[Development of a risk assessment scale and test of its validity and reliability for venous thromboembolism in adult burn patients].

ABSTRACT

Objective: To develop a venous thromboembolism (VTE) risk assessment scale for adult burn patients and to test its reliability and validity. Methods: The scale research method and multi-center cross-sectional survey method were used. Based on the results of literature analysis method and brain-storming method, the letter questionnaire for experts was formulated. Then 27 experts (9 doctors of burn department, 9 vascular surgeons, and 9 nurses) were performed with two rounds of correspondences by Delphi method, and the reliability of the experts was analyzed. The weight of each item was determined by optimal sequence diagram method and expert importance evaluation to form the VTE Risk Assessment Scale for Adult Burn Patients. A total of 223 adult burn inpatients, who were admitted to 5 tier Ⅲ grade A general hospitals including the Affiliated Hospital of Southwest Medical University, West China Hospital of Sichuan University, the Affiliated Hospital of North Sichuan Medical College, Nanchong Central Hospital, and the Second People's Hospital of Yibin City from October 1st 2019 to January 1st 2020, were selected as respondents by convenience sampling method. The first assessment was performed with the VTE Risk Assessment Scale for Adult Burn Patients within 24 hours of admission of patients, and real-time assessment was performed as the patients' condition and treatment changed. The highest value was taken as the result. Correlation coefficient method and critical ratio method were used for item analysis; Cronbach's α coefficient was used to test the internal consistency of scale; content validity index was used to analyze the content validity of the scale, and receiver's operating characteristic (ROC) curve was drawn to test the predictive validity of the scale. Data were statistically analyzed with chi-square test, Pearson correlation analysis, independent sample t test, and Z test. Results: As four questionnaires in the first round of correspondence were rejected as unqualified, and another 4 experts were selected for the 2 rounds of correspondence. Most of them were aged 41 to 50 years with postgraduate degrees, engaging in the current profession for 11 to 30 years, and all of them had professional titles of associate senior or above. The scale, constructed through literature analysis, group brainstorming, and two rounds of correspondence, includes 3 primary items and 50 secondary items. In the first round of correspondence, the recovery rate of valid questionnaires and the ratio with expert opinions were 85.2% (23/27) and 47.8% (11/23), respectively. In the second round of correspondence, the recovery rate of valid questionnaires and the ratio with expert opinions were 100% (27/27) and 11.1% (3/27), respectively. The average collective authority coefficients of experts were both 0.90 in the 2 rounds of correspondence. The mean values of importance assignment, full score rate, and selection rate above 4 were 4.21, 52.5%, and 77.2%, respectively, in the first round of correspondence, and 4.28, 45.2%, and 85.8%, respectively, in the second round of correspondence. The mean coefficients of variation and the mean value of Kendall's coefficient of harmony for each item were 0.21 and 0.30 in the first round of correspondence, respectively, and 0.16 and 0.36 in the second round of correspondence, respectively. In the first and second rounds of correspondence, the Kendall's coefficients of harmony of 3 primary items (age and underlying diseases, burn injury factors, and burn treatment factors) and total secondary items were statistically significant (with χ2 values of 121.46, 107.09, 116.00, 331.97, 169.97, 152.12, 141.54, and 471.70, P<0.01). The weights of primary items for age and underlying diseases, burn injury factors, and burn treatment factors were 0.04, 0.05, and 0.07, respectively. The weights of secondary items ranged from 0.71 to 0.99, with assigned values of 3 to 6. The total burn area of 223 patients ranged from 1% to 89% total body surface area, and the patients were aged from 19 to 96 years, with the risk assessment score from 0 to 98. Nine patients developed VTE, with a risk assessment score of 41 to 90. The scores of 37 items were significantly positively correlated with the total score of scale (with r values of 0.14 to 0.61, P<0.05 or P<0.01), and the items were retained. There were 36 secondary items with statistically significant differences between the patients in high-score group and low-score group (with Z values of -4.88 to -2.09, t values of -11.63 to -2.09, P<0.05 or P<0.01), and the items were retained. The total Cronbach's α coefficient of scale was 0.88. The total content validity index of scale was 0.95. The optimal threshold of the scale for the diagnosis of VTE was 40, at which the sensitivity was 88.9%, the specificity was 87.4%, the Youden index was 0.87, and the area under the ROC curve was 0.96 (with 95% confidence interval of 0.93 to 0.99, P<0.01). Conclusions: The age and underlying diseases, burn injury factors, and burn treatment factors are the risk factors for VTE in adult burn patients. The VTE risk assessment scale for adult burn patients developed based on these factors has good reliability and validity, and provide good reference value for clinical VTE risk assessment.