A study of diet and breast cancer prevention in Canada: why healthy women participate in controlled trials

Influences on clinical trial participation: Enhancing recruitment through a gender lens - A scoping review

Background

Suboptimal clinical trial recruitment contributes to research waste. Evidence suggests there may be gender-based differences in willingness to participate in clinical research. Identifying gender-based differences impacting the willingness of trial participation may assist trial recruitment.

Objectives

To examine factors that influence the willingness of men and women to participate in clinical trials and to identify modifiable factors that may be targeted to optimise trial participation.

Material and methods

Electronic databases were searched with key words relating to 'gender', 'willingness to participate' and 'trial'. Included studies were English language and reported gender-based differences in willingness to participate in clinical trials, or factors that influence a single gender to participate in clinical trials. Studies were excluded if they described the demographic factors of trial participants or if the majority of participants were pregnant. Extracted data were coded, categorized, analysed thematically and interpreted using Arksey and O'Malley's framework.

Results

Sixty-three studies were included. Two main themes were identified: trial characteristics and participant characteristics. A number of gender-based differences moderating willingness to participate were observed although only one, 'concern for self' was found to influence actual trial participation rates between genders.

Conclusion

The relationship between factors influencing willingness to participate in clinical trials is complex. The influence of gender on willingness to participate, while important, may be moderated by other factors including socioeconomic status, ethnicity and health condition. Exploring factors that influence willingness to participate specific to a study cohort likely offers the most promise to optimise trial recruitment of that cohort.

Effects of total fat intake on body fatness in adults

BACKGROUND

The ideal proportion of energy from fat in our food and its relation to body weight is not clear. In order to prevent overweight and obesity in the general population, we need to understand the relationship between the proportion of energy from fat and resulting weight and body fatness in the general population.

OBJECTIVES

To assess the effects of proportion of energy intake from fat on measures of body fatness (including body weight, waist circumference, percentage body fat and body mass index) in people not aiming to lose weight, using all appropriate randomised controlled trials (RCTs) of at least six months duration.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Clinicaltrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) to October 2019. We did not limit the search by language.

SELECTION CRITERIA

Trials fulfilled the following criteria: 1) randomised intervention trial, 2) included adults aged at least 18 years, 3) randomised to a lower fat versus higher fat diet, without the intention to reduce weight in any participants, 4) not multifactorial and 5) assessed a measure of weight or body fatness after at least six months. We duplicated inclusion decisions and resolved disagreement by discussion or referral to a third party.

DATA COLLECTION AND ANALYSIS

We extracted data on the population, intervention, control and outcome measures in duplicate. We extracted measures of body fatness (body weight, BMI, percentage body fat and waist circumference) independently in duplicate at all available time points. We performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity, funnel plot analyses and GRADE assessment.

MAIN RESULTS

We included 37 RCTs (57,079 participants). There is consistent high-quality evidence from RCTs that reducing total fat intake results in small reductions in body fatness; this was seen in almost all included studies and was highly resistant to sensitivity analyses (GRADE high-consistency evidence, not downgraded). The effect of eating less fat (compared with higher fat intake) is a mean body weight reduction of 1.4 kg (95% confidence interval (CI) -1.7 to -1.1 kg, in 53,875 participants from 26 RCTs, I² = 75%). The heterogeneity was explained in subgrouping and meta-regression. These suggested that greater weight loss results from greater fat reductions in people with lower fat intake at baseline, and people with higher body mass index (BMI) at baseline. The size of the effect on weight does not alter over time and is mirrored by reductions in BMI (MD -0.5 kg/m², 95% CI -0.6 to -0.3, 46,539 participants in 14 trials, I² = 21%), waist circumference (MD -0.5 cm, 95% CI -0.7 to -0.2, 16,620 participants in 3 trials; I² = 21%), and percentage body fat (MD -0.3% body fat, 95% CI -0.6 to 0.00, P = 0.05, in 2350 participants in 2 trials; I² = 0%). There was no suggestion of harms associated with low fat diets that might mitigate any benefits on body fatness. The reduction in body weight was reflected in small reductions in LDL (-0.13 mmol/L, 95% CI -0.21 to -0.05), and total cholesterol (-0.23 mmol/L, 95% CI -0.32 to -0.14), with little or no effect on HDL cholesterol (-0.02 mmol/L, 95% CI -0.03 to 0.00), triglycerides (0.01 mmol/L, 95% CI -0.05 to 0.07), systolic (-0.75 mmHg, 95% CI -1.42 to -0.07) or diastolic blood pressure(-0.52 mmHg, 95% CI -0.95 to -0.09), all GRADE high-consistency evidence or quality of life (0.04, 95% CI 0.01 to 0.07, on a scale of 0 to 10, GRADE low-consistency evidence).

AUTHORS' CONCLUSIONS

Trials where participants were randomised to a lower fat intake versus a higher fat intake, but with no intention to reduce weight, showed a consistent, stable but small effect of low fat intake on body fatness: slightly lower weight, BMI, waist circumference and percentage body fat compared with higher fat arms. Greater fat reduction, lower baseline fat intake and higher baseline BMI were all associated with greater reductions in weight. There was no evidence of harm to serum lipids, blood pressure or quality of life, but rather of small benefits or no effect.

Effects of total fat intake on body weight

BACKGROUND

In order to prevent overweight and obesity in the general population we need to understand the relationship between the proportion of energy from fat and resulting weight and body fatness in the general population.

OBJECTIVES

To assess the effects of proportion of energy intake from fat on measures of weight and body fatness (including obesity, waist circumference and body mass index) in people not aiming to lose weight, using all appropriate randomised controlled trials (RCTs) and cohort studies in adults, children and young people

SEARCH METHODS

We searched CENTRAL to March 2014 and MEDLINE, EMBASE and CINAHL to November 2014. We did not limit the search by language. We also checked the references of relevant reviews.

SELECTION CRITERIA

Trials fulfilled the following criteria: 1) randomised intervention trial, 2) included children (aged ≥ 24 months), young people or adults, 3) randomised to a lower fat versus usual or moderate fat diet, without the intention to reduce weight in any participants, 4) not multifactorial and 5) assessed a measure of weight or body fatness after at least six months. We also included cohort studies in children, young people and adults that assessed the proportion of energy from fat at baseline and assessed the relationship with body weight or fatness after at least one year. We duplicated inclusion decisions and resolved disagreement by discussion or referral to a third party.

DATA COLLECTION AND ANALYSIS

We extracted data on the population, intervention, control and outcome measures in duplicate. We extracted measures of weight and body fatness independently in duplicate at all available time points. We performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity and funnel plot analyses.

MAIN RESULTS

We included 32 RCTs (approximately 54,000 participants) and 30 sets of analyses of 25 cohorts. There is consistent evidence from RCTs in adults of a small weight-reducing effect of eating a smaller proportion of energy from fat; this was seen in almost all included studies and was highly resistant to sensitivity analyses. The effect of eating less fat (compared with usual diet) is a mean weight reduction of 1.5 kg (95% confidence interval (CI) -2.0 to -1.1 kg), but greater weight loss results from greater fat reductions. The size of the effect on weight does not alter over time and is mirrored by reductions in body mass index (BMI) (-0.5 kg/m(2), 95% CI -0.7 to -0.3) and waist circumference (-0.3 cm, 95% CI -0.6 to -0.02). Included cohort studies in children and adults most often do not suggest any relationship between total fat intake and later measures of weight, body fatness or change in body fatness. However, there was a suggestion that lower fat intake was associated with smaller increases in weight in middle-aged but not elderly adults, and in change in BMI in the highest validity child cohort.

AUTHORS' CONCLUSIONS

Trials where participants were randomised to a lower fat intake versus usual or moderate fat intake, but with no intention to reduce weight, showed a consistent, stable but small effect of low fat intake on body fatness: slightly lower weight, BMI and waist circumference compared with controls. Greater fat reduction and lower baseline fat intake were both associated with greater reductions in weight. This effect of reducing total fat was not consistently reflected in cohort studies assessing the relationship between total fat intake and later measures of body fatness or change in body fatness in studies of children, young people or adults.

Prior fractures are common in patients with subsequent hip fractures

Treating osteoporosis in patients with prior fractures potentially results in a 50% reduction of risk of future fractures. We retrospectively reviewed 632 patients with incident hip fractures to evaluate (1) the prevalence of prior fractures in incident hip fractures, (2) whether prior fractures led to an increase in the treatment of osteoporosis, and (3) the cost utility of osteoporosis treatment after a prior fracture. The patients were treated at three hospitals from January 2000 to June 2001 and 514 (80%) were women. A minimal trauma fracture was defined as a fracture resulting from a fall while standing or walking or falling from a height less than 4 feet. Two hundred eighty-two patients (45%) with incident hip fractures described a prior minimal trauma fracture. Osteoporosis was diagnosed in 43 (13%) women and three (5%) men. In 107 cases (17%), the incident hip fracture was the second hip fracture. A prior minimal trauma fracture did not increase treatment for osteoporosis. Presuming a 50% reduction in fracture risk with medications, treating the 282 patients with prior minimal trauma fracture would have resulted in a savings of $3.5 million.

Retention in a Breast Cancer Risk Information Trial: Motivations of a Population-Based Sample of Women

A better understanding of factors influencing retention in breast cancer risk education and prevention programs can improve the design and effectiveness of such programs. Such information may also be useful to researchers seeking to maximize full retention in research trials involving low risk and low perceived benefit by the participants. These data are from a population-based study of 481 women from the Seattle, Washington, area, with diverse levels of breast cancer risk. This study sought to describe motivations for retention, to relate motivation variables to demographic characteristics, and to evaluate predictors of retention. Increasing age predicted study assessment completion, and both cancer worry and White ethnicity predicted intervention retention.

Dietary attitudes and changes as well as use of supplements and complementary therapies by Australian and Finnish women following the diagnosis of breast cancer

OBJECTIVE

This study investigated self-reported dietary attitudes and changes, and use of complementary approaches among breast cancer patients in relation to age, education and time since diagnosis.

DESIGN AND SETTING

Australian (ABC, N=215) and Finnish (FBC, N=139) breast cancer patients were surveyed at the university cancer centres with voluntary participation. Logistic regression models were used to adjust for differences in demographic patient characteristics between the groups. The influence of demographic variables was further studied separately or combined.

RESULTS

In all, 30% of FBC patients and 39% of ABC patients reported having changed their diet (P=0.033). Higher education, younger age and longer time from diagnosis were significantly associated with the probability of changes. The main changes reported included reduced consumption of animal fat, sugar and red meat, and increased consumption of fruits and vegetables. In all, 6% of ABC and 4% of FBC patients had stopped smoking and 24% of ABC and 27% of FBC patients reported to have increased their level of physical exercise. Choices were associated with age (P<0.007), length of the disease history (P <0.01) and level of education (P <0.002).

CONCLUSION

One-third of breast cancer patients surveyed reported to have changed their dietary habits. Both populations reported a need for dietary and lifestyle counselling. This need was experienced as poorly recognised by the physicians at present, and warrants future studies in dietary behaviour of breast cancer patients.

Barriers to participation in randomised controlled trials: a systematic review

METHOD

A systematic review of three bibliographic databases from 1986 to 1996 identified 78 papers reporting barriers to recruitment of clinicians and patients to randomised controlled trials.

RESULTS

Clinician barriers included: time constraints, lack of staff and training, worry about the impact on the doctor-patient relationship, concern for patients, loss of professional autonomy, difficulty with the consent procedure, lack of rewards and recognition, and an insufficiently interesting question. Patient barriers included: additional demands of the trial, patient preferences, worry caused by uncertainty, and concerns about information and consent.

CONCLUSIONS

To overcome barriers to clinician recruitment, the trial should address an important research question and the protocol and data collection should be as straightforward as possible. The demands on clinicians and patients should be kept to a minimum. Dedicated research staff may be required to support clinical staff and patients. The recruitment aspects of a randomised controlled trial should be carefully planned and piloted. Further work is needed to quantify the extent of problems associated with clinician and patient participation, and proper evaluation is required of strategies to overcome barriers.

The effect of physician recommendation on enrollment in the Breast Cancer Chemoprevention Trial

BACKGROUND

The purpose of this study was to evaluate the effect of physician recommendation on whether to enroll in a randomized controlled chemoprevention trial for breast cancer.

METHODS

We surveyed 360 women who were at increased risk for breast cancer regarding social and behavioral factors that could influence their decision to enroll or not to enroll in the Breast Cancer Prevention Trial (BCPT). Respondents completed a questionnaire following attendance at an informational session about the trial. The analysis was restricted to 175 women who discussed the possibility of their participation in the trial with their primary care physician (PCP) and who reported what their physician advised them to do regarding participation.

RESULTS

Logistic regression modeling showed that among women who discussed the trial with their physician, physician recommendation was the most important factor that influenced the respondent's decision to enroll in the BCPT. Women who reported that their physician advised them to enroll in the trial were 13 times more likely to participate than were women who reported that their physicians advised them not to participate.

CONCLUSIONS

The results of our study show that PCPs play an important role in influencing preventive health behavior, specifically, regarding enrollment in a randomized breast cancer chemoprevention trial. Efforts to increase recruitment to a trial should include enlisting the support of PCPs.

What attitudes and beliefs underlie patients' decisions about participating in chemotherapy trials?

The theory of reasoned action, which postulates that personal attitudes and external social influences predict intentions to undertake a behavior, was used as a conceptual framework for developing a questionnaire to elicit beliefs and attitudes associated with the decision to participate in a hypothetical cancer chemotherapy trial. After completing the questionnaire, two-thirds of the 150 respondents indicated they would enroll in such a trial if it were available. Considerable variation existed in both "universal" and "trial-specific" beliefs and attitudes underpinning their intentions. A substantial amount of the variance in "intention" to participate was explained by "attitude" alone (75%). Social influences, although statistically significant, made a mere 1% additional contribution. One interpretation is that subjective expected-utility theory, which essentially predicts beliefs or "attitude," is a better model. The authors conclude that both theories may be criticized regarding how well they capture the rationality and nuances of decision behavior.

Making sense of randomization; responses of parents of critically ill babies to random allocation of treatment in a clinical trial

Randomized controlled trials (RCTs) are widely accepted by the scientific community as the most rigorous way of evaluating interventions in health care. Although their central feature, random allocation of treatment, is generally seen as methodologically appropriate, its application has caused much debate amongst health professionals and ethicists. This paper describes the views of parents who consented that their critically ill newborn baby should be enrolled in a neonatal trial. In-depth interviews were used to determine their response to the trial and randomization. The nature of the trial was often poorly understood. The random basis of the allocation of treatment and the rationale behind this approach were also problematic issues. Some parents did not perceive a random element in the process at all. These findings advance understanding of the perceptions of trial participants and raise important issues for those concerned with RCTs. Greater understanding of participants' views provides the potential to improve the management of future trials and so the experience of those agreeing to take part.

Participants' perceptions of a phase I colon cancer chemoprevention trial

To assess participants' perceptions of a phase I colon cancer chemoprevention trial using a calcium intervention, questionnaires were mailed to trial participants at the conclusion of the study. Responses to questionnaire items reported here include (1) perceived benefits and barriers of participation, (2) interest in participating in future trials, (3) willingness to pay trial expenses out of pocket, and (4) posttrial continuation of the calcium regimen. The study found that the most highly rated trial benefit was the perception of potential colon cancer prevention; the trial barrier reported to be the most troublesome was inappropriate or mistaken billing for study visits. Three fourths of the subjects expressed an interest in future trials of the same duration. For trials of longer duration, this percentage decreased to 66%. Approximately half did not object to participation in future trials involving placebos, and just over one third indicated that they would either definitely (8%) or probably (27%) have joined the calcium trial even if they had to pay some study expenses out of pocket. Over 90% indicated they would continue taking the calcium pills if calcium is shown to be effective. The level of perceived benefits was positively associated with reported interest in participating in future trials of the same and longer durations, and the level of reported difficulty with trial pills and procedures was inversely related to interest in future placebo-controlled trials. The results of this study, in conjunction with results of prospective studies of trial participation, may be applied in future chemoprevention trials to facilitate recruitment, reduce attrition, and promote positive trial experiences for participants by emphasizing frequently reported benefits and minimizing frequently reported barriers.

The evolution of breast cancer mortality and morbidity in Spain (1977-1988)

A study of breast cancer mortality and cancer morbidity has been carried out in Spain recently for the period 1977-1988, covering the population of the 17 Autonomous Communities and 50 provinces of the country. Data was obtained from INE, Instituto Nacional de Estadística (National Institute of Statistics), with age standardization using the indirect method. The different Autonomous Communities and provinces were compared in order to establish possible significant differences. The crude mean mortality rate was 21 cases per 100,000 inhabitants/year; Las Palmas, Gerona, Barcelona, the Balearic Islands, Navarra and Zaragoza have the highest mortality rates, with a proportional increment of 54% in that period. The crude national mean morbidity rate for the considered period was 64.0 cases per 100,000 inhabitants, and the proportional increment 180%. According to provincial figures, Alava had the highest fitted mean morbidity rate, 135 cases per 100,000 inhabitants, whilst the highest fitted mean rate was Las Palmas (28 cases/100,000 inhabitants), and the highest proportional increment was the rate for the province of Huesca (169%). When using the ANOVA test on the mean rate of the period, for mortality as well as morbidity, we observed significant differences among provinces and among Autonomous Communities (p < or = 0.05).

Informed consent in clinical trials

A review is provided in this paper on the empirical literature on informed consent from 1979 to 1995 referring to information disclosure and trial participation in clinical trials. Articles being reviewed focus upon information disclosure, reactions to disclosure and recall, features of consent and perceptions of informed consent, both in hypothetical and in real life situations. It is concluded that further research is needed to study the process of informed consent in clinical trials, to obtain a better insight into the myth and reality of informed consent in daily practice. Future studies should come forward on the limitations of previous empirical research on informed consent. Additional research should focus on the perspectives of patients who accept or decline trial participation.

Factors related to enrollment in the breast cancer prevention trial at a comprehensive cancer center during the first year of recruitment

BACKGROUND

Using an a priori theoretic model of behavior change, factors predicting enrollment in a randomized chemoprevention trial during the first year of recruitment were assessed prospectively.

METHODS

Eligible participants were asked to complete a 90-item semistructured questionnaire after attendance at an informational meeting. Components of the Health Belief Model (including perceived susceptibility, perceived severity, perceived benefits and barriers, cues to action, and health motivation), health status, preventive health behaviors, and social influence were assessed in relation to enrollment.

RESULTS

Overall, 331 women attended one of the meetings, and 73% completed a questionnaire; 45% enrolled on the trial and 55% did not. In bivariate analyses, all but one of the perceived barriers were associated negatively with enrollment; however, items assessing perceived susceptibility, perceived severity, and perceived benefits were not. Nonparticipants also were more likely to be over 49 years of age, to be currently or to have been on estrogen replacement therapy, and to have had hot flashes. In logistic regression analysis, not being able to take estrogen replacement therapy was the strongest predictor of nonparticipation (odds ratio [OR], 12.13, 95% confidence interval [CI], 3.63, 40.60). Other factors associated with nonparticipation were concern about side effects of tamoxifen (OR, 5.06; CI, 2.37, 10.80); the possibility of getting a placebo (OR, 7.75; CI, 1.51, 39.67); the costs associated with the trial (OR, 3.21; CI, 1.12, 9.24); and absence of concern that significant others would be reassured if the respondent was taking tamoxifen (OR, 2.58; CI, 1.04, 6.41).

CONCLUSIONS

These findings support the view that recruitment efforts for chemoprevention trials should address barriers specific to their circumstances. In addition, increasing the support available from personal social networks may enhance recruitment to chemoprevention trials for breast cancer.