Background: This study reports the reliability and validity of a questionnaire designed to measure the time from detection of a breast cancer to arrival at a cancer hospital, as well as the factors that are associated with delay.
Methods: The proposed questionnaire measures dates for estimation of the patient, provider and total intervals from detection to treatment, as well as factors that could be related to delays: means of problem identification (self-discovery or screening), the patients' initial interpretations of symptoms, patients' perceptions of delay, reasons for delay in initial seeking of medical care, barriers perceived to have caused provider delay, prior utilisation of health services, use of alternative medicine, cancer-screening knowledge and practices, and aspects of the social network of support for medical attention. The questionnaire was assembled with consideration for previous research results from a review of the literature and qualitative interviews of patients with breast cancer symptoms. It was tested for face validity, content validity, reliability, internal consistency, convergent and divergent validity, sensitivity and specificity in a series of 4 tests with 602 patients.
Results: The instrument showed good face and content validity. It allowed discrimination of patients with different types and degrees of delay, had quite good reliability for the time intervals (with no significant mean differences between the two measurements), and fairly good internal consistency of the item dimensions (with Cronbach's alpha values for each dimension between 0.42 and 0.85). Finally, sensitivity and specificity were 74.68% and 48.81%, respectively.
Conclusions: To the best of our knowledge, this is the first published report of the development and validation of a questionnaire for estimation of breast cancer delay and its correlated factors. It is a valid, reliable and sensitive instrument.