A total of 200 patients completed the questionnaires out of 235 patients that were invited to participate, representing an 85% response rate. The main reason given for refusal was lack of time. The mean ± standard deviation age of the participants was 58.3±12.8 years, and 45.9% (N = 90) were males. The most common cancer sites were breast (21.9%), colorectal (17.2%) and lung (10.4%). Almost one-half of the population (49.2%, N = 93) was born in Israel, defined themselves as being non-religious (62.3%, N = 124) and had some level of academic education (43.7%, N = 86). The questionnaire included the official Israeli government-issued statistic on average monthly income in New Israeli Shekels and 100 participants (50%) reported that their income level ranged from average to high. Most participants reported living with a partner (70.9%, N = 141, Table 1).
Nearly one-half of the surveyed population (47.7%, N = 92) agreed or very much agreed that they have a high level of understanding of how clinical trials work. The majority of them (63.8%, N = 120) would agree to participate in a clinical trial were they offered to, and 35.6% (N = 67) would decline.
Analysis of past experience in clinical trials
Forty-six (23.4%) of the respondents had participated in a clinical trial in the past. Most of them had an academic education compared with those who had no experience in clinical trials (67.4%, N = 31 vs. 36.9%, N = 55, respectively, p < 0.0001), the majority of them defined themselves as secular (non-religious Jews; 76.1%, N = 35 vs. 58.3% religious Jews, N = 88; p = 0.037) and were more likely to live alone rather than with a partner or caregiver (28.3%, N = 13 vs. 14.6%, N = 22, respectively, p = 0.046). As expected, patients with clinical trial experience were significantly more likely to define themselves as having a good understanding of how medical research works, compared to those without experience (84.4%, N = 38 vs. 36.5%, N = 54, p < 0.0001). They were also more inclined to participate in a future study, compared to those with no experience (73%, N = 33 vs. 44.9%, N = 66, p = 0.01). The participants’ demographic characteristics and analysis of their responses according to past experience in clinical trials are presented in Table 1.
Analysis according to level of knowledge
The vast majority of the participants (164 out of 200, 82%) did not meet the minimum knowledge level on the knowledge test, with similar proportions of high- vs. low-level knowledge among Israeli-born and non-Israeli-born respondents. There were notable differences between the high- and low-level knowledge groups. Those with high-level knowledge were more likely to have an academic education compared with those with low-level knowledge (66.7%, N =24 vs. 38.5%, N = 62, respectively, p = 0.003). The proportion of patients with a "much higher than average" level of income was higher for the high–level knowledge group (11.5%, N = 4 vs. 2.5%, N = 2, p = 0.039).
As expected, the high-level knowledge group contained a significantly larger proportion of patients with past experience in clinical trials compared with the low-level knowledge group (47.2%, N = 17 vs. 18%, N = 29, p < 0.0001). Also as expected, those with high-level knowledge were significantly more interested in participating in a future clinical trial than those with low-level knowledge (94.3%, N = 33 vs 57.5%, N = 88, p < 0.0001; Figure 1. Interestingly, patients with high-level knowledge who had no past experience in clinical research were more inclined to participate in a clinical trial compared to those with low-level knowledge (94.4%, N = 17 vs 50.8% N = 64, p < 0.0001) (Table 2).
The patients who would decline to participate in clinical trials were asked to rate the importance of selected parameters that would affect their decision. The difference between the 2 knowledge groups regarding the fear of receiving a placebo drug and not the experimental drug reached a level of near significance: most of those with high-level knowledge considered the argument as "not important" while most of those with low-level knowledge considered the argument as "important" (p = 0.055 Mann-Whitney U Test).
Major misconceptions and common knowledge
We analyzed our questions according to the rate of correct answers for each question. Questions that had 80% correct answers represented “common knowledge”, and questions that had a maximum of 40% correct answers represented the most frequent misconceptions. According to our questionnaire, common knowledge in the study’s population consisted of: 1. The aims of a clinical trial were to evaluate the safety and the efficacy of an experimental drug, and 2. A new drug must be studied in a preclinical setting prior to the administration to a human patient. Common misconceptions that were revealed from this analysis were: 1. Receiving a placebo precludes receiving the standard of care; 2. Signing an informed consent abolishes the possibility of a future refusal; 3. The choice of the experimental drug depends entirely upon the oncologist’s preferences; 4. The recruiting physician personally benefits from the patient’s enrollment into clinical trials.