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Biomedical subjects

W Insull

Publications and source records attributed to W Insull.

At least 55 records · Page 3Linked to original sources
PubMed1990

Diet intervention methods to reduce fat intake: nutrient and food group composition of self-selected low-fat diets.

A multicentered pilot study was conducted to test an intervention protocol designed to reduce fat intake to 15% of energy intake. Eligible subjects were postmenopausal women with stage II breast cancer whose baseline fat intake was more than 30% of energy intake. The low-fat diet intervention protocol consisted of bi-weekly individual counseling sessions with emphasis on substitution of lower-fat foods for high-fat foods and maintenance of nutritional adequacy. Nutrient intakes were calculated from 4-day food records collected at baseline and after 3 months of diet intervention. Mean daily fat intake for the 17 patients on the low-fat diet dropped significantly from 38.4 +/- 4.3% of energy intake at baseline to 22.8 +/- 7.8% at 3 months (p less than .001). A 25% reduction in mean energy intake, from 1,840 +/- 419 kcal at baseline to 1,365 +/- 291 kcal at 3 months, was accompanied by significant increases in protein and carbohydrate as percent of energy intake. A mean weight loss of 2.8 kg and a 7.7% reduction in serum cholesterol were observed; both changes were significant at the p less than .01 level. Absolute intakes of zinc and magnesium were significantly reduced. However, mean intake on the low-fat diet for 14 vitamins and minerals, including zinc and magnesium, exceeded two-thirds of the 1989 Recommended Dietary Allowances (RDAs). When expressed as nutrient density (i.e., amount of nutrient per 1,000 kcal), increases were observed for all micronutrients. These results support the hypothesis that a nutritionally adequate low-fat diet can be successfully implemented in a highly motivated, free-living population.

Aged↗
PubMed1990

Results of a randomized feasibility study of a low-fat diet.

A 2-year randomized clinical trial was conducted to test whether free-living women aged 45 to 69 years can reduce the fat content of their diet from the typical US level of approximately 39% to 20% of energy from fat, using readily available foods, when given nutritional and behavioral counseling and social support. Three clinical units randomized 303 selected volunteers into intervention (low-fat eating plan) or control (customary diet) groups. The two groups were comparable at baseline. The intervention group received nutrition instruction and behavioral counseling largely in permanent groups of 12 to 15 participants meeting weekly, then biweekly, and finally monthly. At 6 months, they had substantially reduced the mean proportion of total energy from fat from 39.1% to 20.9%, compared with the control group's nonsignificant reduction from 39.0% to 38.1%. At 12 and 24 months, they sustained the reduction of energy from fat. Weight loss and plasma cholesterol level changes in the intervention group supported the self-recorded dietary intake changes. Attendance at intervention sessions averaged 75% during the first 6 months and, subsequently, 60% to 70%. Four-day food records for the randomized women were obtained at 6 and 12 months from approximately 95% and at 24 months from 87%. A clinical trial of a low-fat diet is feasible in women.

Aged↗
PubMed1989

Unpublished Data Summaries and the design and conduct of clinical trials. The Nutrition Adjuvant Study experience and commentary.

A trend in cancer clinical investigation has been the application of new analytic techniques and reporting forums to summarize developing trial results. Examples include: Consensus Conferences, Meta-Analyses, and most recently (in the breast cancer area), the "Clinical Alert." These Unpublished Data Summaries have been widely disseminated in lay and scientific communities and have frequently engendered debate conducted in the absence of primary information. We now report the impact of this process on a national, cooperative group effort (the Nutrition Adjuvant Study [NAS] ) designed to test a novel hypothesis involving dietary fat reduction as potential adjuvant breast cancer treatment. It is clear that these Unpublished Data Summaries in the breast cancer area directly resulted in changes in the NAS protocol design and may have influenced patient accrual. The challenge for clinical investigators and governmental agencies is to integrate the positive aspects of the new information forums with those of traditional "peer-review" publication into a system where the conduct of clinical investigation in a timely manner can be facilitated.

Breast Neoplasms↗
PubMed1989

Fenofibrate for the treatment of type IV and V hyperlipoproteinemias: a double-blind, placebo-controlled multicenter US study.

The results of a randomized, double-blind, placebo-controlled multicenter trial of fenofibrate in the treatment of type IV/V hyperlipoproteinemia are reported. Ten study centers in the United States recruited 147 adults with a history of type IV or V hyperlipoproteinemia. After a six- to 12-week dietary stabilization period and a four-week placebo period, patients whose 12-hour fasting total plasma triglyceride levels ranged from 350 to 1,500 mg/dl were continued in the study; 55 patients with levels of 350 to 499 mg/dl were placed in group A and 92 with levels of 500 to 1,500 mg/dl in group B. Patients in each group were randomly assigned to receive 100 mg of fenofibrate or placebo three times daily for eight weeks. In both groups A and B fenofibrate-treated patients showed statistically significant reductions in levels of total cholesterol, very-low-density lipoprotein cholesterol, total triglycerides, and very-low-density lipoprotein triglycerides, and significant increases in high-density lipoprotein cholesterol; patients in group B also showed a significant increase in low-density lipoprotein cholesterol levels. Sixteen of the 75 fenofibrate-treated patients and 11 of the 72 placebo patients reported adverse events that were potentially drug related; most of these were gastrointestinal and a few reported musculoskeletal and skin reactions. It is concluded that fenofibrate is an effective and safe agent in the treatment of type IV/V hyperlipoproteinemia.

Adolescent↗
PubMed1988

Statistical design of the Women's Health Trial.

The National Cancer Institute has initiated a randomized trial to determine whether a low fat diet can reduce the incidence of breast cancer among women at increased risk for this disease. A feasibility trial involving 303 women has been conducted to examine recruitment strategies, study short-term compliance and, more generally, develop and refine trial procedures. The feasibility trial group also developed a detailed full-scale trial design plan, and randomization of participants to such a trial is currently underway. The purpose of this report is to describe the major design features of this Women's Health Trial, with particular emphasis on the statistical aspects of the design. The trial is planned to last 10 years and to include 32,000 participants. Of these 32,000 women, 12,800 will be assigned to a low fat diet intervention, and the other 19,200 will constitute a control group. The sample size of 32,000 arises from a range of estimates and assumptions pertaining to (a) the incidence of breast cancer at enrollment corresponding to selected eligibility criteria, (b) the relative risk of breast cancer as a function of a woman's history of dietary fat intake, (c) compliance assumptions in terms of average percent fat in the intervention and control groups as a function of time from randomization, and (d) rates of competing causes of death. These estimates and assumptions will be discussed, as will the robustness of the intended sample sizes to departures from such design assumptions.

Aged↗
PubMed1987

A breast cancer Nutrition Adjuvant Study (NAS): protocol design and initial patient adherence.

To evaluate the feasibility of using a reduction in dietary fat intake as a component of treatment regimens for patients with resected breast cancer, a multi-disciplinary cooperative group protocol was developed. Females 50 to 75 years of age with stage II breast cancer who completed primary local therapy were eligible for randomization to a Control Dietary Group in which dietary fat intake was to remain unchanged from baseline level (at approximately 38% of calories derived from fat) and an Intensive Intervention Dietary Group designed to reduce dietary fat intake. Both Dietary Groups were given tamoxifen 20 mg/day. To facilitate early experience with dietary regimen delivery, patients entered during an initial pilot phase could receive any chemotherapy and/or hormonal treatment. A prerandomization nutrition 'run-in' of clinically eligible patients assessed adherence to nutrition data collection procedures and screened patients for nutrition eligibility criteria. Of 59 patients beginning 'run-in', 49 were randomized and, at present, 32 have completed at least three months follow-up. The change in dietary fat intake (as assessed by Four Day Food Records) seen in both arms is outlined below. Formula see table. The 56% reduction in total daily fat gram intake achieved in the Intensive Intervention Dietary Group suggests that protocols designed to reduce dietary fat intake in an adjuvant treatment setting can be developed and implemented using a multi-institutional, cooperative group approach.

Adult↗
PubMed1986

Successful program for recovery of dropouts to a clinical trial.

This is a report of a successful program to return dropout participants to active participation at a single clinic of a multicenter long-term clinical trial, the Coronary Primary Prevention Trial of the Lipid Research Clinics Program. The specific objectives were to re-engage dropouts into active participation and to have them resume study medication. Thirty-six men had been absent from the Baylor-Methodist Clinic for 10 months to over four years. The program focused on resolving the presenting problems: psychosocial, somatic, and drug adherence. It was based on six general principles with corresponding goals and employed 13 activities and procedures in a specific operational sequence for reinstitution of the Coronary Primary Prevention Trial protocol. Counseling techniques were used to improve protocol adherence. The recovery program was monitored bi-weekly by computer. The dropout group did not appear to exhibit any biases and approximated the remainder of the Baylor-Methodist cohort demographically. At six months into the recovery program, 90 percent of the dropouts had been recovered. Seventy percent of the recovered participants re-established medication-taking behavior. The mean rate of adherence to medication for all of the recovered group was 35 percent of the prescribed dose, 8 g per day. Review of the data for the cholesterol differential between the two treatment groups demonstrated a favorable effect of the reinstitution of the study medication. The program's methods are applicable to clinical practice.

Adult↗
PubMed1986

The association of dyslipoproteinemia with corneal arcus and xanthelasma. The Lipid Research Clinics Program Prevalence Study.

The prevalence rates of xanthelasma and corneal arcus were computed for normolipidemic and dyslipoproteinemic participants in the Lipid Research Clinics population surveys. The prevalence of both xanthelasma and corneal arcus increased with age, was highest in persons with type II phenotype, and usually low in those with type IV phenotype. The relative effects of age and use of gonadal hormones were different in the two lesions. Both xanthelasma and corneal arcus were associated with increased levels of plasma cholesterol and low-density lipoprotein cholesterol (LDL-C), especially in young males. In general, persons with either lesion had increased odds of having type IIa dyslipoproteinemia but decreased odds of having type IV. Xanthelasma and corneal arcus were highly associated with each other, especially in young people. There was no consistent univariate association of xanthelasma and corneal arcus with smoking, alcohol consumption, blood pressure, obesity, sedentary lifestyle, family history of ischemic heart disease, or glucose and uric acid plasma concentrations. Adjusted odds ratios for ischemic heart disease in participants with xanthelasma and corneal arcus were generally increased, except in older female nonusers of gonadal hormones, in whom they were significantly decreased. Neither xanthelasma nor corneal arcus showed a consistent association with manifestations of peripheral arterial disease. Thus the clinical findings of xanthelasma or corneal arcus, especially in young people, seem to identify persons with plasma lipoprotein abnormalities.

Adult↗
PubMed1985

Management of adherence to prescribed medication.

Nonadherence is a major problem for long-term use of drugs affecting lipid metabolism. Effective programs for comprehensive management of adherence are available. Their administration and operation can be readily integrated within the usual operations of both large and small clinical trials. The programs are subject to quality control and, hence, can be administered effectively. The cost of a comprehensive adherence program is approximately 10% of the conventional cost of clinical trials, varies according to the nature and number of adherence tests, and is probably totally recovered through resultant economies. All of the elements of the adherence program can be adapted to private practice. The relative risks of nonadherence to drugs affecting lipid metabolism are estimated from analyses of four regimen characteristics.

Clinical Trials as Topic↗
PubMed1985

Examination of medical professions for counseling on medication adherence.

The abilities of 68 professional staff members (physicians, physician assistants, dietitians, nurses, and counselors) from 12 clinics of the Coronary Primary Prevention Trial of the Lipid Research Clinics Program in 28 specific skills fundamental to interviewing and counseling for medication adherence were examined. Each staff member was provided with confidential data regarding his or her abilities, and each clinic's trial director received the group data for his or her staff's possession and use of these skills. Analyses of trial-wide data showed substantial differences among clinics in possession and use of the skills, with overall greater strength in interviewing skills, as compared with assessment and counseling skills. No professional group consistently possessed most or fewest of these skills. It is suggested that trained non-physician personnel could be used to complement physician efforts to counsel patients for medication adherence.

Adult↗
PubMed1985

Plasma lipid and lipoprotein response of humans to beef fat, coconut oil and safflower oil.

This study's purpose was to evaluate the fasting human plasma lipid and lipoprotein responses to dietary beef fat (BF) by comparison with coconut oil (CO) and safflower oil (SO), fats customarily classified as saturated and polyunsaturated. Nineteen free-living normolipidemic men aged 25.6 +/- 3.5 yr consumed centrally-prepared lunches and dinners of common foods having 35% fat calories, 60% of which was the test fat. The test fats were isocalorically substituted, and each fed for five weeks in random sequences with intervening five weeks of habitual diets. Plasma total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) concentrations among individuals follows the same relative rank regardless of diet. Triglycerides (TG) concentrations among individuals also maintain their relative rank regardless of diet but in a different order from that of the cholesterols. Plasma TC, HDL-C, and LDL-C responses to BF were significantly lower and TG higher than to CO. As compared to SO, BF produced equivalent levels of TG, HDL-C, and LDL-C and marginally higher TC. Thus, the customary consideration of BF as "saturated" and grouping it with CO appears unwarranted.

Adult↗
PubMed1984

Statement of the problem and pharmacological and clinical requirements for the ideal marker.

Patients' nonadherence or low adherence to low adherence to prescribed medication regimes threatens the satisfactory conduct of controlled clinical trials for the efficacy of drug treatment. Suboptimal adherence is costly since an increased sample size must be used to achieve and maintain study power. Accurate measurements of patients' adherence to test medications are not generally available. Current, popular, indirect methods provide uncertain estimates of adherence. As a result, behavioral strategies for management of adherence during trials have been handicapped, and analyses of trial results utilizing adherence levels are poorly developed. These problems could be solved by the ingestion, concomitant with the test medication, of a metabolically and pharmacologically inert compound (adherence marker) whose measurement in body fluids or secretions would indicate the extent of ingestion of the prescribed dose of the test medication. An adherence marker with proven wide applicability has not yet been developed or identified. The detailed requirements for an adherence marker include that it be pharmacologically and chemically inert, nontoxic, unaffected by the physical and chemical properties of body tissues and fluids, not accumulated in the body, and undetectable by the patient. The pharmacodynamics and tissue distribution of the marker should be appropriate for the medication being evaluated. The interindividual and intraindividual variances of marker metabolism should be small enough to permit precise and accurate estimates of adherence. For each trial, the choice of using an adherence marker in lieu of direct analysis of the test medication must be evaluated considering the circumstances of the trial and the pharmacokinetics of the test medication.

Body Fluids↗
PubMed1984

The statistical analysis of adherence data obtained from markers.

Adherence markers provide new kinds of clinical trial data. Adherence data on individual participants obtained from markers can be used for designing the trial sample size and stratification, evaluating the adequacy of randomization, directing the management of adherence, and analyzing and interpreting the trial's final results. Examples of these are presented. Analyses of adherence data can employ conventional procedures. Box plot techniques are proposed for flagging extreme values of the distribution of adherence either at a single time point or in a time continuum. The effect of difference in distribution of the markers in two or more groups in a clinical trial is discussed. Survival analysis is illustrated as one technique in univariate and multivariate analysis of markers with covariate effects. Design considerations with markers in a clinical trial are discussed, with particular emphasis on some of the assumptions and biases that must be considered for the analysis.

Clinical Trials as Topic↗
PubMed1984

Clinical trials methods and the practice of medicine.

An important potential byproduct from clinical trials is validated clinical methods applicable to clinical practice. The potential for improved patient care is separate from the scientific and intellectual answers gained in such trials. The current mechanisms for the transfer of methodological information from clinical trials are inefficient and have identifiable barriers. Methods validated in clinical trials must be recognized and accentuated as a valuable resource. A central repository of clinical trials' methods and a retrieval system dedicated to this unique body of scientific literature is warranted. Reports of methodological advances from clinical trials should be published in the literature read by clinical practitioners. The effective transfer of methods information from clinical trials to the office of the clinical practitioner is possible but requires increased efforts on the part of clinical trials scientists.

Clinical Trials as Topic↗
PubMed1984

Coronary risk factors and exercise test performance in asymptomatic hypercholesterolemic men: application of proportional hazards analysis.

The association of established coronary risk factors with submaximal graded treadmill exercise test performance was examined in 6,850 asymptomatic, white 34--59-year-old hypercholesterolemic men screened between 1973 and 1976 at 12 North American Lipid Research Clinics for participation in their Coronary Primary Prevention Trial. The prevalence of ischemic electrocardiographic responses (greater than or equal to 1 mm S-T segment depression) was 8.6%. The Cox proportional hazards method was adapted so as to take into account the level of exercise at which ischemic responses occurred and to which subjects without ischemic responses were exposed. The results were compared with those obtained by standard logistic regression. In both models, age, blood pressure, plasma cholesterol, and (inversely) plasma high-density lipoprotein cholesterol and alcohol consumption were significant independent predictors of an ischemic response to exercise. Surprisingly, ischemic responses were less frequent in smokers than in nonsmokers. However, when the proportional hazards method was used, cigarette smoking was weakly but significantly (p less than 0.01) predictive of an ischemic response on the treadmill. Results from this model differed from those of the logistic model because the former takes into account the reduced exercise capacity of smokers, which renders them less likely to reach workloads sufficient to induce myocardial ischemia. The proportional hazards model similarly demonstrated a possible beneficial effect of habitual physical activity which was not apparent in the logistic model. Quetelet index and plasma triglyceride were only weakly associated with the probability of an ischemic response, and did not contribute significantly to either model.

Adult↗
PubMed1984

Intervention specialist: new role for dietitians' counseling skills.

Dietitians who want to expand their clinical responsibilities beyond dietary counseling should consider the role of the intervention specialist. The role is a logical expansion of the duties of the dietitian who is already serving as a health behavior counselor. The concept of dietitians' functioning as intervention specialists originated in clinical trials, when they served as adherence counselors. The intervention specialists in the clinical trials used the health behavior counseling process to help research participants adhere to the trials' protocols. This counseling process uses a systematic, problem-solving approach to assess, diagnose, intervene, and follow up on a targeted behavioral problem. Dietitians can prepare for the expanded counseling role of intervention specialist through interviewing and counseling skill assessment and further training. They must take an active role in defining how the services of an intervention specialist can be beneficial to physicians as well as to their patients. They should address the cost-effectiveness of behavior counseling in order to justify the increased initial costs. Dietitians will need to actively promote the role of intervention specialist in the medical community if they want this opportunity for increased professional responsibility.

Behavior Therapy↗