·To develop a knowledge-attitude-practice questionnaire for mechanical prophylaxis of deep venous thrombosis for orthopedic nurses in China, and analyze its reliability and validity.

·On the basis of literature review, combined with the characteristics of orthopedic diseases and orthopedic nurses, a preliminary questionnaire for mechanical prophylaxis of deep venous thrombosis was prepared. In January 2020, two rounds of expert letter consultation were conducted to demonstrate and modify the items in the first draft and form the test version of the questionnaire for mechanical prophylaxis of deep vein thrombosis.In March 2020, tests were conducted among 620 orthopedic nurses from 36 medical units in 13 cities in Jiangsu Province. Item analysis was carried out with critical ratio method and homogeneity test. Reliability analysis was carried out from internal consistency reliability, split-half reliability and retest reliability. Validity was analyzed from content validity and structure validity.

·The first draft of the questionnaire contained 37 items; after the first round of expert consultation, 4 items were revised and 7 items were added; after the second round of expert consultation, a test version of the questionnaire containing 44 items was formed. A total of 620 questionnaires were distributed. The effective recovery rate of the questionnaire was 96.77%. The critical ratio method showed that the item decision values t, which reflected the t-test results of independent samples of high and low groups, ranged from 5.89 to 20.31, and the difference was statistically significant (all P<0.05). The homogeneity test showed that Pearson correlation coefficient r, which reflected the correlation between the score of each item and the total score of the scale, ranged from 0.49 to 0.79, and the difference was statistically significant (all P<0.05). Therefore, 44 items were retained after item analysis. The Cronbach's α coefficient reflecting the internal consistency of the total questionnaire was 0.893, the Spearman-Brown coefficient reflecting the half-fold reliability was 0.794, and the intraclass correlation coefficient reflecting the retest reliability was 0.909. The scale-level content validity index reflecting content validity was 0.926 and the item-level content validity index was 0.833?1. Kaiser-Meyer-Olkin measure of sampling adequacy and Bartlett's sphericity test chi-square value which reflected the structure validity were 0.883 and 12 560.176 (df=666, P<0.05) respectively. These values indicated that the questionnaire was suitable for exploratory factor analysis. In addition, 7 items were deleted according to the absolute value of factor load. Finally, 37 items remained. Seven common factors with eigenvalue greater than 1 were extracted. The 7 common factors were named the act of mechanical prophylaxis, risk perception of mechanical prophylaxis, indications of mechanical prophylaxis, contraindications of mechanical prophylaxis, conceptual cognition of mechanical prophylaxis, mechanical preventive response and health education cognition of mechanical prophylaxis, respectively. The cumulative variance contribution rate was 61.992%.

·The questionnaire in this study shows good reliability and validity. It can be used as an investigation tool to study the current attitude, knowledge and behavior of mechanical prophylaxis of orthopedic nurses.