwent previous major orthopedic surgery, (2) had VTE previously, and (3) dropped out. Of these, 156 participants were included in a preliminary experiment to test the reliability of a questionnaire designed by experts from the China-Japan Friendship Hospital.

Survey questionnaire
The questionnaire was designed by experts from the China Pulmonary Embolism and Deep Vein Thrombosis Prevention Capacity Building Program office, and it had a high Cronbach's alpha coefficient (0.885). The questionnaire consisted of two parts and 42 items. The first part intended to collect demographic data (11 items), which included sex, age, highest level of education attained, marital status, living condition, payment of hospital expenses, experience in hospital, surgical experience, knowledge of VTE before hospitalization, having received knowledge of VTE prevention during hospitalization, and operation method. The second part intended to investigate knowledge of VTE prevention in patients undergoing major orthopedic surgery (31 items), which included risk factors for VTE (10 items), clinical manifestations of VTE (12 items), and preventive measures for VTE (9 items). The questionnaire did not ask for any personally identifying information. The second part of the questionnaire was a judgment question; a correct answer was awarded 1 point, and an incorrect one did not receive a point. The results were classified into three grades: good, qualified, and poor. A correct response rate of more than 80%, 60%-80%, and less than 60% was considered as good, qualified, and poor, respectively. Higher scores represented better knowledge.

Survey procedure
Before the formal investigation, two investigators attended a unified training program. After the training, the investigators handed out questionnaires on site and collected them once they had been completed. It took about 30 minutes to fill out the questionnaires anonymously. The data were recorded immediately on the day after the questionnaires were collected, and any questions expressed by the patients were clarified immediately. The survey period lasted for 11 months, and during this time, the 464 patients undergoing major orthopedic surgery responded to the survey.

Statistical analysis
All data analyses were performed using IBM SPSS Statistics for Windows version 25.0 (IBM Corp., 5 Armonk, NY, USA). Descriptive statistics were used to summarize the patients' demographic characteristics. Categorical data were reported as absolute numbers and proportions, and comparisons were made using Pearson's chi-squared test. A two-tailed p-value of < 0.05 was considered statistically significant.

Descriptive results
The demographic characteristics are shown in Table   The clinical manifestations of VTE were well understood by 29.3% participants and poorly understood by 40.9% participants. In total, 13.8% participants had knowledge of preventive measures for VTE, and 31.2% had poor knowledge of preventive measures.

Influence of patients' demographic characteristics on knowledge of VTE prevention
The influence of patients' demographic characteristics on knowledge of VTE prevention is shown in Table 2.

Poor knowledge of prevention of VTE in patients undergoing major orthopedic surgery
As Fig.1 shows, patients undergoing major orthopedic surgery had poor knowledge of VTE prevention.
The results are consistent with those of previous studies [12][13]. Other than poor knowledge of VTE preventive measures, the findings also indicated poor knowledge of the risk factors for VTE and its 6 clinical manifestations, and the percentage of participants with poor knowledge was greater than 30%; these findings are serious enough to warrant the attention of medical staff. In particular, among the 464 respondents, 40.9% had poor knowledge of clinical manifestations of VTE. These results might be related to the lack of such knowledge among medical staff [14]. Patients with major orthopedic surgery are at high risk of VTE, so health education on VTE prevention must be strengthened. There is a lot of room for improvement in clinical work for patients undergoing major orthopedic surgery. Table 2 indicates the association of participants' demographic characteristics with VTE prevention knowledge. The study showed that patients' living condition, knowledge of VTE before hospitalization, and receiving VTE prevention knowledge during hospitalization were important factors associated with the knowledge of VTE prevention in patients undergoing major orthopedic surgery. The findings suggest that it is necessary to popularize VTE-related knowledge outside the hospital setting, and patients should be provided with VTE-related knowledge during hospitalization. As things stand, this is clearly not enough. Ways of homogenizing the training program for patients undergoing major orthopedic to prevent VTE is the next avenue of investigation.

Conclusion
The study focused on investigating the knowledge of VTE prevention in patients undergoing major orthopedic surgery. Clearly, the situation is not encouraging. Medical personnel should pay full attention to this knowledge deficit and provide knowledge of VTE prevention during hospitalization.
Meanwhile, we suggest that it is necessary to popularize VTE-related knowledge outside the hospital setting.
Our study has some limitations worth noting. First, participants were purposively selected from patients undergoing major orthopedic surgery in the orthopedic department of a level III, first-class hospital. Due to the uneven distribution of medical resources, the overall situation of the knowledge of VTE prevention in patients undergoing major orthopedic surgery may be even less optimistic in China. Second, the sample size was not large enough, which may limit the generalizability of our 7 results. Considering these limitations and issues, we will explore the establishment of a homogeneous training path to improve knowledge of VTE prevention in patients undergoing major orthopedic surgery.   Figure 1 Participants' knowledge of VTE prevention (N=464)