Cardiotoxicity is a leading cause of mortality among breast cancer patients treated with chemotherapy. Therefore, an early risk assessment is vital for the clinical prevention and treatment of cardiotoxicity in breast cancer patients treated with chemotherapy, although a recognized tool is scant in our country.

To develop a cardiotoxic risk assessment scale for breast cancer patients undergoing chemotherapy and to test its reliability and validity.

Through reviewing relevant domestic and international literatures, a pool involving items to assess the risk of cardiotoxicity in breast cancer patients treated with chemotherapy was created. Semi-structured interviews with healthcare providers at Jiangsu Cancer Hospital from September to October 2022 were performed by purposive sampling, thus primarily forming a tool of items for the cardiotoxic risk assessment scale. In addition, breast cancer patients treated with chemotherapy in Jiangsu Cancer Hospital were randomly selected for a pre-survey and validation of the reliability and validity of the scale. Ranked by the score of the cardiotoxic risk assessment scale, the top 27% of participants were assigned into the high-score group, and the remaining were in the low-score group. Cronbach's α coefficient was used to evaluate the internal consistency of the scale. Validity of the scale was verified by measuring the item-level content validity index (I-CVI) and scale-level content validity index (S-CVI). Exploratory factor analysis was performed to assess the structural validity. Receiver operating characteristic (ROC) curves were plotted, and the area under tcurve (AUC) was calculated to determine the predictive validity.

Twenty healthcare providers were included in the semi-structured interviews. After two rounds of expert consultations, a 19-item cardiotoxic risk assessment scale in breast cancer patients treated with chemotherapy was developed. In this study, there were 79 patients in the low-score group and 83 in the high-score group. No significant differences in the history of smoking, endocrine treatment and immunotherapy were detected between the two groups (P>0.05). Correlation analysis showed that the history of smoking and immunotherapy was not significantly correlated with the total scores (P>0.05). Eventually, three items of smoking history, history of endocrine treatment and history of immunotherapy were removed, forming a 16-item scale. The Cronbach's α coefficient, test-retest reliability and inter-rater reliability were 0.739, 0.983 and 0.984, respectively. Content validity results showed that I-CVI ranged from 0.83 to 1.00, and S-CVI was 0.98. Predictive validity results showed the AUC of 0.887 (95%CI=0.827-0.947, P<0.001), with a cut-off value of 32.50 points, Youden's index of 0.649, specificity of 89.1%, and sensitivity of 75.9%. Exploratory factor analysis results showed a Kaiser-Meyer-Olkin (KMO) value of 0.700. Bartlett's sphericity test showed the χ² value of 1 037.898 (df=120, P<0.001). Five common factors were extracted, with a cumulative variance contribution rate of 61.991%. Risk stratification results indicated a low risk at 32-38 points, medium risk at 39-56 points, and high risk at 57 points and above.

The cardiotoxic risk assessment scale for breast cancer patients undergoing chemotherapy has good reliability and validity. It can better predict the high-risk population of cardiotoxicity and provide an effective assessment tool for clinicians and nurses to effectively identify the high-risk population of breast cancer patients undergoing chemotherapy.