Development and validation of the Cancer Knowledge Scale for the general population: An item response theory approach

OBJECTIVE

To develop and validate a new measure of cancer knowledge for members of the general population who have never been diagnosed with cancer.

METHODS

Initially, 20 items were generated to measure cancer knowledge. After expert refinement and cognitive interviews, 11 items remained and were completed by 1,076 adults with no history of cancer. Responses were assessed using an item response theory (IRT) approach and differential item functioning.

RESULTS

Items were analyzed using a two-parameter logistic IRT model. Two items with tetrachoric correlation coefficients>0.8 and one item with a discrimination parameter>2.0 were excluded. The final eight items demonstrated a good range of discrimination (1.13 to 1.86) and difficulty (-1.11 to 0.85). No meaningful differential item functioning by participant attributes was detected for these eight items.

CONCLUSION

The Cancer Knowledge Scale appears to be a reliable and valid measure for the general population.

PRACTICE IMPLICATIONS

The eight-item scale could be used to assess the effects of psychoeducational programs, including those on cancer knowledge, for members of the general population with no cancer history.

"Tell me what you suggest, and let's do that, doctor": Patient deliberation time during informal decision-making in clinical trials

Informed consent is an essential part of an ethical clinical trial; to this end, researchers have developed several interventions to promote participants’ full understanding of trials and thereby improve the consent process. However, few empirical studies have examined how patients make the decision of whether to give consent. The objective of this study, therefore, is to analyze patients’ decision-making process when participating in clinical trials. We conduct an internet survey (n = 2,045) and interview data analysis (n = 40) with patients and categorize respondents into three types of participants: active, passive, and non-participation. Our results show that patients often make informal and quick decisions before medical staff provide them with relevant information during the informed consent process. For example, 55.9% of patients received initial information on clinical trials from an online article or web advertising, and 54.5% consulted no one about whether to participate in the clinical trial before making a decision. Only 20.7% of respondents subjectively spent time making the decision whether to participate; 43.0% of patients who said that they “spent time” coming to a decision took four or more days to reach a decision, while 8.3% of people who “did not spend time” making a decision took this among of time. Based on these results, we were able to break patients’ decision-making process into four steps: first contact, informal decision making, relevant information, and formal decision making. Our results show that patients are most likely to make a decision based on the first information they receive on the clinical trial, whatever the source. To this end, having a list of questions for potential participants to ask researchers would be useful in helping better collecting information of clinical trials. In addition, research teams should give patients more than four days to decide between providing them with relevant information and obtaining written consent, even if the patient seems to make a quick decision.